Heart

From Dr Joseph Mercola

Story at-a-glance

• For several decades, saturated fat was wrongly blamed for heart disease, while vegetable oils quietly caused a surge in obesity, inflammation, and chronic metabolic disorders
• Newly appointed FDA commissioner Dr. Marty Makary is now leading efforts to revise outdated dietary guidelines that were built on cherry-picked data from Ancel Keys’ Seven Countries Study
• A 2016 BMJ-published reanalysis found replacing saturated fat with linoleic acid-rich vegetable oils increased cardiovascular deaths, despite lowering cholesterol
• Investigative journalist Dr. Maryanne Demasi faced vicious backlash after exposing the flawed science behind saturated fat demonization in her documentary “Heart of the Matter”
• Industrial seed oils like canola and soybean are now linked to mitochondrial damage, inflammation, and chronic illness — while saturated fat is finally being recognized as metabolically supportive

For decades, the dominant narrative insisted that saturated fat was deadly — even though the actual data never proved it. As a result, the health advice shifted toward seed oils and processed margarine, which quietly ushered in new health problems, from metabolic disease to obesity and inflammatory disorders — all while the original hypothesis remained unchallenged by mainstream medicine.

Now, for the first time, high-ranking officials are openly criticizing these outdated guidelines. So, if you still believe that butter, beef, and full-fat cheese clog your arteries and are damaging your health, it’s time to relearn everything you know about these fat sources.

New FDA Commissioner Aims to End the 70-Year War on Saturated Fat

On July 14, 2025, Dr. Marty Makary, the newly appointed U.S Food and Drug Administration (FDA) commissioner, along with Sec. Robert F. Kennedy, Jr. of the Department of Health and Human Services and Sec. Brooke Rollins of the Department of Agriculture, held a press conference addressing their plans to significantly overhaul the U.S. dietary guidelines.¹

•One of the primary areas that they will work on is revising the guidelines on saturated fat — During the press conference, Makary highlighted how the changes to the food guidelines will be made based on scientific findings. He mentions that the demonization of saturated fat began with a flawed study — the Seven Countries Study by Ancel Keys.

•Why the Seven Countries Study was significantly flawed — The study, which started in 1958 and continued until 1983, explored the heart health of different populations in several prominent Western countries. According to Keys’ hypothesis, there is a significant link between saturated fat and heart disease. When he published his data, it showed perfect correlations between cardiovascular disease and the dietary consumption of fat.²

However, there was just one problem with the research — Keys cherry-picked the data. He selectively chose the countries that fit his hypothesis while ignoring data from 16 other countries that went against his recommendations.³ Had he chosen a different set of countries, the data would have been the opposite — that increasing the percent of calories from fat actually reduces the number of deaths from coronary heart disease.

•Despite the methodological flaws in his data, the medical community accepted Keys’ study — This led to the promulgation of “low-fat, low-cholesterol” foods as healthy. Butter, coconut oil, red meat, dairy, and eggs were all shunned, while polyunsaturated fats (PUFs) like margarine, vegetable oils, and shortening were popularized.

•The medical establishment “locked arms and walked off a cliff together” — This was how Makary described the shift from saturated fat to polyunsaturated fat — basically, the health community back then took a look and decided that Keys’s study was gospel truth — despite many experts contesting his hypothesis and many studies^4,5 showing the opposite.

“The medical establishment started with a robust debate in the New England Journal of Medicine among academics of the National Academy. But that debate ended in the 1970s because there was groupthink,” Makary said.

“Well, that dogma still lives large and you see remnants of it in the food guidelines that we are now revising. So, we’re going to ensure that the new guidelines are based on science and not medical dogma.”⁶

To see the tide finally turning and the government health agencies taking the lead on these monumental changes is something I applaud. Over the past couple of decades, I’ve published countless articles about the flaws in Keys’ study — and why saturated fats are not to be feared, as they are actually integral to your health.

Documentary Exposed the Flaws and Received Fierce Backlash

Just like me, Maryanne Demasi, Ph.D., has been speaking out about the erroneous demonization of saturated fat for a long time. Several years ago, I wrote about a two-part documentary she produced called “Heart of the Matter,” which aired on the Australian Broadcasting Corporation’s show (ABC) Catalyst in 2014. I was extremely impressed by the film, as it did an excellent job of exposing the cholesterol/saturated fat myths and its financially links to cholesterol-lowering drugs called statins.

In her recent Substack post, Demasi detailed the severe backlash she received after she released the documentary, and her thoughts on these recent developments from the U.S. government agencies. “It was a stunning moment — not because the criticism was new, but because it was coming from someone in an official position to do something,” she said.⁷

•“Heart of the Matter” focused on two primary points — The first part examined the demonization of saturated fat, while the second part dwelled on the widespread use of statins.

“The medical dogma was firmly entrenched: saturated fat raised cholesterol, and cholesterol caused heart disease. But the science behind it was shaky — built on cherry-picked data and upheld more by consensus than by critical evaluation,” she said.

