A large new U.S. study brings much-needed clarity to the long-term health effects of butter and plant-based oils -and the findings are hard to ignore. Butter, despite recent attempts to rehabilitate its image, does not appear to be the harmless fat many claim it to be. In contrast, plant oils such as olive oil, soybean oil and canola oil are associated with meaningful health and longevity benefits.
This is particularly relevant at a time when, in the U.S., the MAHA (Make America Healthy Again) initiative is issuing new dietary recommendations. While these guidelines rightly emphasize reducing ultra-processed foods and added sugars, at the same time they promote a high intake of saturated fats -such as animal fats and butter-without strong support from peer-reviewed scientific evidence. That makes this an ideal moment to step back and examine the actual data.
As a registered dietitian-nutritionist specializing in autoimmune conditions and inflammation, with advanced training in plant-based nutrition, I firmly believe that nutrition guidance must be grounded in evidence -without data, the conversation quickly becomes ideological rather than scientific. Dietary recommendations should be based on demonstrated benefits and risks, not trends, narratives or political agendas.
Study design
The study followed 221,054 adults from three large U.S. cohorts -the Nurses’ Health Study, Nurses’ Health Study II, and the Health Professionals Follow-up Study- for up to 33 years. At baseline, participants were free of cancer, cardiovascular disease, diabetes and neurodegenerative disorders. Dietary intake was assessed every four years using detailed food-frequency questionnaires, with particular focus on butter and plant oils, including olive oil, soybean oil, canola oil, corn oil, and safflower oil.
Key findings
Over the follow-up period, 50,932 deaths were documented, including 12,241 from cancer and 11,240 from cardiovascular disease. Clear patterns emerged:
- Butter: Higher butter intake was associated with a 15% higher risk of total mortality and a 12% higher risk of cancer mortality compared with lower intake.
- Plant oils: Higher consumption of plant oils was linked to a 16% lower risk of total mortality. Each additional 10 grams per day was associated with an 11% lower risk of cancer mortality and a 6% lower risk of cardiovascular mortality. Olive oil, soybean oil, and canola oil showed particularly strong protective associations.
- Replacing butter with plant oils: Substituting just 10 grams per day of butter with an equivalent amount of plant oils was associated with an estimated 17% reduction in total mortality and a 17% reduction in cancer mortality.
What this means in practice
These findings suggest that replacing butter with plant-based oils is a simple yet powerful dietary shift that can meaningfully reduce the risk of premature death. Importantly, this is not only about cardiovascular health -the choice of dietary fats appears to influence overall longevity, including cancer-related outcomes.
In short, butter does not appear to be “innocent,” while plant oils -especially olive oil, soybean oil, and canola oil- offer tangible health benefits. This research reinforces long-standing nutrition guidance that favors plant oils over animal fats in daily eating patterns.
At the same time, it raises serious questions about dietary initiatives that promote high saturated fat intake without solid scientific backing. The data are clear: long-term health is not supported by blanket endorsements of butter, but by informed fat choices -namely plant-based oils with demonstrated protective effects that support cardiovascular health, reduce cancer risk and promote longevity.
Resources
https://www.pcrm.org/news/health-nutrition/butter-associated-increased-risk-death-all-causes
https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2831265
