Rethinking Saturated Fat: Were Nutrition Experts Wrong?

For more than 50 years saturated fat has been portrayed as the primary culprit behind heart disease. Nutrition experts we admire and have interviewed many times are absolutely convinced that sat fat is dietary enemy # 1. Medical students, dietitians and most other health professionals learned that foods rich in this type of fat would boost cholesterol and ultimately clog arteries. Public health experts warned Americans to avoid butter, eggs, cheese, whole milk and red meat to prevent cardiovascular disease. Although this advice still seems logical to many, research that has been accumulating for decades has forced us to start rethinking saturated fat as the cause of most heart attacks.

Americans Bought the Message:

A great many Americans accepted the concept that saturated fat was a dietary evil. Everyday eating habits changed radically. Many people stopped eating eggs in favor of sweet breakfast cereals. Waffles or pancakes topped with margarine and sugary syrup somehow became healthy because there was “no cholesterol” in such breakfasts

We embraced low-fat or no-fat dairy products: milk, cottage cheese and yogurt. Nutritionists did not complain about the sugary jams at the bottom of most low-fat yogurt containers. There was a general suspicion of anything naturally creamy or “rich,” unless it was filled with chemicals and came with a zero cholesterol claim.

Despite these massive dietary changes and the widespread prescribing of cholesterol-lowering drugs, heart disease has persistently remained our # 1 killer for decades. And that is after Americans dramatically cut back on smoking, a major contributor to cardiovascular disease. What went wrong?

The Latest Research Forcing a Rethinking of Saturated Fat:

The problem is that numerous scientific studies contradict the idea that saturated fat remains the villain behind heart disease. The most recent meta-analysis was published in the Japan Medical Association JMA Journal, March 21, 2025.

The title:

“Saturated Fat Restriction for Cardiovascular Disease Prevention: A Systematic Review and Meta-analysis of Randomized Controlled Trials”

The authors point out in their “background” that the recommendations to cut back on sat fat were based upon “observational” studies rather than “randomized controlled trials.” This paper was designed to systematically review and analyze randomized controlled trials.

The investigators reviewed nine prevention trials involving 13,532 participants. In these randomized controlled studies (the gold standard of research), people consuming saturated fat were no more likely to have heart attacks or die than those on restricted diets. The researchers concluded:

“The findings indicate that a reduction in saturated fats cannot be recommended at present to prevent cardiovascular diseases and mortality.”

Such a statement is the equivalent of Galileo claiming that the earth was not the center of the universe. The Church proclaimed him a heretic and confined him to house arrest for challenging dogma. He died there in 1642, even though he recanted his own scientific findings. It took more than three centuries for the Church to acknowledge that Galileo was right.

Rethinking Saturated Fat Is

Many nutrition experts would like to proclaim that the conclusion from the Japanese researchers represents dietary heresy. It is not, however, the first time researchers have had to reconsider the idea that saturated fat causes heart disease.

More than a decade ago, investigators published an analysis involving 32 observational studies of dietary intake, 17 studies of fatty acid biomarkers and 27 randomized controlled trials. There were over 600,000 participants (Annals of Internal Medicine, March 18, 2014).

Their rethinking of saturated fat:

“In conclusion, the pattern of findings from this analysis did not yield clearly supportive evidence for current cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of saturated fats.”

When such comprehensive analyses challenge long-standing assumptions, it becomes essential to revisit the broader scientific landscape. Over the past several decades, scientists have been reexamining old beliefs with more rigorous methods. Large-scale analyses published in highly reputable journals have repeatedly shown that lowering saturated fat intake does not reliably reduce heart attacks or prevent premature death.

Just as historical beliefs resisted revision, modern nutrition guidance has sometimes struggled to keep pace with new evidence.

Rethinking Dietary Guidelines About Saturated Fat: When Foods Behave Differently:

This is where more nuanced research enters the picture, suggesting that the health impact of saturated fat depends heavily on the food that carries it.

