Using plant-based oils such as olive, soybean, or canola instead of butter may help prevent premature deaths, as reported in a large study.

Analyses of data from three large cohorts in the US showed that over 33 years of follow-up, the likelihood of death was 15-percent greater among participants in the highest vs lowest quartile of butter intake (hazard ratio [HR], 1.15, 95 percent confidence interval [CI], 1.08?1.22; p<0.001). Conversely, the highest vs lowest intake of total plant-based oils was associated with a 16-percent risk reduction (HR, 0.84, 95 percent CI, 0.79?0.90; p<0.001). [JAMA Intern Med 2025;doi:10.1001/jamainternmed.2025.0205]

Every 10-g increase in daily butter intake contributed to an increase in the risk of cancer death (HR, 1.12, 95 percent CI, 1.04?1.20; p<0.001), whereas every 10-g increase in the daily intake of plant-based oils intake was protective against both cancer death (HR, 0.89, 95 percent CI, 0.85?0.94; p<0.001) and CVD death (HR, 0.94, 95 percent CI, 0.89?0.99; p=0.03). 

The results were presented at EPI Lifestyle 2025 by first author Dr Yu Zhang from the Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, US, and published simultaneously in JAMA Internal Medicine. 

“What’s surprising is the magnitude of the association that we found,” Zhang noted.

Substituting 10 g of butter intake per day with an equivalent amount of total plant-based oils was associated with 17-percent reduced risk of mortality overall (HR, 0.83, 95 percent CI, 0.79?0.86; p<0.001) and 17-percent reduced risk of cancer death (HR, 0.83, 95 percent CI, 0.76?0.90; p<0.001).

“That is a pretty huge effect on health,” the author added.

Not all equally healthy

In a linked editorial, Drs Yong-Moon Mark Park and Yikyung Park, both from the University of Arkansas for Medical Sciences in Little Rock, Arkansas, US, pointed out that plant-based oils vary in terms of their nutritional value, with some being healthier than others. [JAMA Intern Med 2025;doi:10.1001/jamainternmed.2025.0203]

Indeed, a survival benefit was observed for every 5-g increase in the daily intake of canola oil (HR, 0.85, 95 percent CI, 0.78?0.92), olive oil (HR, 0.92, 95 percent CI, 0.91?0.94), or soybean oil (HR, 0.94, 95 percent CI, 0.91?0.96). But the same did not apply for corn and safflower oils, Park and Park noted.

“However, this association [for corn and safflower oils] may not be robust due to the relatively low consumption of these oils compared with other plant oils in the study population. Additionally, there are other plant-based oils, such as palm oil and coconut oil, that were not examined in the study but have been linked to adverse health outcomes in other studies,” they continued.

How replacing butter with plant-based oils may promote longevity and reduce cancer- and CVD-related deaths may be explained by their respective nutrient profiles. Park and Park pointed to the contrast between butter’s harmful saturated fats and plant-based oils’ beneficial unsaturated fatty acids and bioactive compounds.

“Dietary guidelines should emphasize the use of plant-based oils while minimizing saturated fats, like butter, for optimal health outcomes,” they said.

Study details

For the study, Zhang and colleagues used data from the Nurses’ Health Study (1990-2023), the Nurses’ Health Study II (1991-2023), and the Health Professionals Follow-up Study (1990-2023). They identified 221,054 adults (mean age at baseline, 56.1 years for Nurses’ Health Study, 36.1 years for Nurses’ Health Study II, and 56.3 years for Health Professionals Follow-up Study) who were free of cancer, cardiovascular disease (CVD), diabetes, or neurodegenerative disease at baseline for inclusion in the analysis.

The participants completed validated semiquantitative food frequency questionnaires every 4 years, which assessed intakes of butter and plant-based oil (safflower, soybean, corn, canola, and olive oil). Total butter intake included butter from butter and margarine blend, spreadable butter added to food and bread, and butter used in baking and frying at home. Intake of plant-based oils was estimated based on the reported use in frying, sauteing, baking, and salad dressing.

Over 33 years of follow-up, 50,932 deaths occurred, including 12,241 due to cancer and 11,240 due to CVD.