A 30-year study of over 200,000 people reveals that substituting butter with plant-based oils like olive, soybean, or canola could significantly reduce the risk of premature death. The study was published in JAMA Internal Medicine, March 6, 2025.
Why it matters
Swapping just 10 grams of butter (less than a tablespoon) daily with plant oils could lower your risk of dying from cancer or other causes by 17%. That’s the headline finding from one of the largest and longest-running study on dietary fats ever conducted.
Context: Small changes add up. This swap could prevent thousands of preventable deaths linked to chronic diseases.
"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," Daniel Wang, MD, ScD, of the Channing Division of Network Medicine at Brigham and Women's Hospital.
By the numbers
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221,054 participants tracked for 30 years across three major U.S. health studies.
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15% higher risk of death for those eating the most butter compared to those eating the least.
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16% lower risk of death for those prioritizing plant oils.
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17% drop in mortality when substituting 10g of butter with oils daily.
Clear win for plant oils over butter.
"What's surprising is the magnitude of the association that we found — we saw a 17% lower risk of death when we modeled swapping butter with plant-based oils in daily diet. That is a pretty huge effect on health," —Yu Zhang, MBBS, Harvard T.H. Chan School of Public Health
A closer look
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Fatty acids differ significantly in health impacts. Saturated fats like those in butter can raise cholesterol and promote inflammation. In contrast, unsaturated fats found in plant oils such as olive oil are associated with heart health and lower cancer risk.
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Simple swaps work: Use olive oil for sautéing, canola oil for baking, or soybean oil for dressings. Small shifts matter over time.
Yes, but
Participants were mostly nurses and health professionals—groups more health-conscious than the average American. However, researchers say the biological benefits of unsaturated fats hold universally, but they’re pushing to confirm this in broader populations.
The takeaway
You don’t need a diet overhaul. Start small:
- Replace butter on toast with olive oil.
- Bake with canola oil instead of butter.
- Sauté veggies in soybean oil.
