A New Study Questions Low-Fat Diets

Here we go again?.for years, dietitians have been telling you to eat more fruits and vegetables to help reduce the risk for heart disease and certain types of cancer. Now a study, published in the respected Journal of the American Medical Association (JAMA), of 48,835 women (part of the Women's Health Initiative) says that healthier diets bring no such benefits. Here are the questions we should ask about this study:


1.  What did the study actually examine?

2.  Do its data support such sweeping conclusions?


The study set out to compare women eating 'normal' diets with women asked to eat less fat and more fruits and vegetables. But the two groups' diets didn't really differ that much. Those with "healthier" diets cut calories from fat by only 8.2% compared with the normal group, and ate only 1.1 additional servings of fruits and vegetables per day. This is too small a difference to expect any health benefits and to draw such a dramatic conclusion.


In addition, we now know that the TYPE of fat consumed is much more important than the quantity. Monounsaturated fats, such as those found in olive oil, and omega-3's found in oily fish (salmon, tuna, mackerel) are healthier than saturated fat, found in animal products such as butter and beef. Worst of all are the trans-fats, the contrived fat used in processed foods to prolong shelf life. Trans-fats have been definitively linked with increased risks for the development of the risk factors that lead to heart disease (high LDL, low HDL, chronic vascular inflammation). By simply focusing on total fat intake, the study missed out on the opportunity to examine the effects of these different types of fats. And we do know that there are definitive data that vegetables contain chemicals that boost DNA repair and protect against cancer. It is clear that the function of crucial cancer genes can be influenced by compounds in the things that we eat. And eating more fruits and vegetables displaces some other types of foods and diet regimens that clearly predispose individuals to risk factors for heart disease and other vascular problems such as stroke, or cerebrovascular accident.


This study fails to examine the limitations, including research design/methods and reporting results in relative terms. The actual numbers in this particular study are too small to be statistically significant. There is certainly no mystery about why results are often exaggerated: researchers, medical centers and scientific journals are all competing for funds and publicity, just like everyone else. And even when a study does point out a clear benefit or danger, the results may not be applicable to the real world. Individuals have complicated health issues, and medicine is never black and white. What does this all mean for diet? Try to stay fit, keep your weight down and aim for a relatively healthy diet using the guidelines we have reviewed in our meetings together. And above all, don't worry too much about the latest headlines in medical journals!

Sources: The McGraw-Hill Companies, John Carey