Interpreting the 'newer knowledge of nutrition': Science, interests, and values in the making of dietary advice in the United States, 1915--1965

This dissertation explores the diversity of interpretations given by health professionals and other Americans to the so-called "newer knowledge of nutrition" between the 1910s and the mid-1960s. Within two decades of the discovery of vitamins in the 1910s, nutrition experts had begun to speculate that the increased use of vitamin- and mineral-rich foods could enhance vitality, defer aging, and extend life; and that many of the common ailments suffered by Americans were caused by the consumption of nutritionally impoverished diets.; These assertions were embraced by some and challenged by others. The great discoveries of the first half of the twentieth century created more uncertainties than they resolved. As a result, disputes emerged as to the composition of the ideal diet, the desirability of consuming particular foods, and usefulness of dietary supplements and vitamin-fortified foods. During these controversies, individuals took sides according to their interests and values. Professions with an antiquackery bias tended to discount the significance of nutrition, whereas those committed to improving the American diet offered an expansive view of the influence of food on health. External circumstances also affected the interpretation of the scientific data. Concerns about national fitness on the eve of World War II led health authorities to maintain that tens of millions of Americans suffered from nutritional deficiencies, despite the tenuousness of the evidence upon which this conclusion was based. Once the war ended and economic prosperity returned, the problem of malnutrition receded from public view, despite evidence showing that many Americans were still eating poorly.; The newer knowledge also gave rise to a grass-roots dietary reform movement dedicated to the proposition that much of the ill health in the United States was caused by the consumption of nutrient-depleted processed foods. Although health authorities maintained that the movement's claims were unscientific, the physicians and dentists who founded the health food movement in the 1930s believed that they were offering legitimate interpretations of nutrition science. Their interpretations, however, were colored (and distorted) by an ideology that held that urban-industrial society and modern food processing methods, in particular, disrupted the natural order and thereby threatened man's well-being.