CANCER AND NUTRITION: VITAMINS, MINERALS, AND OTHER NUTRIENTS

Living cells contain proteins, nucleic acids, carbohydrates, lipids, and certain organic substances that function in very small amounts, called vitamins. It has been known for centuries that many diseases are directly related to diet. Night blindness was cured by eating liver. In the eighteenth century, cod liver oil was used to treat rickets. The juice of limes was found to prevent the symptoms of scurvy among British sailors in the late eighteenth century (and from then on, the sailors were known as "limeys"). F.G. Hopkins in England proved in 1912 that animals require certain "accessory factors" in addition to proteins, fats, and carbohydrates. In the same year, Casimer Funk lessened the symptoms of beriberi among Japanese sailors by giving them an extract of rice husks, which was an amine. He was the first to denote this essential amine as vitamine (vita means life). Shortly thereafter, a scientist in the United States named E.V. McCollum showed that animals need both water-soluble and fat-soluble vitamins to maintain proper existence. Then it was discovered that bacteria which normally live in our intestines to help with food digestion can produce some of the vitamins that we require.

Vitamins are divided into two groups: those that are soluble in fat and those that are soluble in water. Fat-soluble vitamins are vitamins A, D, E, and K. And those that are soluble in water are thiamine (B1), riboflavin (B2), nicotinic acid, pantothenic acid, pyridoxine (B6), biotin, folic acid, vitamin B12, and ascorbic acid (C).

Vitamins are essential to life and play a crucial role as helper enzymes in important chemical functions of the body. If there are deficiencies of vitamins, a variety of diseases may occur, and the immune system will not function properly.

Vitamins interact with each other, and a few are toxic in high doses. Some vitamins can be stored for long periods of time, while others have to be supplied on a daily basis. We now know that certain drugs and hormones can produce a gradual vitamin deficiency by interfering with the ways in which vitamins are broken down for use in the body. Vitamins are also needed for normal prenatal development. They are of great interest because of their interplay among all organ systems of the body, especially the immune system.

What are the proper amounts of vitamins that we should ingest daily? The 1990 Recommended Dietary Allowances were published by the National Academy of Sciences. Recommended Dietary Allowances (RDAs) are the levels of intake of essential nutrients considered to be adequate to meet the nutritional needs of most healthy people in the United States, as judged by the Committee on Dietary Allowances of the Food and Nutrition Board. Individuals with special nutritional needs are not covered by the RDAs.

Recommended Dietary Allowances were established in 1943 to be used as a guide for planning and purchasing food supplies for the armed forces. RDAs are recommendations for the average daily amount of nutrients that healthy people should consume over a period of time and are estimated to exceed the requirements of most individuals. The RDAs are revised every five years. Needs for extra nutrients arise from such problems as inherited disorders, infections, cancer, chronic diseases, and the use of some medications.

After the food for our American diet has been harvested or slaughtered, it is prepared in large volume for sale and loses much of its nutritional value. You see, the RDAs represent the minimum nutrient levels needed to prevent obvious signs of vitamin deficiencies. These recommended levels are probably not the maximum needed for good health. Dr. Linus Pauling, a Nobel laureate, has recently shown in animal studies that the levels of vitamins required to maintain good health varied by 2,000 percent from one animal to another of the same species. Dr. Pauling extrapolates from this study that human requirements may vary just as greatly, and therefore the RDA for a given food may be one person's exact requirement but not the next person's. Dr. Pauling is quoted by the Washingtonian magazine in March 1981 as saying that today's diet does not provide as many vitamins as the diet of two generations ago. Over the past seventy-five years people have increased their consumption of fat by 30 percent and sugar by 50 percent, and have decreased their consumption of vegetables, grains, and fruits by 40 percent. In fact, Dr. Pauling found that 110 raw, natural foods eaten by our grandparents contained two to five times more vitamin A, thiamine (B1), riboflavin (A2), and pyridoxine (A6) than these same foods contain today.

It is more difficult to identify a person who is only marginally deficient in vitamins than someone who is obviously deficient. Whereas a person who is grossly deficient in vitamins demonstrates many physical problems and complains about specific symptoms related to the deficiencies, a person with only marginal deficiencies demonstrates no such signs or symptoms and does not appear to be ill. The RDAs were designed for healthy people, and the values recommended may not be adequate for persons developing undetected marginal deficiencies.

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