The Use of Vitamin and Mineral Supplements
Are vitamins and minerals necessary?
A large number of apparently healthy people believe that they need vitamin and mineral supplements every day to stay healthy. About one-half of adult Americans regularly use a vitamin supplement which frequently contains iron or other minerals. Pregnant women, small children and the elderly are frequent consumers of vitamin or mineral supplements.
Some people believe they need additional vitamins for extra energy. Some believe that cancer, heart disease, the common cold, arthritis and other disease are caused by mineral and vitamin deficiencies. Many people believe that a faulty diet is a major cause of their health problems. Consumers often claim that they need dietary supplements because depleted soils and the heavy refining of foods have produced food that is deficient in nutrients. Enthusiasts would have you believe that vitamin and mineral pills can delay old age, offset the ill effects of stress, cure aches and pains and give you a better memory.
Despite a lack of evidence that vitamin and mineral supplements can cure or treat anything but rare deficiencies and absorption disorders, their benefits are widely extolled. The promotion of vitamin and mineral supplements has been referred to as the most widespread form of quackery in America today. The annual sale of supplements now exceeds $3 billion in the United States.
But, don't some people need supplements?
There are certain groups of people who may have a greater risk than others of developing a nutrient deficiency. These include premature babies, persons on very low-calorie reducing diets, pregnant women, women with excessive menstrual bleeding, heavy smokers, alcoholics, elderly people who do not eat properly or who cannot properly absorb the nutrients they eat, and others whose nutrient needs are altered by medications or illness. Unless the total vegetarian has a sure source of vitamin B12 they may need to regularly take a vitamin B12 supplement. There are also a number of rare hereditary disorders which may respond to large doses of a particular vitamin or mineral. It is important that these individuals be under the care of a physician rather than being treated by self-medication.
Are megadoses of vitamins and minerals safe?
Many people believe that if small amounts of vitamins and minerals are good for you, then large amounts (i.e. megadoses, or at least 5 times the RDA) will be even better. This notion is not true. Vitamins and minerals are potentially toxic when ingested in large amounts. When physiological mechanisms become saturated there is no improvement of any body function with additional intake of vitamins or minerals. Overdoses of vitamins A, D, B6, and C and the minerals zinc and selenium are of particular concern because of their potential for toxicity.
Vitamin D is the most toxic of the fat-soluble vitamins. Vitamin A toxicity (symptoms include headache, hair loss, loss of appetite, dry skin, joint pains, and vomiting) has been seen in young people who have been taking relatively low megadoses of this vitamin over a period of two years for skin disorders. Large doses of vitamin A or vitamin A analogs (such as Accutane and Tegison) are particularly detrimental for women during early pregnancy due to the risk of serious birth defects or spontaneous abortions. While large amounts of vitamin A is toxic, beta-carotene (the plant pigment found in abundance in dark-green leafy vegetables and yellow-orange fruits and vegetables) is not toxic. Persons who consume an ample supply of foods that are rich in beta-carotene have lower rates of cancer.
It was thought that water-soluble vitamins were non-toxic because they are readily excreted. However, some water-soluble vitamins are in fact toxic. Large doses of vitamin B6 (over 150 milligrams/day) are commonly taken for carpal tunnel syndrome and premenstrual syndrome. Such amounts can produce toxic effects on the peripheral nervous system that may not be reversible. Many women consuming even less than 100 mg of B6 per day for over 6 months had neurological symptoms (twitching, numbness, burning, spine tingling, etc.), shooting chest pains and muscle weakness.
Many people consume large amounts of vitamin C on a regular basis in an attempt to protect themselves against the common cold, cancer, heart disease, and countless other disorders. Actually, it requires less than 100 mg daily to saturate body tissues. In scientific studies cancer patients given high levels of vitamin C have not done appreciably better than those not treated with vitamin C. A number of research studies have shown that people consuming up to six grams of vitamin C daily tended to have as many colds as those not taking the vitamin C but the colds tended to be slightly less severe and did not last as long. Adverse effects of megadoses of vitamin C have been reported. Large doses of vitamin C also cause false readings with a number of important laboratory measurements.
In the body vitamins and minerals are involved in a whole array of biochemical interactions. Taking megadoses of one or more of these micronutrients could interfere with the normal absorption and metabolism of other nutrients. Large doses of vitamins A and E are antagonistic to the action of vitamin D and thereby increase the vitamin K requirement. Large iron supplements impair the absorption of zinc and copper while prenatal folate supplements can decrease zinc absorption. Vitamin and mineral supplements can also affect drug action by interfering with the body's absorption, use or elimination of the drug. For example, calcium and iron supplements decrease the absorption of penicillamine while folic acid supplements interfere with the anticonvulsant action of phenytoin.
Are calcium supplements helpful?
With the present concern about osteoporosis the sale of calcium supplements has skyrocketed. While opinion is divided as to whether calcium supplements can actually slow the onset of osteoporosis, there are risks in taking large doses of calcium. There "natural" sources of calcium (oyster shells, bone meal, and dolomite) often contain significant amounts of the toxic heavy metals. Urinary tract stones may result in susceptible persons who consume at least 1000 mg per day. Excessive amounts of calcium can also cause diminished iron absorption and may interfere with the normal blood clotting mechanisms.
What about other supplements?
There are a number of other substances sold as supplements which are not essential in the diet. These substances include PABA, bioflavanoids, nucleic acids, pangamic acid, "vitamin B-15", inositol, and choline. Money spent on such supplements could be better spent to buy wholesome foods. Also, laetrile has no known function in humans and does not combat cancer, and may in fact cause cancer.
Fatty fish has been suggested to lower risk of heart disease, since it lowers blood triglycerides and inhibits blood clotting. However, the use of concentrated fish oils is not recommended because of certain hazards, such as a potential for bleeding, vitamin E deficiency, and vitamin A and D toxicity. Fish oils may also contain high levels of PCB's and other environmental pollutants. Diabetics are strongly advised not to use fish oil supplements as they interfere with insulin utilization.
Some believe that natural vitamins are better than synthetic ones. The unfounded claim is made that the natural vitamins are better absorbed. The "natural" or "organic" vitamins are not only more expensive but are in fact largely synthetic. For example, "Rose Hip Vitamin C" tables are largely synthetic ascorbic acid containing a small amount of vitamin C concentrated form rose hips.
What does the Nutrition Council recommend?
Since dietary supplements are not needed by the majority of people to obtain a nutritionally adequate diet and may be toxic, their use is not advised unless prescribed by a physician. Both the American Dietetic Association and the American Medical Association have advised Americans to get their nutrients from food rather than from pills whenever possible. Research indicated that there are no benefits to self supplementation beyond the RDA's. For those who desire to take a supplement, a low-dose multivitamin/mineral supplement would be better than ingesting a whole range of high potency supplements. Good nutrition results from appropriate choices made within a wide selection of wholesome, unrefined foods.