•The findings were supported by some of the top experts in the field of cardiovascular health — Among the interviewees featured were Dr. Michael Eades, an early advocate for low-carb, high-fat diets, cardiologists Dr. Stephen Sinatra and Dr. Ernest Curtis, nutritionist Dr. Jonny Bowden, and science journalist Gary Taubes. All of these experts voiced their concerns regarding the warnings against saturated fat. Demasi said:

“Eades, for instance, highlighted the absurdity of the prevailing narrative: ‘You very seldom see the words ‘saturated fat’ in the public press when they’re not associated with artery clogging. So it’s like it’s all one term — ‘artery clogging saturated fats.’’

And Taubes, author of Good Calories Bad Calories, known for his meticulous dismantling of diet dogma, cut to the core: ‘There’s no compelling evidence that saturated fat is involved in heart disease.’”

To present both sides equally, the documentary also featured experts who vigorously defended the warnings against saturated fat. Robert Grenfell, the director of the National Heart Foundation, and Professor David Sullivan, a cardiologist, shared their thoughts in the film.

•Still, the backlash was overwhelming — Demasi describes it as “immediate, vicious, and unrelenting.” The media not only turned against her, but they also went against the experts who challenged the saturated fat dogma. And even though no factual inaccuracies were found, ABC still pulled both episodes from its website.

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Numerous Experts Have Sounded the Alarm on Keys’ Flawed Research

The fact that Ancel Keys’ hypothesis was purely observational and could not establish causation has long been raised by many health experts — even during the first years when the Seven Countries study came out. According to Demasi, John Yudkin, a British physiologist and nutritionist warned that sugar, not fat, was the real cause of heart disease. However, he was mocked and marginalized by Keys, who considered Yudkin his fiercest opponent.⁸

Yudkin was the first, but he wasn’t the only one — numerous researchers like Uffe Ravnskov and Malcolm Kendrick, also publicly challenged Keys’ hypothesis, co-authoring publications that exposed the flaws of this study. Many others soon followed, which Demasi outlined in her blog post.

•“Saturated fat is not the major issue” — In 2013, cardiologist Dr. Aseem Malhotra published a commentary on the BMJ, saying that the flawed advice from Keys caused people to aggressively lower cholesterol — which may have led to higher rates of heart disease.

“The mantra that saturated fat must be removed to reduce the risk of cardiovascular disease has dominated dietary advice and guidelines for almost four decades. Yet scientific evidence shows that this advice has, paradoxically, increased our cardiovascular risks,” Malhotra wrote.⁹

•”The Big Fat Surprise” — Nina Teicholz wrote her best-selling exposè in 2014,¹⁰ which helped bring the issue to public attention. Her deeply researched book challenged the conventional wisdom on dietary fats, especially saturated fat. “Teicholz documented how weak science, political pressure, and food industry lobbying created a false consensus that demonised fat and distorted public health policy,” Demasi remarked.¹¹

•“Re-evaluation of the traditional diet-heart hypothesis” — In 2016, a group of researchers published a landmark re-analysis of the Minnesota Coronary Experiment in the BMJ, to evaluate the accuracy of Keys hypothesis. They found that when saturated fat was replaced with linoleic acid (LA) from vegetable oils, cholesterol levels were lowered — but paradoxically led to an increase in deaths, particularly from cardiovascular disease.

“Findings from the Minnesota Coronary Experiment add to growing evidence that incomplete publication has contributed to overestimation of the benefits of replacing saturated fat with vegetable oils rich in linoleic acid,” the researchers concluded.¹²

The Cholesterol Hypothesis Is a ‘Professional Litmus Test’

The plans to overhaul the U.S. dietary guidelines give hope to many researchers like Demasi, who have long raised their concerns about this flawed science — but were ostracized as a result.

“For the first time, real change may be coming — not from the margins, but from the very top of the U.S. health establishment…

It’s taken decades. The cholesterol hypothesis wasn’t just a scientific claim — it became a professional litmus test. To challenge it was to risk your funding, your career, your credibility. Many of us paid that price. Even now, entrenched interests remain,” she wrote.

•But why was the myth allowed to persist in the first place? Apparently, it’s all because of the food and drug industry. In a video podcast, Dr. Paul Saladino and Teicholz discussed how the low-fat, low-cholesterol myth rapidly led to dramatic changes in the food and drug industries — changes that have proven to be highly lucrative, financially speaking.¹³

•Acknowledging that saturated fat is healthy means to relinquish big industry profits — The Big Food industry is raking in millions of dollars from the low-fat and low-cholesterol (yet highly processed) foods, including industrial vegetable oils. To admit that these “healthier options” are actually decimating public health would lead to great financial losses. The healthy alternative is real food — however, there’s no big industry profits to be made from that.

•Moreover, statin sales and other Big Pharma profit areas would suffer — The whole point of prescribing statins was to lower cholesterol, but if the notion that cholesterol is bad would be overturned, then what would be the point of taking these drugs?

