For decades, dietary fat has been at the center of public health debates, especially in the realm of cardiovascular care. Butter, once vilified, has enjoyed a recent resurgence in popularity with some trendy diets. But emerging large-scale research continues to reinforce what many cardiologists have long advised: when it comes to heart health and longevity, not all fats are created equal.
A new comprehensive study, presented in MedPage Today and published by researchers from Harvard T.H. Chan School of Public Health, has shed critical light on the long-term cardiovascular and mortality effects of different types of dietary fat. The conclusion? Eating more butter may shorten your life, while replacing it with plant-based oils could help you live longer.
Let’s dive into the findings and why they matter—especially for cardiologists and patients concerned about long-term heart health.
The new research draws on data from two massive ongoing cohort studies: the Nurses’ Health Study (1986–2018) and the Health Professionals Follow-Up Study (1986–2018), encompassing over 120,000 U.S. adults. Over a follow-up period of up to 32 years, researchers evaluated the associations between butter consumption and all-cause mortality, as well as specific causes like cardiovascular disease (CVD) and cancer.
The major takeaway? Higher butter intake was associated with a greater risk of all-cause mortality, particularly when butter was not substituted with healthier fats.
But the study didn't stop there. Researchers also explored what happened when butter was swapped with other fat sources—like olive oil, soybean oil, or other vegetable oils. They found that:
Substituting plant-based oils for butter was associated with a significantly lower risk of death.
Specifically, replacing one tablespoon of butter per day with an equivalent amount of olive oil, soybean oil, or corn oil was associated with a 5% to 9% reduction in total mortality.
Conversely, replacing butter with margarine or low-fat dairy showed little to no significant benefit.
In other words, it’s not just about reducing saturated fat—it’s about what you replace it with.
Butter is rich in saturated fats, which are known to raise low-density lipoprotein (LDL) cholesterol levels. Elevated LDL is a major risk factor for the development of atherosclerosis, coronary artery disease, and stroke.
This is consistent with the findings from previous research, including the American Heart Association's scientific advisory, which reaffirmed that replacing saturated fats with polyunsaturated fats reduces the risk of cardiovascular disease by approximately 30%—a similar effect to taking statins.
In the new study, this biological mechanism plays out in the form of better survival rates for individuals who consistently opted for heart-healthy plant oils over butter.
One of the most crucial insights from the study is that dietary advice must go beyond simply telling patients what not to eat. Instead, guidance should focus on positive substitutions.
Here’s how common substitutions impact longevity based on the study:
✅ Butter → Olive Oil: Among the most beneficial swaps. Olive oil is rich in monounsaturated fats and contains polyphenols with anti-inflammatory and antioxidant properties.
✅ Butter → Soybean or Corn Oil: These are high in polyunsaturated fats (PUFAs), which have been linked to lower cholesterol levels and reduced heart disease risk.
❌ Butter → Margarine (especially older formulations): May contain trans fats, which are even more harmful to cardiovascular health.
❌ Butter → Low-fat dairy: Offers limited benefit in terms of replacing saturated fat, and does not provide the cardiovascular advantages that come from PUFA-rich plant oils.
In a cardiology practice, this distinction is vital. Telling patients to “avoid butter” is incomplete; advising them to “use olive oil instead of butter” is a tangible, positive behavior change with proven benefits.
Cardiologists are often at the frontlines of nutrition-related guidance, particularly for patients with coronary artery disease, hypertension, or a family history of stroke and heart disease. This study reinforces several key points for patient education:
Fats are not inherently bad. The type of fat consumed matters more than the total fat intake.
Butter in moderation is still a concern. Despite trends that attempt to rehabilitate its image, butter consumption—particularly when it replaces healthier fats—remains linked to higher mortality.
Plant oils should be the go-to. Emphasizing olive oil, soybean oil, and other vegetable oils can have a meaningful impact on patient longevity and cardiovascular outcomes.
So what should patients take away from this?
Use olive oil or avocado oil in place of butter for cooking.
Add a splash of flaxseed or walnut oil to salads for a dose of omega-3s.
Read labels carefully—avoid spreads high in trans fats.
Try incorporating more nuts, seeds, and fatty fish into meals.
These small changes—especially when maintained consistently over the years—can translate into longer life and fewer cardiac events.
The implications of this study reach beyond individual health. Encouraging healthier fats in place of saturated ones aligns with the goals of a more sustainable, preventive-focused healthcare system. If more people adopt such dietary changes, the burden on cardiology departments could be meaningfully reduced through fewer heart attacks, strokes, and related complications.
As researchers noted, both the realized and unrealized potential of these substitutions offer clear, evidence-based steps toward a healthier population and a more cost-effective healthcare system.
For decades, butter has enjoyed a complex reputation in the American diet—alternatively demonized and embraced. But the latest research offers a clear signal to cardiologists and healthcare providers: while butter may be delicious, its regular use can shorten lifespan when healthier options exist.
By guiding patients to make smart substitutions—particularly using heart-healthy oils like olive oil and soybean oil—healthcare providers can promote longer life, improved cardiovascular health, and reduced healthcare costs.
It’s not about fearmongering or eliminating pleasure from eating. It’s about empowering patients with the knowledge to make choices that will serve their hearts—and their lives—for the long haul.
MedPage Today. (2025). More Butter Linked With Worse Survival in Large Longevity Study.
https://www.medpagetoday.com/primarycare/dietnutrition/114531
BulletinHealthcare. (2025). Butter and Mortality: What Long-Term Data Show About Fat Substitutions.
https://mailview.bulletinhealthcare.com/mailview.aspx?m=2025030701acc&r=1553449-5162&l=014-ea3&t=c
Harvard T.H. Chan School of Public Health. (2023). The Nutrition Source: Fats and Cholesterol.
https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/
American Heart Association. (2017). Dietary Fats and Cardiovascular Disease: A Presidential Advisory. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000510
Mozaffarian, D. et al. (2010). Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a meta-analysis of randomized controlled trials.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2864560/
