Dietary deficiencies are disorders that occur because of a lack of essential nutrients in the diet, or because the body cannot absorb and process those nutrients once they are eaten. Most dietary deficiency diseases are caused by a lack of protein, vitamins, or minerals.
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The human diet is divided into five nutritional groups: proteins, carbohydrates, fats, vitamins, and minerals. These five groups include about 50 nutritional items that are necessary for good health and growth. Each of these items plays a vital role in the functioning of the human body. The amount of nutrients needed for good health varies from individual to individual. Age, gender, and overall health condition affect how much of these nutrients a person needs for good health.
Whenever a person does not get enough of an essential nutrient, they are at risk for a dietary deficiency disease. Most dietary deficiency diseases are caused by a lack of protein, vitamins, or minerals. Protein deficiency diseases occur when a person does not eat enough protein; these diseases are prevalent in developing countries where people are too poor to buy protein-rich foods or where such foods are hard to find. Generally speaking, vitamin and mineral deficiencies are due to diets that lack some of the nutrients found in fresh vegetables and fruit, as well as milk, cheese, or eggs. In some cases, genetic* disorders, metabolic* disorders, or illnesses that prevent the body from digesting or absorbing particular nutrients will cause the deficiencies.
- * genetic
- (je-NET-ik) pertains to genes, which are chemicals in the body that help determine a person’s characteristics, such as hair or eye color. They are inherited from a person’s parents and are contained in the chromosomes found in the cells of the body.
- * metabolic
- (met-a-BOL-ik) pertains to the process in the body that converts food into energy and the chemical processes necessary for growth, maintenance, and function of body tissues.
A trend toward taking vitamin and mineral supplements has been growing in the United States. It is estimated that anywhere from 30 to 40 million people in the United States alone are using nutritional supplements on a daily basis. The potency of small amounts of vitamins to cure deficiency diseases may have led to the unrealistic expectation that vitamins and minerals can ensure good health when taken in large amounts as supplements. Despite this widespread habit, very few scientific studies exist to prove these supplements can make a difference.
It is important to check with a doctor before adding nutritional supplements to the diet, and to keep in mind the following facts:
- Most vitamins are water-soluble. The body can absorb only so much of a vitamin, and the rest is excreted in the urine throughout the day.
- Large doses of some vitamins, such as A and D, can be harmful. Vitamins A and D are fat-soluble vitamins and can accumulate in the liver to the point of becoming toxic.
- Too much of certain trace elements, like zinc, copper, fluoride, and selenium, can be toxic.
- Most nutritionists recommend eating a well-balanced diet as the most effective and least expensive way of getting the nutrients needed to stay healthy.
- Vitamin supplements are warranted for certain people, such as pregnant women, newborns, and people on special diets.
- The health-food and vitamin industries that market supplements claim that the minimum daily amounts recommended by the U.S. Food and Drug Administration (FDA) are too low. The American Dietetic Association (ADA) recommends that doctors or licensed dietitians be the source of supplement prescriptions.
Proteins are the essential components of all organs and chemical activities. Proteins make up body tissues such as muscle, connective tissue, and skin. Other proteins are enzymes, chemicals that cause reactions to occur that allow the body to function. For example, some enzymes digest food or convert sugar into energy. Proteins are composed of building blocks called amino acids. When proteins are eaten and digested, they are broken down into amino acids that are then redistributed throughout the body, where they form new proteins and enzymes. When protein is missing from the diet, the body cannot function properly. Milk, meat, and legumes are important sources of dietary protein.
Protein-energy malnutrition (PEM)
The term protein-energy malnutrition (PEM) is used to describe the range of conditions related to calorie (energy) and protein deficiency disorders. These diseases are prevalent in developing countries where people lack sufficient food. In this category of malnutrition are the diseases kwashiorkor (kwash-e-OR-kor) and marasmus (ma-RAZ-mus). These diseases affect mainly children, with as many as half of the children in starvation-prone countries not surviving to their fifth birthdays. Adults rarely suffer from protein deficiency diseases unless there is a problem in the intestines that prevents absorption of amino acids.
