Association of Specific Dietary Fats With Mortality
What is the association between specific types of dietary fats and mortality?
Data from the Nurses’ Health Study (NHS) (July 1, 1980, to June 30, 2012) and the Health Professionals Follow-up Study (HPFS) (February 1, 1986, to January 31, 2012) were used for the present analysis. Participants were free of cardiovascular disease (CVD) and diabetes (both types 1 and 2) at baseline. Dietary fat intake was assessed at baseline and updated every 2-4 years. Information on mortality was obtained from systematic searches of the vital records of states and the National Death Index, supplemented by reports from family members or postal authorities. Data were analyzed from September 18, 2014, to March 27, 2016. The primary outcomes of interest were total and cause-specific mortality.
A total of 83,349 women from NHS and 42,884 men from HPFS were included. During 32 years of follow-up in the NHS (2,464,852 person-years), 20,314 deaths occurred; during 26 years of follow-up in the HPFS (975,102 person-years), 12,990 deaths occurred. At baseline, participants with higher saturated fatty acid and monounsaturated fatty acid intakes had higher body mass index and were less likely to be physically active. After adjustment for known and suspected risk factors, dietary total fat compared with total carbohydrates was inversely associated with total mortality (hazard ratio [HR] comparing extreme quintiles, 0.84; 95% confidence interval [CI], 0.81-0.88; p < 0.001 for trend). The HRs of total mortality comparing extreme quintiles of specific dietary fats were 1.08 (95% CI, 1.03-1.14) for saturated fat, 0.81 (95% CI, 0.78-0.84) for polyunsaturated fatty acid, 0.89 (95% CI, 0.84-0.94) for monounsaturated fatty acid, and 1.13 (95% CI, 1.07-1.18) for trans-fat (p < 0.001 for trend for all). Replacing 5% of energy from saturated fats with equivalent energy from polyunsaturated fatty acid and monounsaturated fatty acid was associated with estimated reductions in total mortality of 27% (HR, 0.73; 95% CI, 0.70-0.77) and 13% (HR, 0.87; 95% CI, 0.82-0.93), respectively. The HR for total mortality comparing extreme quintiles of ω-6 polyunsaturated fatty acid intake was 0.85 (95% CI, 0.81-0.89; p < 0.001 for trend). Intake of ω-6 polyunsaturated fatty acid, especially linoleic acid, was inversely associated with mortality owing to most major causes, whereas marine ω-3 polyunsaturated fatty acid intake was associated with a modestly lower total mortality (HR comparing extreme quintiles, 0.96; 95% CI, 0.93-1.00; p = 0.002 for trend).
The investigators concluded that different types of dietary fats have divergent associations with total and cause-specific mortality. These findings support current dietary recommendations to replace saturated fat and trans-fat with unsaturated fats.
Replacing saturated fats with poly- and monounsaturated fats was associated with significant reductions in mortality. Counseling patients regarding the benefits of replacing saturated fats with poly- and monounsaturated fats is recommended.
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