The importance of nutrition to the preservation of human health cannot be reasonably denied. However, the extent of its power may have been overstated in recent years. For millions of Americans, “natural foods and vitamins” are seen as almost magical preservers of health, beauty, and longevity. Indeed, claims for the healing properties of nutrients have become an integral part of the post–World War II “baby-boomer” generation’s vision of the world. For many, “faith” in the power of proper nutrition is part of a secular religion that comes close to denying the inevitability of aging and death. Vitamin C is considered a panacea one day and beta-carotene the next, as are such foods as broccoli and garlic. With such a cornucopia of natural “medicines,” who would ever think that the history of humankind would reveal so much disease and ill health?

Although such popular exaggerations of the benefits of various nutriments are easily dismissed by serious scholars, other more scholarly claims are not. One suggestion dealing with the historical importance of nutrition has received remarkably widespread support in academic circles and, among historians, has become the orthodox explanation for understanding a key aspect of the modern world: increased longevity.

The McKeown Thesis

The classic formulation of this explanation was provided by the medical historian Thomas McKeown (1976, 1979), who argued that the reasons for the decline of mortality in the Western world over the last three hundred years have been largely the result of rising living standards, especially increased and improved nutrition. Equally important, the decline was not the result, as so many had rather vaguely believed, of any purposeful medical or public-health interventions.