Chapter 3
VITAMINS

In 1976, Linus Pauling, the Nobel Prizewinning chemist, announced that vitamins (especially vitamin C) could help prevent strokes, mental illness, heart disease, cancer, and infection. With “optimal intake,” he claimed, people could extend their lives an extra 12–18 years. (Pauling defined “optimal intake” as falling somewhere between 3,200 and 12,000 milligrams a day, or what a person could obtain from consuming 45 to 170 oranges.) Pauling's dramatic claim, although subsequently challenged by many scientists, set off international studies of possible links between vitamins and disease prevention. By the late 1980s, one of every three Americans was taking vitamin C supplements, and today Americans spend $2 billion a year on vitamins, according to David Zimmerman, author of Zimmerman's Complete Guide to Nonprescription Drugs . A growing body of evidence gathered from both underdeveloped and fully industrialized countries now strongly reinforces the late Pauling's once-maverick contention that vitamins play a significant role in maintaining good health and in helping to treat infection and disease.

The Role of Vitamins

Vitamins are chemical compounds that must be included in the human diet to ensure growth and health. They are needed only in small amounts to build, maintain, and repair tissues and usually are available in a balanced diet that features a variety of fresh fruits and vegetables.

To obtain sufficient vitamins, most nutritionists recommend that a daily diet include multiple servings of cereal or bread; dairy products (milk, cheese, ice cream, cottage cheese); meat, fish, or eggs; and vegetables and fruits. Several vitamins are recommended as supplements, either because they are deficient in the diet or because the body does not produce them.

However, vitamins alone will not take the place of a good diet, nor will they provide energy. The human body needs substances found in food such as protein, minerals, carbohydrates, and fats, and vitamins themselves often cannot work without the presence of various foods.

There is substantial controversy as to whether people should take vitamin supplements and whether such supplements can prevent chronic diseases. Individuals should be fully informed of the supplements' potential levels of toxicity because they are medicines and can cause either desirable or undesirable changes in the body's physiology or internal anatomy. Some vitamins, when taken in excessive doses, can cause side effects, adverse interactions with other drugs, and other problems.

This chapter analyzes each of the essential vitamins and describes its chemical composition, its physiological functions, its occurrence in natural foods or supplements, and the current Recommended Daily Allowance (RDA). The RDA for each vitamin represents the best current assessment of safe and adequate intakes and serves as the basis for information that appears on product labels. Each section discusses concerns about deficiency and toxicity and concludes with results of clinical trials of vitamin therapies.