History

It has been long known that certain foods are essential for human nutrition. Hippocrates noted nearly 2000 years ago that the symptoms of scurvy were found in armies that ate only dried rations for long periods of time.

During the 15th and 16th centuries, scurvy was endemic in navies due to a lack of fresh foods.
 
In 1747, James Lind, a surgeon in the Royal Navy, found that a rapid recovery from scurvy could be effected by giving patients oranges and lemons to eat each day. This is how the American term "Limey" for British sailors came about.

Captain James Cook (1728—1779) was also noted for the precautions he took in regard to the health of his men. He had the men eat sauerkraut and citrus fruit. There was only one death among his crews during all three years of the second voyage of discovery in the Resolution and Adventure in 1772—1775.

Although the benefits were known, it was not until the classical experiments of F. Gowland Hopkins (1861-1947) were published in 1912, that what he called "accessory substances" were essential for health.
 
The name "vitamine" was suggested by biologist Casimir Funk (1884—1967) in the belief that they were amines. Subsequently, when it was realised that they were not amines, the term was altered to "vitamin" on the suggestion of Jack Drummond (1891—1952).

The 1970s saw an increased public awareness of vitamins and their potential therapeutic uses, stirred along by Linus Pauling’s advocacy of Vitamin C for a variety of ailments. Life Extension movements and the promotion of self-help therapies have led to a proliferation of health food stores and books on the subject. Vitamins, minerals and supplements have almost become a "sub-culture" within the health food industry. It is estimated that some 75 million Americans take a daily dietary supplement (Health Foods Business 8/92, & Levy, A.S.) and spend more than $4 billion a year for vitamin and mineral products (Consumer Health 1997).

Theory
There are several reasons why people take vitamins and supplements. Some for insurance, others take megadoses in the belief that they can be used as preventatives or cures for various diseases.
 
Practice
Ingestion of tablets, pills, capsules or intravenous injection.
Sublingual tablets and sprays.

Assessment
All classes of living beings — man, microorganisms, plants and animals — require vitamins for growth and well-being. However, vitamins are differentiated from other essential organic ingredients on the basis of the very small amounts required in the diet. Thiamine for example, may comprise 0.001% of an adequate diet, whereas an essential amino acid is required in amounts of about 1%.
 
About thirteen vitamins are known and deficiencies of all are causative of disease in human beings. It is generally accepted by physicians and dietitians, that a balanced diet is adequate to maintain good health and that vitamin and mineral supplements are only necessary in cases where they are deficient in one's diet. Apart from fat-soluble vitamins, excess of which is stored, any amount over and above the Recommended Dietary Allowances (RDAs), that is, those normally required by the body, is simply excreted as urine.

The principal danger and a major concern with vitamin supplements are toxicity and side effects. The advocacy of megadoses, in particular vitamin C, which has been variously prescribed for the common cold, infections and as a cancer cure, have proved ineffective.
 
A further danger is in self-medicating, where people take it upon themselves to take vitamins without medical advice.

Well designed experiments have been conducted under a strict set of rules known as the scientific method. This method is a system of logical steps designed to separate cause-and-effect from coincidence. Trials with vitamin C conducted in 1972, 1974 and 1975 by Drs. Coulehan and Anderson at the University of Toronto, Canada, showed no reduction in the incidence of colds, nor their prevention.
 
A double-blind Australian trial in 1981 with 95 pairs of identical twins reported that the vitamin C group had slightly more colds but of a shorter duration.

Another study in 1984 by Dr. M.H. Briggs reported no prevention and no benefit. In many other scientifically conducted trials the conclusion has been the same — there is no difference in the prevention or severity of colds by taking vitamin C. The misconception of some people is that if a little is good for you then more must be better, leading to overdosing.

Some of the results include serious birth defects and stunting of growth, atrial fibrillation and other cardiac arrhythmias, flushing and the burning of the skin, and liver irritation (Niacin), allergy-type reactions (Thiamine), diarrhoea and water retention (pantothenic acid), neurological damage (Pyridoxine), discomforting symptoms in patients with existing neurological problems (Riboflavin, and Folic add), symptoms of brain tumours and drying and peeling of the skin (Vitamin A), diarrhoea (Vitamin C), and increased calcium absorption and calcification of soft tissues (Vitamin D). Studies of vitamin E have proved inconclusive. Two epidemiologic studies published in The New England Journal of Medicine, 1993, found that people who took vitamin E supplements had fewer deaths from heart disease. However, these studies did not prove that taking vitamin E supplements was useful because they did not rule out the effects of other lifestyle factors or consider death rates from other diseases. The down side of vitamin E is that it increases the anticoagulant action of warfarin and can promote excessive bleeding. Mineral supplements in large amounts are also questionable. Although potassium is prescribed by doctors to counteract the effect of a diuretic, cardiac arrest can be caused by excess amounts. Too much zinc, iron or copper will cause nausea and vomiting, and high levels of zinc may also increase susceptibility to infection and increase serum cholesterol and low density lipoprotein levels.

One fact which negates the alleged benefits of consuming water-soluble supplements over and above those obtained through a balanced diet is the kidney threshold level. If the concentration of a substance in the blood exceeds its kidney threshold level, the excess is not reabsorbed and is released into the urine as unwanted waste. If it’s not needed, it won’t be accepted, and becomes urine.

One supplement worth mentioning is folic acid, recommended for the prevention of birth defects. Although a well-balanced diet which includes foods such as liver, green leafy vegetables, legumes, wheat germ, yeast, egg yolks, beets, whole wheat bread, fortified cereal, citrus fruits and juices provides this requirement, many women (in America) are only consuming half the U.S. Recommended Dietary Allowance.

The best advice to anyone contemplating supplementing their diet with vitamins or mineral supplements is not to self-medicate, but consult a physician.


References:

Barrett, Stephen. 1989. Megavitamin Therapy: Claims and Cautions. Priorities, Spring 1989.

-------------------- and Herbert, W. 1994. The Vitamin Pushers, Prometheus Books, Buffalo, NY.

-------------------- and Jarvis, William T. 1993, The Health Robbers, Prometheus Books, Buffalo. New York.

Barrett, Jarvis, Kroger, London, 1997, Consumer Health: A Guide to Intelligent Decisions, Brown & Benchmark.

Jarvis, William. 1984. Vitamin Use and Abuse, Contemporary Nutrition. 9:1-2.

Kastner, Mark & Burroughs, Hugh. 1993, Alternative Healing, Halcyon Publishing, La Mesa, California.

Levy, A.S. (No date) Patterns of Nutrient Intake Among Dietary Supplement Users: Attitudinal and Behavioral Correlates. Center for Food Safety and Applied Nutrition, FDA, Washington D.C.

Marshall, C. W. 1992. Can Megadoses of Vitamin C Help Against Colds? Nutrition Forum, Vol. 9, No.5.

------------------- 1982. Vitamins & Minerals, Help or Harm? Stickley.

Raso, Jack, 1994, Alternative Healthcare, Prometheus Books.

Zwiky, Hafner, Barrett and Jarvis. 1993. Reader's Guide to Alternative Health Methods, American Medical Association, Chicago, IL. 60610.