By Craig Rinder, MD

Links between diet and preventing prostate cancer seem to get a lot of media attention. Newspapers frequently run articles about new studies claiming that specific foods, beverages or supplements prevent or slow the advance of prostate cancer. When visiting websites of very reputable institutions like Johns Hopkins or the Mayo Clinic, you’ll find long lists of certain foods you should eat or avoid in the name of better prostate health.

Craig Rinder, MD
Craig Rinder, MD

The excitement is understandable. Prostate cancer is the most common, non-skin, solid cancer in American men. It is the second leading cause of cancer-related death here in the United States and, in the United Kingdom, it is number one. When you start to read these articles, however, it’s amazing to see how little research has actually been done and how many of the findings end up contradicting other studies.

Last year, the Journal of the American Board of Family Medicine published a review of articles linking certain foods and dietary supplements to prostate cancer prevention. The review was conducted by a group of researchers from the University of Montreal who found several hundred examples between 1996 and 2010. The group narrowed their review to 61 articles based on studies involving large numbers of participants. Any article based on studies using animals or that merely made assertions about diet and prostate cancer without clinical research was omitted.

One interesting thing the group found was related to lycopene, a chemical compound that gives tomatoes and other red fruits and vegetables their color. Over the past ten years there has been a lot of interest in lycopene after one study showed that tomato sauce — though not tomato juice — was protective against prostate cancer. Later on, a follow-up trial involving thousands of subjects found that lycopene had no effect on preventing prostate cancer or any other type, so it’s difficult to draw any definitive conclusions.

In fact, the University of Montreal group did not feel there was enough information to recommend lycopene or any other single dietary element as helpful in preventing prostate cancer. They noted that randomized trials involving vitamin A, vitamin C and multi-vitamins provided no benefit. Vitamin E and Selenium were two other supplements that showed promise for reducing prostate cancer risk in small studies, but a planned long-term trial involving over 35,000 men found that vitamin E actually increased the risk of prostate cancer in men by 17 percent, while selenium had no benefit and was actually associated with an increased risk of diabetes. The trial was ended early because of these findings.

These examples are an important lesson for anyone who puts too much emphasis on a single dietary element or supplement resulting from one study. No matter how dramatic the results seem to be, they have to be confirmed in large trials in order to become widely recommended.

Most clinicians will recommend a generally healthy diet because we know there is a higher incidence of prostate cancer in countries that have higher fat in their diets, like the United States. This only applies to clinically-diagnosed prostate cancer, however. If you were to biopsy the prostate of men who died from other causes anywhere in the world, the rate of microscopic prostate cancer is the same. That suggests your dietary choices don’t protect you from getting prostate cancer, but they can slow the progress to the point where it can be better detected before it causes harm.

Just last month at the European Cancer Congress, a group from the University of California at San Francisco presented a paper on a study involving 46,000 men. The group had examined six specific prostate cancer reduction strategies and healthy lifestyle activities over a period of 25 years: (1) reducing consumption of red meat; (2) increasing tomato consumption, (3) not smoking, (4) exercising regularly, (5) consuming fatty fish, such as salmon, sardines and trout, and (6) having a body-mass index of less than 30, which means not being obese. The group found that men who adopted at least five of these six habits reduced their risk of lethal prostate cancer by 39 percent compared to those who adopted one or none. That strongly suggests that what is considered a heart-healthy lifestyle is also a prostate-healthy lifestyle.

Other recommendations along those lines include getting more of the fat in your diet from plants instead of animals. Olive oil and canola oil are fats that aid both cardiac and prostate health. Soy products, like tofu, are believed to be preventive, though not proven to everyone’s satisfaction. Eating more fruits and vegetables in general is probably healthy, as is eating less dairy products.

Coffee has no proven link to lowering the risk of prostate cancer. There is some limited evidence that green tea may be preventive. This is based on a Japanese study showing people who consumed at least 10 cups of green tea every day had a lower risk of prostate cancer risk than people who consumed three cups of green tea. That’s a lot of green tea.

That brings us to early detection and screening which, in my view, is very important for preventing prostate cancer. It has been clearly demonstrated that the death rate from prostate cancer in America has declined significantly since early detection became the standard. Men over the age of 40 should see their primary provider regularly and talk with him or her about whether they should be tested for prostate cancer and when that should occur.

Craig Rinder, MD, is a board-certified urologist and Director of the Men’s Health program at Brattleboro Memorial Hospital. He can be reached at 802-254-8222.

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