A LARGE cohort study of 221,054 US adults has revealed that higher butter intake is associated with increased mortality, while plant-based oils like olive, soybean, and canola oils are linked to lower risks of death from cancer, cardiovascular disease (CVD), and all causes.
Dietary fats play a significant role in long-term health outcomes, but the relationship between butter, plant-based oils, and mortality remains debated. This study investigated associations between long-term intake of these fats and mortality risks using data from three major US cohorts. With growing interest in dietary strategies to reduce chronic disease burden, clarifying the health impacts of common fats is critical for public health guidance.
The prospective cohort analysis pooled data from the Nurses’ Health Study (1990–2023), Nurses’ Health Study II (1991–2023), and Health Professionals Follow-up Study (1990–2023), tracking 221,054 adults without baseline chronic diseases. Participants’ diets were assessed every four years using validated food frequency questionnaires. Over 33 years of follow-up, 50,932 deaths were recorded, including 12,241 cancer-related and 11,240 CVD-related deaths. After adjusting for confounders, the highest quartile of butter intake (vs. the lowest) was associated with a 15% higher total mortality risk (HR 1.15; 95% CI 1.08–1.22). Conversely, the highest plant-based oil intake reduced total mortality by 16% (HR 0.84; 95% CI 0.79–0.90). Each 5g/day increase in canola, soybean, or olive oil intake lowered total mortality risk by 15%, 6%, and 8%, respectively. Substituting 10g/day of butter with plant-based oils reduced total mortality by 17% (HR 0.83; 95% CI 0.79–0.86) and cancer mortality by 17% (HR 0.83; 95% CI 0.76–0.90). Butter intake also correlated with a 12% higher cancer mortality risk (HR 1.12; 95% CI 1.04–1.20).
These findings highlight the importance of replacing butter with plant-based oils to reduce premature mortality. For clinical practice, prioritising oils like olive, soybean, or canola in dietary counselling could offer substantial public health benefits. Future research should explore biological mechanisms, assess other plant-based oils, and validate results in diverse populations to refine dietary guidelines.
Katrina Thornber, EMJ
Reference
Zhang Y et al. Butter and plant-based oils intake and mortality. JAMA Intern Med. 2025;DOI:10.1001/jamainternmed.2025.0205.
