he largest study ever to ask whether a low-fat diet keeps women from getting cancer or heart disease has found that the diet had no effect.
The $415 million federal study involved nearly 49,000 women aged 50 to 79 who were followed for eight years. In the end, those assigned to a low-fat diet had the same rates of breast cancer, colon cancer heart attack and stroke as those who ate whatever they pleased, researchers are reporting today.
"These are three totally negative studies," said Dr. David Freedman, a statistician at the University of California at Berkeley, who is not connected with the study but has written books on clinical trial design and analysis. And, he said, the results should be taken seriously for what they are — a rigorous attempt that failed to confirm a popular hypothesis that a low-fat diet can prevent three major diseases in women.
And the studies were so large and so expensive that they are "the Rolls Royce of studies," said Dr. Michael Thun, who directs epidemiological research for the American Cancer Society. As such, he said, they are likely to be the final word.
"We usually have only one shot at a very large scale trial on a particular issue," Dr. Thun said.
The studies were part of the Women's Health Initiative of the National Institutes of Health, the same program that showed that hormone therapy after menopause can have more risks than benefits. In this case, the diet studies addressed a tricky problem. For decades, many scientists have been saying, and many members of the public have been believing, that what you eat — the composition of the diet — determines how likely you are to get a chronic disease. But it has been hard to prove. Studies of dietary fiber and colon cancer failed to find that fiber was protective. Studies of vitamins thought to protect against cancer failed to show an effect.
Gradually, many cancer researchers began questioning the dietary fat-cancer hypothesis, but it has retained a hold on the public imagination.
On the other hand, like folks who lie to pollsters about going to church...this could be simply made up data by the participants...