The evolution of nutrition science from clinical studies by Hippocrates in the fourth century BC to the current preoccupation with molecular biology is a unique odyssey. Contributions by physicians to the recognition of the classical vitamin and amino acid deficiency diseases in humans in the eighteenth and nineteenth centuries were followed by the development of animal models to explore the etiology of these diseases in the twentieth century. In the eighteenth century, Lavoisier taught that animal respiration is a chemical process that results in the consumption of oxygen and the production of carbon dioxide. This observation led to a better appreciation of the nature of metabolism and to the assignment of caloric values to macronutrients. The development of enzymology in the first half of this century and the identification of vitamins as coenzyme precursors enabled investigators to study enzyme activity as a function of nutritional status.

The discovery of the structure of DNA by Watson and Crick in 1953, the elucidation of the genetic code, the exploration of gene structure, and the regulation of gene expression have led to the expansion of biochemical genetics. These new concepts and methods in molecular biology have, in turn, led to the cloning of genes, the identification of genomic receptors for hormones and growth factors, and the implementation of genetic engineering. The recent discoveries of genomic receptors for retinoic acid and 1,25-dihydroxycholecalciferol have further strengthened the linkage between nutrition and genetics.

I view genetics and nutrition as reciprocal sciences. The development of nutritional requirements for organisms during the millions of years that have elapsed since the first blue-green algae became functional on this planet is the result of genetic deletion of enzymes for nutrient synthesis. In humans, most primates, and the guinea pig, the deletion of the enzyme L-gulonolactone dehydrogenase has blocked the synthesis of ascorbic acid from glucose and created the need for dietary intake of vitamin C. Furthermore, the extent to which nutrients are metabolized or conserved is under genetic control and modulates the pattern of under- and overnutrition that we see in the world. In the Western countries the diseases of overnutrition are more prevalent than the diseases of undernutrition, and all of them have genetic determinants. With every passing day new genes are discovered that play critical roles in the etiology of obesity, hypertension, coronary artery disease, osteoporosis, and diabetes mellitus.

A conference on "Genetic Variation and Nutrition" organized by Barton Childs and Artemis P. Simopoulos was held in Washington, DC, in June 1989. It defined the interaction between genetics and nutrition in (a) the determination of nutritional requirements, (b) the development of chronic diseases, (c) the role of nutrients in gene expression, (d) the appraisal of health risks in individuals, and (e) the development of public policy. The proceedings of this conference have recently appeared as a monograph.¹ Volume 11 of the Annual Review of Nutrition presents a broad range of subjects in the fields of basic, clinical, and public health nutrition. Biochemical genetics is emphasized in reviews of obesity, vitamin D receptors, regulation of glycolysis and gluconeogenesis, and the use of phosphorus magnetic resonance spectroscopy to quantitate defects in AXP synthesis in genetic as well as nutritional disorders. The prefatory chapter by Fredrick Stare presents the research history of the Department of Nutrition at Harvard University as it moved in time from the study of vitamins and coenzymes to the study of the pathogenesis of the variably nutrition-responsive and often genetically dominated chronic diseases. In previous volumes the genetic contributions to coronary heart disease and the hyperlipidemias have been reviewed.

In Volume 11, reviews devoted to lipids discuss the biosynthesis of prostaglandins, the effect of glyceride structure on their metabolism, the structure and function of lipoprotein lipase, and the use of niacin as a drug for regulating lipoprotein metabolism. Metabolism is addressed by essays on insulin-like growth factors, glutamine as a substrate for the splanchnic bed, fructose metabolism, the regulation by nutrients of cytochrome P450, the role of pipecolic acid in lysine metabolism, and the use of doubly-labeled water to measure energy metabolism. Reviews on trace minerals discuss copper, molybdenum, and fluoride. An important review in clinical nutrition considers the effect of parenteral nutrition on bone and mineral homeostasis. Contributions to public health are represented by reviews on vegetarianism and the indications for intervention to alter serum lipids in children.

I thank my associates on the Editorial Committee, the consultants who aided us in assembling the list of topics and authors, and the authors who contributed the excellent reviews that appear in Volume 11. Production editor Joan Cohen in Palo Alto, California, deserves our thanks for her important role in producing this volume.

Robert E. Olson, Editor

l-World Review of Nutrition and Dietetics, 1990, Vol. 63, Karger, Basel/New York.