Kwashiorkor is a disease caused specifically by a lack of protein in the diet. The term originates from an African word that describes the situation of an infant being weaned* from breast milk to make room for the next baby. When weaning occurs and protein-rich food (such as milk, meat, or legumes) is not available, the baby experiences tiredness, muscular wasting, and edema (water retention). The hair and skin lose color, the skin becomes scaly, and the child may experience diarrhea and anemia.
- * weaning
- means accustoming a child to take food other than by breastfeeding.
Marasmus is a wasting away of body tissue from a lack of both calories and protein in the diet. A child with marasmus is cranky and irritable, and is skinny rather than swollen with edema.
There are 13 vitamins essential for healthy growth, development, cell function, and metabolism: vitamins A, C, D, E, K, and eight B vitamins (together they are called the B complex vitamins). All vitamins must be taken into the body from outside food sources, except for vitamins D and K, which can be made under specific circumstances by the body.
Vitamin A, night blindness, and xerophthalmia
Vitamin A is necessary to protect the retina*, and for the normal growth and health of skin and membrane cells. A deficiency of vitamin A can cause night blindness, a condition in which the eyes fail to adjust to the dark because of problems with the retina. The deficiency also may cause “glare” blindness, or problems seeing when the eye is exposed to too much light or to a sudden change in the amount of light when entering a darkened room.
- * retina
- (RET-i-na) is a structure lining the back of the eye that is necessary for vision.
Vitamin A deficiency also can cause a disease called xerophthalmia (zeer-off-THAL-mee-a). The symptoms of this disease are eye dryness and thickening of the surface of parts of the eye. If left untreated, xerophthalmia may lead to blindness.
Vitamin A can be obtained directly from foods such as milk, eggs, and liver, as well as from carotene, a chemical that is found in green and yellow fruits and vegetables such as apricots, cantaloupe, oranges, peaches, collards, broccoli, turnip greens, kale, carrots, sweet potatoes, and squash. Carotene is converted to vitamin A in the body.
Beta-Carotene and Vitamin A Research
As of 1999,22,000 physicians under the supervision of the Department of Medicine at Harvard University were studying the long-term effects on the body of beta-carotene (vitamin A).
Among the questions about beta-carotene that researchers hope to answer:
- Can it lower the incidence of cancer?
- Can it boost resistance to infection?
- Can it be useful in the treatment of AIDS?
Vitamin B1 and beriberi
Beriberi (BER-ee-BER-ee) is a disease that affects the heart, digestive system, and nervous system. It results from a lack of vitamin B1 (also called thiamin) in the diet. Thiamin is used to help the body make energy. Food sources for this vitamin are meats, wheat germ, whole grain and enriched bread, legumes, nuts, peanuts, and peanut butter. The early stages of beriberi are characterized by fatigue, loss of appetite, and a numb, tingling feeling in the legs. There are three forms of beriberi:
- Infantile beriberi: Although a nursing mother may not have the disease herself, her infant gets sick from not getting enough thiamin in the breast milk. The child may die in infancy, or the child may develop wet or dry beriberi.
- Wet beriberi: This is characterized by an accumulation of fluid throughout the body, and a rapid heart rate that can lead to sudden death.
- Dry beriberi: In this form of beriberi there is no fluid accumulation, but there is a loss of sensation and a weakness in the legs. People with dry beriberi often need to walk with the aid of a cane and may become bedridden and susceptible to infectious diseases.
Beriberi is still found in Japan, Indonesia, China, Malaysia, India, Burma, the Philippines, Brazil, Thailand, and Vietnam. In the United States and other developed nations, it usually occurs in a milder form, often accompanying malnutrition and alcoholism. Beriberi also may affect pregnant women who have a poor diet, and people in institutions where there is poor nutritional planning, such as some prisons, geriatric hospitals, or institutions for the mentally ill.
Vitamin B3 and pellagra
A deficiency of vitamin B3 (also called niacin) leads to a disease called pellagra (pe-LAG-ra). Good sources of niacin include liver, lean meat, whole wheat products, fish, eggs, roasted peanuts, the white meat of poultry, avocados, dates, figs, prunes, kidney, wheat germ, and brewer’s yeast.
