A Delicate Balance of Antioxidants May Determine Recurrence of Breast Cancer

Study Finds Beta-Carotene Supplements May Actually Be Dangerous

Women who have had breast cancer may have a lower or higher risk of recurrence if they take antioxidant supplements, depending on the supplement they take.
 
A newly published study of 2,264 women who had breast cancer in the journal Cancer found that women who took vitamins C and E were 27% less likely to die of breast cancer and 24% less likely to die of any cause during the study period. On the other hand, women who took carotenoid supplements (vitamin A, beta-carotene, gamma-carotene, and lutein) were 107% more likely to die of breast cancer and 75% more likely to die of any cause during the same period.
 

Why should vitamin A be harmful while vitamins C and E seem to be helpful?

First, it is important to understand that the data on antioxidants and breast cancer are equivocal. Just a month before the Cancer study came out, a study of 4,824 women in Canada found that among women who had never had cancer:

• Taking a multivitamin regularly reduced the risk of ever having breast cancer by 26%,
• Taking beta-carotene supplements regularly reduced the risk of ever having breast cancer by 42%,
• Taking vitamin C regularly reduced the risk of ever having breast cancer by 21%,
• Taking vitamin E regularly reduced the risk of ever having breast cancer by 25%, and
• Taking zinc regularly reduced the risk of ever having breast cancer by 53%, if

women had taken these supplements for 10 years or more. Eating healthy foods did not lower (or raise) the risk of getting breast cancer for the first time, and taking supplements for less than 10 years did not lower (or raise) the risk of getting breast cancer for the first time. It is possible, of course, that women who take nutritional supplements for much of their lives also have other healthy habits that reduce the risk of breast cancer.

So it seems that something about the usefulness of antioxidants changes when women have cancer. What could be going on?

The answer seems to be that vitamin A, beta-carotene, and lycopene protect DNA from changes. In women who have never had breast cancer, they keep DNA damage from causing the formation of cancerous cells. In women who have already had breast cancer, they probably keep DNA from being repaired. The effect is greatest in women who have breast cancer tumors that are activated by both estrogen and progesterone.

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The contraceptive Pill contains both estrogen and progesterone. Yet another study, the European Prospective Investigation into Cancer and Nutrition (EPIC), tracked 7,052 German women, some of whom developed invasive breast cancer. In this study, both beta-carotene and vitamin C offered some protection (an estimated 4% to 34% reduction in risk of developing cancer) in women who were on the Pill or who took estrogen replacement therapy, but not for other women.

The bottom line of the studies of women's breast cancer and nutrition seems to be that long-term use of supplements may be helpful to women's health but they are not a guarantee against breast cancer. Once breast cancer has occurred, supplements not only don't help, they may even hurt. But what about the same antioxidant supplements and cancer in men?
 

Beta-Carotene Supplements May Also Increase Risk of Prostate Cancer

Antioxidant supplements are also potentially harmful for men. For over a decade, health experts have been admonishing men to get a regular dose of the antioxidant pigment lycopene, which is abundant in tomatoes and best absorbed when the tomatoes are consumed with a small amount of oil. Lycopene is an antioxidant chemically similar to vitamin A.

This antioxidant, holistic health gurus claimed, stopped damage to DNA in the prostate that causes cancer. When the US National Institutes of Health took a closer look at lycopene and prostate cancer, however, they found that consuming just one serving of tomatoes a week offered greater protection against the disease than consuming 2 or more servings of tomatoes per week, or no tomatoes at all.

The National Institutes of Health Study also found that eating pizza, lasagna, and spaghetti with tomato sauce was more beneficial than eating raw tomatoes or drinking tomato juice.

The reason cooked tomatoes offer additional benefits for men's health is that cooking them changes the lycopene they contain. Raw tomatoes contain lycopene molecules that are in a trans- form (chemically similar to a trans- fat). The lycopene in supplements is also in a trans- form.

Cooked tomatoes contain lycopene molecules that are in a cis- form. Chopping or pureeing the tomatoes before they are added to the sauce also releases more lycopene that is changed into the form of the molecule the body needs.
 

Simply getting more and more lycopene does not protect against cancer. A study of 28,000 men in the Prostate, Lung, and Colorectal Cancer Screening Trial found that men who consumed the most lycopene did not have fewer cases of prostate cancer or less aggressive tumors. And this study also found that men who consumed the highest amount of beta-carotene were three times more likely to develop the most aggressive, untreatable forms of prostate cancer. Men who took beta-carotene supplements were 52% more likely to develop the worst forms of prostate cancer, but stopping supplementation also lowered risk.

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Beta-carotene supplements have proven problematic for other forms of cancer. In 1994, Finnish researchers stopped a clinical trial when they learned to their horror that giving men who smoked beta-carotene supplements made them more likely to develop lung cancer. This was even true when blood tests indicated that men who smoke have unusually low levels of beta-carotene in their bloodstreams. More is not necessarily better. It is possible that beta-carotene protects certain kinds of cancer cells in the same way it protects healthy cells.

So should everyone stay away from beta-carotene supplements?

There seem to be three important exceptions to the rule.

• Women who have been diagnosed with cervical dysplasia are less likely to develop cervical cancer if they get enough alpha- and beta- carotene.
• Both men and women are less likely to develop pancreatic cancer if they have adequate levels of beta-carotene in their bloodstreams.
• Carrots, the best source of beta-carotene, are the only vegetable known to help prevent mesothelioma, the aggressive, untreatable form of lung cancer triggered by exposure to asbestos.

The most helpful level of consumption of carrots, however, is just one serving a month. As little as one serving a month may be sufficient. With certain antioxidants, a little is vital, but it is also essential not to get too much.