Replacing butter with plant-based oil may have 'significant long-term health benefits’

Key takeaways:

• Those with the highest consumption of plant-based oils had a 16% lower death risk.
• Plant-based oils also lowered the risk for mortality from cancer by 11%.

Adults who consume a large amount of butter have a 15% greater mortality risk, according to an analysis published in JAMA Internal Medicine.

But, opting to replace this consumption with plant-based oils instead could significantly lower the risk for death from all causes and cancer.

“Primary care providers might consider advising patients to reduce butter intake and substitute it with plant-based oils, as this dietary shift could yield significant long-term health benefits,” Yu Zhang, MBBS, a research assistant at Brigham and Women's Hospital, explained to Healio.

In the study, which was also presented at the American Heart Association’s Epidemiology, Prevention, Lifestyle & Cardiometabolic Scientific Sessions, Zhang and colleagues examined the dietary and mortality data of 221,054 adults from the Nurses’ Health Study, Nurses’ Health Study II and Health Professionals Follow-up Study.

The researchers used dietary data to assess how much butter and plant-based oils participants consumed. Total butter intake included butter from butter and margarine blend, butter used in frying and baking at home and spreadable butter added to food and bread, while plant-based oils was estimated based on the reported use in frying, sautéing, salad dressing and baking, according to a Mass General Brigham press release

The researchers assessed over 30 years of follow-up data.

Findings

Zhang and colleagues reported that those who consumed the most butter had an increased risk for death (HR = 1.15; 95% CI, 1.08-1.22) compared with those who consumed the least, while each daily 5-gram increment of butter added to food or bread intake was associated with a 4% increase in total mortality (HR = 1.04; 95% CI, 1.02-1.05).

In contrast, those who consumed the most plant-based oils had a 16% lower risk for death (HR = 0.84; 95% CI, 0.79-0.9) vs. those with the lowest intake.

There were also associations between a lower death risk and daily 5-gram increments of:

• soybean (HR = 0.94; 95% CI, 0.91-0.96);
• olive oils (HR = 0.92; 95% CI, 0.91-0.94); and
• canola (HR = 0.85; 95% CI, 0.78-0.92).

Specific types of mortality were also influenced by consumption. For example, every daily 10-gram increment of plant-based oils intake was tied to a 11% lower risk for cancer mortality (HR = 0.89; 95% CI, 0.85-0.94), whereas higher butter intake increased the risk for cancer mortality (HR = 1.12; 95% CI, 1.04-1.2).

Zhang and colleagues noted that the high saturated fat content of butter “can trigger adipose tissue inflammation, a key pathogenic pathway in the development of various cancers.”

Meanwhile, plant-based oils “are rich in polyunsaturated fats, which are known to confer considerable benefits for heart health, including decreasing low-density lipoprotein cholesterol, reducing inflammation and lowering mortality risk,” they wrote.

They also pointed out that substituting daily 10-gram intakes of total butter with an equal amount of total plant-based oils was associated with 17% risk reductions for total mortality (HR = 0.83; 95% CI, 0.79-0.86) and cancer mortality (HR = 0.83; 95% CI, 0.76-0.9).

Zhang noted that the magnitude of this finding “was surprising.”

The study investigator reported some limitations, like possible residual confounders. The sample was also predominantly health care professionals and white, limiting the findings’ generalizability.

“Future studies should focus on elucidating the molecular mechanisms underlying the different metabolic effects of butter and plant-based oils, as well as exploring the broader health implications of these dietary fats," Zhang told Healio.

Benefits still achievable in suboptimal diets

In a related editorial, Yong-Moon Mark Park, MD, PhD, an assistant professor at the University of Arkansas for Medical Science, and Yikyung Park, ScD, an assistant professor of surgery at the Washington University School of Medicine, explained that the health effects of plant-based oils and butter “may depend not only on their dominant fatty acid composition but also on their role within broader dietary patterns.”

“Butter is often associated with unhealthier dietary patterns, while plant-based oils are more commonly linked to healthier patterns, such as the Mediterranean diet and plant-based diets,” they wrote. “For individuals with poorer overall diet quality who may find it challenging to adhere to comprehensive dietary recommendations, making a single, achievable change — such as substituting plant-based oils for butter — could still improve health outcomes and reduce mortality risk.”

Park and Park added that the findings show that certain plant-based oils, “such as canola and soybean oils, may serve as accessible alternatives to olive oil, which tends to be more expensive.”

References:

• Large study of dietary habits suggests more plant oils, less butter could lead to better health. Available at: https://www.massgeneralbrigham.org/en/about/newsroom/press-releases/dietary-habits-study-suggests-more-plant-oils-less-butter-lead-to-better-health. Published March 6, 2025. Accessed March 6, 2025.
• Park Y, Park Y. JAMA Intern Med. 2025;doi:10.1001/jamainternmed.2025.0203.
• Zhang Y, et al. JAMA Intern Med. 2025;doi:10.1001/jamainternmed.2025.0205.