A nutrition assessment is an in-depth evaluation of both objective and subjective data related to an individual's food and nutrient intake, lifestyle, and medical history.
Once the data on an individual is collected and organized, the practitioner can assess and evaluate the nutritional status of that person. The assessment leads to a plan of care, or intervention, designed to help the individual either maintain the assessed status or attain a healthier status.
Elements of the Assessment
The data for a nutritional assessment falls into four categories: anthropometric , biochemical , clinical, and dietary.
Anthropometrics are the objective measurements of body muscle and fat . They are used to compare individuals, to compare growth in the young, and to assess weight loss or gain in the mature individual. Weight and height are the most frequently used anthropometric measurements, and skinfold measurements of several areas of the body are also taken.
As early as 1836, tables had been developed to compare weight and height in order to provide a reference for an individual's health status. The Metropolitan Life Insurance Company revised height and weight tables in 1942, using data from policyholders, to relate weight to disease and mortality. There has been much discussion about the relevance (and appropriateness) of using the individuals who buy life insurance as a basis for "ideal" height and weight. There are also a number of problems with using a table to determine whether an individual is at the right weight—or even what the "ideal
|Height Feet–Inches||Small frame||Medium frame||Large frame|
|Height Feet–Inches||Small frame||Medium frame||Large frame|
weight" means. Tables should therefore be used only as a guide, and other measurements should be included in the data collection and evaluation.
In 1959, research indicated that the lowest mortality rates were associated with below-average weight, and the phrase "desirable weight" replaced "ideal weight" in the title of the height and weight table.
To further characterize an individual's height and weight, tables also include body-frame size, which can be estimated in many ways. An easy way is to wrap the thumb and forefinger of the nondominant hand around the wrist of the dominant hand. If the thumb and forefinger meet, the frame is medium; if the fingers do not meet, the frame is large; and if they overlap, the frame is small.
Determining frame size is an attempt at attributing weight to specific body compartments. Frame size identifies an individual relative to the bone size, but does not differentiate muscle mass from body fat. Because it is the muscle mass that is metabolically active and the body fat that is associated with disease states, Body Mass Index (BMI) is used to estimate the body-fat mass. BMI is derived from an equation using weight and height.
To estimate body fat, skinfold measurements can be made using skin-fold calipers. Most frequently, tricep and subscapular (shoulder blade) skin-folds are measured. Measurements can then be compared to reference data—and to previous measurements of the individual, if available. Accurate measuring takes practice, and comparison measurements are most reliable if done by the same technician each time.
To estimate desirable body weight for amputees, and for paraplegics and quadriplegics, equations have been developed from cadaver studies, estimating desirable body weight, as well as calorie and protein needs. Calorie needs are determined by the height, weight, and age of an individual, which determine an estimate of daily needs.
The Harris-Benedict equation is frequently used, but there are quicker methods to estimate needs using just height and weight. Opinions and methods vary on how to estimate calorie needs for the obese . As previously mentioned, body fat is less metabolically active and requires fewer calories for support than muscle mass. If an individual's current body weight is more than 125 percent of the desirable weight for the individual's height and age, then using body weight to estimate calories needs usually leads to an over-estimation of those needs.
Laboratory tests based on blood and urine can be important indicators of nutritional status, but they are influenced by nonnutritional factors as well. Lab results can be altered by medications, hydration status, and disease states or other metabolic processes, such as stress . As with the other areas of nutrition assessment, biochemical data need to be viewed as a part of the whole.
Clinical data provides information about the individual's medical history, including acute and chronic illness and diagnostic procedures, therapies, or treatments that may increase nutrient needs or induce malabsorption . Current medications need to be documented, and both prescription drugs and over-the-counter drugs, such as laxatives or analgesics, must be included in the analysis. Vitamins , minerals , and herbal preparations also need to be reviewed. Physical signs of malnutrition can be documented during the nutrition interview and are an important part of the assessment process.
There are many ways to document dietary intake. The accuracy of the data is frequently challenged, however, since both questioning and observing can impact the actual intake. During a nutrition interview the practitioner may ask what the individual ate during the previous twenty-four hours, beginning with the last item eaten prior to the interview. Practitioners can train individuals on completing a food diary, and they can request that the record be kept for either three days or one week. Documentation should include portion sizes and how the food was prepared. Brand names or the restaurant where the food was eaten can assist in assessing the details of the intake. Estimating portion sizes is difficult, and requesting that every food be measured or weighed is time-consuming and can be impractical. Food models and photographs of foods are therefore used to assist in recalling the portion size of the food. In a metabolic study, where accuracy in the quantity of what was eaten is imperative, the researcher may ask the individual to prepare double portions of everything that is eaten—one portion to be eaten, one portion to be saved (under refrigeration, if needed) so the researcher can weigh or measure the quantity and document the method of preparation.
Food frequency questionnaires are used to gather information on how often a specific food, or category of food is eaten. The Food Guide Pyramid suggests portion sizes and the number of servings from each food group to be consumed on a daily basis, and can also be used as a reference to evaluate dietary intake.
During the nutrition interview, data collection will include questions about the individual's lifestyle—including the number of meals eaten daily, where they are eaten, and who prepared the meals. Information about allergies , food intolerances, and food avoidances, as well as caffeine and alcohol use, should be collected. Exercise frequency and occupation help to identify the need for increased calories. Asking about the economics of the individual or family, and about the use and type of kitchen equipment, can assist in the development of a plan of care. Dental and oral health also impact the nutritional assessment, as well as information about gastrointestinal health, such as problems with constipation , gas or diarrhea, vomiting, or frequent heartburn.
After data are collected, the practitioner uses past experience as well as reference standards to assimilate the information into an assessment that provides an understanding of the individual's nutritional status. The practitioner uses the anthropometric data to assess ideal and desirable weight, as well as skinfold measurements to determine body fat. Height, weight, and age are plugged into the Harris-Benedict equation to determine calorie and protein needs. Using the clinical, biochemical, and dietary data, influences on the nutritional status can be determined. A nutritional intervention, which usually includes dietary guidance and exercise recommendations, is then formulated and discussed with the individual.
see also Adolescent Nutrition; Adult Nutrition; Anthropometric Measurements; Body Mass Index; Dietary Assessment; Eating Habits; Food Guide Pyramid; Nutrition; Nutrition Education; Obesity.
Carole S. Mackey
Christie, Catherine, and Mitchell, Susan, eds. (2000). Handbook of Medical Nutrition Therapy: The Florida Diet Manual. Lighthouse Point, FL: Florida Dietetic Association.
Grant, Anne, and DeHoog, Susan (1999). Nutrition Assessment and Support, 5th edition. Seattle, WA: Grant and DeHoog.
Williams, Sue Rodwell (1997). Nutrition and Diet Therapy, 8th edition. St. Louis, MO: Mosby.
Winkler, Marion Feitelson, and Lysen, Lucinda (1993). Suggested Guidelines for Nutrition and Metabolic Management of Adult Patients Receiving Nutrition Support. Chicago, IL: American Dietetic Association.
DIETARY ASSESSMENT. Dietary assessment is the process of evaluating what people eat by using one or several intake indicators. It is the best approach for identifying nutrients that are likely to either be under-or overconsumed by the individual or groups of interest. It also can be used to identify food patterns and preferences.
Dietary Status versus Nutritional Status
Dietary status is related to but not necessarily reflective of nutritional status. Nutritional status is a more comprehensive term, referring to health status as it is affected by nutrition. It is measured not only by assessing dietary status, but also by anthropometric, biochemical, and clinical measures. Because dietary methods are less invasive, somewhat easier to obtain than other physiological measures, and do not require medical training, they often are used initially for assessing nutritional inadequacy or excess. Physiological measurements are then used to confirm and corroborate dietary intake evaluation and to arrive at definitive assessments of nutritional status.
Tools and Standards for Assessment
To assess dietary intake, food composition tables for translating foods consumed into nutrients, and a reference against which dietary intakes may be compared, are needed. These tools have been updated and refined periodically and appropriate ways for applying them to assessment tasks are steadily clarified.
Overcoming Imperfections in Assessing Dietary Intake
All dietary assessment methods are imperfect, regardless of how well they are designed. Their major shortcomings and measures for dealing with the imperfections are described briefly below.
