A healthy skepticism

The Providence Journal: The huge health study that found no obvious benefit for women from taking calcium supplements leaves very mixed feelings. On one hand, it indicates that women may have far less power to prevent broken bones and colorectal cancer than previously thought. We all like a sense of being in control. On the other hand, it relieves some of the guilt over not doing enough to protect one's health. It is less depressing to accept fate than the idea that we didn't take care of ourselves.
The findings come out of the Women's Health Initiative, a big and ongoing federal study. Earlier this month, the researchers reported that low-fat diets do not appear to offer protection against breast cancer or heart disease.
For women, these reports are a thunderbolt. Calcium supplements and a low-fat diet have been the first two commandments on their list of preventive health practices.
Clinical trials
These studies are important because they are clinical trials. Other investigations have sought links between populations that do certain things and their health outcomes. The problem with such studies is that the groups most disciplined about following instructions, such as taking calcium supplements, may also be more likely to do other things beneficial to health. The clinical trial randomly assigns women to either follow the regimen -- in this case, take 1,000 milligrams of calcium and 400 international units of vitamin D a day -- or take a placebo.
How should women respond to all this? For starters, they should not take the news as a green light to ignore their calcium intake or binge on burgers. The studies did turn up some promising evidence. For example, among "adherent" women -- those who took 80 percent of their calcium pills -- hip fractures were reduced by 29 percent.
Likewise in the study on low-fat diets, researchers did see a possible 9 percent reduction in risk of breast cancer. Now, 9 percent is considered statistically insignificant, but 10 percent is deemed significant. That 1-percent difference suggests that low-fat diets may help, even if the evidence is not slam-dunk.

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