A large prospective cohort study found that greater intake of plant fat, particularly from grains and vegetable oils, may be associated with a lower risk of overall and cardiovascular disease–related mortality. In contrast, higher intake of animal fat, especially from dairy and eggs, was linked to an increased risk of all-cause and cardiovascular disease–related mortality.
In the study, published in JAMA Internal Medicine, investigators at the National Institutes of Health (NIH) analyzed data from 407,531 men and women (mean and standard deviation [SD] age = 61.2 and 5.4 years, 56.9% male) in the NIH-AARP Diet and Health Study over a 24-year follow-up period. During 8.1 million person-years of follow-up, 185,111 deaths occurred, including 58,526 from cardiovascular disease (45,634 from heart disease and 10,877 from stroke).
Comparing the highest vs lowest quintiles of intake, plant fat consumption was associated with a 9% lower risk of overall mortality (hazard ratio [HR] = 0.91, 95% confidence interval [CI] = 0.89–0.93, adjusted absolute risk difference [ARD] = –1.10%) and a 14% lower risk of cardiovascular disease–related mortality (HR = 0.86, 95% CI = 0.82–0.89, ARD = –0.73%) after multivariable adjustment. The strongest inverse associations were observed for fat from grains (overall mortality: HR = 0.92, 95% CI = 0.89–0.94, ARD = –0.98%; cardiovascular disease–related mortality: HR = 0.86, 95% CI = 0.82–0.90, ARD = –0.71%) and vegetable oils (overall mortality: HR = 0.88, 95% CI = 0.87–0.90, ARD = –1.40%; cardiovascular disease–related mortality: HR = 0.85, 95% CI = 0.82–0.89, ARD = –0.71%).
In contrast, animal fat intake in the highest vs lowest quintile was associated with a 16% higher risk of overall mortality (HR = 1.16, 95% CI = 1.12–1.19, ARD = 0.78%) and 14% higher risk of cardiovascular disease–related mortality (HR = 1.14, 95% CI = 1.08–1.20, ARD = 0.32%). Dairy fat (overall mortality: HR = 1.09, 95% CI = 1.07–1.11, ARD = 0.86%; cardiovascular disease–related mortality: HR = 1.07, 95% CI = 1.03–1.11, ARD = 0.24%) and egg fat intake (overall mortality: HR = 1.13, 95% CI = 1.11–1.16, ARD = 1.40%; cardiovascular disease–related mortality: HR = 1.16, 95% CI = 1.12–1.20, ARD, 0.82%) showed the most robust positive associations with mortality risk.
Substituting 5% of energy from animal fat with an equivalent amount from plant fat sources was estimated to lower overall mortality by 4% to 24% and cardiovascular disease–related mortality by 5% to 30%.
The study adjusted for important confounders including age, sex, race/ethnicity, BMI, smoking, physical activity, and dietary factors. Subgroup analyses revealed generally consistent results, although some associations were modified by age, sex, BMI, alcohol intake, and duration of follow-up. Sensitivity analyses excluding the first 2 or 5 years of follow-up, participants with diabetes, or missing covariate data did not materially change the findings.
Strengths of the study included the large sample size, long follow-up, and detailed data on dietary fat intake and potential confounders. Limitations included the observational design, which precluded causal inferences, potential residual confounding, and limited generalizability to other racial/ethnic groups.
"These findings offer detailed insights relevant to dietary guidelines that could be useful for improving human health and related mortality outcomes," the study authors underscored.
However, they noted the effect sizes were small and residual confounding could not be ruled out given the observational design.
The authors declared having no competing interests.