Capture Actual Intakes
The various methods for assessing dietary intake are summarized in Table 1 and elsewhere in detail (Dwyer, 1999). All assessment methods fail to capture actual energy intakes precisely and probably intakes of nutrients as well. Some of the errors are inevitable because human beings tend to misreport their food intakes, but the method used also influences assessment outcomes.
Dietary intake is sometimes assessed by an objective observer rather than by the eaters themselves. For example, the intake of a hospitalized patient often is assessed from measured differences of the food served to a patient less any unconsumed amounts. Such objective methods have the advantage of being less subject to reporting biases than those that rely solely on recall. However, more objective methods are time-consuming, costly, cannot usually be employed to assess typical intake, and fail to record all intake. Moreover, they may not reflect what people really eat, since people may eat differently when they know that they are being observed. For these reasons, most commonly used dietary assessment methods rely on eaters' self-reported intakes.
Most methods such as twenty-four-hour recalls, food records, and diaries underreport actual energy intake by at least 20 percent. Underreporting errors are even higher (30 percent or more) in certain groups, such as the obese, women, and the elderly. However, they also vary among individuals in ways that are not always easily identified by demographic or other distinguishing characteristics. The causes of underreporting include forgetting, unconscious alterations in recalling foods eaten (for example, when the individual knows that he or she is being watched), attempts to please the questioner, and occasionally lack of cooperation by the subject. Non-random biases are difficult to deal with statistically.
Intakes obtained using semiquantitative food frequency questionnaires have other shortcomings. This method presents the respondent with a food list. These prompts may decrease forgetting, but insertions and "false memories" of foods consumed or of the consumption of socially desirable foods may be reported rather than true intakes. Semiquantitative food frequency questionnaires are too imprecise to estimate individual intakes quantitatively. Nutrient intakes from semiquantitative food frequency questionnaires usually are overestimated. They usually are adjusted statistically to obtain more accurate estimates of usual intakes. Measures of usual energy intakes for accurate groups specified by sex and age obtained by other methods or from estimates of energy outputs are used to adjust them. They are often derived by "food frequency" approaches and may be accurate enough to provide reasonable group estimates, although such measures are not sufficiently accurate for individuals. Also, precise quantification of absolute amounts (as opposed to levels of intake ranked into quartiles or quintiles) is not possible. The biases involved in food frequency questionnaires are complex, and statistical methods for obtaining valid estimates of intakes are unavailable.
Understandably, retrospective methods that rely on memory are subject to "forgetting bias." Prospective methods, which rely on reporting food intake immediately or shortly after eating, are more subject to alterations in intake due to the individual's awareness that his or her intake is being recorded. The extent to which social desirability and reporting biases intrude in the various methods is unknown, but is probably considerable.
Not all of the problems associated with misreporting can be overcome by the method of choice, but some can be minimized by selecting the appropriate tool for the task at hand.
Obtain Representative Intakes
Dietary assessments must be done frequently and randomly to reflect usual intake faithfully. This is an important shortcoming because only usual intake is
|Dietary assessment methods|
|Method||Description, advantages, and limitations of method|
|Retrospective Methods 24-hour recall||Respondent recalls all foods and beverages consumed in a given 24-hour period and reports them to a trained interviewer, who probes to get additional details on portion sizes, frequency, and forgotten items. Positive aspects include low respondent burden, ease in administration, and minimization of biases associated with altering food intake because of knowledge that one is being observed. Negative aspects of the method include forgetting, deliberate misreporting, need for a trained observer to administer, need for several days of intakes to obtain estimate of usual diet, and costs associated with computerized analysis of records|
|Telephone recall||The respondent is contacted or instructed in advance and given instructions about estimating portion sizes and other details. Then the respondent is called by telephone and asked to report dietary intake over the past 24 hours. Probes and techniques are usually standardized to minimize reporting error. Positive aspects of the method include those listed above plus ability to obtain representative random days of intake, and decreased cost of administration. Negative aspects include inability to obtain interviews from those without telephones, and for those who find telephones difficult to use, and errors in reporting portion sizes.|
|Food frequency and semiquantitative food frequency questionnaire||Respondent chooses from a list of different foods or food groups usually eaten over the past month or year. The number and type of foods, and whether portion sizes are specified, varies from one questionnaire to another. Positive aspects of the method include ease of administration, low expense, less forgetting because of prompts furnished by food lists, somewhat more of an estimate of usual intake (perhaps equivalent to 2–3 days), and low costs of data analysis. Negative aspects of method include incomplete reporting of items not included in food lists, overreporting, incomplete or inaccurate response, inaccurate translation of food and food groups to nutrients, and imprecise estimates of nutrient intake|
|Dietary history||Respondent reports all foods and beverages consumed on a usual day to a trained interviewer. The interviewer then probes further on the frequency amount and portion size consumed. Diet diaries are sometimes used to assist respondents in recalling their intakes. Positive aspects of the method are that respondent burden is low and complete intakes are provided. Negatives include high cost, need for trained interviewers, and lack of standardization|
|Prospective Methods Weighed food record||After being instructed, respondent weighs all food and drink consumed on a small weighing scale and reports it on a record that is kept as close to the time of consumption as possible. If observers are available, they can carry out the weighing themselves. Positive aspects of the method are lack of forgetting bias, and ability to obtain random days of intake. Negatives include high respondent burden, refusal to record intakes, need for an expert observer to review and clarify intakes reported, tendency of respondents to alter food intake when they know they are under observation, and costs of data analysis.|
|Food diary||The respondent records all foods consumed in household measures, usually without measuring them, or only measuring foods that are particularly difficult to estimate. Positive aspects are same as food records but respondent burden is less. Negative aspects are that more errors in estimation of portion size may occur|
|Duplicate portion analysis||An observer takes duplicate portions of all foods consumed by the individual and weighs or measures them; in some cases, these may also be chemically analyzed. Positive aspects are similar to food records. Negative aspects are lack of respondent cooperation, need for trained observers, cost of food analysis, and inability to obtain estimate of usual intake.|
|Other: Direct observation by trained observers or by videotaping subjects||Observer records or watches food intake in a controlled or highly supervised environment in which it is possible to videotape or directly observe food intakes. Positive aspects of the methods are that they do not rely on respondent burden. Negative aspects are that the methods are usually too imprecise for obtaining valid estimates of individual intakes.|
correlated with nutritional status. A representative sample of randomly chosen days that includes both weekdays and weekends is best for obtaining accurate twenty-four-hour recalls or records. Semiquantitative or other food frequency questionnaires also may assist in providing information on usual food intake patterns.
Obtain Total Intakes
Many foods and beverages are fortified with nutrients, and a substantial proportion of the population takes nutrient supplements on a regular basis. For some individuals, these nutrient sources contribute a substantial amount of vitamins and minerals. Nutrient intakes from all sources, including foods and beverages, fortified foods, and nutrient supplements must be included in all dietary assessments. If only food sources are queried, this fact should be noted.
Use Complete Food Composition Tables
Once food intakes are obtained, these must be translated into nutrients using food, beverage, and supplement composition tables. Accurate nutrient intakes can be obtained if up-to-date and complete food composition tables are available; that is, the composition of fortified foods, nutrient supplements, and beverages must be included and tables must be complete for all nutrients and other bioactive substances of interest.
Estimated nutrient intakes must be compared with appropriate references; in the United States and Canada, these are the Dietary Reference Intakes, or DRIs. Their use in dietary assessments is the subject of a recent report (Dietary Reference Intakes, 2000).
Inadequacies, Excesses, and Imbalances May Coexist
In the past, dietary assessments focused on dietary inadequacies. Although these are still relevant, nutrient excesses and imbalances of nutrients also are of concern in most Western countries, and therefore also must be considered. Several of the DRIs are helpful in these respects. DRIs for macronutrients will be published in the near future.
