Appropriate diet and lifestyle are twice as effective as pharmaceutical therapy in preventing adult-onset diabetes in certain high-risk populations. Diet and lifestyle also influence cardiovascular disease, cancer, and other major causes of mortality. A historical perspective of diet and health, ends with a discussion of conjugated linoleic acids (CLAs): possibly the most potent cancer-fighting substances in the human diet. Plant and animal genomics will help improve our understanding of genes that encode antioxidants, vitamins, etc., and how supplements and functional foods affect disease.