The Science of Nutrition

A clear and cogent guide

In fact, the best section of Eat Drink and Be Healthy is Chapter 2, "What Can You Believe About Diet?" Because Willett is a researcher himself and one of the leaders of the Nurses Health Study and the Health Professions Follow-up Study, he has produced a clear and cogent guide to evaluating nutritional research. Not too long ago, such a chapter might have seemed a little heavy for a nutrition book aimed at the general public. Today people need better tools to sort through the flood of nutritional information and misinformation in print, on television, and on the Net. And remarkably, Willett manages to avoid sounding like a textbook, probably thanks to P.J. Skerett, "an experienced science writer" he acknowledges in the preface.

Willett sticks to the evidence, even when it contradicts earlier nutrition policy. Many authors have continued to advise women to eat less fat to prevent breast cancer, although, as Willett notes in writing about the Nurses Health Study, "There is no hint of an increase in breast cancer with higher dietary fat." Advocates of low-fat eating have tried to explain away these findings with claims that it's the childhood diet that counts, or that there wasn't enough difference in fat intake among the nurses to eliminate the possibility that an extremely low-fat diet (less than 10 percent of calories) might be helpful. That's the kind of speculation that makes it easier for those who don't respect the scientific method to gain a foothold. It is not prudent to scare women into modifying their diet for no reason. On the other hand, the connection between saturated fat and heart disease is amply supported by scientific evidence.

Over the past 20 years, our understanding of dietary fat has grown steadily more detailed, like a bedtime story embellished night after night. Willett devotes a chapter to the new findings about different kinds of fats. He discusses the benefits of Omega 3 (n3) fatty acids and the dangers of partially hydrogenated fats. Overall, he advocates a variant of the Mediterranean diet, a regimen with less meat, milk, and sugar in favor of lots of fruits and vegetables, whole grains rather than white flour bread and pasta, and more olive oil and canola oil, rather than butter. In other chapters, he argues that women have been oversold the benefits of calcium and soy. He also blames an increased consumption of refined flour and potatoes for the jump in obesity that has occurred in the United States despite a decline in dietary fat.

Obesity epidemic

According to the Centers for Disease Control and Prevention, 61 percent of Americans are overweight, and in fact, the CDC has called for a comprehensive approach to the epidemic of obesity, including stepping up exercise programs for schoolchildren and discouraging their consumption of fast food -- a dual effort to get teen-agers to snack on carrot sticks instead of fries and a soda. Adults could also benefit from more exercise, CDC officials say, so why not redesign communities so that they encourage walking instead of driving to the local store? All of this is on top of the CDC's fundamental recommendations for better nutrition at school and at home.

Willett's chapter on obesity reflects the impotence of the nutrition community in the face of this issue. Willett devotes many pages to convincing the reader that obesity has a negative impact on health. Then he acknowledges, "Over the last few decades, we've been learning that it is far easier to prevent weight gain than it is to lose excess pounds." He does emphasize the importance of exercise, although he does not cite the many studies that suggest that your level of fitness may be more important than absolute weight as a factor in overall health risk. Nor does he take the opportunity to consider public health rather than personal approaches to obesity.

When Willett disagrees with the food pyramid developed by the Department of Agriculture, he mentions that "what's good for some agricultural interests isn't necessarily good for the people who eat their products." That's about all he has to say about nutrition politics. If obesity is an epidemic, as he claims, it might be time to consider restrictions on fast-food advertising aimed at children, similar to the restrictions on cigarette advertising, or public service advertisements to promote an active lifestyle.

At the end of the book, Willett includes a week's worth of menus and healthy recipes developed by Maureen Callahan, a dietitian. These are somewhat awkward (who wants to visit the health food store to add a few tablespoons of oat groats and flaxseed to a whole wheat pizza crust?) but creative. My teen-age daughter liked the "Mango Energy Blitz" smoothie, despite the carrot juice, which she won't drink by itself. Willett says that the rhythm of nutrition research is like the cha-cha, two steps forward, one step back. That rhythm also describes the efforts of the average family to make healthier food choices. Eat, Drink and Be Healthy is a step forward.


Eat Drink and Be Healthy: The Harvard Medical School Guide to Healthy Eating
By Walter C. Willett, MD
Simon and Schuster
352 pp

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