Investigators have found that the consumption of plant-based oils instead of butter may provide beneficial health effects and potentially reduce the risk of premature mortality, according to recent findings presented at the American Heart Association Epidemiology, Prevention, Lifestyle & Cardiometabolic Health Scientific Sessions 2025 and simultaneously published by Zhang et al in JAMA Internal Medicine.
Background
Key differences between butter and plant-based oils are the types of fatty acids they contain. For instance, butter is rich in saturated fatty acids, while plant-based oils have more unsaturated fatty acids. Although many studies have explored dietary fatty acids, few studies have focused on their primary food sources like butter and plant-based oils. Prior research has focused on an individual’s diet at a single point in time and has been conducted in a small population, limiting their applicability to public health.
Study Methods and Results
In the study, the investigators examined dietary and health data from 221,054 individuals who participated in the Nurses’ Health Study, Nurses’ Health Study II, and Health Professionals Follow-up Study. Every 4 years, the participants were asked to answer questions regarding how frequently they consumed certain types of foods, including butter and plant-based oils. 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. The intake of plant-based oils was estimated based on the reported use in frying, sautéing, baking, and salad dressing. The investigators then identified which participants had died and their causes of death, comparing mortality rates across different diet intake levels.
After a follow-up of 30 years, the investigators found that a higher intake of plant-based oils—especially soybean, canola, and olive oils—was associated with a lower rate of all-cause, cancer-related, and cardiovascular disease–related mortality; whereas a higher intake of butter was associated with a greater risk of all-cause and cancer-related mortality. They noted that the participants who consumed the highest amount of butter had a 15% higher risk of mortality compared with those who consumed the lowest amount of butter. In contrast, those who consumed the highest amount of plant-based oils had a 16% lower risk of mortality compared with those who consumed the lowest amount of plant-based oils.
“What's surprising is the magnitude of the association that we found—we saw a 17% lower risk of death when we modeled swapping butter with plant-based oils in daily diet. That is a pretty huge effect on health,” emphasized lead study author Yu Zhang, MBBS, a research assistant at the Channing Division of Network Medicine at Brigham and Women’s Hospital and a student in the Department of Epidemiology at the Harvard T.H. Chan School of Public Health.
The investigators also performed a substitution analysis, which mimicked the health impact of swapping butter for plant-based oils. They revealed that substituting 10 g of butter per day with equivalent calories of plant-based oils could lower cancer-related mortality and all-cause mortality by 17%.
Conclusions
“[Individuals] might want to consider that a simple dietary swap—replacing butter with soybean or olive oils—can lead to significant long-term health benefits,” indicated senior study author Daniel Wang, MD, ScD, Assistant Professor in the Department of Nutrition at the Harvard T.H. Chan School of Public Health, of the Channing Division of Network Medicine at Brigham and Women’s Hospital, and an associate member at the Broad Institute of the Massachusetts Institute of Technology and Harvard University. “From a public health perspective, this is a substantial number of deaths from cancer or from other chronic diseases that could be prevented,” he underscored.
The investigators detailed that one of the study limitations was that the participants are mainly health professionals, so they may not represent the U.S. population as a whole. They hope to further assess the biological mechanisms underlying why this dietary change confers a large benefit to health.
“Even cutting back butter a little and incorporating more plant-based oils into [the] daily diet can have meaningful long-term health benefits,” Dr. Wang concluded.
Disclosure: The research in this study was supported by research grants from the National Institutes of Health. For full disclosures of the study authors, visit jamanetwork.com.
