Dietary Systems: A Historical Perspective
DIETARY SYSTEMS: A HISTORICAL PERSPECTIVE
DIETARY SYSTEMS: A HISTORICAL PERSPECTIVE. The urge to classify foods and frame complex dietary laws is as old as civilization itself, if not older. Most dietary systems around the world are explicitly religious. But some dietary systems that arose were more secular in nature; their ultimate goal was to maintain or restore physical health. The most influential of these were produced in Greece, India, China, and the modern West.
The superficial similarity of the ancient systems may have arisen from a common prehistoric root, or they may have influenced each other across trade routes. Separate civilizations also may have arrived at similar ways of describing physiologic functions because some human experiences are universal. The fact that most of these systems assess food qualitatively, using descriptive terms such as hot, cold, moist, and dry, appears to be coincidental. They do not understand or apply these terms in the same way.
The Greek dietary tradition stems ultimately from the body of writings attributed to Hippocrates of Cos. Dietary regimen in all these works was considered the most important way to prevent and cure disease, but the concept of diet encompassed much more than food intake. It also considered air quality, exercise, sexual activity, emotions, and the elimination of waste products. Although a fully elaborated theory of the four humors was not yet in place among the Hippocratic writers, in later years and especially in the writings of Galen of Pergamum it came to be the cornerstone of this system. Just as four elements were considered the building blocks of all physical matter, so four basic regulatory fluids were believed to control the human body. These are blood, phlegm, choler, and black bile or melancholy. Each in turn was described as hot and moist, cold and moist, hot and dry, or cold and dry, respectively. Every individual is born with a tendency for one humor to predominate, sometimes excessively so. This was called the complexion, which also was considered affected by age, gender, and a variety of external factors.
The Greeks also classified foods according to their propensity to increase particular humors in the body. Thus cucumbers were considered cold and moist, spices hot and dry. In a body with an abundance or plethora of any given humor, a food or medicine of the opposite quality would act as a corrective. This therefore was an allopathic system that corrected with opposites. The Greeks also were intensely conscious of the texture and consistency of food and how easily it might be broken down and passed through the body.
The Greek system was elaborated upon in several succeeding civilizations, the most important of which were the Byzantine Empire; the Muslim world, which stretched from northern India to Spain; and medieval and Renaissance Europe. Although folk beliefs in Central and South America were influenced by Hippocratic ideas introduced by the Spanish, it appears that an older native system forms the foundation of ideas there.
Ayurvedic medicine is rooted in medical texts known as the Carakha Samhita, which may have originated before the first millennium b.c.e. but were written down much later. They include a dietary system still practiced in the twenty-first century. This system bears some similarities to the Greek system, but in practical application it is quite different. Ayurvedic physiology also begins with elements, but it recognizes five: air, fire, water, earth, and space. Each in combination with another creates what is called a dosha, a basic life force that governs physiologic functions but not exactly a humor. For example, space and air combine to create the vata dosha, which controls movements within the body, such as respiration, circulation, nerve impulses, and even ideas. Fire and water combine to form the pitta dosha, which is the principle of digestion and metabolism. Water and earth create the kapha dosha, which is the structural principle, giving solidity to the body. Too much or too little of each of these forces causes illness. The key here is a balance. As in the West, individuals are presumed to be born with a certain predilection toward an excess of one dosha. This is the prakriti, comparable to the concept of complexion in the West.
Just as in the Western system, foods and medicines can increase or decrease the power of any one of the doshas. For example, a weak digestion (pitta) is improved by heating the body with spicy foods, while an excess of pitta causes inflammation and dehydration and is corrected with foods that moisten the body. A weak kapha dosha leads to brittle bones and joints, so solid foods that strengthen the body are required.
Another concept in this system is that of the ojas, a form of vital energy that supports the immune system. Ojas can be increased by meditation and moderate eating but also with special substances like ghee or saffron. Foods also are classified according to their specific virtues or gunas, twenty in total, which assign foods values, such as cold or hot, soft or hard, oily or dry, heavy or light, dull or sharp, solid or liquid. All these terms reflect how food behaves in the body. With an excess of hot pitta (digestion), a cold food would be prescribed. With an excess of vata (transport), something heavy or dry would be corrective. Like the Greek system, this one is allopathic.
Another major system arose in ancient China, and it too was based on a revered text, in this case The Yellow Emperor's Classic of Internal Medicine, composed by one of the so-called celestial emperors, Huang-ti. Probably it was written during the Han dynasty and thus is roughly contemporaneous with the other systems. The first important concept in this system is qi, translated as energy, life force, or spirit. Qi supports life and helps fight off malign external influences. It also flows through the entire universe, so the individual microcosm is linked to the macrocosm. Health results when the two are in harmony, as do prosperity, peace, and good crops.
The central governing principle in the Chinese system is the opposition of two basic universal forces, yin and yang. Yin is female, dark, cold, soft, empty, night. Yang is male, light, warm, firm, full, day. Universal as well as physical harmony depends on a balance of these two forces. In addition, phases or processes of transformation in nature, not exactly elements as building blocks of nature, exist. Here too are five: earth, fire, wood, metal, and water. As processes of change, they govern, for example, generation. Water makes trees grow, wood burned creates fire, fire creates ash. Earth is the source of metals, and metals flow like water when heated.
All physiological functions can be described in terms of these transformations, like breaking down and processing foods. Specific foods or drugs aid a particular process, build up good qi, or promote the flow of qi through the body, as does acupuncture. Just as in the other systems, this is a holistic medicine that takes into account exercise, air quality, sleep patterns, sexual activity, and of course diet to keep the yin and yang forces in balance, the qi flowing, and physiological transformations in good order. The idea that certain foods are heating, cooling, drying, or moistening appears to have been imported from India around the sixth century c.e.
The Modern West
The modern concept of diet is much narrower than in the ancient systems, for it is concerned merely with food intake, calories, vitamins, and the like. Little consideration is given to the holistic aspect of living in harmony with external influences. Diet is not carefully prescribed according to the individual's unique complexion and habits. Calorie needs are defined by the rate at which energy is expended. All bodies are assumed to require the same nutrients of a specified range to allow for genetic and other sources of variation. This line of reasoning stems from envisioning the body as an engine fueled by food, a concept that arose in the nineteenth century following the research of the chemist Antoine-Laurent Lavoisier and later of Justus von Liebig. Only with the discovery of vitamins in the early twentieth century was this transformation complete. The concept of diet also was defined more narrowly as food intake or as a strict regimen intended to promote weight loss.
See also Calorie; China: Ancient and Dynastic China; Dietetics; Greece, Ancient; Indus Valley; Nutrition Transition: Worldwide Diet Change.
Anderson, E. N. "Traditional Medical Values of Food." In Food and Culture: A Reader, edited by Carole Counihan and Penny Van Esterik. New York: Routledge, 1997.
Fieldhouse, Paul. Food and Nutrition: Customs and Culture. 2d ed. London: Stanley Thornes, 1998.
Galen. Galen on Food and Diet, translated by Mark Grant. New York and London: Routledge, 2000.