The third volume of Advances in Nutritional Research continues the precedent set in previous volumes of providing authoritative reviews on the current state of kwledge with respect to major topics of ongoing nutritional research. This series is designed to be of value to investigators engaged in fundamental research as well as to those involved in its application to problems in human and animal nutrition. This volume contains three chapters on recent developments in research on irganic elements, including a review, by F. H. Nielsen, of the evidence for a requirement for additional trace elements; a conspectus, by C. E. Casey and K. M. Hambidge, on the occurrence of trace element deficiencies in man; and a description, by M. Janghorbani and V. R. Young, of new methods of assessing the bioavailability of minerals in the diet. There are also three chapters on current topics of lipid research. One (by F. D. Sauer) is devoted to the cardiopathic effects of certain dietary moeic fatty acids, ather (by C. Galli) to the influence of diet on prostaglandin synthesis, and the third (by H. 0. Bang and J. Dyerberg) to an analysis of the role of the unusual polyunsaturated fatty acids found in marine oils in the prevention of ischemic heart disease.