OPINION | July 14, 2002
Challenging the Accepted Wisdom

These have not been good times for established medical practices. In realms as disparate as breast cancer, menopause, arthritis and weight control, the prevailing orthodoxy finds itself under attack. For the past several months a controversy has raged over whether mammograms to detect tiny tumors in the breast have any proven value in reducing breast cancer mortality. Last week a federal study of hormone pills to treat postmenopausal women for a wide range of ailments was terminated when prolonged use of the pills was found to do more harm than good. A day or so later researchers reported that a popular operation for arthritis of the knee worked no better than a sham procedure that left patients thinking they had received treatment when in fact they had not.

In all of these cases, the issue was whether commonplace medical practices were able to prove their worth in carefully controlled clinical studies. A common long-term hormone replacement therapy and arthroscopic surgery for arthritis of the knee failed that test. Mammography's value remains in dispute.

Now a similar debate is roiling the always contentious arena of dietary recommendations. As laid out in a provocative article by Gary Taubes in The New York Times Magazine last Sunday, some influential researchers are beginning to wonder whether the government's recommendations for a healthy diet are causing more harm than good.

The nightmarish prospect raised in the article is that the government's incessant exhortations to eat less fat and more carbohydrates may have inadvertently contributed to the obesity epidemic that has exploded out of control in the past two decades. The supposed link is that low-fat diets inexorably drive people to eat more carbohydrates, which often make them hungrier, can make it harder to burn off fat and can increase triglycerides, which increase the risk of heart disease, the very danger that low-fat diets are trying to avert. Instead of low-fat diets, some researchers say, we should be emphasizing low-carbohydrate diets, the very opposite of the current official approach.

All that is highly speculative, and plenty of experts would disagree. But surely one lesson that emerges from the endless arguments over which dietary recommendations or best-selling diet plans work best is the need for some rigorously controlled clinical trials to sort out the differences. The National Institutes of Health has already started to finance some comparative studies of popular diets and could clearly do lots more.

The obesity epidemic has become an enormous public health problem, with no clear cure in sight, yet the federal government has not tackled it with the vigor applied to other scourges like smoking, alcohol or drug abuse. Given all the new and disturbing information they have been receiving on other health fronts, Americans have a right to wonder whether that food pyramid they have been taught to revere has been upside down all along. Researchers have an obligation to give them more vigorously tested answers about which of the popular diets flogged in best-selling books have any evidence to back their claims.