There is no question that what we eat affects our health. After all, our body is composed of molecules that originate from food. We are literally what we eat. But teasing out the affects of specific components of food on health is extremely challenging. That鈥檚 because we don鈥檛 eat individual compounds, we eat food. And in our body all the dietary ingredients intermingle and affect the actions of each other. The chemistry becomes extremely complex. Take for example the role of fats in prostate cancer. A number of studies have shown that a high content of dietary fat increases the risk of prostate cancer. But not all studies have shown this. How come? Because fats can be very different chemically. Although of course there are some common features, the saturated fats found in animal products can behave quite differently from the unsaturated fats in vegetable oils which in turn affect us differently from the unsaturated fats in fish oil.
There are theoretical reasons to think that fats can increase the risk of prostate cancer. Dietary fat increases the production of male sex hormones which are linked with prostate cancer. Many pesticides are fat soluble and a high fat diet may increase the body鈥檚 pesticide load. When certain fats are metabolized they produce free radicals which can damage our DNA. And some specific fats may be more problematic than others. Which brings us to alpha-linolenic acid, an unsaturated fat found in meat and more extensively in beans, walnuts, wheat germ, soybeans, canola and flaxseed. In a much publicized study published in the American Journal of Clinical Nutrition, researchers found that a diet high in alpha-linolenic acid was associated with an increased risk of prostate cancer. This sent shockwaves through the community of males who had been encouraged to eat flaxseed to reduce the risk of prostate cancer. That advice was based on a study which showed that men who added 30 grams of flaxseed a day to their diet lowered their PSA, which is thought to reflect a lowering of cancer risk. How do we mesh these two apparently diverging results? Flaxseed contains many other compounds than just alpha-linolenic acid. Lignans, for example, are though to lower cancer risk. So at this point, it might be prudent not to take flax oil as a supplement because of its high alpha-linolenic acid content but there is no reason to avoid flaxseed at all.
The studies linking prostate cancer to fats have come up with another interesting finding. Fish oils can reduce the risk! Adding these to the diet makes sense. And remember, don鈥檛 make too much of the report that alpha-linolenic acid is bad for the prostate. First of all, not all studies have shown this, and there is a wealth of information linking alpha-linolenic acid to a lower risk of heart disease! And that is a far bigger killer than prostate cancer. So you can keep eating those flaxseed flaxseeds.
