Relationship between plasma fatty acid composition and diet over previous years in the Italian centers of the European Prospective Investigation into Cancer and Nutrition (EPIC)

Fatty acid levels in plasma phospholipids were related to food intake over the previous year as estimated by semiquantitative food frequency questionnaires compiled by 280 men and 246 women from the EPIC centers of Varese, Turin, Florence and Ragusa (Italy). Fatty acid content was determined by gas chromatography and analyzed in relation to age, sex and center. The most important finding was that plasma monounsaturated fatty acid levels, mainly oleic acid, were associated with olive oil consumption (r = 0.28 men, r = 0.19 women, both P <0.01). To our knowledge, this is the first time that these nonessential plasma fatty acids have been related to their dietary source in a population eating a varied and freely chosen diet. We confirmed that long-chain n-3 fatty acids in plasma phospholipids are associated with fish consumption and that odd chain 15: 0 and 17: 0 fatty acid levels are associated with dairy products and pizza-with-mozzarella consumption. N-6 polyunsaturated fatty acid levels reflected dietary intake of seed oils, mayonnaise and biscuits. Alcohol intake was positively associated with palmitic and palmitoleic acid and negatively associated with linoleic acid. These associations suggest indirect relations between alcohol consumption and other features of diet, and also that ethanol has an effect on fat metabolism. We found numerous indirect relationships (ie, not due to dietary consumption of food sources of the fatty acids) between plasma fatty acids and diet, which we propose as due to the influence of complex life-style factors.