Appropriate Interpretation of Assessment Results
The estimated average requirement, or EAR, is the nutrient intake estimated to meet the requirement of half the healthy individuals in a particular life stage or gender group. The recommended dietary allowance, or RDA, is the average daily dietary intake that suffices to meet the nutrient requirement of nearly all (97–98 percent) healthy individuals in a particular life stage and gender group. The adequate intake, or AI, is a recommended intake based on observed or experimentally determined approximations or estimates of nutrient intake by a group (or groups) of healthy people whose intakes are assumed to be adequate. The AI is used when an RDA cannot be determined. When the AI's are not based on mean intakes of healthy populations, these values are likely to be less accurate. The tolerable upper intake level (UL) is the highest usual daily nutrient intake likely to pose no risk of adverse health effects to almost all individuals in the general population. As intakes increase above the UL, the risks of adverse effects also increase. The assessment of dietary adequacy is imprecise. A specific individual's actual requirement for a specific nutrient generally is never known. Second, often the number of days that intakes are measured are likely to be insufficient to overcome errors in measuring intake and normal day-to-day variation. Although dietary data alone are not sufficient to assess nutritional status, intakes of individuals can be compared to certain of the DRIs. A usual intake based on a large number of days that is at or above the RDA or AI has a low probability of inadequacy. An intake above the UL places an individual at risk of adverse effects from excessive nutrient intakes. When observed intakes are habitually below the EAR, increased intakes usually are needed because the probability of adequacy is 50 percent or less. Habitual intakes between the EAR and the RDA also probably need to be improved because the probability of adequacy is less than 97 to 98 percent. Quantitative estimates of risk of inadequacy are more difficult to obtain. However, they can be calculated using methods described in a recent report (Dietary Reference Intakes, 2000).
The DRIs also are used to assess the dietary intake of groups. These assessments determine the percentage of individuals whose intakes are estimated to be inadequate. The EAR is used to estimate the prevalence of inadequate intakes within a group. A mean usual group intake at or above the AI implies a low prevalence of inadequate intakes. The UL is used to estimate the percentage of the population at risk of adverse effects from excessive intakes consumed on a chronic basis. Thus, the RDA is not used to assess nutrient intakes of groups.
Dietary assessment is a necessary component of nutritional status assessment of individuals, and also is useful for other purposes. It can be done using a variety of methods, each of which has advantages and limitations. However, regardless of which method is chosen, it is important that certain criteria be met. Intake from all sources (food, fortified food, beverages, and nutrient supplements) must be included. Sufficient numbers of days to represent usual intakes must be obtained. Complete food and supplement composition tables must be employed. Appropriate reference standards and statistical procedures for assessing intakes must be used. Dietary assessment methods work best in combination with other methods for the assessment of nutritional status.
See also Dietary Guidelines; Nutrition.
Dwyer, J. T. (1997). "Assessment of Dietary Intake." In Modern Nutrition in Health and Disease, edited by M. Shils, J. A. Olson, M. Shike and A. C. Ross, 8th ed., pp. 887–904. Baltimore: Williams and Wilkins, 1997.
Dwyer, J. T. "Dietary Assessment." In Modern Nutrition in Health and Disease, edited by M. Shils, J. A. Olson, M. Shike, and A. C. Ross, 9th ed., pp. 937–962. Baltimore: Williams and Wilkins, 1999.
Nusser, S., A. L. Carriquiry, K. W. Dodd, and W. A. Fuller. "A Semiparametric Transformation Approach to Estimating Usual Daily Intake Distributions." Journal of the American Statistical Association 91 (1996): 1440–1449.
Poehlman, E. T. "Energy Needs: Assessment and Requirements in Humans." In Modern Nutrition in Health and Disease, edited by M. Shils, J. A. Olson, M. Shike, and A. C. Ross, 9th ed., pp. 95–104. Philadelphia: Williams and Wilkins, 1999.
Subcommittee on Interpretation and Uses of Dietary Reference Intakes and Upper Reference Levels of Nuturients, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes: Applications in Dietary Assessment. Washington, D.C.: National Academy Press, 2000.
Nutritional assessment is a comprehensive evaluation done to define a person's nutrition status. Assessment includes gathering information from the person's medical history, dietary history, a physical examination, anthropometric measurements, and laboratory tests.
In recent decades, healthcare providers have placed increasing emphasis on the role that nutrition plays in a patient's overall health. They also have recognized the way in which various diseases and conditions affect a person's nutritional status.
Anorexia nervosa, disease, test procedures, surgeries, therapeutic regimens such as chemotherapy and radiation, and some medications can affect dietary intake. The natural aging process also can lead to increased nutritional problems among the elderly. As many as 65% of elderly patients are calorie-protein undernourished when admitted to a hospital or they develop nutritional deficits while in the hospital.
Older adults are at risk for poor nutrition for a number of reasons:
- normal aging changes in the senses of smell and taste
- the effects of chronic diseases on food intake or food utilization
- dental problems and ill-fitting dental appliances that result in difficulty chewing
- depression and other psychological changes
- confusion, memory loss, and dementia
- social isolation
- side effects from multiple medications
- restricted financial resources
- diminished function that subsequently limits their ability to shop or prepare meals
Nursing home patients and cancer patients are among the individuals who most often require ongoing nutritional counseling and intervention. Patients with life-ending illnesses receiving palliative care have special nutrition support needs as well. The nutrition care of these subgroups of patients should be based on careful nutrition assessment.
In addition to increasing the use of nutrition assessment in hospitals, nursing homes, and other facilities caring for patients who are aging or chronically ill, nutrition assessment may be used to help guide the treatment of patients with a number of manageable chronic diseases such as chronic obstructive pulmonary disease (COPD), congestive heart failure, coronary heart disease, diabetes mellitus, and hypertension. Nutrition assessment also plays a role in caring for infants, children, and people who have health or dietary conditions such as anorexia, diabetes, severe food allergies, and obesity.
The emphasis on nutritional assessment and screening has led to the development of new assessment tools, standards, and regulations. For example, the Centers for Medicare and Medicaid Services (CMS), the agency that oversees Medicare, requires long-term care facilities to "conduct initially and periodically a comprehensive, accurate, standardized, reproducible assessment of each resident's functional status." The facility also "must ensure that a resident maintains acceptable parameters of nutritional status, such as body weight and protein levels, unless the resident's clinical conditions demonstrate that this is not possible." The Joint Commission on Accreditation of Healthcare Organization (JCAHO) standards and various state regulations also may require regular assessment or monitoring of a patient's nutrition status.
Little agreement exists concerning the best nutrition assessment tools for patients in all subgroups and settings. Healthcare organizations are working on standards and protocols for nutrition assessment, but many of these are still in development. Some nutrition assessment tools are complicated and require careful cooperation of a team of healthcare professionals to complete an accurate patient evaluation.
Nutrition assessment of elderly patients is further complicated by the physiologic and metabolic changes associated with aging. Nutrition assessment involves a combination of examinations and patient history, and as such, no single laboratory test or finding should be used to indicate poor nutrition. Finally, some nutrition assessments rely on patient memory and self-assessment, which may be somewhat problematic if the patient has a condition such as dementia or if one is assessing a young child.
A further concern is that obese patients who are compromised nutritionally may have a severe nutritional deficiency that goes unnoticed if an assessment relies too heavily on markers that aim at the whole-body level, such as body mass index (BMI). This is one reason why registered dietitians emphasize a comprehensive approach to assessment.
There are varying levels of nutritional assessment. A complete nutritional assessment generally is reserved for seriously ill patients, those at high nutritional risk, or individuals with signs of malnutrition. Clinicians may also perform a dietary assessment, which is less involved than a nutritional assessment, but helps ensure adequate nutrition by providing guidance for improving diet.
The nutrition assessment is a complex procedure involving several steps, including obtaining a patient's medical, dietary, and social history, a physical examination, anthropometric measurements, laboratory tests, and evaluation of energy, protein, and fluid requirements.
This phase of the nutrition assessment is critical in determining a patient's status and needs. It helps bring to light potential medical or social causes of a patient's nutrition problems. For example, many patients take a variety of vitamins, minerals, non-prescription medications or complementary and alternative therapies without informing their physicians. These substances may not be included in the patient's medical record and only a careful interview with the patient, family members, or other caregiver will reveal this information. The interviewer should also determine the patient's past and current medical conditions, as well as the patient's family history.
Medical conditions that can affect nutrition, particularly among the elderly, include:
- Cancer. Patients of all ages can suffer from cancer anorexia or absence of appetite. Therapies used to treat cancer can cause nausea, diarrhea, and other side effects that affect nutrition, as can some cancers themselves. Cancer cachexia can cause specific nutrition difficulties.
- Chronic obstructive pulmonary disease. As with cancer, many patients with COPD suffer from depression, which may affect their eating habits and nutritional status. Patients may not be able to eat large meals. Some medications cause loss of appetite or nausea; others cause weight gain.
- Congestive heart failure. Patients may have unrecognized cardiac cachexia. Medications may lead to electrolyte imbalances, anorexia, and nausea. Many patients may not be physically active as a result of this disease.
