The Annual Review of Nutrition, in conformity with the goals of Annual Reviews Inc., provides a systematic, periodic examination of scholarly advances in nutrition through "critical, authoritative surveys of the recent original literature describing the current developments in the science of nutrition." The purpose of a critical review is not only to summarize a topic, but to root out errors of fact or concept and to provoke discussion that will lead to vigorous new research activity. The critical review is as essential a part of the overall scientific method as the original experiments and is part of a continuing peer-review process. The experimenter creates a hypothesis, plans an experiment, records his data, and evaluates his hypothesis. In due time he publishes a paper that is reviewed by peers in the field for adequacy of materials and methods, originality, and soundness of its conclusions. As other papers accumulate, however, it is necessary to take a second look at the published record to see what new scientific discoveries have been made and corroborated, what new areas have been opened, and which research should be encouraged. Fallacies and questionable hypotheses must also be combatted in these reviews in order to limit research in less promising directions. No human judgment, of course, is infallible, but the overall scientific effort depends upon a critical review at each stage in the development of a scientific report, from the experimental plan to the integration of the results into a broader field of science. This is particularly important for nutrition science at this time because of two major threats to the integrity, stability, and funding of the nutritional sciences. These factors apply to all science to an extent but it appears to me at the moment that nutrition science is particularly vulnerable.

The first factor is the turf battle between nutrition scientists and nutrition politicians for control of the data base that underlies food and health policy. Nutrition scientists depend upon the scientific method for their data base. Nutrition politicians, on the other hand, lean on descriptive epidemiology and anecdotal evidence, influenced by their particular beliefs about foods and by those of their constituents (consumerists, corporate interests, the media, and the public). It is regrettable that some scientists have joined these politicians in supporting unsound programs in nutrition education. Critical reviews play an important role in separating nutrition fact from fancy.

In addition, the tightening of the Federal Budget under such political phenomena as the Gramm-Rudman-Hollings Anti-deficit Act creates a gloomy financial future for the NIH and the NSF, particularly in the biological sciences. Such constraints in Federal funding make it extremely important that the most imaginative ideas in the hands of the most productive scientists be supported. Again, the critical review can be of value in guiding the assessment of grant applications, so that the scientific study of nutrition can grow. Such study is crucial, not only in clarifying the function of nutrients but also in elucidating the interactions of genetics, metabolism, and nutrition in the pathogenesis and prevention of the chronic degenerative diseases.

The Annual Review of Nutrition strives to cover the wide range of subjects that constitute the field of nutrition. Nutrition is not a single discipline; it draws from a variety of disciplines in both the basic and clinical areas. In the first six volumes, 50% of the pages deal with basic and experimental nutrition, 33% are devoted to clinical nutrition, and the remainder are related to epidemiology, anthropology, and public health nutrition.

The present issue, Volume 6, begins with a prefatory chapter by Dr. Hamish Munro of the Massachusetts Institute of Technology. He pleads for application of the modern disciplines of molecular and cell biology to problems in nutrition science. Nutrition science is not in any sense limited by its past or present technologies but must demand the application of new technologies and concepts to the study of nutrient requirements, metabolism, function, and the relationship of nutritional status to health.

This issue also includes reviews on the energetics of ethanol, the role of sugars in nutrition, the regulation of cholesterol biosynthesis, the metabolism of sulfur-containing amino acids, and the function of inositol phospholipids. The biochemical function of vitamins C and D, metabolism of carotenoids, and the function of carnitine in humans are also reviewed.

In clinical nutrition, Volume 6 includes reviews of the physiological adaptation to lower intakes of energy and protein; nutrition and infection; calcium and hypertension; mutagens and carcinogens in foods; labile methyl groups in the promotion of cancer; and inheritable disorders of biotin metabolism. In comparative nutrition we have essays on the nutrition of fish and of ruminants and an article on the role of gastrointestinal microflora in mammals. In the field of nutritional anthropology we present chapters on the impact of culture on food habits; diet and human behavior; and food likes and dislikes.

I would like to thank my associates on the Editorial Committee, the consultants who aided us in assembling the reviews, and the authors who have provided such excellent reviews for Volume 6. Our work has been ably complemented by that of Ms. Margot Platt, the Production Editor of the Annual Review of Nutrition in Palo Alto.

Robert E. Olson, Editor