Study stirs debate about low-fat diet and reduction in disease risk.

At one time or another, you've no doubt heard that eating a diet low in fat can help protect you against everything from cancer to heart disease. But according to headlines earlier this year, a low-fat diet doesn't significantly reduce a woman's risk of developing breast cancer, colorectal cancer or cardiovascular disease.

These headlines were based on the findings of the Women's Health Initiative (WHI) Dietary Modification Trial, which were published in the Feb. 8, 2006 issue of the Journal of the American Medical Association (JAMA).

Study specifics

The WHI study, which followed nearly 49,000 women between the ages of 50 and 79 for about eight years, compared women eating a typical American diet with women eating a diet low in fat and high in fruits and vegetables. Its specific goal was to test whether cutting total dietary fat to 20 percent of calories would reduce a postmenopausal woman's risk of breast cancer.

At the end of the trial period, the women in the low-fat-diet group didn't achieve a statistically significant reduction in the risk of invasive breast cancer, when compared with the other group. Two other studies using data from the dietary trial were published in the same issue of JAMA. They found that eating a low-fat diet didn't reduce the risk of colorectal cancer or cardiovascular disease in postmenopausal women.

Not all fats are created equal

Despite these findings, experts say the public shouldn't conclude that diet isn't important to your well-being -or that there's no need to watch your fat intake. What's their argument? For one thing, the WHI study didn't differentiate between good and bad fats. For another, most of the women assigned to the low-fat-diet group didn't achieve the goals of the eating plan and didn't lose weight.

In recent years, more knowledge has been gained about how different fats might impact disease development. For instance, saturated fat and trans-fatty acids (trans fats)--commonly found in processed foods, meats and full-fat dairy products--can raise the levels of low-density...

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