The Great Fat Debate: What Science Really Says About Butter and Plant Oils

A recent study published in JAMA Internal Medicine has sparked significant media attention by suggesting that replacing butter with plant-based oils may reduce the risk of premature death. Headlines have since labelled butter as a "deadly delight," while social media users have rejected its findings, calling it “junk science.” Here, we cut through the noise and conflicting advice from different media sources to review the relevance of this new study to your health.

The study

The study involved over 221,000 adults from three large American cohorts who were followed for up to 33 years. Researchers measured their intake of butter and plant-based oil over this period and the subsequent risk of dying from cardiovascular disease and cancer or premature death from any cause. 

It's important to note that the study referenced in this article, published by JAMA Internal Medicine, specifically focused on a select group of vegetable oils, including olive oil, canola oil, and soybean oil. While these oils were associated with reduced mortality and cancer risk, the study did not comprehensively cover all seed oils, such as sunflower oil or others that some criticis have suggested are inflammatory, read our fact-check on seed oils and inflammation. Our intention is to reflect the findings of this particular study rather than make broad generalizations about all seed oils.

The results

Higher butter consumption was associated with a 15% increased risk of total mortality compared to the lowest intake. In contrast, a higher intake of plant-based oils, including safflower, soybean, corn, canola, and olive oil, was linked to a 16% lower risk of total mortality.

Moreover, the results suggest that swapping 10 grams of butter daily with plant-based oils could lower the risk of dying from any cause by 17% and cancer by 17%.

The results are likely explained, in part, by the different types of fatty acids found in butter and plant oils. Butter contains high amounts of saturated fatty acids, which can contribute to higher cholesterol levels, hardening of the arteries, and increased cardiovascular risk (source). The authors explain that the high saturated fat content in butter can also contribute to inflammation in fat tissue and alter hormonal activity, both of which can contribute to the development of various cancers. 

On the contrary, plant-based oils are rich in polyunsaturated fatty acids, which have significant heart health benefits, including lowering low-density lipoprotein cholesterol and reducing inflammation (source). They also have a higher antioxidant content than butter, particularly vitamin E, which may protect against oxidative stress and diseases such as cardiovascular disease (source).

Significant associations were seen between canola, soybean, and olive oils and a reduced risk of premature death from any cause.

Social media buzz around seed oils

This study calls into question the recent debate around seed oils online, where many influencers have been claiming that they are detrimental to health, and gaining major attention for doing so. Previous research shows these claims are not evidence-based, and the current study provides further evidence that seed oils, such as canola and soybean oils, are not harmful to health and may provide health benefits across the lifespan. 

The seed oil claims support a growing narrative that anything that is ‘natural’ is inherently healthier, which can easily lead to false conclusions. In this case, some influencers argue that the industrial process used to produce seed oils makes them an unnatural product, unlike butter.

While this argument makes for compelling social media content and storytelling, it is not rooted in scientific evidence. 

The context in which substituting butter for plant oils is beneficial is also important. What often gets conflated on social media is the use of seed oils in everyday cooking and its addition to ultra-processed, “junk” foods, which we already know are not healthy. 

Why might people call it junk science? 

Dr. Matthew Nagra remarked that the release of this study led to a very emotional response from social media users, leading some people to comment without having read the paper. 

Critics of the study may argue that people who consume more butter may be more likely to follow an overall less healthy diet that is associated with worse health outcomes, such as eating more high-fat, and high-salt foods. On the other hand, someone who consumes more plant oils and less butter may be more likely to follow a healthier diet overall, such as the Mediterranean diet. 

Dr. Matthew Nagra notes that the people who raised this “healthy user bias” failed to mention that it also applied to seed oils, so “those confounders weren’t enough to completely flip the results.” He also adds that

“The researchers are well aware of these potential confounders and they adjusted for them, limiting their influence on the final results anyway, but the double standard from the critics is worth noting.” The researchers also adjusted for other concerns that critics often point out with these types of studies, such as reverse causation. That said, this study is still only measuring an association between food and health, and cannot determine cause and effect. 

Dr. Nagra concludes,

“The fact of the matter is that unsaturated fat rich plant oils are much healthier choices than butter and this is supported by long term randomised controlled trials dating back decades. This is nothing new.”

Cherry Picking Fallacy

These comments from Dr. Nagra illustrate another social media trend, where influencers resort to the cherry picking fallacy to push a narrative that their diet is the only way to eat right. The cherry picking fallacy happens when studies which seem to support an argument (or diet) are selected, while others which point in an opposite direction are either entirely ignored, or dismissed because of design flaws, for example.

It can also be seen when influencers pick on such flaws to make the case that researchers are profiting from getting us sick and therefore cannot be trusted, but will then highlight other studies that fit their own narratives. 

Social media narratives often sensationalise new studies, but this overlooks the fact that scientific understanding evolves incrementally. All studies have strengths and weaknesses. But they also need to be interpreted in the context of the rest of the evidence that is already available to answer a question or address a topic. 

In this case, this new study helps to answer specific questions about the health impact of long-term butter intake, and of substitutions with plant oils to better inform dietary recommendations. But its results are not groundbreaking; they directly align with previous evidence that substituting saturated fats with unsaturated fats leads to better health outcomes.

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Why We Focused on Olive Oil and Other Specific Oils:

Some readers have expressed concerns about cherry-picking data by focusing primarily on olive oil and a few other oils. We want to clarify that the selection of oils discussed in this article directly reflects the oils studied in the JAMA Internal Medicine paper. The study did not include sunflower oil or other seed oils commonly labeled as inflammatory. While olive oil is widely recognized as a beneficial oil due to its unique composition and health effects, we acknowledge that other seed oils can vary significantly in their nutritional profiles and health impacts. We strive to provide accurate and contextually relevant information while also acknowledging the complexity of this topic.
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Article Update: "Butter vs. Plant Oils: The Debate" - Updated on 22nd March

This article was updated to clarify the scope of the JAMA Internal Medicine study discussed, emphasizing that it specifically focused on olive oil, canola oil, and soybean oil. We also addressed reader feedback regarding the potential perception of cherry-picking data and acknowledged that not all seed oils were covered in the study. We value reader input and are committed to providing transparent, evidence-based information.

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