Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating

5:04 AM | Labels: Diets, Health Food, Nutrition, Weight Loss

There is an interesting dilemma for those who would influence nutrition. In many places in the world, there are governmental agencies concerned with food security, food safety, agriculture, health, and trade that may, from time to time, implement policies that are at least intended to reduce the risk of chronic diseases. Most often, when the goals of agriculture and human health clash, it is the will of the agriculture sector that prevails (remember the European Union's ``butter mountain'' and ``wine lake''?). In the United States, perhaps more than anywhere else, this has left an opening for self-help nutrition books. In a land where individuality and self-reliance are valued above many other virtues and where disease is sometimes seen to be a mark of personal failure, gaining access to the best data on health-related food consumption may be central to maintaining control over one's health. The quality of such books varies enormously, from the bizarre to the mundane. The feature they share is the promise of better health and control over one's destiny. Only occasionally do bona fide researchers step into the maelstrom. Enter Walter Willett of Harvard University and Eat, Drink, and Be Healthy.
Willett's book is based on evidence derived almost exclusively from large cohort studies of diet and disease. He has been the architect of several such studies and is a major contributor to what we know about methods of collecting and analyzing data; he formerly served the Journal well in this capacity. His position in this regard is preeminent but not unchallenged. He encapsulates his position on the evidence in a new ``Healthy Eating Pyramid,'' a gauntlet thrown at the feet of the U.S. Department of Agriculture (USDA). He notes that the USDA Food Guide Pyramid, like Rudyard Kipling's elephant's child, got pulled into shape by competing interests, few of which cared about human health. He goes on, ``You deserve more accurate, less biased, and more helpful information than that found in the USDA Pyramid.'' Thus, the book brings us the promise of science in the service of nutrition, and as with any good scientific claims, Willett makes sure we know, up front, that all findings are provisional and all recommendations subject to change.
The central chapters of the book are derived from and explicate the layers of the new pyramid. Central to Willett's recommendations is the control of body weight, in which exercise, rather than caloric restriction, has the primary role. However, there is also helpful and practical advice on defensive eating strategies; for example, Willett states, ``Recognize that we are victims of our culture, one that glorifies excess.''
Indeed, much of what is presented in the book is sensible and practical and demystified. For example, the data and associated recommendations on fluid intake include the following: we should drink water; tap water is OK; soft drinks are full of empty calories; and fruit juice contains more beneficial substances and less sugar than soft drinks but cannot simply be substituted for water, because, of course, it does contain calories. There is also useful information on more arcane subjects: for instance, we should be careful of grapefruit juice because it modifies the absorption and metabolism of a variety of drugs in ways that may be detrimental. And there is a proper assessment of coffee drinking that I like to summarize as follows: If drinking moderate amounts of coffee is your worst nutritional vice, you are in excellent shape. Even in the area of alcohol, Willett, who has been and remains a champion of the beneficial effects of moderate consumption (which he has the courage to define), notes that if you do not drink alcohol you should not ``feel compelled'' to start. Possibly, this is a nice antidote to the widely held notion that if some is good, more is better, but his choice of words is just a little disturbing. Finally, although many self-help books with much poorer pedigrees than this one offer recipes, it is not often that they include useful rules of thumb about shopping and places to shop and even practical tips on how to make substitutions in recipes.
Are there areas where Willett's Healthy Eating Pyramid and the associated information may not be warmly embraced by others in the nutrition-and-disease research community? Certainly the switch from vilifying total fat (a position Willett abandoned early) to asserting that carbohydrate is the bad guy (a position that Willett has made his own) and that there are ``good fats'' and ``bad fats'' does not meet everybody's sniff test. The field of nutrition and chronic disease is populated by those who will agree with Willett on none, one, two, or all three of these positions. It is probably fair to say that reality is not as clear as this book suggests. It is quite clear that diets high in potatoes, olive oil, or even sugar are not harmful to all (or beneficial to all). It seems probable that in the future there will be increasingly clearer advice that is based on metabolic variations -- variations in body shape and fat distribution and subtle genetic differences in the capacity to handle major nutrients -- and that echoes what we already know about micronutrients. It may well be that the ability to handle specific foods and nutrients differs substantially from person to person and that the only universal may prove to be Willett's central tenet: match the energy ingested to the energy expended by controlling both eating and exercise.
It is an interesting paradox that doctors, scientists, and engineers are highly regarded in Western societies but that only a minority of people in those societies like reading about science or are even interested in the topic. Couple that with data from Robin Dunbar of the University of Liverpool in Britain, who found that perhaps two thirds of all human speech is gossip, and it will not be surprising if Willett's book (perhaps like those by Stephen Hawking) sells well but has no impact at all on human behavior or even understanding.