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Greater intake of plant fat, particularly fat from grains and vegetable oils, was associated with lower overall and cardiovascular disease (CVD) mortality in findings of a new study published in JAMA Internal Medicine.

Conversely, greater consumption of animal-based fat, including fat from dairy and eggs, was associated with an increased risk of overall and CVD mortality, according to results from the prospective cohort study of over 405 000 persons with 24 years of follow-up. These associations were independent of key mortality risk factors, researchers reported.

In addition, results showed that replacing 5% of energy from animal fats with an equivalent amount of plant fats was associated with a 4% to 24% lower risk for overall mortality and a 5% to 30% lower risk for CVD mortality (P < .001), highlighting the potential benefits of replacing unhealthy dietary fats.

“These findings offer detailed insights relevant to dietary guidelines that could be useful for improving human health and related outcomes,” corresponding author Demetrius Albanes, MD, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health (NIH), Bethesda, Maryland, and colleagues wrote in the study published online August 12, 2024.

Albanes and coauthors noted that relatively few prospective studies have evaluated the associations of specific dietary fat sources with long-term health. To fill this gap in research, investigators examined dietary and health data from 1995 to 2019 as part of the NIH’s AARP Diet and Health Study Cohort. A total of 407 531 individuals (56.9% men; mean age, 61.2 years) were included in the current study.

Dietary fat intake was assessed using a validated food frequency questionnaire (FFQ) that collected information on specific food sources of dietary fats. The FFQ included 124 dietary items and portion sizes, based on the US Department of Agriculture’s Continuing Survey of Food Intakes by Individuals. Total dietary fat intake included both plant sources (ie, grains, nuts, legumes, and vegetable oils) and animal sources (ie, red and white meat, dairy foods, and eggs), according to the study.

Participants were divided into 5 quintiles, where each quintile represented 20% of the study population, ranked from the lowest (quintile 1) to the highest (quintile 5) intake of dietary fats. The primary outcomes of interest were estimated 24-year adjusted absolute risk differences (ARDs) for the association between dietary fat intake and mortality. Albanes and colleagues adjusted for various confounding factors, including body mass index (BMI), race or ethnicity, smoking status, physical activity, education, marital status, diabetes, health status, and other dietary components.

Findings

During 8 107 711 person-years of follow-up, 185 111 deaths were documented, including 58 526 CVD deaths.

After multivariable adjustment (including adjustment for relevant food sources), when researchers compared the highest quintile to the lowest quintile, they observed that a diet with a higher intake of plant fat (HRs 0.91 and 0.86; adjusted ARDs, −1.10% and −0.73%; P for trend < .001), particularly fat from grains (HRs, 0.92 and 0.86; adjusted ARDs, −0.98% and −0.71%; P < .001) and vegetable oils (HRs, 0.88 and 0.85; adjusted ARDs, −1.40% and −0.71%; P < .001), was associated with a lower risk for overall and CVD mortality, respectively.

In contrast, after comparing the highest quintile to the lowest quintile, investigators reported that higher consumption of total animal fat (HRs, 1.16 and 1.14; adjusted ARDs, 0.78% and 0.32%; P < .001), dairy fat (HRs, 1.09 and 1.07; adjusted ARDs, 0.86% and 0.24%; P < .001), or egg fat (HRs, 1.13 and 1.16; adjusted ARDs, 1.40% and 0.82%; P < .001) was associated with an increased risk for mortality for overall and CVD mortality, respectively.

Albanes and colleagues noted several limitations to their study, including the fact that the FFQ used to assess dietary fat intake could be subject to measurement error and dietary fat intake being calculated based on baseline data and, therefore, may not reflect possible dietary changes during follow-up. Also, most participants were non-Hispanic White, which limits the generalizability of the results to other racial and ethnic populations.

Reference: Zhao B, Gan L, Graubard BI, et al. Plant and animal fat intake and overall and cardiovascular disease mortality. JAMA Intern Med. Published online August 12, 2024. doi:10.1001/jamainternmed.2024.3799