One of the possible bene?ts of 30 years of medical practice is the ability to develop some sense of perspectivewith regardto majortransitionsin medicine. Manyphy- cians who graduated from medical school in the mid- to late 1970s may recall fe- ing less than comfortable about counseling patients regarding lifestyle modi?cation and heart disease risk. A total cholesterol of 250 mg% at that time was considered within normal limits. The best information on the causation of heart disease came from epidemiologic data showing associations between increased consumption of dairy products and fat in...