VITAMINS & PROSTATE CANCER

VITAMINS & PROSTATE CANCER

Listen up if you're a man and are popping large amounts of vitamins and dietary supplements in the hope that they'll improve your health. You may instead be raising your risk of prostate cancer.

About one-third of the 300,000 men in a National Institutes of Health (NIH) study of prostate cancer were taking a daily multivitamin; and the approximately 5 percent of them who were swallowing more than 7 multivitamin tablets a week had a 32 percent increased risk of advanced prostate cancer and a two-fold greater risk of dying of prostate cancer.


The strongest association with these advanced forms of prostate cancer was found among the men who had a family history of prostate cancer or who took other supplements like selenium, beta-carotene, or zinc along with the extra amounts of multivitamin pills.

Taking one or more multivitamin pills a day did not raise the risk of localized prostate cancer, so it is possible that the vitamins did not cause prostate cancer but instead prodded cancer cells that were already present to grow faster.

Now, add to these findings from the NIH study above some more bad news for supplement takers, this time about lycopene, a carotene abundant in tomatoes that earlier large studies had found protected against prostate cancer.



A study of more than 28,000 men between the ages of 55 and 74 from the Fred Hutchinson Cancer Research Center in Seattle has demonstrated that higher blood levels of lycopene did not diminish the risk of either total or aggressive prostate cancer. Moreover, the men with the highest blood levels of beta-carotene had a 3-fold greater risk of aggressive prostate cancer than did those with the lowest beta-carotene levels.

This latter finding is not surprising, since earlier studies demonstrated that taking supplements of beta-carotene increased the risk of lung cancer among cigarette smokers.



And, just for good measure, another small study at Wake Forest University recently found that adding lycopene to one's dietary supplements did not slow the progression of cancer in men with recurrent prostate cancer.

Still, it's difficult to understand how extra doses of multivitamins would foster aggressive prostate cancer or why the latest results show no protection from higher blood levels of lycopene when earlier observations found that a higher intake of lycopene reduced prostate cancer risk.

While much data indicate that ample intake of fruits and vegetables protects against cancer, the discrepant findings in the studies described above illustrate how difficult it can be to prove that a particular dietary component will prevent cancer.



Quite frankly, I'm not sure that taking an extra multivitamin pill a week is harmful or that lycopene fails to prevent aggressive prostate cancer. I do agree, however, with the position of the American Cancer Society (ACS), which does not recommend the use of multivitamin supplements but recommends instead that people get their vitamins from natural food sources.

And I continue to decry the gullibility of the American public, whose naïve trust encourages the practices of manufacturers of vitamins and other dietary supplements. Whenever a study suggests that something new may have health benefits, these manufacturers stuff it into a pill, advertise it stridently so that Americans waste lots of money on it, and end up with big profits.