August 2002

• Dietary Antioxidants May Decrease Risk of Alzheimer's Disease
• Birth Control Pills and Breast Cancer
• No link found between prostate cancer and vasectomy

Dietary Antioxidants May Decrease Risk of Alzheimer's Disease

Alzheimer’s disease (AD) is a complex disease that spreads through the brain. It affects some 4 million Americans, causing memory loss, impaired thinking, and changes in personality. Scientists have suspected that substances called antioxidants — vitamin C, vitamin E, and beta carotene, for example — may guard against AD. However, studies testing the relationship between antioxidant supplements and the risk of AD have not found consistent evidence of a benefit. But now two studies published in the Journal of the American Medical Association have found that high intakes of antioxidants from food may reduce the risk of developing AD.

In the first study, researchers recruited 5,395 participants with an average age of 67.7 years, who lived independently. All participants reported their eating habits and went through two mental state examinations to ensure that they were free of dementia at the start of the study.
During six years of follow-up, the researchers re-screened the participants for Alzheimer’s disease. They found that high dietary intake of vitamin C significantly reduced the risk of developing Alzheimer’s disease and that the reduced risk of AD from high dietary intake of vitamin E was also borderline significant. These antioxidants were most effective at preventing AD in current smokers, compared with current non-smokers.

Use of dietary supplements was controlled in this study, so the beneficial effects of vitamins C and E were only from food. Vitamin C is found in large amounts in citrus fruits, kiwi, and broccoli, and good sources of vitamin E include nuts, milk, and egg yolk.

In the second study, participants were also free of Alzheimer’s disease at the beginning and completed a food frequency questionnaire. The questionnaire helped researchers keep track of the intake of certain foods and supplements. The 815 subjects were 65 years and older, and were followed for four years.

After adjusting for age, education, sex, race, and presence of APOE e4 (a genetic characteristic that makes a person more likely to develop AD), the researchers found that those with the highest dietary intake of vitamin E were 70% less likely to develop AD than those with the lowest dietary intake of vitamin E. However, the highest Vitamin E intake for the study was 363.6 International Units (IU) per day, well above the Recommended Dietary Allowance of 22 IU.

The other dietary antioxidants tested in this study, vitamin C and beta carotene, did not reduce the risk of AD. More research will need to be performed to find out why vitamin C proved effective in one study but not in the other. While dietary antioxidants are proving more effective in reducing Alzheimer's risk than antioxidant supplements, these weren't randomized, clinical trials, so these studies won't translate into dietary recommendations.

August 2002 Update

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Birth Control Pills and Breast Cancer

Good news for women who take the Pill — a new study, published in the June 27, 2002, issue of the New England Journal of Medicine, shows that current or former use of oral contraceptives does not increase the risk of breast cancer later in life.

Previous research indicated women who use or had used oral contraceptives in the past ten years were at an increased risk for breast cancer compared to women who had never used the Pill or had used it less recently. The new study was necessary now because the first generation of women to use the Pill at a younger age is reaching the period in their lives when the risk for breast cancer is greatest.

The study, conducted in Atlanta, Detroit, Los Angeles, Philadelphia, and Seattle, involved 4,575 women with breast cancer and 4,682 without. Study participants were between the ages of 35 and 64. Seventy-seven percent of the women with breast cancer and 79% of the women with no personal history of breast cancer had used oral contraceptives in their lives. The results were analyzed according to race, age, family history of breast cancer, and type of oral contraceptive used.

According to the results, women who took the Pill were as likely to have breast cancer as those who had never taken it. The results also showed the risk for breast cancer did not increase with longer periods of use or with higher doses of estrogen. Age, race, weight, and family history did not affect the risk of breast cancer in women using the Pill compared to women who did not.

Researchers interviewed only Caucasian and African American women. They also evaluated the risk of breast cancer in relation to a family history in first-degree relatives only (not including grandmothers, aunts, and cousins). Regardless, the results of this study should allay the fear that breast cancer may be related to use of the Pill.

August 2002 Update

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No link found between prostate cancer and vasectomy

Good news for the millions of men worldwide who've had vasectomies: a new study disputes a link between this birth-control operation and prostate cancer. Two 1990 studies that connected prostate cancer and vasectomies caused men to question the procedure, even though no medical explanation for the connection could be found. Other research has both confirmed and denied the association in the past 10 years.

But the new study, published in the June 19, 2002, Journal of the American Medical Association, should ease men's minds. It involved over 2,000 men of European descent living in New Zealand, the country with the highest rate of vasectomies.

Researchers asked 953 men with prostate cancer and 1,260 who were cancer free about their medical histories — including whether they had had a vasectomy. It turned out that slightly fewer men with prostate cancer had undergone the surgery, which supports claims that going under the knife doesn't cause cancer. The same held true for the 38% of men studied who had had the procedure more than 25 years ago, which suggests that there are no long-term effects.

One reason why the link may have been found in earlier studies is that men who have vasectomies generally see their urologists more often, which may lead to more tumors being found in these men as compared to others, the researchers said. The study also found no link between prostate cancer and history of sexually transmitted disease, smoking, drinking alcohol, and number of children.

Prostate cancer will be diagnosed in 198,000 Americans this year, and it will take 31,500 lives. Although prostate cancer lags behind heart attacks, strokes, and lung cancer as the leading cause of death in American men, it's the disease many men fear most.

August 2002 Update

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