Swapping Butter for Plant-Based Oils Could Help You Live Longer, Study Suggests

Living forever may not be on the table for humanity just yet, but there are several things you can do to increase your chances of living into old age. And they are quite simple, too.

In March, researchers from Mass General Brigham, Harvard T.H. Chan School of Public Health, and the Broad Institute released the findings of their study, published in JAMA Internal Medicine, on butter versus plant-based oil intake and how it impacts human health. And the results are quite revealing. 

Here’s what you need to know. 

How did researchers conduct this study? 

The researchers conducted a “population-based cohort study,” which gathered diet and health data from more than 200,000 people over a three-decade period, giving them rather robust numbers to analyze. According to Harvard, the participants were all part of the Nurses’ Health Study, Nurses’ Health Study II, and Health Professionals Follow-Up Study. As part of these studies, participants were asked to answer questions every four years about “how often they had certain types of food.”

The team then used that information to estimate the participants’ consumption of butter — including margarine blends, spreadable butter used on food and bread, and butter employed in baking and frying — along with plant-based oils. They estimated the use of plant-based oils based on “the reported use in frying, sautéing, baking, and salad dressing.” 

Then, the researchers identified all participants who had died during the study and noted their causes of death. They then conducted a statistical analysis to compare death rates across different levels of dietary intake to determine whether those who consumed butter or oil were more prone to an early death.

Are plant-based oils really much healthier than butter? 

The researchers’ key finding was that “participants who ate the most butter had a 15% higher risk of dying than those who ate the least,” Harvard explained. “In contrast, those who ate the most plant-based oils had a 16% lower risk of death than those who ate the least.”

Moreover, the team found that individuals who ate plant-based oils had health outcomes associated with lower total, cancer, and cardiovascular disease mortality. Conversely, those who consumed more butter had health outcomes linked to an increased risk of total and, specifically, cancer mortality.

It is not the first time butter has been found to be more detrimental than other plant-based cooking oils. A 2022 study out of the Harvard T.H. Chan School of Public Health found that individuals who consumed at least seven grams of olive oil per day — while avoiding animal fats, such as butter, margarine, and mayonnaise, experienced better health outcomes.

Specifically, they showed a “19% lower risk of total and cardiovascular disease mortality, 17% lower risk of cancer mortality, 29% lower risk of neurodegenerative mortality, and 18% lower risk of respiratory mortality.”

So, should you cut out butter completely? 

“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 Daniel Wang of the Channing Division and corresponding author of the study. “From a public health perspective, this is a substantial number of deaths from cancer or from other chronic diseases that could be prevented.”

Wang isn’t the only one who thinks making the little swap is a good idea.

“If you’re using butter regularly, switching to a plant-based oil is an easy change that has long-term health benefits. The study showed that it could lower your risk of early death, especially from things like cancer and heart disease. So, that’s a win in my book,” Catherine Gervacio, a registered dietitian and certified exercise nutrition coach, shared with Food & Wine. 

However, Gervacio noted that not all oils behave the same when heated. “For example, high-heat cooking like frying or grilling needs oils with high smoke points. With this, avocado oil or even canola works best,” she said. “For salad dressings or drizzling on veggies, extra virgin olive oil is the ideal choice.”

Again, the research provides data to show the effects of making this swap. The team found that “substituting 10 grams of butter a day (less than a tablespoon) with equivalent calories of plant-based oils could lower cancer deaths and overall mortality by 17%.”

“Even cutting back butter a little and incorporating more plant-based oils into your daily diet can have meaningful long-term health benefits,” stated Yu Zhang, the study’s lead author and a research assistant at the Channing Division of Network Medicine at Brigham and Women’s Hospital, as well as a student in the Department of Epidemiology at Harvard Chan School.

There is one more important note to add

The authors highlighted that both the findings and the construct of the study rely on participants who are “mainly health professionals,” which may not fully represent the U.S. population. However, they noted, “In the future, they’d like to study the biological mechanisms underlying why this dietary change has such a large impact.”

This data also contradicts recent advice from U.S. Health and Human Services Secretary Robert F. Kennedy Jr., who shared in a 2024 Instagram post that “seed oils are one of the most unhealthy ingredients we have in foods.” 

And that’s precisely the rhetoric Sarah Berry, professor of nutritional sciences at King’s College London (who was not involved in the study), hopes this scientific research will counter. “The study shows that high butter consumption is linked to increased cancer and total mortality, whereas plant-based oils are linked to a lower risk of overall mortality and death due to cardiovascular disease and cancer,” Berry shared. “This research is very timely. Social media is currently awash with influencers promoting butter as a health food and claiming that seed oils are deadly. This large-scale, long-term study finds the reverse. The authors produce further evidence that seed oil consumption is linked to improved health and that butter — delicious as it is — should only be consumed once in a while.”

“In a sane world, this study would give the butter bros and anti-seed oil brigade pause for thought,” she added. “but I’m confident that their brand of nutri-nonsense will continue unabated.”