Calcium intake, health, and prostate cancer

Park et al. have just reported the results of the truly vast NIH-AARP Diet and Health Study, which included data from more than 490,000 older men and women (aged between 50 and 71 when the study started in the 1990s) over an average 7-year follow-up period.

The results of the study clearly show that, in older Americans, a dietary calcium intake level of up to 1300 mg/day in the form of dairy and other foods has a significant impact on risk for cancers of certain types — but not on risk for prostate cancer.

It has long been hypothesized that dairy foods and calcium intakes play roles that differ among individual cancer sites, but the evidence has been limited and inconsistent.

Park et al. examined dairy food and calcium intakes in relation to total cancer as well as cancer at individual sites using a food frequency questionnaire. Incident cancer cases were identified through linkage with state cancer registries.

The results of the study showed that:

  • During an average of 7 years of follow-up, there were 36,965 and 16,605 cancer cases in men and women, respectively.
  • Calcium intake was not related to total cancer in men but was associated with total cancer in women: the risk decreased up to approximately 1300 mg/day, above which no further risk reduction was observed.
  • In both men and women, dairy food and calcium intakes were inversely associated with cancers of the digestive system.
  • Decreased risk was particularly pronounced with colorectal cancer.
  • Supplemental calcium intake was also inversely associated with colorectal cancer risk.

The authors conclude, “Our study suggests that calcium intake is associated with a lower risk of total cancer and cancers of the digestive system, especially colorectal cancer.

An article in today’s USA Today gives additional information. According to that report:

  • More than 10 different kinds of cancer were identified in the study, of which the most common were prostate, breast, lung, and colorectal cancers.
  • The participants who consumed the most calcium had the lowest chances of getting colon cancer.
  • Men in that highest category got on average 1,530 mg/day; women in that category got and average 1,881 mg/dayn.
  • The recommended dietary calcium intake for older people is 1,200 milligrams; apparently, getting much more than that didn’t result in any greater protection.
  • Adults can get that amount of dietary calcium from four cups of milk or calcium-fortified orange juice.
  • Men who got the most calcium from food were about 30 percent less likely to get cancer of the esophagus, about 20 percent less likely to get head and neck cancer, and 16 percent less likely to get colon cancer, when compared to men who got low amounts of calcium.
  • Women who got the most food-based calcium were 28 percent less likely to get colon cancer than low-calcium women.
  • Although some previous studies have linked diets high in calcium with prostate cancer, the current study found no such risk; nor did it show that a high-calcium diet was preventive of prostate cancer.
  • The older adults who ate the most calcium tended to be healthier overall than those who consumed a lower daily amount.

A leading  authority on preventive medicine has noted that, because all those in the study were AARP members, they may have been healthier and wealthier than the general U.S. population, and so it’s not clear if the results would apply to the wider population.

In the spirit of full disclosure, your correspondent should note that he is a member of the AARP (because he travels a lot for work and so he can get the AARP hotel discount) but he did not participate in this study!

What’s the “take away” for men over 50 in Western societies? Simple: drink milk and orange juice and eat your broccoli! It won’t affect your risk for prostate cancer but it will affect your risk for colon cancer — and it’s just good for you anyway!

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