Are plant-based oils linked to a lower risk of mortality especially compared to butter?

December 27, 2025 •

3 min read

A major 33-year Harvard study, published in JAMA Internal Medicine, revealed that higher butter intake was associated with a 15% increased risk of death, while high consumption of plant oils was linked to a 16% lower risk. This compelling evidence helps clarify if and how plant-based oils linked to a lower risk of mortality especially compared to butter.

Quick Summary

Evidence from large-scale studies shows a higher intake of plant-based oils is associated with lower overall mortality, while increased butter consumption links to higher risk. This is primarily due to their differing fat profiles.

Key Points

Lower Mortality Risk: A 33-year Harvard study found high plant-based oil intake linked to a 16% lower mortality risk, while high butter intake was associated with a 15% higher risk.
Unsaturated vs. Saturated Fats: The benefit of most plant oils is their high content of heart-healthy unsaturated fats, which contrast with butter's high concentration of saturated fats.
Reduced Disease Risk: Increased consumption of plant oils, especially olive, canola, and soybean, has been linked to a lower risk of premature death from cardiovascular disease and cancer.
Small Changes, Big Impact: Replacing less than a tablespoon of butter with plant oils daily can lead to a 17% reduction in total and cancer mortality risk.
Cholesterol Management: Unsaturated fats help lower 'bad' LDL cholesterol, while saturated fats in butter tend to raise it, significantly impacting heart health.
Antioxidant Power: Many healthy plant oils, such as olive oil, contain beneficial antioxidants like polyphenols and vitamin E that help protect against chronic disease.

The Scientific Consensus: Unpacking the Study

A recent 33-year observational study from Harvard T.H. Chan School of Public Health involving over 221,000 U.S. adults investigated the link between dietary fats and mortality risk. The findings indicated that individuals with the highest butter intake had a 15% higher risk of premature death from all causes, while those consuming the most plant-based oils, such as olive, canola, and soybean oil, showed a 16% lower risk. Modeling the effects of substitution, the study found that replacing just 10 grams per day of butter with plant-based oils was associated with an estimated 17% reduction in total and cancer mortality. These results align with previous research highlighting the benefits of replacing animal fats with plant-based oils.

The Nutritional Discrepancy: Why Plant Oils Win

The primary reason for the differing health outcomes between butter and most plant oils lies in their fatty acid composition.

Saturated vs. Unsaturated Fats

Butter: Rich in saturated fats, which can increase LDL (bad) cholesterol, a risk factor for cardiovascular disease.
Plant-Based Oils: Generally high in unsaturated fats (monounsaturated and polyunsaturated), which can help lower LDL cholesterol and support heart health when replacing saturated and trans fats.

Antioxidants and Vitamins

Many plant oils, like olive oil, contain beneficial antioxidants such as polyphenols, which can combat inflammation. Some plant oils also provide vitamin E. Butter contains fat-soluble vitamins A and D.

Comparison Table: Plant-Based Oils vs. Butter


Feature	Plant-Based Oils (e.g., Olive, Canola)	Butter	Key Difference	Effects on Health
Primary Fat Type	Monounsaturated & Polyunsaturated	Saturated	Fatty acid composition	Unsaturated fats support heart health; saturated fats can raise LDL cholesterol.
Cholesterol Impact	Can lower LDL (bad) cholesterol, increase HDL (good) cholesterol	Increases LDL (bad) cholesterol	Direction of cholesterol change	Favorable impact on cholesterol profile with unsaturated fats.
Antioxidants	Rich in antioxidants like Vitamin E and polyphenols	Contains trace antioxidants; source of vitamins A, D	Presence of key antioxidants	Antioxidants in plant oils fight inflammation and oxidative damage.
Physical State	Liquid at room temperature	Solid at room temperature	Molecular structure	Reflects the type of fat—unsaturated vs. saturated.
Common Uses	Sautéing, dressings, roasting, moderate-heat cooking	Spreading, baking, low-heat cooking	Cooking applications	Higher smoke points for some plant oils, better for high-heat cooking.
Processing	Varies (e.g., cold-pressed EVOO is minimally processed)	Typically minimally processed from cream	Process level varies by oil type	Refining can strip some nutrients from processed oils.

Practical Steps for a Healthier Diet

Integrating plant-based oils into your diet is a straightforward way to improve health outcomes.

Cooking Swaps: Use olive, canola, or avocado oil instead of butter for cooking. Extra virgin olive oil is great for dressings.
Spreads: Choose non-hydrogenated margarines from plant oils or avocado over butter for spreading to avoid trans fats.
Baking: Substitute liquid plant oils for melted butter in many recipes.
Variety: Include other sources of healthy fats like nuts, seeds, and avocados.
Moderation: Complete elimination of butter isn't necessary; focus on using plant oils as your main fat source.
Long-term Health: Choosing plant-based oils over butter more often supports better long-term health and potentially a longer life.

Conclusion: Looking at the Long-Term Picture

Evidence consistently links higher intake of plant-based oils to a lower risk of premature mortality, including from cardiovascular disease and cancer. This is attributed to the shift from saturated fats in butter to heart-healthy unsaturated fats in most plant oils. Even small dietary changes, like substituting butter with plant oil daily, can have positive impacts on longevity.

Frequently Asked Questions

A large-scale Harvard study published in JAMA Internal Medicine found that higher intake of plant-based oils was associated with a lower risk of overall mortality, while higher butter intake was linked to an increased risk.

No, not all plant-based oils are the same. Oils rich in unsaturated fats, such as olive, canola, and soybean oil, are generally considered healthier than oils high in saturated fats, like coconut or palm oil.

Yes, you can still enjoy butter in moderation. The study's authors emphasize that the goal is not total elimination but rather to make a conscious effort to substitute healthier plant-based oils for butter as your primary fat source for the greatest long-term benefits.

For sautéing, cooking, and salad dressings, extra virgin olive oil and canola oil are excellent choices. Avocado oil is another heart-healthy option with a high smoke point suitable for higher-temperature cooking.

Saturated fats, common in butter, can raise LDL ('bad') cholesterol levels. Unsaturated fats, found in plant oils, can help lower LDL cholesterol and can support beneficial HDL ('good') cholesterol.

Extra virgin olive oil is highly regarded for its heart-healthy monounsaturated fats and high antioxidant content. Its role in the Mediterranean diet is well-documented and associated with significant health benefits.

While the Harvard study compared butter to plant oils, it's also important to minimize trans fats (often found in partially hydrogenated oils). If given a choice between butter and a trans-fat-laden spread, butter may be the lesser of two evils, but pure plant oils are the better choice.