- Coronary heart disease. Many patients with coronary heart disease have a dietary history of high cholesterol and/or high fat and calorie intake. They also may have type 2 diabetes or a pre-diabetic condition. These patients need help maintaining a healthy weight and diet as they are at risk for a number of complications, including nutritional side effects from medications such as nausea, elevated liver enzymes, and gastric distress.
- Dementia. Nearly 50% of all people age 85 and older have Alzh eimer's disease or dementia. They may have difficulty preparing food and remembering what they have eaten. Nutritional problems may also be caused by nausea and diarrhea from commonly prescribed medications. Patients with advanced disease need assistance with food choices and daily feeding.
- Diabetes mellitus. About 16 million Americans have type 2 diabetes. Changes in diet are a major part of their treatment. Improper management of this disease can lead to severe complications.
- Hypertension. Nearly one in four Americans has hypertension. Those who use diuretics may see negative nutritional effects secondary to a depletion of sodium, calcium, magnesium, and/or potassium. Maintaining optimal weight and regulating intake of these substances is critical to controlling hypertension.
Many other conditions and diseases can affect a person's nutritional status, particularly when he or she is at high risk of for malnutrition. In an acute care setting, chronic pain or recent trauma from surgery or injury can lead to rapid weight loss or malnutrition. A patient may have an esophageal or gastric obstruction that impairs food transit, or have a history of chronic alcoholism, severe depression, acquired immunodeficiency syndrome (AIDS ), or chronic renal disease. In some cases, a combination of factors lead to the nutritional problems.
The patient history also should include a dietary and social history. The clinician will need to assess the person's recent diet. Depression can exist in conjunction with most of the conditions and diseases listed above. Depression and the medications prescribed to treat it can affect a person's appetite. If an elderly patient lives alone and has physical or transportation limitations, this may affect his or her ability to shop for and prepare food. Some patients may have involuntary diet restrictions due to poverty, abuse, or caregiver ignorance.
The examination consists of measuring the patient's unclothed weight, and if possible, comparing it to previous measurements to determine weight gain or loss. Weight and height measurement can be used to calculated body mass index. Tables are available that can help provide quick assessment of height and weight to rapidly assign BMI.
During a physical examination, the clinician may look for signs of malnutrition such as dull, brittle hair, brittle nails, and scaling skin. These may be the result of specific nutritional deficiencies.
These measurements may not be reliable over time, but can be helpful when used in initial assessment of the patient's nutritional status. Skinfold measurements provide an approximate measure of subcutaneous fat stores. Skinfold measurements are obtained using special calipers and a tape measure and are usually are taken from the triceps area. Measuring arm and arm muscle circumference can provide data about muscle mass and subcutaneous fat. Waist-to-hip ratios may also be used to evaluate abdominal fat.
The nutritional assessment involves use of specific laboratory tests. The most widely used of these is the measurement of serum albumin. Albumin is a protein that when found in low levels (hypoalbuminemia) in the blood may indicate poor nutritional status. Hypoalbuminemia has been associated with high mortality and high morbidity in some patient populations. Serum albumin should not be used as the sole measurement to indicate malnutrition. Depending on the nutritional concern, laboratory tests for pre-albumin, cholesterol, lipoproteins, triglycerides, hemoglobin, hematocrit, or iron, also may be included in the evaluation. These tests involve the drawing of a blood sample, sometimes after a period of fasting.
Nutrition risk screening tools
To further determine specific diet and intake information, the clinician may employ a nutrition risk screening tool. Several tools have been developed for this purpose. They include:
- Mini Nutritional Assessment (MNA). This tool assigns point scores to information from the physical examination, anthropometric measurements, and questions asked of the patient concerning intake of fruits and vegetables, mode of feeding, use of prescription drugs, mobility, and other findings.
- Mini Nutritional Assessment Short Form (MNASF). This consists of only six questions and the BMI calculation. It is a quick method of assessing malnutrition risk. The short form is designed to cover broad aspects of a patient's weight changes, mobility, food intake, and psychological stress.
- Malnutrition Screening Tool (MST). This tool was developed for rapid assessment of adults in acute care settings. Data focus on recent weight changes and food intake prior to hospitalization.
- Malnutrition Universal Screening Tool (MUST). Also used for inpatients, MUST requires clinical judgment concerning a patient's ability to eat while in the hospital.
Nutrition assessment tools
Some tools used to screen for malnutrition or other nutrition-related conditions also may be used in a nutritional assessment. For example, the MNA, which was developed as a screening tool for people in outpatient settings, has evolved into a nutrition assessment tool. The Subjective Global Assessment (SGA) was developed to evaluate the nutritional status of surgical patients. The Prognostic Inflammatory Nutrition Indicator (PINI) may be helpful in using laboratory values to predict which older adult inpatients need long-term care based on nutrition indicators. Development of reliable tools is still underway, as is evaluation of these tools for use in various populations.
Before completing a nutrition assessment, the patient will need to have laboratory tests performed. Some of the laboratory tests may require fasting or other preparation as directed by the physician ordering the tests.
Nutritional assessment requires no aftercare except follow-up on results and recommendations. Patients may be instructed on how to care for the blood drawing site where possible bruising may develop.
There are some small risks when drawing blood for the laboratory tests. These risks should be considered based on an individual patient's status when setting up the nutritional assessment. Cancer patients, for example, may face a higher risk of infection at the site where blood is drawn because their immune systems are compromised.
The normal BMI ranges from 24 to 27 kg/m2. A BMI of less than 20 combined with unintentional weight loss of more than 5% suggests nutritional support is needed, as does a BMI of less than 18.5 or unintentional loss of more than 10% of body weight in the previous three to six months. Anthropometric values below the tenth percentile for a person's age group should prompt concern about malnutrition. Other measurements may indicate nutrition problems such as obesity. For example, a waist-to-hip ratio greater than 1.0 in males and 0.8 in females can indicate central obesity, increasing risk for diabetes and coronary heart disease.
Physical signs of malnutrition may include hair thinning, easily bruised skin, decreased skin fold thickness, conjunctival pallor, coarse skin, goose bumps (cutis anserina), and lower extremity rashes.
Serum albumin levels below 3.5g/dL may be a cause for concern. Serum cholesterol below 160mg/dL or above 240mg/dL indicate that nutritional intervention may be necessary. Other laboratory values may be used to detect underlying conditions such as triglycerides and C-reactive protein measurement for coronary heart disease or blood pressure over 120/80 mm Hg for diabetes mellitus.
Anorexia nervosa— A psychiatric disorder in which the individual intentionally starves him or herself.
Anthropometric measurements— Comparative body measurements such as height, weight, and percent body fat as determined by skin folds or hydrostatic weighing.
Cachexia— Wasting with anorexia, abnormal metabolism and negative balance of energy that is disproportionate to nutrient intake. This occurs in many cancer or otherwise chronically ill patients.
Palliative— Intended to control pain and make the patient more comfortable when a cure is not possible.
Screening and assessment tools provide forms with distinct areas in which the clinician will record all relative results from interviews, measurements, physical examination, and laboratory findings. These results then can be assessed and/or assigned point values that are added for a final score. For example, the MNA provides levels for evaluation. A sum score above 23.5 represents satisfactory nutritional status; a score of 17 to 23.5 represents malnutrition risk with good prognosis if the patient is given early intervention. A score below 17 means the patient has protein energy malnutrition, requiring immediate consideration of intervention and further nutrition assessment.
Healthcare team roles
Physicians are responsible for assessing, diagnosing, and treating conditions associated with or contributing to poor nutrition status, and working with registered dietitians to develop a nutrition care plan. Registered dietitians provide medical nutrition therapy to patients and tailor the therapy to individual patient needs. They also advise patients, family, and other caregivers on medical nutrition.
Actually ensuring that patients in acute and long-term care settings are appropriately fed normally is the responsibility of the nurses and nurse aides caring for them. It takes a cooperative effort of physicians, nurses, and dietitians to adequately assess patients for nutrition in these settings. Increasingly, nurses are making the patient's nutritional status a priority and are involving the patient's family members assisting the patient in following dietary guidelines.
Dharmarajan, T.S., and Ajit J. Kokkat. "Geriatric Nutrition," in Clinical Geriatrics, ed. T.S. Dharmarajan and Robert A. Norman. New York: Parthenon Publishing, 2003, 93-104.
