NEW YORK, March 8: A new study conducted by researchers from Mass General Brigham, Harvard T.H. Chan School of Public Health, and the Broad Institute of MIT and Harvard suggests that replacing butter with plant-based oils may lead to significant health benefits, including a lower risk of premature death. The study, which analyzed diet and health data from over 200,000 participants followed for more than 30 years, found that higher consumption of plant-based oils—such as soybean, canola, and olive oil—was associated with lower risks of total, cancer, and cardiovascular disease mortality. Conversely, butter intake was linked to an increased risk of total and cancer-related mortality.

The findings were published in JAMA Internal Medicine and presented at the American Heart Association EPI/Lifestyle Scientific Sessions. "What's surprising is the magnitude of the association we found — a 17% lower risk of death when we modeled swapping butter with plant-based oils in the daily diet. That is a pretty huge effect on health," said study lead author Yu Zhang, MBBS, a research assistant at Brigham and Women's Hospital and a student at Harvard T.H. Chan School of Public Health.

The key distinction between butter and plant-based oils lies in their fatty acid composition. Butter is rich in saturated fatty acids, whereas plant-based oils contain more unsaturated fatty acids, which are considered healthier. While previous studies have examined the health impacts of dietary fatty acids, this new study focuses on the primary food sources—specifically butter and oils—providing more actionable insights for public health.

The study analyzed dietary data from 221,054 participants in three major health studies: the Nurses' Health Study (NHS), Nurses' Health Study II (NHSII), and Health Professionals Follow-up Study (HPFS). Participants reported their food consumption every four years, providing a comprehensive picture of their butter and plant oil intake. The researchers also tracked causes of death over the course of the study.

The results showed that participants who consumed the most butter had a 15% higher risk of death compared to those who consumed the least. In contrast, those who consumed the most plant-based oils had a 16% lower risk of death. "People might want to consider that a simple dietary swap — replacing butter with soybean or olive oil — can lead to significant long-term health benefits," said corresponding author Daniel Wang, MD, ScD, from Brigham and Women’s Hospital and Harvard T.H. Chan School of Public Health.

The researchers also conducted a substitution analysis, simulating the health effects of replacing butter with plant oils. They found that replacing just 10 grams of butter a day (about a tablespoon) with an equivalent amount of plant-based oils could reduce cancer deaths and overall mortality by 17%.

"Even cutting back on butter slightly and incorporating more plant-based oils into your diet can have meaningful long-term health benefits," Wang added.

While the study offers promising results, one limitation is that the participants were primarily health professionals, which may not represent the broader U.S. population. The researchers also plan to investigate the biological mechanisms behind the substantial health benefits observed from this dietary change.