Replacing butter for some plant oils could significantly lower risk of mortality, new study finds

CNN

06-03-2025

Swapping your daily butter intake for certain plant-based oils may help reduce your risk of death, a new study finds.
These findings challenge the growing social media trend that attacks seed oils in favor of butter, ghee and animal fats.
'Seed oils are one of the most unhealthy ingredients we have in foods,' said US Health and Human Services Secretary Robert F. Kennedy Jr. in an Instagram video in 2024, who continues to promote the slogan 'Making Frying Oil Tallow Again.'
Many other influencers have supported similar claims, including Dr. Paul Saladino, who promotes an animal-based diet and has amassed 2.6 million Instagram followers.
'Butter is a health food with amazing nutrients,' he said in a post, adding that butter is good for the gut, brain, cardiovascular health, and overall health and vitality.
The evidence doesn't support that view, according to study coauthor Walter Willett, professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health in Boston.
'For some reason that is not clear to me, a myth has been floating around the internet that butter is a healthy fat, but there is no good evidence to support this,' said Willett, who has authored over 2,000 articles and numerous books and has spent 40 years studying the impact of diet on the development of major diseases, via email.
Willett and his team's latest research revealed that higher butter consumption was associated with a 15% higher risk of mortality, whereas higher intake of plant-based oils — including soybean, canola and olive oil — was linked to a 16% reduction in total mortality, according to the study published Thursday in the journal JAMA Internal Medicine.
In addition, substituting just 10 grams (0.35 ounces) of butter with these plant-based oils daily was associated with a 17% lower risk of both total mortality and cancer-related deaths.
'Seventeen percent is quite a big change, especially when you look at the public health perspective,' said Dr. Yu Zhang, study coauthor and researcher at the Channing Division of Network Medicine at Brigham and Women's Hospital. 'Imagine how many deaths we can reduce in the general population.'
Comparing butter and plant-based oils
The study analyzed 33 years of dietary data from more than 221,000 participants in the Nurses' Health Study (NHS), Nurses' Health Study II (NHS II) and Health Professionals Follow-up Study.
Participants self-reported their dietary habits every four years, allowing researchers to track changes over time and calculate long-term intake averages. Researchers adjusted their findings to account for variables such as age, body mass index (BMI), smoking status, total calorie intake, as well as other dietary patterns using the Alternative Healthy Eating Index.
Butter intake included any amount used in cooking and baking, as well as any extra butter spread on food. Plant-based oil consumption was estimated based on the type of oil used in frying, sautéing, baking or making salad dressings.
Dr. Marion Nestle, Paulette Goddard Professor of Nutrition, Food Studies and Public Health Emerita at New York University, noted the new study is correlational and shows association, not causation.
'Even so, it's consistent with decades of evidence linking saturated fat to health risks and demonstrating quite substantial health benefits of substituting plant oils (including seed oils) for animal fats,' she said.
Seed oils are derived from plant seeds, whereas plant-based oils are extracted from a variety of different plant parts. All oils examined in the study fall under the seed oil category, except for olive oil.
'Olive oil, canola oil, and soybean oil were each more consistently associated with benefit: a lower risk of dying,' said cardiologist Dr. Dariush Mozaffarian, director of the Food is Medicine Institute at the Friedman School of Nutrition Science and Policy at Tufts University. 'These findings add to a large body of scientific literature on the health benefits of these plant oils, whose positive effects have been demonstrated in both large observational studies and dozens of randomized trials.'
Should you eliminate butter from your diet?
While the study indicates that some plant oils lead to better health outcomes, Zhang clarified that this doesn't mean butter should be eliminated altogether.
'We are not suggesting that people should avoid butter entirely, but we are recommending that even a small reduction in butter in replacement for plant-based oils in a daily diet could lead to very substantial, long-term health benefits,' Zhang said.
The choice to use butter may depend on available options for the consumer, Willett said. If given the choice between butter and a partially hydrogenated plant oil rich in trans fats, he said, butter might be a better option.
Despite the 2015 ban on trans fats passed by the US Food and Drug Administration, manufacturers can still use up to a half of gram of trans fat per serving. That can add up fast in a daily diet, according to the Mayo Clinic.
However, if the decision is between butter and beef tallow — which has been promoted by Kennedy as a healthier substitute for seed oils — canola, soybean and olive oils are the superior choice, Willett said.
'Although beef tallow was not examined in this study, on the basis of its composition we would expect it to be no better than butter,' Willett said, pointing to a previous analysis he authored that found fat from red meat, which is mostly composed of beef fat, was marginally worse than dairy fat in regards to mortality or cardiovascular disease.
'Butter is very high in saturated fat, approximately 2/3 of the fat, and it contains almost none of the beneficial, essential polysaturated fats,' Willett said in an email.
'Our findings don't mean that we should never consume butter, but it is best to use it just when its specific flavor is important, not as a primary source of fat,' he added. 'For me, this is the several times a year that I have lobster … butter is absolutely essential!'
Which plant-based oil is the best?
If you're looking to make the switch to plant oils or debating which ones to use, it's all about finding a balance to include some of the essential nutrients your body needs.
Olive, canola and soybean oils had the most beneficial impact on health outcomes in the study, according to Zhang, which comes from their high levels of anti-inflammatory omega-3 fatty acids. Omega-3s maintain the body's cells, provide energy, maintain immune defense and reduce inflammation when it's at optimal levels (like most things, too much omega-3 may be harmful).
Other seed oils such as corn, peanut, safflower and sunflower contain higher levels of omega-6 fatty acids, which are also necessary to maintain good health.Omega-6 molecules stimulate hair and skin growth, regulate metabolism, support bone health, and in some cases, may even have anti-inflammatory properties.
However, omega-6s can also be converted into molecules such as prostaglandins that signal the initiation of inflammation — not a bad thing when your body is trying to quickly repel an invader or tumor, but devastating if left smoldering for long periods without resolution.
Americans have an overabundance of omega-6s in their bodies due to their use in ultraprocessed foods and eating at fast food establishments. One omega 6, linoleic acid, is the most common omega-6 in the US food supply.
'We need both omega-6 and omega-3 fatty acids; soybean and canola oil have both,' Willett said. 'Corn and sunflower oil have very little omega-3 fatty content; these can be part of a mix of different oils, but should not be relied upon as a sole source of plant oil.'
No matter which oils you're using in your diet, it's best to use them sparingly, Nestle said.
'I'm always for varying food intake to the extent possible and that goes for oils, as well,' she said. 'All oils, no matter which, provide about 120 calories per tablespoon so are best used in the proverbial moderation.'