Do we really know what makes us healthy?

Some students may be interested in an article entitled

"Do we really know what makes us healthy" by Gary Taubes

published in the New York Times, Sept 16, 2007. The article

discusses why causal effects suggested in observational

studies are often not confirmed or are even contradicted in

subsequent clinical trials. A main focus of the article is

Hormone Replacement Therapy (HRT). Reports in 1985 from the

Nurse's Health Study (a large prospective observational study)

suggested that HRT lowers the risk of heart attacks. A

subsequent clinical trial found that HRT actually increases

the risk of heart attacks among older women. The author

discusses the difficulties in drawing valid conclusions

about cause-and-effect relationships from observational

studies and recommends skepticism when reading reports from

such studies. The article is available at

Gary Taubes, New York Times, Sept 16, 2007