Wednesday, August 28, 2013

Prostate Cancer and Selenium

Today at BigThink (and here) I'm blogging about prostate cancer, which is the second leading cause of cancer death in American men. In particular, I want to get the word out about selenium's well-documented ability to protect again prostate carcinomas. It turns out there are other important health benefits (for people of both sexes) to selenium, some of which I summarize in my BigThink post.

While selenium's exact mode of action is still not wholly known, it appears the mineral induces apoptosis of cancer cells by triggering caspase-3 a cysteine-aspartate protease involved in the "execution phase" of programmed cell death (apoptosis).

After writing the BigThink post, I decided to have a little fun and try for some do-it-yourself epidemiology graphs. I was startled by the results. This is what I came up with.

Prostate cancer in the U.S., 1970-2004 (obtained from

The above map shows U.S. prostate cancer by county. Rates are population-adjusted (so you're not seeing mere population density effects). It's obvious that the cancer rate is not randomly distributed by geography. But what, I wondered, could account for the uneven distribution?

I searched online for a map of soil selenium distribution, and this is what I found (at

Obviously the inverse correlation between selenium and prostate cancer is not perfect. (How could it be? Americans are a mobile lot; and people don't simply eat locally grown vegetables, etc.) But I think the two maps speak pretty clearly to the role of selenium in protecting against prostate cancer. If you want to draw a different conclusion, so be it.