The nutrition community is having an identity crisis. Both those who work in the field of nutrition and those who observe us appear to be confused about our goals and responsibilities. Who are nutrition scientists and who are nutritionists and what do they do? Can they be distinguished from one another by background, education, and professional training? The simple answer is that nutrition scientists are scientists from many biological disciplines who investigate scientific problems in nutrition. Nutritionists, on the other hand, are practitioners from diverse backgrounds (medicine, dietetics, nursing, public health) who apply nutrition science to clinical and public health problems. The distinction becomes blurred for some individuals who engage in both research and practice.

Nutrition scientists, like all scientists, should be devoted to the discovery of new knowledge, whereas nutrition practitioners should combat malnutrition wherever it is found. This dichotomy is not unlike the one that distinguishes medical scientists from medical practitioners. At present, new stresses and strains are appearing in the relationship between scientists and practitioners no matter in what field they work, particularly now as both groups face diminishing financial and political support.

In the prefatory chapter in this volume (13) of the Annual Review of Nutrition, Alan Berg, a public health practitioner with the World Bank, criticizes nutrition scientists for not providing graduate students with the practical tools and skills needed to effectively apply nutrition concepts to the problems of malnutrition in the Third World. Berg states that a "marriage of research and operations is required...what we need are nutrition engineers." He suggests that academic nutrition departments (which like the MIT department are disappearing at an appalling rate) should divert more resources and trainees to applied nutrition. His essay, while admirable in concept, underscores tensions that already exist between nutrition scientists and nutrition practitioners and provides no clear prescription except to indicate that a new institutional setting is needed. It is my opinion that an institutional setting is available for just the sort of training that Berg envisions, namely university-based schools of public health, many of which have unwisely abandoned programs in nutrition during the past two decades.

The problem of nutrition science vs its application was considered earlier in this series by Austin & Overholt in their chapter on "Building the Bridge Between Science and Politics" (Annual Review of Nutrition, 1988, 8:1–20). They urged students of nutrition to learn more about the political process in order to cope with the world's nutritional problems. Berg and Austin & Overholt have made strong points about the tactics required to correct malnutrition on our planet, but their advice remains largely in the realm of the theoretical because of obstacles in translating their recommendations into practice.

The reason for this predicament is the diminishing state of nutrition as a biological science. At present, fewer students are applying to fewer departments which have reduced resources. Advances in nutrition knowledge, as represented by our reviews, are coming increasingly from different departments in the biological and medical sciences and not from departments of nutrition. It is not essential for advances in nutrition science to come from members of a nutrition department, but the fact is that nutrition as a field has become so dispersed that it is hardly recognizable.

Many practitioners of nutrition, furthermore, are undertrained and over- worked. Nutrition education in medical schools is sadly neglected since only 21 of 124 medical schools in North America offer required courses in clinical nutrition. The electives offered by other schools provide only a kiss and a promise. The same can be said of the paramedical schools that provide nutrition education. The practitioners of nutrition, furthermore, are overwhelmed by propaganda from food companies, health food organizations, and proponents of "alternative (unconventional) medicine" that continue to confuse and mislead the public. One of the casualties in this interplay between nutrition practioners and nutrition politicians is the definition of an essential nutrient.

Although there is evidence that some vitamins may ameliorate some of the chronic degenerative diseases when used as drugs over long periods of time, there is no evidence that they are functioning in their usual preventive mode. Even the Food and Nutrition Board (FNB) of the National Academy of Science/National Research Council, which is composed mainly of nutrition scientists, is considering altering the Recommended Dietary Allowances (RDAs) to increase the allowance of certain vitamins because of their possible long-term effects in reducing the risk of cancer and heart disease. Nutrients are required to prevent deficiency diseases at levels of 0.5 to 1.5 X the RDA, which are defined as "levels of intake of essential nutrients that on the basis of scientific knowledge are judged by the FNB to be adequate to meet the known nutrient needs of practically all healthy persons." The RDAs do not apply to persons with illnesses such as malabsorption, hypermetabolism, and genetic disorders affecting the disposition of nutrients that alter nutritional requirements. Likewise they should not be recommended to combat the susceptibility of some individuals to the chronic degenerative diseases. Vitamins and other nutrients recommended at levels of 5 x the RDA or more should be considered drugs that are not needed by "practically all healthy persons."1

Even the use of a supplement of 400-4000 jjig (1-10 x RDA) of folic acid in pregnancy to prevent neural tube defects is not needed by "practically all healthy persons." In fact there is no relationship between the folate status of an individual woman and her risk of neural tube defects. The same is true for the use of antioxidant vitamins to retard aging, vitamin A for acne, nicotinic acid for hyperlipidemia, and 1,25-dihydroxycholecalciferol for osteoporosis. The prescription for these agents should be in the hands of physicians, not public health agencies or the health food lobby.

Besides the prefatory chapter by Berg, Volume 13 of the Annual Review of Nutrition contains a wide range of reviews dealing with basic nutrition, clinical nutrition, and public health nutrition. This year 60% of the reviews are devoted to fundamental studies of the metabolism, regulation, and function of nutrients. More is being learned about the genetics of nutritional events. The genetics of obesity, the molecular biology of nitrogen fixation and glucokinase, and the genetic engineering of plants are considered in four reviews. Eight reviews deal with the metabolism and regulation of lipids including short-chain fatty acids and carotenoids, lipoprotein receptors, flavin coenzymes, amino acid transport, tetrahydrobiopterin-dependent systems, and pyruvate dehydrogenase.

Three reviews focus on minerals (aluminum, iron, and selenium), and a very interesting essay asks whether oxygen is an essential nutrient. The toxicology of fungi in food is also considered. The clinical reviews address the nutritional management of glycogen storage disease, the effects of somatotropins on lactation, the effect of polyunsaturated fatty acids on blood pressure, and the nutritional management of osteoporosis and cystic fibrosis. Finally, there is a review on the clinical physiology of taste and smell. I thank my associate editors, Dennis M. Bier and Donald B. McCormick, for reviewing manuscripts, all members of the Editorial Committee for their help in assembling the list of topics and authors, and the authors who contributed the excellent reviews that appear in Volume 13. Production editor Joan Cohen in Palo Alto, California, deserves our thanks for her diligence in producing this volume.

Robert E. Olson, Editor

1-Council on Scientific Affairs of the AMA, 1987. Vitamin preparations as dietary supplements and as therapeutic agents. Am. Med. Assoc. 257:1929-36.