Low-fat diet study raises questions

Robert Bazell Chief science and health correspondent • Profile • E-mail

Dr. Walter Willett is a top nutrition expert at Harvard School of Public Health. I asked him a few questions that many people have today, the day after a study was released showing that eating less fat late in life failed to lower the risk of cancer and heart disease among older women.

Does this mean I can eat all the fat I want?

Dr. Willet:  It doesn't mean that people can run out and load up on sausage and cheeseburgers and French fries. For one thing, the type of fat is very important.

Willett and others say that olive and other vegetable oils are actually healthy, while the fat in meat and the so-called “trans fat” in processed foods cause health risks — especially increased heart disease.

Do the latest findings raise doubts about the connection between diet and health?

Dr. Willett: This study absolutely does not mean there is no connection between diet and health. This is a study focused on a very specific question.

The question the study raised was based on an idea many scientists had 20 years — that total fat in the diet increased cancer risk. But since then new evidence has cast doubt on that idea.

Why do we get nutrition advice that seems to be so contradictory?

Dr. Willett: One of the real problems is that 10, 20 years ago we had pretty limited data. What people were being told was based on best guesses or hunches for the most part.

Willett and other experts say science today is far more reliable. But they have to admit that new studies like the latest one about fat can always provide unexpected answers.

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