Changes in our understanding of diet and health drive changes in the way foods are processed. Conversely, what is available on the shelf will have an impact on the choices consumers make, thereby affecting their health. Historical examples of industrial manipulation of the diet include fortification and enrichment of cereal grains with vitamins; increased production of unsaturated vegetable oils and margarine as substitutions for hydrogenated fat, lard, and butter; lowered cholesterol content foods; reduced sugar content foods; lower sodium foods; decreased portion sizes or caloric density in prepackaged foods for use in weight loss or maintenance; and increased calcium levels to prevent osteoporosis. However, degenerative diseases such as cancer, atherosclerosis, bone disease, arthritis, and dementia will continue to be prevalent in the future. Whether or not the food systems available on the shelf can influence all of these disease states is not clear; however, studies have indicated that nutritional factors do contribute to the development of some of these diseases. Patterns in food consumption have changed and will continue to change as recommendations such as decreased consumption of saturated fats, salt, and cholesterol continue to be made. Increased ingestion of fish and/or fish oil is one recommendation that has been suggested because of the effect of omega-3 fatty acids on platelet aggregability and circulating levels of lipids. Wildly speculating from preliminary studies, fish oil has also been recommended for disease states including arthritis, cancer, and diseases of the immune system.(ABSTRACT TRUNCATED AT 250 WORDS)