Sullivan, Dennis H., and Larry E. Johnson. "Nutrition and Aging," in Principles of Geriatric Medicine and Gerontology, William R. Hazard, et al., eds. New York: McGraw-Hill, 2003, 1151-1170.
Booth, Joanne, Alex Ledbetter, Morag Francis, et al. "Implementing a Best Practice Statement in Nutrition for Frail Older People: Part 1." Nursing Older People (Feb. 2005): 26-29.
"Care and Treatment of Residents." Healthcare Food & Nutrition Focus (Dec. 2002): 7-11.
Edwards, Douglas J. "Nutrition: Making Up for Hospital Shortfalls." Nursing Homes (April 2002): 9-10.
Hoban, Victoria. "Improving Patient Nutrition." Nursing Times (June 7, 2005): 18-20.
"Identifying Patients at Risk; ADA's Definitions for Nutrition Screening and Nutrition Assessment." Journal of the American Dietetic Association (Aug. 1994): 838-839.
"Independent Nurse: Screen New Patients for Undernutrition." GP (May 20, 2005): 2.
Jackson, Rita. "Assessment of Residents." Healthcare Food & Nutrition Focus (June 2002): 1-6.
Jackson, Rita. "Troubleshooting Your Care Plans: Improving the Quality of Nutrition Care in LTC." Healthcare Food & Nutrition Focus (Aug. 2002): 1-7.
Lee, Virginia K. "Problems With Eating and Nutrition: Geriatric Self-learning Module." Medsurg Nursing (Dec. 2004): 405-408.
"Pitfalls of Nutritional Screening in Injured Obese Patients Outlined." Obesity, Fitness & Wellness Week (Nov. 27, 2004): 15.
American Dietetic Association. 216 West Jackson Blvd., Chicago, IL 60606. (800)366-1655. http://www.eatright.org.
Nutrition Screening Initiative. 1010 Wisconsin Avenue, NW, Suite 800, Washington, DC 20007. (202)625-1662. http://www.aafp.org/nsi.xml.
Charney, Pamela. "Nutrition Screening and Assessment in Older Adults." Today's Dietitian 2005. http://www.todaysdietitian.com/archives/td_0505p10.shtml. (May 2005).
"Clinical Evaluation of the Malnourished Patient." McGraw-Hill's Access Medicine, Harrison's Online 2005. http://www.accessmedicine.com.
A Physician's Guide to Nutrition in Chronic Disease Management for Older Adults. 2005. http://www.aafp.org/x16105.xml.
A dietary assessment is an estimation of food and nutrients eaten over a particular time period. A number of dietary assessment tools are used by dietitians, nutritionists, and physicians to aid in dietary counseling. These include:
- food records or diaries (including weighed food intakes)
- dietary recalls
- food frequency questionnaires (FFQs)
- dietary histories
- observed intakes
- chemical analyses of duplicate collections of foods consumed
- biological assessments (e.g., doubly labeled water, plasma carotene, etc.)
A dietary assessment is often conducted to determine the macronutrient (energy or caloric, protein, carbohydrate, and fat) content and the micronutrient (vitamin and mineral) content of the diet to assist in guiding dietary counseling. Validation of dietary assessment instruments is important in order to accurately evaluate the diet for certain risk factors associated with chronic diseases such as diabetes. A dietary assessment is often used as a tool to help the patient lose weight or to prevent or treat conditions or diseases that are influenced by food intake and nutritional status (e.g., cardiovascular disease, obesity, diabetes, hyperlipidemia).
Consumption of too little or too much of certain vitamins and minerals may lead to a nutrient deficiency or a nutrient toxicity respectively. A guide to the amount or vitamins, minerals, and marconutrients an average person needs to consume to remain healthy has been developed. In the United States, this guide is called the Dietary Reference Intakes (DRI). The DRIs have replaced Recommended Dietary Allowances (RDAs), an earlier measure of these nutrients. DRIs encompass both the RDAs and the upper recommended intake limits for each nutrient. The RDA designates a level of vitamin and minerals that is adequate for approximately 97-98% of healthy people in the population. The dietitian may use a dietary assessment to compare an individual's intake to the general population's requirements for nutrients to ensure the diet has the proper balance of calories, protein, carbohydrate, fat, vitamins, and minerals.
Dietary assessments are estimations based on food intake at a particular time and can only estimate dietary adequacy or inadequacy since intake varies from day to day. For example, fruit and vegetables may be lacking on a day that was surveyed for the dietary assessment, while overall the diet may be adequate in fruit and vegetable intake. Thus, care must be taken regarding generalizations about deficiencies or adequacy of nutrient intake. Intake of calories, fats, carbohydrates, and protein varies less from day to day and may be estimated more accurately than vitamin and mineral intakes.
Some of the most common tools that assist in providing dietary guidance include food records, 24-hour dietary recalls, food frequency questionnaires, diet histories, and certain biochemical indices. These tools are explained in greater detail below. Furthermore, a scientific assessment of nutritional status may be made by using a combination of the information collected from clinical evaluations, biochemical tests, and dietary information. The clinical evaluation includes measurements of various anthropometric parameters such as height, weight, and percent body fat as determined by skin folds or hydrostatic weighing. In addition, a clinical evaluation may include observation for signs of nutrient deficiencies in the mouth, skin, eyes, and nails. The information collected from a clinical evaluation can be compared with that obtained from the dietary assessment and biochemical tests to provide a comprehensive picture of the patient's current nutritional status and relative risk factors for diet-related illnesses.
This method of dietary assessment instructs individuals to record the time of consumption of all foods and beverages consumed for a specified duration, typically one to seven days. This is done in order to quantify intake. Three- or seven-day food records are the most commonly used. Recorded amounts for food records can be estimated or weighed. The weighed food record is preferred for assessing individual requirements because of its ability to determine intake quantitatively. Disadvantages of the method are that it is laborious and it may be a considerable burden to correctly measure and record intake. Portion sizes can be obtained through the use of household measures, cups, spoons, and scales.
The 24-hour recall is a method for quantifying dietary intake for a group average and is not suited for individual dietary characterization, although it is often used for this purpose. A person's previous 24-hour food intake is assessed by an interviewer to provide detailed descriptions of portion sizes, condiments used, cooking method, and brand names of food items consumed within a 24-hour period. Quantities are often estimated in household measures or by using pictures or models of portion sizes to assist in more accurately quantifying intake. Advantages of the 24-hour recall are that it is inexpensive, quick, and places little burden on the patient. Single 24-hour recalls do not provide sufficient information about nutrient intake and do not account for day to day variations in intake. However, 24-hour recalls can be repeated on several occasions with the same individual in order to increase accuracy and precision of the assessment.
Food frequency questionnaire
The FFQ is generally designed to provide qualitative data regarding food consumption patterns rather than solely evaluating nutrient composition and intake. The aim is to assess the frequency at which certain foods are eaten on a daily, weekly, monthly or yearly basis. Advantages of the FFQ are that it is quick, inexpensive, and can be administered by patients themselves. One disadvantage is that it cannot provide adequate quantitative data to use for individuals, although semi-quantitative FFQs provide some measure of information about the quantity of food consumed. In addition, the FFQ does not often address culture-specific foods since it usually contains lists of standard North-American foods. Accuracy and validation in specific cultures necessitates the use of another dietary assessment tool.
The diet history attempts to measure an individual's food intake over a longer time period than provided by other methods of dietary assessment. It consists of three parts: a 24-hour recall, a food frequency questionnaire, and a 3-day food record, although the components are often modified. Portion sizes are estimated using a variety of methods including household measures, food models or pictures, household utensils, or actual food. An advantage of the diet history is that it provides qualitative and quantitative data of food intake. It also considers seasonal and day to day variations. One disadvantage is that the method is labor-intensive.
Diagnostic laboratory tests may also be used to further identify a patient's nutritional status. Serum albumin, hemoglobin, or hematocrit are used to measure plasma protein. Lymphocytes counts and various skin tests are used to measure immune system integrity, and various urine tests, such as a calculation of urinary nitrogen, are used as an indication of protein metabolism. Other indices include urinary potassium, serum concentrations of carotenoids, and stable isotopes that measure water turnover, which is an indicator of energy expenditure. These indices are often more reliable and representative of true intake than methods that rely solely on the subject's ability to record or recall intake.
