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 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 , 1.15; 95% CI, 1.08-1.22; P for trend < .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 < .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/d 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 < .001). Every 10-g/d 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 < .001) and a 6% lower risk of CVD mortality (HR, 0.94; 95% CI, 0.89-0.99; P for trend = .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 < .001). Substituting 10-g/d 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 < .001) and a 17% reduction in cancer mortality (HR, 0.83; 95% CI, 0.76-0.90; P < .001).

Conclusions and RelevanceIn 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.

Accepted for Publication: January 14, 2025.

Published Online: March 6, 2025. doi:10.1001/jamainternmed.2025.0205

Corresponding Author: Dong D. Wang, MD, ScD, Channing Division of Network Medicine, Brigham and Women’s Hospital and Harvard Medical School, 181 Longwood Ave, Boston, MA 02115 (dow471@mail.harvard.edu).

Author Contributions: Dr Wang had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Zhang, Chadaideh, Hu, Willett, Stampfer, Wang.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Zhang, Wang.

Critical review of the manuscript for important intellectual content: Chadaideh, Yanping Li, Yuhan Li, Gu, Liu, Guasch-Ferré, Rimm, Hu, Willett, Stampfer, Wang.

Statistical analysis: Zhang, Chadaideh, Yanping Li, Yuhan Li, Gu, Liu, Willett.

Obtained funding: Wang.

Administrative, technical, or material support: Chadaideh, Hu, Willett, Stampfer, Wang.

Supervision: Rimm, Wang.

Conflict of Interest Disclosures: Dr Guasch-Ferré reported grants from the Novo Nordisk Foundation and the International Nut and Dried Fruit Council outside the submitted work. Dr Willett reported grants from the National Institutes of Health during the conduct of the study. Dr Stampfer reported grants from the National Institutes of Health during the conduct of the study. No other disclosures were reported.

Funding/Support: This study was supported by research grants from the National Institutes of Health (UM1 CA186107, P01 CA87969, R01 HL034594, R01 HL088521, U01 CA176726, U01 HL145386, U01 CA167552, R01 HL35464, R01 HL60712, P30 DK46200, R00 DK119412, R01 AG077489, and R01 NR019992).

Role of the Funder/Sponsor: The National Institutes of Health had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Meeting Presentation: This study was presented at the American Heart Association EPI/Lifestyle Scientific Sessions 2025; March 6, 2025; New Orleans, Louisiana.

Data Sharing Statement: See Supplement 2.

Additional Contributions: For their contributions to this study, we thank the central cancer registries supported through the Centers for Disease Control and Prevention’s National Program of Cancer Registries and/or the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program. Central registries may also be supported by state agencies, universities, and cancer centers. Participating central cancer registries include the following: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Indiana, Iowa, Kentucky, Louisiana, Massachusetts, Maine, Maryland, Michigan, Mississippi, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Puerto Rico, Rhode Island, Seattle (Surveillance, Epidemiology, and End Results Program Registry), South Carolina, Tennessee, Texas, Utah, Virginia, West Virginia, and Wyoming. We also thank the participants in the HPFS, NHS, and NHSII for their continuing outstanding level of cooperation, as well as the staff of the HPFS, NHS, and NHSII for their valuable contributions.