Changes in fatty acid intake and subsequent risk of all-cause and cause-specific mortality in males and females: a prospective cohort study.

BACKGROUND

The associations between changes in fatty acid intake over time and subsequent mortality are unclear.

OBJECTIVES

The objective of this study was to prospectively examine associations between changes in fatty acid intake (as percentage of total energy) and mortality.

METHODS

Among 65,179 adults from the Nurses' Health Study and Health Professionals Follow-up Study, free from cardiovascular disease, cancer, and diabetes at baseline in 1994, we documented 20,571 deaths through 2020 (1,334,603 person-years). Diets were assessed every 4 years using validated questionnaires. Hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality risk were estimated from Cox proportional hazards models.

RESULTS

A 5% energy increment in total fat intake was associated with 5% lower all-cause mortality (HR: 0.95; 95% CI: 0.93, 0.96; isocaloric comparison was total carbohydrate). The HRs of all-cause mortality (95% CI) were 0.83 (0.78, 0.89) and 0.91 (0.87, 0.94) for a 5% increment in energy intake from polyunsaturated fatty acid (PUFA) and monounsaturated fatty acid (MUFA), respectively, and was 1.10 (1.04, 1.17) for a 1% increase in energy intake from trans fatty acid (TFA; all P ≤ 0.001). Changes in saturated fatty acid (SFA) were not associated with all-cause mortality. Increases in intakes of linoleic acid, marine n-3 PUFA, and MUFA from plant sources were each significantly associated with lower all-cause mortality. In substitution analyses, replacing 5% energy from SFA with PUFA was associated with 19% lower all-cause mortality (HR: 0.81; 95% CI: 0.75, 0.87), whereas replacing 0.3% of energy from SFA with marine n-3 PUFA was associated with 11% lower all-cause mortality (HR: 0.89; 95% CI: 0.84, 0.93). Isocaloric substitution of SFA by PUFA, particularly marine n-3 PUFA, was associated with lower mortality due to cardiovascular, neurodegenerative, and respiratory diseases.

CONCLUSIONS

These findings support replacing SFA with unsaturated fatty acids (especially from plant sources) and eliminating dietary TFA to reduce premature death.