The use of a portable electronic tape recording scales, photographs, voice-taped, and videotaped recordings also have been used as dietary assessment tools.
Other sources that can be used for dietary reference and guidance for food choices are The Dietary Guidelines for Americans, published by the United States Department of Agriculture (USDA) and the United States Department of Health and Human Services (HHS). These agencies provide science-based guidance to help promote health and reduce risk for major chronic diseases through diet and physical activity.
Systematic problems exist in tracking the quantification of food intake using dietary assessment tools that depend on self-reported measures (when patients subjectively report their own food intake). This is because these methods rely on the patient's ability to recall or record their food intake accurately. Therefore, selection of the appropriate method for dietary assessment is important to meet the goals of dietary counseling.
Measurement of dietary intake typically relies on self-reported data. Most dietary collection tools using self-reported intake have not included a test for accuracy or bias to validate the data collected. These validations are logistically difficult to conduct for individuals eating at home.
There are also subgroups of the population that may be more likely to provide inaccurate intake data, creating error. In general, obese people are more apt to underestimate their food consumption because they may go on a diet or deliberately omit foods during the food-recording period. Individuals may also alter their food intake temporarily in order to conform to socially acceptable levels and types of food consumption if they are aware that their food intake is being monitored. For example, during a 24-hour recall, obese people may be unwilling to admit to a dietitian that they over indulged the previous day; therefore, they may underreport their food intake.
Another source of error may be due to inaccurate weighing and measuring of foods. Errors involved in the estimation of food portions can reach 90% but are more typically 20-50% when scales are not used to weigh foods.
Dietary assessments may indicate a nutritional problem or inadequacy, but it is up to the individual to implement the necessary dietary modifications. If an individual fails to follow the recommended dietary guidance following dietary assessment, he or she will not receive any benefit from the assessment.
Health care team roles
In general, only registered dietitians(RD's)have sufficient training and knowledge to accurately assess the clinical evaluation and nutritional adequacy of a patient's diet. The term "nutritionist" is not regulated by law. Therefore anyone can call him or herself a nutritionist. A physician may also have a nutrition background or specialization and thus be able to conduct a dietary assessment or provide nutrition advice. However, individuals should be aware that many physicians do not have any specialized nutritional backgrounds or diet-related knowledge.
Dietary assessment— An estimation of food and nutrients eaten over a particular time period. Some of the most common dietary assessment methods are food records, dietary recalls, food frequency questionnaires, and diet histories.
Dietitian— A dietitian is a health professional who has a bachelor's degree, specializing in foods and nutrition, and in addition undergoes a period of practical training in a hospital or community setting. Many dietitians further their knowledge by pursuing master's or doctoral degrees. The title "dietitian" is protected by law so that only qualified practitioners who have met education qualifications can use that title.
Macronutrient— A nutrient such as protein, carbohydrate, or fat.
Micronutrient— An substance such as a vitamin or mineral that in small amounts is essential to the growth and health of humans and animals.
Nutritionist— Some dietitians call themselves "nutritionists," but in general, the term "nutritionist" is not protected by law; therefore anyone may choose call themselves a nutritionist.
Bronner, Felix, ed. Nutritional and Clinical Management of Chronic Conditions and Diseases. Boca Raton, FL: CRC Press, 2005.
Institute of Medicine, ed. Dietary Reference Intakes for Energy, Carbs, Fiber, Fat, Fatty Acids, Cholesterol, Protein, And Amino Acids. Washington: National Academies Press, 2005.
Lutz, Carroll A., and Karen Rutherford Przytulski. Nutrition And Diet Therapy, 4th ed. Philadelphia: F. A. Davis Company, 2006.
Temple, Norman J., Ph.D., et al. Nutritional Health: Strategies For Disease Prevention, 2nd ed. Totowa, NJ: Humana Press, 2005.
Cheng, C., Graziani, C., Diamond, J.J. " Validation Of The Dietary Risk Assessment Food Frequency Questionnaire Against The Keys Score For Saturated Fat And Cholesterol." Journal of Nutrition Education and Behavior. 37 no. 3 (2005): 152-153.
Kennedy, E., Meyers, L. "Dietary Reference Intakes: Development And Uses For Assessment Of Micronutrient Status Of Women—A Global Perspective." American Journal of Clinical Nutrition. 81 no. 5 (2005): 1194S-1197S.
Probst, Y.C., and L.C. Tapsell "Overview Of Computerized Dietary Assessment Programs For Research And Practice In Nutrition Education." Journal of Nutrition Education and Behavior 37 no. 1 (2005): 20-6.
American Dietetic Association. 120 South Riverside Plaza, Suite 2000, Chicago, IL 60606-6995. (800) 877-1600. http://www.eatright.org.
American Heart Association National Center. 7272 Greenville Avenue, Dallas, Texas 75231. (800) AHA-USA1. http://www.americanheart.org.
Food and Nutrition Information Center, Agricultural Research Service, USDA. National Agricultural Library, Room 105, 10301 Baltimore Avenue, Beltsville, MD 20705-2351. (301) 504-5719. Fax: (301) 504-6409. http://www.nal.usda.gov/fnic.
International Food Information Council. 1100 Connecticut Avenue, NW, Suite 430, Washington, DC 20036. (202) 296-6540. Fax (202) 296-6547, http://www.ific.org.
USDA Food and Nutrition Service. 3101 Park Center Drive, Alexandria, VA 22302. http://www.fns.usda.gov/fns.
U.S. Department of Health and Human Services. 200 Independence Avenue, S.W., Washington, D.C. 20201. (202) 619-0257 or (877) 696-6775. http://www.hhs.gov.
U. S. Department of Agriculture (USDA), Agricultural Research Service. 5601 Sunnyside Avenue, Beltsville, Maryland 20705. "USDA Nutrient Database for Standard Reference, Release 18." Nutrient Data Laboratory Homepage, 2005. www.ars.usda.gov/ba/bhnrc/ndl.
Esha Research. Total Dietary Assessment Software Revised CD-Rom (CD-ROM) New York: John Wiley & Sons, 2006.
A dietary assessment is an estimation of food and nutrients eaten over a particular time point. There are a number of dietary assessment tools used by dietitians, nutritionists, and doctors that aid in dietary counseling . These include:
- food records or diaries (including weighed intakes)
- dietary recalls• food frequency questionnaires (FFQs)
- dietary histories
- observed intakes
- chemical analyses of duplicate collections of foods consumed
- biological assessments (e.g. doubly-labelled water, plasma carotene, etc.)
A dietary assessment is often conducted to determine the macronutrient (energy or caloric, protein, and fat) content and the micronutrient (vitamin and mineral) content of the diet to assist in providing dietary counseling. The validation of dietary assessment instruments is important to evaluate the diet in terms of a chronic disease risk factor. It is often used as a tool to help the patient lose weight, or to prevent or treat conditions or diseases that are influenced by food intake and nutritional status (i.e. cardiovascular disease, cancer , obesity , diabetes, hyperlipidemia).
A guide to the amount an average person needs each day to remain healthy has been determined for each vitamin and mineral as well as macronutrients. In the United States, this guide is called the recommended daily allowance (RDA). Consumption of too little or too much of certain vitamins and minerals may lead to a nutrient deficiency or a nutrient toxicity respectively. The RDA suggests a level of vitamin and minerals that is adequate for approximately 98% of healthy people in the population. The dietitian may use the dietary assessment to compare it to population requirements for nutrients (such as the RDA) to ensure the diet has proper intakes of energy, protein, fat, vitamins, and minerals. The RDA is under revision and will become the Dietary Reference Intakes, and will be applicable to Canadians and Americans.
Dietary assessments are estimations based on an intake of a particular time point and cannot generalize that the diet is adequate or inadequate since intake varies day to day. For example, fruit and vegetables may be lacking on a day that was surveyed for the dietary assessment while overall the diet may be adequate in fruit and vegetable intake. Thus, care must be taken regarding generalizations about deficiencies or adequacy of nutrient intake. Intake of energy, carbohydrates , and protein varies less from day to day and may be estimated more closely than vitamin and mineral intakes.
