Butter and Plant-Based Oils Intake and Mortality

Abstract

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 221054 adults (mean [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), 50932 deaths were documented, with 12241 due to cancer and 11240 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% CI, 1.08-1.22; P for trend