University of California at Berkeley Wellness Letter: The Newsletter of Nutrition, Fitness, and Stress Management from the School of Public Health -- Volume 12, Issue 7, April 1996

Good health depends on consuming a good diet, and nutritional supplements are no substitute for nutritious foods. Nevertheless, because so few Americans eat all the fruits, vegetables, and whole grains they should, we decided a few years ago to recommend the following daily supplements of antioxidants for all adults:

*6 to 15 milligrams (10,000 to 25,000 IU) of beta carotene.

*200 to 800 IU (133 to 533 milligrams) of vitamin E.

*250 to 500 milligrams of vitamin C.

In January, however, the National Cancer Institute announced, on the basis of two rigorously designed clinical trials, that beta carotene supplements offer no protection against cancer and heart disease and could even be harmful in some cases. Thus, our editorial board, led by Drs. Sheldon Margen, Gladys Block, and Leonard Syme of the School of Public Health at the University of California at Berkeley, is reconsidering its position on beta carotene.

The recently completed Physicians' Health Study tested beta carotene supplements (50 milligrams every other day) as a means of preventing cancer and heart disease. After 12 years it was clear that the supplements offered no benefit.

The other study, known as CARET (Beta Carotene and Retinol Efficacy Trial), tested beta carotene and vitamin A in people at high risk for lung cancer -- smokers, former smokers, and asbestos-industry workers. (Beta carotene is the plant from of vitamin A, and the body can convert it into vitamin A.) The study, scheduled to continue for 21 more months, was halted on ethical grounds because there was no evidence of benefit and indeed some evidence of harm. After four years, those taking the supplements actually had a higher lung cancer rate and higher overall mortality rate than the control group. This was particularly troubling in light of a large study from Finland, published in 1994, which also found that beta carotene supplements increased the risk of lung cancer for smokers. That study was the first hint that beta carotene supplements might actually do harm. It's still a mystery how they could cause harm.

Antioxidants: the key to good health Health-conscious people and researchers (not to mention the supplements industry) were deeply troubled by this news. How did we get into this beta carotene trap? First. let's backtrack a bit.

In the past decades, scientists have made great strides in understanding the relationship between diet and health, and have suggested that cancer, heart disease, and other chronic ailments may in some sense be "deficiency" diseases. That is, if we would improve our eating habits, maybe we could decrease our risk of chronic diseases.

How can this be? It's known that electrons, which are electrically charged atomic particles, are always being released and shifted around. In the process, so-called free radicals are born. This is part of then normal chemical processes of living cells. External factors such as exposure to cigarette smoke, radiation, or ozone, for example, can also intensify free radical activity. Free radicals can damage the basic structure of cells, leading to chronic disease and accelerating the aging process. It's now known that the body has elements to protect against free radicals. These are known as antioxidants, chemical "good guys" that quench or "mop up" free radicals and help repair damage to cells. Some antioxidants are manufactured by the cells themselves. Others are nutrients we eat. Chief among them are two antioxidant vitamins, C and E, plus beta carotene, one of the carotenoids, which are also antioxidants.

Beta carotene: how it took center stage Not strictly classified as vitamins, the carotenoids are a huge family of substances occurring in plants. The most famous member of this family is beta carotene, but there are actually 600 different carotenoids. Only about 400 have so far been chemically identified and named. In studies, foods that provide carotenoids--particularly beta carotene, which has been the much studied star of the family--show up time and again as promoters of good health. Study after study has shown that people who have consumed foods rich in beta carotene and thus have high blood levels of it also have a lower risk of heart disease, cancer, certain eye disorders, and/or other chronic problems.

The implication of these findings is tricky. If you have a high blood level of beta carotene (and aren't taking the supplement), that shows that you eat a lot of fruits and vegetables and probably a good diet overall. It also indicates that you have a lot of other carotenoids in your bloodstream, too--some still not even named or known. One or many of these carotenoids may be the true hero, or heroes. Or maybe they all work together. Or perhaps beta carotene is a marker for other beneficial substances in fruits and vegetables.

But, alas, the idea that taking beta carotene in a pill (isolated beta carotene) would have the same health effects as eating lots of fruits and vegetables may not be valid. We are a long way from being able to create a pill that will duplicate all the carotenoids in foods.

In their efforts to make the most of emerging knowledge, health experts (including ourselves) may have been too quick to jump on the beta carotene bandwagon, as Dr. Block calls it. This may have happened because scientists first focused on beta carotene's link to vitamin A rather than its functions as just one of many carotenoids. In addition, of all carotenoids, it was the easiest to measure in the blood. It certainly looked like a key to lowering the risk of heart disease and cancer. And it was obvious that Americans weren't consuming enough of it. Thus came the recommendation to take supplements. It's time to rethink this issue.

First line of defense: diet Once again we emphasize the importance of what you eat. A minimum of five fruits and vegetables a day will supply a lot of carotenoids and other vital nutrients. Yet most Americans don't come close.

Here's a short list of foods rich in carotenoids: carrots, oranges, tomatoes, grapefruit (especially the pink or red kind), broccoli, Brussels sprouts, kale, spinach and other leafy greens, cantaloupe, yellow corn, sweet potatoes, pumpkin, butternut and acorn squashes, apricots (fresh and dried), peaches, tangerines, mangoes, sweet red peppers, hot chili peppers, and guavas.

In short, go for orange, red, yellow, and green foods.

One real difficulty here is that the two new studies are not scheduled for publication and may not see the light of day for some time. Until we see the full reports ourselves, we believe it is prudent to rely on the National Cancer Institute's statements. This is what we recommend, for now, concerning supplements:

*If you smoke, don't take beta carotene pills. Most important, stop smoking--nothing else will lower your risk of lung cancer and heart disease as much. And because smoking so damages the body, smokers have added reason to eat well, especially foods rich in antioxidants.

*For others, including former smokers, we see no harm but also no proven benefit in taking beta carotene supplements. You're better off spending the money on food. Skip the pill and eat the carrot. If you chose not to eat fruits and vegetables, perhaps you should take a beta carotene supplement, but no more than 6 to 15 milligrams daily. This is enough to raise your blood level of beta carotene to what a good diet would provide. According to Dr. Block, there's some evidence that beta carotene may reverse certain precancerous conditions, if not lung cancer.

*Do keep taking your vitamin E and C supplements. A large body of evidence indicates that they offer a number of potential health benefits.