In a recent study published in JAMA Internal Medicineresearchers determined the relationship between animal and vegetable fat intake and mortality from cardiovascular disease (CVD) and other causes.
Background
Dietary fats are crucial for the maintenance of cell membranes and metabolic fuel, the absorption and transport of fat-soluble vitamins, the regulation of ion channel activities, and the regulation of signal transduction. Vegetable fats contain more monounsaturated and polyunsaturated fats, while animal fats are higher in saturated fat. There is increased scientific interest in the effects of dietary fat consumption on health outcomes, which depend on food sources.
However, there are limited data establishing associations between dietary fat intake from various sources and human health. Although previous experimental and cross-national studies suggest that reducing dietary fat consumption is beneficial, recent cohort-based research, meta-analyses, and clinical trials provide conflicting results.
About the study
In the present prospective cohort study, researchers investigated whether consumption of fat from animal or vegetable sources could increase all-cause mortality and cardiovascular disease in the United States.
The researchers obtained data from participants in the National Institutes of Health (NIH)-AARP Nutrition and Health Study between 1995 and 2019 and analyzed data between February 2021 and May 2024. They used questionnaires to collect demographic, anthropometric, lifestyle and dietary data, including specific sources of fat.
Researchers obtained dietary data using the National Cancer Institute (NCI) Dietary History Questionnaire (DHQ). They determined the cause of death through subsequent links to the Social Security Administration’s master death record. They followed participants until December 31, 2019 or death, whichever occurred first.
The researchers used multivariate-adjusted Cox proportional hazards regressions to calculate hazard ratios (HRs) and absolute risk differences (ARDs) over 24 years. Study covariates included age, sex, body mass index (BMI), ethnicity, race, physical activity, smoking status, education level, marital status, health status, diabetes, vitamin supplements, protein intake, carbohydrates, trans fat, cholesterol , fiber and alcohol intake at baseline.
The researchers conducted subgroup assessments to explore whether relationships differed by age, gender, BMI, diabetes, smoking, alcohol consumption, Healthy Eating Index 2015 (HEI-2015) scores, vitamin supplements, health status, postmenopausal hormone treatments and follow-up. . To reduce confounding effects from other nutrients, they conducted stratified analyzes with low and high intakes of protein (plant, animal, or total), fiber, carbohydrates, total vegetables, and fruit. They also performed a permutation analysis to determine the relationship between replacing 5.0% of calories from vegetable fat with an equivalent reduction in animal fat from various sources from any cause and the risks of CVD-related mortality.
Results
Among 407,531 participants, 231,881 (57%) were men, with a mean age of 61. The mean values for daily dietary fat intake from animal and plant sources were 29 grams and 25 grams, respectively. People who consumed more vegetable fat tended to be physically active, have diabetes, and have an increased BMI, with increased intake of calories, alcohol, fiber, vegetables, and fruit, and fewer supplemental vitamins.
Over 8,107,711 individual years, the group recorded 185,111 deaths, of which 58,526 were due to cardiovascular disease. After multivariate adjustments (including adjustments for relevant dietary sources), vegetable fat intake increased (HR, 0.9 and 0.9; ARD reductions, 1.1% and 0.7%), especially from cereals (HR , 0.9 and 0.9, ARD reductions, 1.0% and 0.7%) and vegetable oils (HR, 0.9 and 0.9; ARDs, 1.4% and 0.7%) were related with reduced risks of death from any cause and especially for cardiovascular disease, respectively.
In contrast, increased intake of animal fat (HR, 1.2 and 1.1; ARDs, 0.8% and 0.3%) from dairy products (HR, 1.1 and 1.1; ARD reductions, 0.9% and 0.2%) or eggs (HR, 1.1 and 1.2; ARD reductions, 1.4% and 0.8%) were associated with increased risk of all-cause and CVD mortality, respectively. Replacing 5.0% of calories from animal fat with 5.0% from vegetable fat, particularly fat from vegetable oils or grains, reduced the risk of all-cause mortality by 4.0% to 24% and cardiovascular mortality disease by 5.0% to 30%. They also performed sensitivity analyses, adjusting for total calorie intake and excluding patients with diabetes and the initial two to five years of follow-up.
The inverse associations of vegetable fat intake with all-cause mortality were statistically significant among people younger than 60 years who consumed one to three alcoholic drinks per day. In contrast, the positive animal fat-mortality associations were stronger for men between 60 and 65 years of age with a lower BMI. The association of animal fat consumption with CVD mortality was strongest among younger individuals. Stratified and sensitive analyzes yielded similar findings.
Conclusion
The study findings showed that increased intake of vegetable fat, especially fats from vegetable oils and grains, reduced deaths from any cause and especially from cardiovascular disease. Conversely, increased intake of animal fat, especially from eggs and dairy products, was associated with an increased risk of mortality. The findings could inform dietary choices and guidelines for improving human health.