Some of the most common tools that assist in providing dietary advice include food records, 24 hour dietary recalls, food frequency questionnaires, diet histories, and several other methods including biochemical indices. These tools are explained in greater detail below. Furthermore, a scientific assessment of nutritional status may be made by using a combination of the information collected from clinical evaluations, biochemical tests, and dietary information. The clinical evaluation includes measurements of various anthropometric parameters such as height, weight, and percent body fat (determined by skinfolds or hydrostatic weighing). In addition, a clinical evaluation may also include observations for signs of nutrient deficiencies in the mouth, skin, eyes, and nails. The information collected from a clinical evaluation can be compared with that obtained from the dietary assessment and biochemical tests to provide a comprehensive picture of the patient's current nutritional status and relative risk factors for diet-related illnesses.
This method instructs subjects to record at the time of consumption all foods and beverages consumed for a specified duration, typically one to seven days, in order to quantify intake. Three or seven day food records are the most common. Food records can be estimated or weighed, the latter providing a more precise measure of intake. Portion sizes can be obtained through the use of household measures, cups, spoons, and scales. All days of the week should be proportionally included to avoid day of the week effects on nutrient and compositional intake. The weighed food record is the preferred method for assessing individual requirements because of its ability to determine intake quantitatively. Disadvantages of the method are that it is laborious and it may be a considerable burden to correctly measure and record intake.
The 24-hour recall is a method for quantifying dietary intake for a group average and is not suited for individual dietary characterization although it is often used for this purpose. A person's previous 24-hour food intake is probed by an interviewer to provide detailed descriptions of portion sizes, condiments used, cooking method, and brand names. Quantities are often estimated in household measures or using food models for assistance to more accurately quantify intake. Recalls can be repeated on several occasions in the same person in order to increase accuracy and precision. Advantages of the 24-hour recall is that it is inexpensive, quick, and places little burden on the patient. Single 24-hour recalls do not provide sufficient information on nutrient intakes and cannot account for day to day variation in intake, however, repeated 24 hour recalls can be used to more precisely estimate intake.
Food frequency questionnaire
A food frequency questionnaire (FFQ) is generally designed to provide qualitative data regarding food consumption patterns rather than nutrient composition and intake. The aim is to assess the frequency at which certain foods are consumed, for example, daily, weekly, monthly or yearly. Advantages of the FFQ are that it is quick, inexpensive, and can be administered by patients themselves. Disadvantages are that it cannot provide adequate quantitative data to use for individuals, although semi-quantitative FFQs provide some measure of quantity. As well, it does not address culture-specific foods since it primarily contains lists of somewhat standard North-American type foods. Accuracy and validation in specific cultures necessitates the use of another dietary assessment tool.
The diet history attempts to measure usual intake in the past over a longer time period than other methods of dietary assessment. It consists of three parts, although it is often modified, including a 24 hour recall, a food frequency questionnaire, and a 3 day food record. Portion sizes are estimated by a variety of methods including household measures, food models, household utensils, photographs, or actual food. An advantage of the diet history is that it provides qualitative and quantitative data of food intake. It also considers seasonal and day to day variations. Disadvantages are that the method is labor-intensive.
The use of a portable electronic set of tape recording scales (PETRA), photographs, voice-taped, and videotaped recordings have been used as dietary assessment tools.
Biochemical tests may also be used to further identify a patient's nutritional status. Serum albumin, hemoglobin or hematocrit are used to measure plasma protein. Lymphocytes and various skin tests are used to measure immune system integrity, and various urine tests such as a calculation of urinary nitrogen are used as an indication of protein metabolism . Other indices include urinary potassium, serum concentrations of carotenoids, and stable isotopes that measure water turnover which is an indicator of energy expenditure. These indices are often more reliable and representative of true intake than methods which rely on the subject's ability to record or recall intake.
Other sources that can be used for dietary reference and guidance for food choices are "The Dietary Guidelines for Americans" which is published by the U.S. Department of Agriculture and Health and Human Services. The "Food Guide Pyramid" was created by the U.S. Department of Agriculture to help Americans choose foods from each food grouping. It focuses on fat intake, which is too high in most Americans.
There are also a number of internet websites where food records or recalls can be self-administered by patients for dietary assessment. Some of these websites are listed in the resources sections below.
Systematic problems exist in the quantification of food intake using dietary assessment tools that depend on self-reported measures (i.e. when the patient subjectively reports their own food intake). This is due to the fact that these methods rely on the patient's ability to recall or record food intake accurately. Therefore, selection of the appropriate method for dietary assessment is important to meet the goals of dietary counseling.
Measurement of dietary intake typically relies on self-reported data. Most dietary collection tools using self-reported intake have not included a test for accuracy or bias to validate the data collected. These validations are difficult to conduct because in an individual who is eating at home, there are few methods to use as a reference to validate the dietary intake data.
There are subgroups of the population that are more likely to provide inaccurate intake data, creating error. In general, obese people are more apt to underestimate their food consumption because they may go on "a diet" or deliberately omit foods during the food-recording period. Individuals may alter their food intake temporarily as they are cognizant that their food intake is being monitored, possibly to conform to socially acceptable foods and food habits. For example, during a 24 hour recall, an obese person may not want to admit to a dietitian that they overate the previous day, therefore, they may under-report their food intake.
Another source of error comes from weighing and measuring foods. Errors involved in the estimation of food portions can reach 90% but are typically 20-50% when scales are not used to weigh foods.
Dietary assessment —An estimation of food and nutrients eaten over a particular time point. Some of the most common dietary assessment methods are food records, dietary recalls, food frequency questionnaire, and diet histories.
Dietitian —A dietitian is a health professional who has a bachelor's degree, specializing in foods and nutrition, and undergoes a period of practical training in a hospital or community setting. Many dietitians further their knowledge by pursuing master's or doctoral degrees. The title "dietitian" is protected by law so that only qualified practitioners who have met education qualifications can use that title.
Macronutrient —A nutrient such as protein, carbohydrate, or fat.
Micronutrient —An organic compound such as vitamins or minerals essential in small amounts and necessary to growth and health of humans and animals.
Nutritionist —Some dietitians call themselves "nutritionists," but in general, the term "nutritionist" is not protected by law, therefore anyone can call themselves a nutritionist.
A dietary assessment may indicate where a nutritional problem or inadequacy may lie, but it is up to an individual to implement the necessary dietary modifications. If a patient does not follow the recommended dietary guidance following dietary assessment, then they will not receive any benefit from dietary assessment. Typically, modest effects are seen in weight loss or reduction in serum lipids often due to failure to fully comply with the dietary recommendations provided.
Health care team roles
In general, only registered dietitians (R.D.s) have sufficient training and knowledge to accurately assess the clinical evaluation and nutritional adequacy of a patient's diet. Although there are many websites and software programs that provide guidance for self-use for conducting a basic dietary assessment, these should be used with caution. The term "nutritionist" is not regulated by law; therefore anyone can call themselves a nutritionist. A doctor may also have a nutrition background or specialization and may thus be able to conduct a dietary assessment or to provide general nutrition advice. However, one research study demonstrated that even though most doctors admitted they had ready access to a publicly funded dietician, 50% of doctors refer less than a quarter of their patients to dieticians. Major barriers for doctors to improving dietary counseling for patients include short visit times, limited nutrition coursework in medical schools, and poor patient compliance with physicians' dietary prescriptions.
Institute of Medicine, ed. Dietary Reference Intakes: Applications in Dietary Assessment. Washington: National Academy Press, 2001.
Institute of Medicine, ed. Dietary Reference Intakes: Risk Assessment (Compass Series). Washington: National Academy Press, 1999.
Larson-Duyff, Roberta. The American Dietetic Association's Complete Food & Nutrition Guide. New York: John Wiley & Sons, 1998.
Netzer, Corinne T. The Complete Book of Food Counts. New York: Dell Publishing Co., 2000.
American Dietetic Association. 216 W. Jackson Blvd. Chicago, IL 60606-6995. (312) 899-0040. <http://www.eatright.org/>.
Food and Nutrition Information Center Agricultural Research Service, USDA. National Agricultural Library, Room 304, 10301 Baltimore Avenue, Beltsville, MD 20705-2351. (301) 504-5719. Fax: (301) 504-6409. <http://www.nal.usda.gov/fnic/>. <[email protected]>.
U.S. Department of Agriculture, Agricultural Research Service. "USDA Nutrient Database for Standard Reference, Release 13." Nutrient Data Laboratory Homepage 1999. <http://www.nal.usda.gov/fnic/foodcomp>.
Food and Nutrition Professionals Network <http://nutrition.cos.com/>.
Crystal Heather Kaczkowski, MSc.
During a dietary assessment an individual's food intake is recorded and analyzed.
