Beta Carotene
Beta Carotene Makes the News
On Friday January 19, 1996, an article appeared in the New York Times. The article reported on two studies that were conducted. One study, to see, if beta-carotene could forestall the onset of cancer in people who had either smoked all their lives, or had worked with asbestos. The other study, involved 22,071 doctors, who were randomly assigned to take beta carotene. The results of these studies, gave plenty of ammunition to those like Dr. Victor Herbert, who warn against taking any vitamin supplement.
According to Dr. Richard Klausner, director of the National Cancer Institute, which financed both studies, "With clearly no benefit, and even a hint of possible harm, I can see no reason that an individual should take beta carotene."
Beta carotene, is a naturally occurring substance, found in fruits and vegetables, that is converted to vitamin A in the body. The notion that beta carotene had a protective effect, came from epidemiological studies, that showed, that people who ate a substantial amount of fruits and vegetables in their diets had a significantly less chance of developing cancer or heart disease. Furthermore, many vitamin manufacturers claimed, that beta carotene, if given orally, would protect against cancer and heart disease. What both of these conclusions neglected to consider is: that no vitamin works alone. To credit any vitamin with claims of improving ones health, is forgetting this fact. Because we as a nation, are always looking for the Magic Bullet, we get ourselves into this situation. Even more remarkable, is that researchers, whose background is in biochemistry, should warn of never trying to obtain an effect from one nutrient alone.
One of the studies, which was conducted with high risk participants may indicate, that maybe it is easier to prevent the onset of cancer in patients who haven't smoked or worked with asbestos. Its also possible, that many of these people had already contracted cancer that wasn't detected before the study began. The participants in this study were given beta carotene along with vitamin A. Investigators found that the death rate from lung cancer was 28% higher among the participants who had taken the supplements than those who had taken a placebo. The reason for these increases were unclear to the investigators.
To understand why beta carotene may have been unsuccessful, and possibly harmful, lets examine how beta carotene function as a anti-oxidant.
Beta carotene is not only a precursor of vitamin A, but is also a potent antioxidant. It is the most effective quencher of singlet oxygen. Singlet oxygen is very powerful free radical. However, once beta carotene combines with singlet oxygen, it becomes a pro-oxidative free radical; but, in the presence of vitamin E, beta carotene is converted back to a powerful anti-oxidant. Vitamin A also protects our bodies from free radical damage. Vitamin A protects lipids, especially cell membrane lipids, from oxidation. Vitamin C protects vitamin A from becoming a free radical. What would be interesting, would be to evaluate a combination of anti-oxidants in a study, instead of this single bullet approach. When you study anti oxidant functions you see that many substances are involved.
Posted
by Dr. Steven Felder
