Switching from butter to plant oils improves health, study finds

For decades, researchers have studied the effects of different fats on human health. While the dangers of trans fats are well known, the debate over butter and plant-based oils continues.

Many studies highlight that replacing saturated fats with unsaturated fats benefits heart health. However, people choose whole foods, not just individual fatty acids, making it crucial to examine how butter and oils affect overall health.

A recent large-scale study sheds light on this issue. Scientists from Mass General Brigham, Harvard T.H. Chan School of Public Health, and the Broad Institute of MIT and Harvard analyzed dietary patterns of over 200,000 people for more than 30 years.

Their findings, published in JAMA Internal Medicine, suggest that swapping butter for plant-based oils could significantly lower the risk of premature death, especially from heart disease and cancer.

Butter is high in saturated fatty acids, which have long been associated with cardiovascular disease. Plant-based oils, including olive, soybean, and canola oils, contain higher levels of unsaturated fatty acids. These fats are known to reduce inflammation, improve cholesterol levels, and lower the risk of chronic diseases.

However, previous studies often focused on individual fatty acids rather than their food sources. Some research found no strong link between butter and cardiovascular disease, while others suggested butter has a neutral or slightly negative impact.

Many of these studies failed to specify what people were eating instead of butter, making it difficult to draw conclusions about its health risks.

This new study, which included data from the Nurses’ Health Study (NHS), the Nurses’ Health Study II (NHSII), and the Health Professionals Follow-up Study (HPFS), provides a clearer picture. Every four years, participants recorded how often they consumed certain foods, including butter and plant-based oils. Researchers then estimated their intake and analyzed health outcomes.

The study found that people who consumed the most butter had a 15% higher risk of death than those who ate the least. In contrast, those who consumed the most plant-based oils had a 16% lower risk of death.

The data also showed that replacing just 10 grams of butter per day—less than a tablespoon—with the same calorie amount of plant-based oil could reduce overall mortality by 17%.

“What’s surprising is the magnitude of the association we found,” said Yu Zhang, MBBS, the study’s lead author and a researcher at Brigham and Women’s Hospital. “We saw 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.”

The findings align with previous research showing that olive oil, in particular, has strong links to lower rates of cardiovascular disease, cancer, and type 2 diabetes. Other plant-based oils have received less attention in studies, but they also appear to offer health benefits.

“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 Dr. Daniel Wang, the study’s corresponding author and an assistant professor of nutrition at Harvard Chan School.

From a public health perspective, small changes in diet could have widespread benefits. Many chronic diseases, including cancer and heart disease, are influenced by lifestyle choices. The study suggests that adjusting fat sources in the diet is one of the easiest ways to improve long-term health outcomes.

“Even cutting back butter a little and incorporating more plant-based oils into your daily diet can have meaningful long-term health benefits,” Wang explained. While the study’s participants were mainly health professionals and may not represent the entire U.S. population, the results provide strong evidence supporting dietary shifts.

Further research is needed to explore the biological mechanisms behind these effects. Scientists hope to understand why certain fats influence disease risk more than others and how diet interacts with genetics. However, the message remains clear: replacing butter with plant-based oils can lead to a longer, healthier life.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

Like these kind of feel good stories? Get The Brighter Side of News' newsletter.