Pellagra affects the skin, nervous system, and digestion, and can cause the “four Ds”: diarrhea, dermatitis, dementia, and death. A person who is developing pellagra may feel weak and tired, may have trouble sleeping, and may lose weight. The skin that is exposed to the sun may become scaly, rough, and reddened, and painful sores may develop in the mouth. There is a loss of appetite accompanied by indigestion and diarrhea. A
85 Years Ago: Joseph Goldberger
Joseph Goldberger (1881–1929) was a member of the United States Public Health Service. In 1914, he joined a commission to study the high number of pellagra cases in the southern United States. Goldberger determined that pellagra was not an infectious disease, and that a pellagra-preventing factor in certain foods could prevent its occurrence. In 1928, niacin (vitamin B3) was accepted as the factor that prevented pellagra.
Niacin is also known as nicotinic acid. The active form of niacin used by the body is called niacinamide.
person with pellagra also might experience headaches, dizziness, and muscular tremors. Sometimes mental disorders (or dementia) appear.
Pellagra is common around the world, although the “fortification” of processed wheat with vitamin B in the United States keeps the numbers low. Pellagra is seen in people who eat mostly corn rather than wheat and in people whose diets lack enough protein. People with gastrointestinal diseases that prevent their bodies from using B vitamins properly also may develop pellagra.
Other B complex vitamins
Cobalamin (B12) provides protection against certain types of anemia and mental disturbances. Vitamin B6 can protect against anemia, skin problems, and irritability.
Vitamin C and scurvy
Vitamin C affects blood vessels, skin, gums, connective tissue, red blood cells, wound healing, and the absorption of iron. A deficiency of vitamin C leads to scurvy. The main symptom of scurvy is hemorrhaging, or bleeding under the skin, which results in the appearance of many bruises. A person with scurvy also may have swollen and infected gums. Wounds heal slowly, and bleeding in or around vital organs can be fatal.
Scurvy is one of the oldest deficiency diseases recorded and the first one to be cured by adding a vitamin to the diet. It was a common malady of sailors during the age of exploration of the New World. In the modern world, people whose diets lack vitamin C-rich foods, such as citrus fruits, are still at risk of developing scurvy. Those most at risk are infants, the elderly, and people on fad diets.
Vitamin D, rickets, and osteomalacia
Vitamin D is essential for proper bone formation because it helps regulate the amounts of certain bone-forming minerals (calcium and phosphate) in the bloodstream. Vitamin D is added to milk and infant formula and is found in other foods, like sardines, salmon, and tuna. Vitamin D also is made by the skin in response to exposure to sunlight.
Vitamin C Megadoses and Linus Pauling
Two-time Nobel laureate Linus Pauling believed that vitamin C was effective in preventing and lessening the effects of colds. He also proposed the use of vitamin C in the treatment of cancer. Pauling’s program called for extremely large doses (megadoses) of Vitamin C, from 2,000 to 9,000 milligrams (mg), which greatly exceeds the government’s recommended daily requirements. The National Research Council recommends 60 mg daily for non-smoking adults and 100 mg daily for smokers.
Many people follow Pauling’s vitamin C regimen when they feel a cold coming on, despite the lack of supporting evidence for his theory.
Without enough vitamin D, a person can develop a disease called rickets, which is characterized by bone deformities. Rickets affects mainly children, because bone growth occurs during childhood. Rickets can cause the legs to become bowed by the weight of the body, and can cause the wrists and ankles to become thickened. Teeth are badly affected and take a longer time than usual to come in. All the bones are affected by not having sufficient calcium and phosphorous for their growth and development. Childhood rickets once was a common disease of infants and children, but is rarely seen today because milk and infant formulas have vitamin D added to them.
An adult version of rickets caused by a deficiency of Vitamin D, calcium, and phosphorous is called osteomalacia (os-tee-o-ma-LAY-sha). The bones become soft, deformed, and painful. This disease is seen more often in the Middle East and Asia than in Western countries.
Vitamins E and K
Vitamin E helps prevent reproductive problems and promotes good skin health. Vitamin K promotes normal blood clotting by aiding in the manufacture of fibrinogen (fy-BRIN-o-jen) and other proteins needed for clotting. Vitamin E deficiencies are not very common, and Vitamin K deficiencies are rare except in newborns. To prevent newborn bleeding, newborns are given a shot of vitamin K.
