Too little calcium can weaken bones. But too much calcium could spell trouble for the prostate.
Among 47,750 men in the Health Professionals Follow-Up Study, those who took more than 400 mg a day of calcium from a supplement had a 50 percent higher risk of dying of prostate cancer than those who took no calcium.
“We looked at calcium supplements, which allows you to separate the calcium from the dairy, and we found an increased risk of lethal disease,” says Meir Stampfer, professor of epidemiology and nutrition at the Harvard School of Public Health.
However, another study looking at fatal prostate cancer didn’t see a clear link.
“And in small randomized trials giving people calcium to reduce the risk of precancerous colon polyps, they actually found a decreased risk of prostate cancer,” says Stampfer. “But those were almost all screen-detected, indolent cases, so it’s hard to know what it means.
“We went back to look at our own data, and we saw essentially the same thing—a decreased risk of low-grade, indolent disease and an increased risk of lethal cancer. So the calcium studies are difficult because there’s this potential dual effect.”
Stampfer suggests that men skip calcium supplements to play it safe unless a doctor says otherwise for a specific indication.
“People need enough to hit that sweet spot to reduce the risk of colorectal cancer, but most men get enough in their diet, so I would not recommend separate calcium supplements.”
Sources: Cancer Epidemiol. Biomarkers Prev. 15: 203, 2006; Am. J. Epidemiol. 166: 1270, 2007.
Other relevant links:
- Cruciferous vegetables may reduce risk of recurring prostate cancer. See: Cruciferous Vegetables and Prostate Cancer
- Overweight men are more at risk for an enlarged prostate. See: Excess Weight and an Enlarged Prostate
- Does whole milk increase the risk of prostate cancer? See: Dairy and Prostate Cancer