Personally, I believe that statins are among the most overprescribed — and unnecessary — medications on the market today. Not only do the harms far outweigh the benefits, but they’re also ineffective. In fact, in “Heart of the Matter,” the experts repeatedly say that statins only lengthen a life by a few days and, despite their hype and popularity, are shockingly ineffective for all but a few people. Learn more about these drugs in my article, “Statins Do More Harm Than Good.”

Vegetable Oils Undermine Your Health

Perhaps the worst effect of the demonization of saturated fats — including butter, tallow, lard, and coconut oil — is that it paved the way for vegetable oils like soybean, canola, and corn oil, which are loaded with linoleic acid, a polyunsaturated fat (PUF), to become a standard part of the modern diet.

Today, Americans consume LA at levels that would have been unimaginable a century ago. In the 1860s, we only consumed 2 grams of LA per day; that number has now increased to close to 30 grams per day for most people. It now makes up 15% to 25% of a typical American’s caloric intake. And the cost of this overload? Your cells become more vulnerable to oxidative stress.

•Excessive LA causes your mitochondria to break down — The mitochondria, which are the powerhouse of your cells, responsible for creating energy, are significantly damaged because of this fat. LA transforms into oxidized linoleic acid metabolites (OXLAMs), dangerous byproducts that damage DNA, disrupt energy production, and drive chronic inflammation throughout your body.

OXLAMs have been linked to not just heart disease, but nearly every chronic disease now plaguing the developed world, such as obesity, Type 2 diabetes, and even neurodegeneration.

•LA stays in your body for years — You don’t simply eliminate it; instead, it LA embeds in your body fat, where it continues to inflict damage even after you clean up your diet. I recommend reading my paper published in Nutrients to understand how this happens — and how you can reverse it. My paper also expounds on the long-term biological effects of this metabolic disruptor.

•Unfortunately, LA is rampant in the food supply — Even if you stop using seed oils, or don’t eat fried foods and fast food, you could still end up eating large amounts of LA mainly because it’s cleverly hidden in so many packaged products where you’d least expect it.

Lowering your intake of industrial seed oils starts with knowing where they hide. I recommend downloading my Health Coach app, which will be out soon. It has a unique feature called Seed Oil Sleuth™, which will help identify every hidden source of seed oils in your meals. It also calculates your daily LA intake to the nearest tenth of a gram.

Saturated Fat Is Not the Enemy — Misinformation Is

So how do you undo the damage of 70 years of misguided health policy? The good news is there are ways to help revert the damage, and it starts by focusing on the root cause — removing industrial seed oils loaded with linoleic acid (LA). Carefully read labels, even in so-called “healthy” snacks; remember, these harmful fats are lurking everywhere.

Once you’ve cleaned up all the unhealthy fats in your diet, start rebuilding your health with saturated fats from clean animal sources, which are stable and nourishing. Choose healthy options like grass fed butter, ghee, beef tallow, and coconut oil, which support your mitochondria, don’t oxidize easily, and provide steady energy. For more healthy lifestyle strategies to eliminate LA from your diet, I recommend reading “Linoleic Acid, Mitochondria, Gut Microbiome, and Metabolic Health — A Mechanistic Review.”

These new developments in the U.S. food supply are certainly a breath of fresh air, and if Makary and others who are part of the “Make America Healthy Again” (MAHA) campaign follow through, we may finally get dietary guidelines that reflect biological truth, not industry agendas. As Demasi concludes:

“[W]e may finally be seeing the collapse of one of the most destructive public health myths in modern history … For those of us who’ve waited decades, it’s not vindication we want (although that would be nice) — it’s change.”¹⁴

Frequently Asked Questions (FAQs) About the War on Saturated Fat

Q: Why is the war on saturated fat finally ending?

A: For decades, saturated fat was wrongly blamed for heart disease due to flawed research like Ancel Keys’ Seven Countries Study. Now, top U.S. health officials, including FDA Commissioner Dr. Marty Makary, are acknowledging these mistakes and working to revise the dietary guidelines based on current science, not outdated dogma.

Q: What was wrong with the original research that demonized saturated fat?

A: Keys’ study selectively included countries that supported his hypothesis and ignored those that didn’t. This cherry-picking created a false link between fat and heart disease, leading to widespread promotion of low-fat, high-seed oil diets that have been harmful to public health.

Q: How have vegetable oils impacted health since replacing saturated fats?

A: Vegetable oils like soybean, corn, and canola are loaded with linoleic acid (LA), which damages mitochondria, promotes inflammation, and contributes to chronic diseases like obesity, diabetes, and neurodegeneration. These oils now make up 15% to 25% of caloric intake in the average American diet.

Q: What role did media and government play in spreading misinformation?

A: Mainstream media and government agencies endorsed and enforced the cholesterol hypothesis without fully examining the evidence. Whistleblowers like Maryanne Demasi, Ph.D., were attacked for speaking out, and even accurate documentaries were censored to protect the status quo.

Q: What changes are being proposed for the U.S. dietary guidelines?

A: Upcoming revisions may eliminate the cap on saturated fat and elevate full-fat foods like butter and dairy. Officials aim to base the guidelines on actual science, not outdated industry-driven dogma.

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