In 1988, research suggested that high intake of saturated fat increased the risk of cardiovascular disease and cancer, and feeding polyunsaturated fatty acids decreased plasma lipid values. However, understanding of the roles of specific types of fatty acids in nutrition and health remained limited. This was primarily because the technology for analysis of fatty acid compositions in human tissue had only recently achieved the required specificities and secondarily because application of the technology on the large scale of an epidemiologic study had to await recent advances in automation of the chromatography. Also intervention studies, aimed at reducing dietary intake of polyunsaturated fatty acids for long periods of time, were either impractical or unethical. The study was conducted to confirm preliminary results suggesting greater prevalence of low levels of essential fatty acids, particularly w3 fatty acids, among people with cardiovascular disease and hypertension, and to provide further confirmatory evidence to results that hyperlipidemia was inversely associated with essential fatty acid levels.