Specific Dietary Fats in Relation to Total and Cause-Specific Mortality

Abstract

Importance

Previous studies have shown distinct associations between specific dietary fat and cardiovascular disease. However, evidence on specific dietary fats and mortality remains limited and inconsistent.

Objective

To examine the associations of specific dietary fats with total and cause-specific mortality in two large ongoing prospective cohort studies.

Design, setting, and participants

We investigated 83,349 women from the Nurses’ Health Study (1980-2012) and 42,884 men from the Health Professionals Follow-up Study (1986-2012) who were free from cardiovascular disease, cancer and diabetes at baseline. Dietary fat intake was assessed at baseline and updated every 2 to 4 years.

Main outcomes and measures

We performed systematic searches of the vital records of states and of the National Death Index, supplemented by reports from family members or postal authorities.

Results

We documented 33,304 deaths during 3,439,954 person-years of follow-up. After adjustment for known and suspected risk factors, dietary total fat, compared to total carbohydrate, was inversely associated with total mortality ( P for trend <0.001). The hazard ratios (HRs) of total mortality comparing extreme quintiles of specific dietary fats was 1.08, (95% confidence interval (CI), 1.03-1.14) for saturated fat, 0.81 (95% CI, 0.78-0.84) for polyunsaturated fat, 0.89 (95% CI, 0.84-0.94) for monounsaturated fat and 1.13 (95% CI, 1.07-1.18) for trans fat ( P for trend <0.001 for all). Replacing 5% of energy from saturated fats with equivalent energy from polyunsaturated fats and monounsaturated fats was associated with 27% (HR =0.73, 95% CI, 0.70-0.77) and 13% (HR =0.87, 95% CI, 0.82-0.93) estimated reductions in total mortality, respectively. HR of total mortality comparing extreme quintiles of n-6 polyunsaturated fat intake was 0.85 (95% CI, 0.81-0.89). Intake of n-6 polyunsaturated fat, especially linoleic acid, was inversely associated with mortality due to most major causes, while marine n-3 polyunsaturated fat intake was associated with a modestly lower total mortality (HR comparing extreme quintiles =0.96, 95% CI, 0.93-1.00).

Conclusions and relevance

Different types of dietary fats have divergent associations with total and cause-specific mortality. These findings support current dietary recommendations to replace saturated and trans fat with unsaturated fats.