Medical memo

Food for thought: Tomatoes, broccoli, and prostate cancer

Scientists don't know what causes prostate cancer, but they have good reason to think that diet plays an important role. Since obesity increases risk, calories are the biggest culprits. Among specific foods and nutrients, saturated fat from animal sources (especially whole-fat dairy products and red meat) appears to be the major worry. Large amounts of calcium and alpha-linolenic acid (the omega-3 fat in canola oil and flaxseeds) may also increase the risk of aggressive prostate cancer. In contrast, whole grains, fruits and vegetables, fish, selenium, vitamin D, and perhaps vitamin E (in smokers) may decrease risk. Soy products, red wine, and pomegranates have also been touted as possibly protective, but the evidence is far from conclusive.

It will take time for researchers to sort this out. Human biology is complex, and clinical studies are slow and expensive. For example, although the 35,500-person SELECT trial should give us the answers about vitamin E and selenium, results are not expected until 2012. To gain insights at a faster pace, scientists often turn to animal studies. And reports make tomatoes and broccoli look awfully good, at least for rats.