Nutrition

Nutrition is the study of the relationship between diet and states of health and disease. Absent appropriate nutrition, functioning will be compromised and diseases can take hold, potentially resulting in death.

History and recent developments

The role of nutrition in health was recognized by the ancient Greeks - and probably also much earlier - who advised that food should be one's medicine. Especially Eastern cultures have for more than two thousand years used certain foods (e.g. herbs) as remedy. Clearly these early insights were based on simple observations that nutrition - aside from the obvious need to eat sufficient energy - has a direct effect on the health of the organism (though the placebo effect may have overstated its significance in some cases).

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

In the 18th century, many sailors on long journeys died from scurvy; indeed, some naval ships lost more men through illness than through enemy action. The cause of this was not understood until it was discovered that adding fresh limes to the ship's supply of preserved food seemed to boost the sailors' resistance to the illness and resulted in fewer deaths. The existence of separate compounds/elements in food that are essential for survival had been discovered, and this discovery of vitamin C, which prevents scurvy, spurred the search for other so-called 'essential nutrients' (see next section). 'Vitamins' were first written about in 1912 by Sir Frederick Gowland Hopkins, who was knighted and received the 1929 Nobel Prize in Physiology or Medicine for his achievements.

Related Topics:
Scurvy - Vitamin C - Vitamins - 1912 - Sir Frederick Gowland Hopkins - Nobel Prize in Physiology or Medicine

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

A hidden epidemic gradually emerged in the post World War II years, where non-communicable endemic illnesses began to flourish, such as heart disease, cancer, diabetes, and obesity. Although medical drugs are used large scale to manage this development, more and more people are becoming aware that the post-war modern lifestyle (e.g. poor choice of foods, less physical activity) may be the primary cause of such so-called lifestyle-related diseases. Despite this realization, however, lifestyle- and obesity-related diseases are becoming increasingly prevalent all around the world (see Nutrition, industry and food processing).

Related Topics:
Epidemic - World War II - Heart disease - Cancer - Diabetes - Obesity

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

In the latter half of the 20th century, technological developments and a world-wide epidemic of lifestyle related diseases has spurred detailed research into the specific health effects of different foods. For example, in the years following the Second World War, the prevalence of heart disease in Western countries began escalating and came under the scrutiny of nutritional researchers around the world, especially in the USA. An increased intake of fat and cholesterol was thought to be a major cause, but later epidemiologic research has demonstrated that the prevalence of heart disease has continued to increase markedly despite a significant decrease in fat intake. Further, none of the performed randomized controlled trials assessing the role of dietary cholesterol or saturated fat in heart disease convincingly support the hypotheses that dietary cholesterol (unoxidized) and saturated fat (from fresh, whole foods) in and of themselves promote heart disease.

Related Topics:
Second World War - Epidemiologic - Randomized controlled trials - Saturated fat - Hypotheses - Cholesterol - Unoxidized

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Later research has revealed the potential adverse effects on (heart) health of trans fatty acids, which were introduced to the human diet large scale with the new technology of lipid hydrogenation. Partially hydrogenated oils were added to many processed foods and helped make possible the production of solid margarine from cheap liquid vegetable oils, and helped increase the shelf-life of many foods. In the late 90?s the harmful effects of excess trans fatty acids in the diet came into the attention of the public and governments began restricting or banning its use.

Related Topics:
Trans fatty acids - Hydrogenation

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

While one ?camp? of researchers focused on the hypothetical benefits of reduced intake of fat and cholesterol, another ?camp? emphasized the possible benefits (initially for diabetics) of reducing intake of carbohydrates and thereby preventing excess blood sugar raise and stimulation of the fundamental, all-important hormone insulin. In the early 80's, researchers began to systematically measure the amount of sugar in subjects? blood before and after consumption of foods containing a standard amount of digestible carbohydrate (e.g. 50 grams). The resulting comparable values of the blood sugar raising potential of different carbohydrate foods are ranked in the Glycemic Index. In general, the Glycemic Index demonstrates that eating processed, carbohydrate-dense foods (higher GI) results in a higher blood sugar raise and insulin release than does eating whole, unprocessed carbohydrate-containing foods (lower GI). In more recent years, researchers have focused more on the glycemic load which factors in the amount of carbohydrate eaten, whereas the glycemic index only compares the blood sugar raising potential of foods with a set amount of carbohydrate (i.e. eating large amounts of low GI foods can result in a higher blood sugar raise and insulin stimulation than eating small amounts of high GI foods).

Related Topics:
Cholesterol - Diabetics - Hormone - Insulin - Glycemic Index - Glycemic load

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The recent advances in molecular biology and gene technology, for example with the use of 'knock-out' animal models where specific genes are inactivated, have enabled a more informative study of how nutrition 'communicates' with our genes and thus with the chief metabolic hormones. Since the Human Genome Project was completed, the focus has shifted towards study of the proteome. The study of hormones and other cell-to-cell signalling molecules is receiving special attention.

Related Topics:
Molecular biology - Human Genome Project - Proteome

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The previous mechanistic view of food merely as fuel thus falls short. Foods and their diverse components are capable of affecting the control of metabolism directly via hormones and genes, to the effect that different foods can for example affect energy expenditure to varying degrees, also when energy intake is constant.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~