Do Vitamin C and Other Antioxidants Benefit Health

Using Observational and Experimental Studies to Test Medical Hypotheses

Linus Pauling was a creative and prolific chemist who was awarded two Nobel Prizes: the Chemistry Prize in 1954 for fundamental work on the structure of molecules and the Peace Prize in 1963 for articulating the dangers of nuclear proliferation. He might have become the only person to receive three Nobels if he had beaten Watson and Crick in deducing the structure of DNA . Late in his long life, Pauling became a proponent of the multiple health benefits of large daily doses of vitamin C. I remember hearing Pauling lect ure about v itamin C to a large and enthusiast ic audience at the University of Nevada, Reno, in 1985, when he was 84 years old. He was a persuasive advocate who used charm and humor, as well as an arsenal of data and anecdotes, to deflect criticism. He summarized his ideas in a book called Vitamin C and the Common Cold, first published in 1970. Many books of nutritional advice for the general public have been published, but his has had a staying power matched by few others. One reason may be that Pauling's stature as a scientist gave his ideas automatic credibility. Pauling's expertise in biochemistry makes it tempting to accept his views about vitamin C uncritically, but it is not necessarily wise to do so. His ideas have st imulated many attempts to test various hypotheses about the beneficial effects of vitamin C, and this research illustrates the strengths and limitations of purely observational, as well as experimental, approaches to medical questions. By looking closely at the evidence yourself, I hope you will see the value, as well as the pleasure, that comes from carefully dissecting a scientific problem.

Inadequate intake of vitamin C leads to a disease called scurvy, whose symptoms include dry skin; poor healing of wounds; bleeding from the skin, joints, and gums; and unusual fatigue. Scurvy was especially prevalent among sailors on long sea voyages. Although vitamin C deficiency as the specific cause of scurvy was not discovered until 1911, the British navy learned in the late 1700s that it could easily be prevented by eating fresh fruits and vegetables. Scurvy is uncommon in developed countries today except among alcoholics and indiv iduals who are mentally ill or socially isolated.

It only takes about 10 milligrams (mg) of vitamin C per day to prevent scurvy. The daily intake recommended by the Food and Nutrition Board of the U.S. National Academy of Sciences is 90 mg for males and 75 mg for females (Food and Nutrition Board 2000). These values are sufficient to prevent scurvy, even if a person did not ingest any v itamin C for a month, and may have other health benefit s not specifically documented by the Food and Nutrition Board, but they are well below levels that are widely believed to be beneficial. For example, my personal physician recommends a vitamin C supplement of 500 mg/day to slow aging and protect the heart and vascular system, and a recent survey showed that two-thirds of people in the United States who sought medical care for colds bel ieved that v itamin C allev iated their symptoms (Braun et al. 2000). What evidence exists for these and other purported health benefit s of large doses of v itamin C?

Many researchers have reported such evidence from various types of studies, so vitamin C is a good example to introduce the array of methods that can be used to learn how health and disease are influenced by diet, as well as by different medical treatments. A crit ical evaluat ion of the present state of knowledge should prov ide a foundat ion for sensible interpretation of future studies that are reported in the press, especially if we focus on the strengths and limitations of various methods that can be used to answer questions about diet and health because these fundamental methods will be used in f u-ture studies as well.

Alcohol No More

Alcohol No More

Do you love a drink from time to time? A lot of us do, often when socializing with acquaintances and loved ones. Drinking may be beneficial or harmful, depending upon your age and health status, and, naturally, how much you drink.

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