Esophagus to Small Intestine
JAMA Intern Med. 2025;185(5):549-560
Butter and plant-based oils intake and mortality
Importance: The relationship between butter and plant-based oil intakes and mortality remains unclear, with conflicting results from previous studies. Long-term dietary assessments are needed to clarify these associations.
Objective: To investigate associations of butter and plant-based oil intakes with risk of total and cause-specific mortality among US adults.
Design, setting, and participants: This prospective population-based cohort study used data from 3 large cohorts: the Nurses’ Health Study (1990–2023), the Nurses’ Health Study II (1991–2023), and the Health Professionals Follow-up Study (1990–2023). Women and men who were free of cancer, cardiovascular disease (CVD), diabetes, or neurodegenerative disease at baseline were included.
Exposures: Primary exposures included intakes of butter (butter added at the table and from cooking) and plant-based oil (safflower, soybean, corn, canola, and olive oil). Diet was assessed by validated semiquantitative food frequency questionnaires every 4 years.
Main outcomes and measures: Total mortality was the primary outcome, and mortality due to cancer and CVD were secondary outcomes. Deaths were identified through the National Death Index and other sources. A physician classified the cause of death based on death certificates and medical records.
Results: During up to 33 years of follow-up among 221,054 adults (mean [standard deviation {SD}] age at baseline: 56.1 [7.1] years for Nurses’ Health Study, 36.1 [4.7] years for Nurses’ Health Study II, and 56.3 [9.3] years for Health Professionals Follow-up Study), 50,932 deaths were documented, with 12,241 due to cancer and 11,240 due to CVD. Participants were categorized into quartiles based on their butter or plant-based oil intake. After adjusting for potential confounders, the highest butter intake was associated with a 15% higher risk of total mortality compared to the lowest intake (hazard ratio [HR] = 1.15; 95% confidence interval [CI]: 1.08–1.22; p for trend < 0.001). In contrast, the highest intake of total plant-based oils compared to the lowest intake was associated with a 16% lower total mortality (HR = 0.84; 95% CI: 0.79–0.90; p for trend < 0.001). There was a statistically significant association between higher intakes of canola, soybean, and olive oils and lower total mortality, with HRs per 5-g/day increment of 0.85 (95% CI: 0.78–0.92), 0.94 (95% CI: 0.91–0.96), and 0.92 (95% CI: 0.91–0.94), respectively (all p for trend < 0.001). Every 10-g/day increment in plant-based oils intake was associated with an 11% lower risk of cancer mortality (HR = 0.89; 95% CI: 0.85–0.94; p for trend < 0.001) and a 6% lower risk of CVD mortality (HR = 0.94; 95% CI: 0.89–0.99; p for trend = 0.03), whereas a higher intake of butter was associated with higher cancer mortality (HR = 1.12; 95% CI: 1.04–1.20; p for trend < 0.001). Substituting 10-g/day intake of total butter with an equivalent amount of total plant-based oils was associated with an estimated 17% reduction in total mortality (HR = 0.83; 95% CI: 0.79–0.86; p < 0.001) and a 17% reduction in cancer mortality (HR = 0.83; 95% CI: 0.76–0.90; p < 0.001).
Conclusions and relevance: In this cohort study, higher intake of butter was associated with increased mortality, while higher plant-based oils intake was associated with lower mortality. Substituting butter with plant-based oils may confer substantial benefits for preventing premature deaths.