Flaxseed: Does it increase my prostate cancer risk?

I take flaxseed to control my high cholesterol. But I was recently told that flaxseed increases the risk of prostate cancer. Is this true?

- Jared / Arizona

Mayo Clinic urologist Erik Castle, M.D., and colleagues answer select questions from readers.

Answer

There is limited research on the effects of flaxseed on the risk of prostate cancer. Flaxseed and flaxseed oil are rich sources of alpha-linolenic acid (ALA) — a fatty acid — which can help reduce total cholesterol.

Some research suggests that higher levels of ALA may be associated with an increased risk of prostate cancer. Other preliminary studies report that a low-fat diet supplemented with flaxseed can reduce prostate-specific antigen (PSA) levels in men with enlarged prostate glands (benign prostatic hyperplasia) and in those with prostate cancer. However, these effects may be due to a reduction in dietary fats. The role of flaxseed in such cases isn't clear.

Overall, it remains unclear whether flaxseed or flaxseed oil has a role in the prevention or treatment of prostate cancer. Until more definitive studies are available, it's probably best for men to avoid supplementation with high doses of flaxseed.