Do We Really Know What Makes Us Healthy

This article discusses problems with the research design and protcol for the "Nurses' Health Study," a study highly relied upon for determining relations between lifestyle, diet, and health.

http://www.nytimes.com/2007/09/16/magazine/16epidemiology-t.html?_r=1&ex=1190865600&en=15d99abafa46affb&ei=5070&emc=eta1&oref=slogin