Abstract P358: Dietary Fat Quality and Risk of CHD in the 28 Year Follow-up of a Large Prospective Study of US Women

Background: The importance of fat quality is reflected in the recent 2010 Dietary Guidelines for Americans, which recommend reducing saturated fat intake, and replacing this with polyunsaturated fat. Health effects of dietary fat are often estimated as an isocaloric substitution with carbohydrates (nutrient density models). Expressing fat intake as a % of total fat instead better quantifies fat quality, in overall diet and individual foods, and may provide an alternative approach to evaluate associated disease risk. We evaluated this novel measure of dietary fat quality, the % of fat type relative to total fat intake, on CHD risk among women in the Nurses' Health Study. Methods: We followed 84,531 women, free of chronic disease at baseline, from 1980-2008. Data on diet and other factors were ascertained every 2-4 years via questionnaires. For saturated and polyunsaturated fats, fat quality was calculated as grams of fat type / grams of total fat, and included in Cox proportional hazards models with total fat (fat density model), to estimate the association between fat intake and risk of CHD. We also estimated these associations using traditional nutrient density models, with isocaloric replacement of fat with carbohydrates. Results: Over 28 years, there were 3373 cases of CHD. A greater proportion of fat intake as saturated fat was associated with higher risk of CHD (p, trend<0.001) ( Table ). Conversely, a greater proportion of fat intake as polyunsaturated fat was associated with lower risk (p, trend<0.001), which was seen for both N-6 and N-3 fats. Compared with nutrient density models, RR obtained from fat density models were greater in magnitude for saturated and N-3 fats, but similar in magnitude for total and N-6 polyunsaturated fat. Conclusions: Saturated and polyunsaturated fat, quantified as a % of total fat, were significantly associated with CHD risk. This novel measure of dietary fat may aid in the translation of dietary recommendations of fat quality and may provide guidance in distinguishing foods based on fat quality.