A dietary assessment is done to help provide insight into the possible cause of symptoms, or to provide recommendations for better eating to improve health. Many disease and conditions have a dietary component. A dietary assessment can help the doctor diagnose or rule out the causes of certain problems. In some cases a dietary assessment is done to determine the general eating habits of an individual so that a nutrition professional can make recommendations for improved heath. A good diet is an integral part of the treatment plan of many diseases and conditions.
A dietary assessment can be an extremely valuable tool for helping individuals improve health, and for diagnosing a variety of diseases and conditions. However, getting an accurate accounting of an individual 's food and beverage intake can be very difficult. Even when the intention to be completely honest exists, individuals who eat very little tend to over report their intake, while individuals who eat larger than average amounts tend to underreport their intake. For this reason dietary assessment tools that use objective measures, rather than relying on selfreporting, may be more accurate.
Dietary assessment can also be very challenging for special populations. Individuals who have Alzheimer 's, dementia, or other diseases and conditions that affect memory are difficult to perform an accurate dietary assessment for. However, these individuals are often in the greatest need of a complete assessment, as memory problems can cause problems with skipping meals or eating too frequently. This can lead to a variety of health and other problems which may be manageable with dietary intervention. The involvement of caregivers in the dietary assessment process can help improve the accuracy of the assessment, which in turn can lead to improved health outcomes.
The goal of the dietary assessment is to determine the general eating habits of the individual. This can be done in a number of ways. A nutrition professional often must make tradeoffs between accuracy and time efficiency when performing a dietary assessment.
The most basic form of dietary assessment is a 24 hour food questionnaire or interview, during which the individual self-reports the food consumed in the previous 24 hours. One positive aspect of this type of dietary assessment is that it is usually very short, and can be completed in one appointment. A negative aspect of this type of assessment is that it tends not to be very accurate. What an individual ate in the previous 24 hours is not necessarily representative of the food eaten during an average 24 hour period. It also relies on self-reporting, with the individual having to guess the portion sizes consumed. Because reporting portion sizes larger or smaller than those actually consumed can have a drastic impact of the assessment, this can provide a fairly inaccurate result in some cases. This type of assessment can, however, provide basic insight into dietary habits overall.
In some cases a food frequency questionnaire is used instead of a 24 hour food questionnaire. A food frequency questionnaire asks the individual how many times in a certain time period he or she usually eats a certain food or class of foods. For example, the questionnaire might ask whether the individual usually eats eggs daily, two to four times a week, five to seven times a week, or less than once a week. This type of questionnaire can help the nutrition professional understand an individual's eating habits outside the context of a specific day. This type of questionnaire is often helpful at suggesting broad dietary changes that may be helpful, such as trying to cut back slightly on red meat, or eating more vegetables.
A more in-depth type of dietary assessment is the food record. During a specific assessment time period, such as a day or a week, the individual keeps a journal in which he or she writes down each item consumed, the time and place it was consumed, the quantity of food, how it was prepared, and any other information indicated by the nutrition professional. In some cases the individual is instructed to weigh all food, keeping a weighed food recorded. Food records help the nutrition professional get a more accurate picture of the individual's dietary habits. The record tends to be more accurate, as each food is written down before it is eaten, and the assessment does not rely on later recall. Weighed food records can be even more accurate because they do not rely on self-reporting of portion sizes.
Some nutrition professionals have begun to use photographic and video technologies to do dietary assessments. In these cases, the individual is instructed to take a photo of each food before it is consumed, and may be instructed to photograph the preparation of the food, and the setting in which it was eaten (for example, at a party, at the dinner table, in front of the television). When a video camera is used the individual might be instructed to videotape each food, or the camera may be set up in the kitchen or another location where the individual usually eats.
No special preparation is required for a dietary assessment.
No aftercare is required after a dietary assessment.
No complications are expected from a dietary assessment.
QUESTIONS TO ASK YOUR DOCTOR
- What types of foods am I getting too much of?
- What types of foods am I getting too little of?
- Can you recommend a nutrition professional who can help me improve my dietary habits?
Adietary assessment does not usually yield specific results. Instead, it gives the doctor or nutrition professional a general picture of the individual's dietary habits. In some cases, this can be used to help diagnose or rule out diseases. For example, a diet found to be extremely low in iron could be the cause of the most common type of anemia , iron deficiency anemia . If the individual had visited the doctor with symptoms such as fatigue, dizziness , weakness, and pale skin, all symptoms of anemia, increasing the amount of iron in the diet may relieve these symptoms.
The results of a dietary assessment can also help the doctor or nutrition professional make recommendations about dietary changes that can improve health. The suggestions may be intended to help promote weight loss or weight gain, improve general health, or be designed to help improve a specific disease or condition. There are many different diseases and conditions that dietary changes can help improve. For example, eating a diet that is low in salt can help improve high blood pressure .
A dietary assessment can be done for many different reasons. If a doctor believes that there may be a dietary component to a problem, or if he or she believes dietary intake information will help in making a diagnosis, a doctor may order a dietary assessment. Although a doctor may do a basic dietary assessment, in most cases the individual is referred to a nutritionist , a registered dietician , or certified dietetic technician. The results of the assessment are then reported to the physician. The nutritionist, registered dietician, or certified dietetic technician works closely with the individual and the physician. He or she can also work closely with social workers, hospital or clinic staff, family members, and any other members of the individual's health care team. In this way the individual can have regular dietary assessments to chart progress, and he or she can receive the best nutrition possible for his or her health goals.
Bender, David A. Introduction to Nutrition and Metabolism, 4th ed. Boca Raton, FL: CRC Press, 2008.
Escott-Stump, Sylva. Nutrition and Diagnosis-Related Care, 6th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2008.
Moore, Mary Courtney. Pocket Guide to Nutritional Assessment and Care, 6th ed. St. Louis, MO: Mosby, 2009.
Keller, Colleen, Julie Fleury, and Andriana Rivera. “Visual Methods in the Assessment of Diet Intake in Mexican American Women.” Western Journal of Nursing Research 29.6 (October 2007): 758-774.
Pennington, Jean A.T., et al. “Food Composition Data: The Foundation of Dietetic Practice and Research.” Journal of the American Dietetic Association 107.12(December 2007): 2105–2114.
Stumbo, Phyllis J. “Considerations for Selecting a Dietary Assessment System.” Journal of Food Composition and Analysis 21.1 (February 2008): S13–S19.
American Dietetic Association, 120 South Riverside Plaza, Suite 2000, Chicago, IL, 60606-6995, (800) 877-1600, www.eatright.org.
USDA Center for Nutrition Policy and Promotion, 3101 Park Center Drive, Room 1034, Alexandria, VA, 22302-1594, (888) 7-PYRAMID, www.mypyramid.gov.
A dietary assessment is a comprehensive evaluation of a person's food intake. It is one of four parts of a nutrition assessment done in a clinical setting. These four parameters of assessment include: (1) an assessment of anthropometrics (weight, height, weight-to-height ratio, head circumference, body mass index , etc.); (2) dietary assessment, which includes a diet history or food frequency analysis; (3) a physical examination with a medical history; and (4) biochemical exams or blood/urine tests.
Reviewing a person's dietary data may suggest risk factors for chronic diseases and help to prevent them. Laboratory tests may uncover malnutrition and detect problems before any side effects appear, such as the tiredness and apathy associated with iron-deficiency anemia . The strengths of a simple blood test and food intake record are that these are easy to do and are affordable and appropriate for most people.
Problems with using diet histories can occur because a person's memory about what he or she ate earlier may not be accurate. It can also be time-consuming to collect food intake records. There are also problems with interpreting food intakes, laboratory values, and appropriate weights and heights.
A final area of concern related to dietary assessment is what to do with the information once it has been gathered. Providing nutrition education and counseling to people of different ages and from different backgrounds requires a great deal of skill and a good understanding of diet quality, normal eating, and normal physical and psychosocial development. It is important to treat people as individuals with unique needs and concerns. Dietitians are trained to do this, but many health care workers are not trained to measure diet quality, define dietary moderation, or provide counseling.
see also Nutritional Assessment.
American Heart Association. "Healthy Lifestyle: Diet and Nutrition." Available from <http://www.americanheart.org>
U.S. Department of Agriculture, Food and Nutrition Information Center. "Dietary Assessment." Available from <http://www.nal.usda/fnic>