Folate and birth defects
A deficiency in folate (also known as folic acid or folacin) in pregnant women can result in some central nervous system birth defects in their babies. To help prevent these birth defects, it is important for pregnant women to supplement their diets with folate very early in their pregnancies. The best food sources for folate include deep green leafy vegetables, carrots, liver, egg yolk, cantaloupe, apricot, pumpkin, avocado, beans, and whole wheat and dark rye flours.
There are about 25 mineral elements in the body that usually appear in the form of simple salts. Those minerals that appear in large amounts are called macrominerals, whereas those that are in small or trace amounts are called microminerals. Minerals known to be essential to a healthy body include calcium, phosphorous, cobalt, copper, fluorine, iodine, iron, and sodium. The result of a mineral deficiency depends on the particular mineral that is missing from the diet.
Iodine, goiter, and hypothyroidism
Iodine is necessary for the proper functioning of the thyroid, a gland that controls the body’s metabolic rate and producing essential hormones*. Without sufficient iodine in the diet, the thyroid begins to enlarge its cells in an effort to produce its hormones, and this activity may produce a goiter, which is a swelling in the front of the neck. Most goiters in countries with high standards of living result from diseases of the thyroid rather than from a dietary deficiency of iodine.
- * hormones
- are chemicals that are produced by different glands in the body. Hormones are like the body’s ambassadors: they are created in one place but are sent through the body to have specific regulatory effects in different places.
Some geographic regions lack iodine in the soil, which can lead to hypothyroidism (underactive thyroid) and to arrested physical and mental development in infants. One very common source of iodine is iodized salt. Another excellent source of iodine is the sea vegetable kelp.
Iron and anemia
Iron is necessary for the formation of certain proteins and enzymes. Hemoglobin (HE-mo-glo-bin), which is the oxygen-carrying protein in the blood, is one such iron-dependent protein. Iron deficiency can lead to anemia, a lack of oxygen in the blood, which in turn can lead to fatigue and other complications. Good food sources of iron are liver, lean meats, legumes, dried fruits, and green leafy vegetables.
A zinc deficiency can lead to prostate* and skin disorders, while a copper deficiency can lead to metabolic disorders. Deficiencies of calcium and phosphorus lead to softening of the bones or to hypercalcemia (hy-per-kal-SEE-mee-a), a condition in which too much calcium leads to a surplus formation of bone.
- * prostate
- (PROS-tate) is a gland in the male. Located near the bladder and urethra, it secretes the fluid component of semen.
Zinc and copper are trace elements that are found in a variety of foods. Deficiencies of these minerals are rare. Dairy products, green vegetables, sunflower seeds, cooked dried beans, walnuts, sardines, salmon, and soy products are good sources of calcium. Phosphorous is found in many foods, including fish, poultry, meat, whole grains, eggs, nuts, and seeds.
In most cases, dietary deficiency diseases are treated by giving the affected person foods rich in the missing nutrient and/or by giving them supplements. A person’s recovery (none, partial, or full) depends on the particular disease, at what age the disease developed, and whether the effects are reversible once they have occurred.
Most dietary deficiency diseases can be prevented by eating a well-balanced diet comprising a diversity of foods. Ongoing medical care can help prevent dietary deficiency diseases caused by genetic problems and by metabolic problems that prevent the body from absorbing or utilizing nutrients properly.
In countries where food and money are scarce, however, dietary deficiency diseases remain all too common among children and adults.
Pressman, Alan H., Sheila Buff, and Gary Null. The Complete Idiot–s Guide to Vitamins and Minerals. New York: Alpha Books, 1998.
The U.S. National Institutes of Health (NIH) and its member institutes have a Consumer Health Information website, with links to many different fact sheets about diet.
The World Health Organization (WHO) posts fact sheets about Food and Nutrition at its website.
The International Food Information Council, 1100 Connecticut Avenue N.W., Suite 430, Washington, D.C. 20036. This group’s website posts information about nutrition for adults and for children along with an online glossary of nutrition-related terms.