There are thirteen vitamins and eighteen minerals that are essential to good health and life. Despite the fact that only small amounts of each vitamin are needed, vitamins are essential to all of the body’s biochemical processes. They are required to convert food into energy and to help the body manufacture hormones, blood cells, and nervous system chemicals.
Vitamins are obtained entirely from food, except for Vitamins D, B5 and B7, which come in part from other sources. Pantothenic acid (B5) and vitamin D can be produced by the absorption of sunlight through the skin. Ten minutes of exposure to the bright midday sun produces at least half of what adults require each day. The remainder must be consumed from fatty fish, such as salmon and tuna, and from dairy products. Some of the needed biotin (B7) and pantothenic acid is produced by normal intestinal bacteria, while remaining amounts are easily obtained from food.
Minerals are closely related to vitamins. They originate in soil and water and are found in all plants and animals. The major (or macro) minerals, those needed in relatively large quantities by the body, include calcium, phosphorus, and magnesium. Trace (or micro) minerals are needed in very small amounts. Iron, fluoride, selenium, and zinc are among the eighteen essential trace minerals. Vitamins and minerals work hand in hand, influencing how well the body absorbs both.
Vitamins and minerals have been studied for decades, and a great deal is known about the sources and roles of each, as well as about what happens when the body takes in too much or too little of a particular substance. Researchers and scientists continue the study in this area, working to gain more knowledge about the effects of vitamins and minerals on health and physiological functioning, or learning that a bit more or less of a nutrient can produce better results than had been assumed. This is why the Recommended Dietary Allowances (RDA) are reviewed regularly by the Food and Nutrition Board of the National Research Council of the National Academy of Sciences.
Vitamin supplements are purchased by up to 80% of U.S. households. Despite such widespread use, serious debate continues about the value of vitamin pills and other dietary
supplements for the general public.
Scientific studies indicate that the required nutrients should come from an average balanced diet, and that only certain groups of people need to take supplements. This group include pregnant women, young children, alcoholics, those with diseases that inhibit absorption of nutrients, post menopausal women trying to prevent osteoporosis, and people whose diets do not provide the necessary nutrients.
Recent studies, however, show that less than 1/3 of adults eat 5 servings of fruit and vegetables a day, and many older people consume fewer calories than required to meet their daily nutrient requirements. In addition to vitamin supplements sold to compensate for less than ideal eating habits, supplements are promoted as insurance against inadequate intake of essential nutrients, including proteins. Other supplements focus on people’s special needs, such as to improve athletic performance or to lose weight.
Many products in the market today claim that they can reduce or cure problems such as depression, sleep disorders, cancer, indigestion, arthritis, and obesity. Still others promise to achieve anti-aging effects, rejuvenation, energy, and the elimination of toxins from the body. Literally hundreds of dietary supplements, nutritional aids, and similar products are widely promoted and generally available to the public. However, their promises are rarely substantiated in fact.
A dietary supplement act passed in 1994 removed dietary and nutritional supplements from Food and Drug Administration (FDA) review. Therefore, supplements are not regulated. They are not evaluated for safety or purity, nor are they studied to see whether they live up to promoters’ claims. Many ads for special supplements do not list ingredients, so the buyer does not know what is contained in the capsules that promise results such as improved memory or greater stamina.