Harvard Men's Health Watch

On Call: Carrots and prostate cancer

On Call

Carrots and prostate cancer

Q. My 77-year-old father is healthy, but his older brother has just been diagnosed with prostate cancer. Dad says he read that carrot juice will prevent prostate cancer, and he's now drinking it every day. Is he just kidding himself?

A. The most common internal malignancy in males, prostate cancer is a worry for every man. A man's risk does increase as he grows older, and a family history of the disease also increases risk. However, the effect of family history is much stronger if more than one close relative had the disease, especially if it was diagnosed before the age of 60. That's good news for your dad, and he can also be reassured that unless his brother has an unusually aggressive form of prostate cancer, he is unlikely to die from it.

Unfortunately, there is little scientific evidence to support his remedy. Researchers have not specifically evaluated carrots or carrot juice, but they have studied beta carotene from supplements as well as foods; the evidence is mixed. Three large trials investigated beta carotene supplements. The ATBC Study linked supplements to a 23% increase in the risk of prostate cancer as well as a 15% increase in the risk of dying from the disease. Harvard's Physicians' Health Study reported a 32% reduction in prostate cancer risk from beta carotene supplements — but only in men who had low levels of beta carotene in their blood. However, that effect dissipated in the post-treatment period.

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