One of the clearest insights from modern nutritional epidemiology is that saturated fat doesn’t act in isolation. Red meat and butter may be associated with higher cardiovascular risk in some studies, while fermented dairy such as yogurt and cheese, along with oily fish, often show the opposite pattern. These distinctions rarely appeared in earlier dietary advice, yet they may be crucial for understanding true health effects.

Rethinking Saturated Fat: Olive Oil Surprises Nutrition Experts:

For a long time, the assumption was that eating fat would make people gain weight. Consequently, the finding that people consuming olive oil were less likely to gain weight than those avoiding it came as a surprise (American Journal of Clinical Nutrition, May 2025). After all, olive oil itself contains 10-15% saturated fat, equivalent to about 2 grams per tablespoon. That is a bit more than you would find in a large egg or 3.5 ounces of eye of round steak.

Many dieticians now consider avocados “safe” to consume in moderation. Half an avocado contains about 1.5 to 2 grams of saturated fat, about as much as a tablespoon of olive oil. A small (4 oz) carton of full-fat yogurt could contain from 2 to 4 grams of sat fat. If you went wild and ate a whole 5.3 oz container of Trader Joe’s Greek Yogurt made with whole milk, you would consume 9 grams of saturated fat.

The PREDIMED Study

This study should have rocked the nutrition world to its foundation and changed dietary recommendations long ago. It started in 2003 and the last volunteer was recruited on June 30, 2009. The 7,447 participants ranged from 55 to 80 years of age and they were all at high risk for cardiovascular disease. That’s because they had at least one of the following risk factors:

• Type 2 diabetes
• Hypertension
• Smoker
• Elevated LDL cholesterol
• Low HDL cholesterol
• Overweight or obese

The volunteers were followed for about 5 years. They were divided into one of three groups. One group was assigned a Mediterranean diet supplemented with 4 tablespoons of olive oil daily (about 8 grams of sat fat daily). Group two was also assigned a Mediterranean diet supplemented with a large handful of mixed nuts (30 grams) every day (about 1.5 grams of sat fat). The third group was put on a “control” low-fat diet.

Results were published in the New England Journal of Medicine, June 13, 2018:

“In this study involving persons at high cardiovascular risk, the incidence of major cardiovascular events was lower among those assigned to a Mediterranean diet supplemented with extra-virgin olive oil or nuts than among those assigned to a reduced-fat diet.”

How much lower you might ask. The relative risk reduction was 30%. That was almost as much as the maker of Lipitor bragged about in its 5-year study of the cholesterol-lowering drug atorvastatin. Clearly, the higher fat diet beat out the low-fat diet. Remember, the participants who were eating 4 tablespoons of olive oil (8 grams of sat fat daily) did better than the people in the low-fat group.

The outcomes proved so significant that researchers ended the trial early. The people following a high-fat Mediterranean-style diet had fewer heart attacks, strokes and cardiovascular deaths that the low-fat folks. Did the results change guidelines or alter beliefs about saturated fat? That seems doubtful. Many cardiologists have embraced the Mediterranean diet, even while they scorn saturated fat.

If Food is Medicine (FIM), What Should You Be Eating?

We have written a lot about diet over the last few decades. If you would like to learn why we think a high-carb diet is more dangerous than a low-fat diet, please read this article:

“Just How Scary is Saturated Fat?“

In it you will read about the EPIC study–European Prospective Investigation into Cancer and Nutrition. There is also an overview of the PURE (Prospective Urban Rural Epidemiology) study. It challenges the standard wisdom that a low fat is a healthier healthier diet. You will learn about the Minnesota Coronary Experiment that ran from 1968 till 1973. You may find it as puzzling as we did that the results were not published until 2016. And let’s not forget the Sydney Heart Study. The results were also not published in a timely manner, perhaps because they might have required cardiologists to begin rethinking saturated fat.

Final Words About Rethinking Saturated Fat:

Nutrition science is continually evolving. As researchers differentiate between whole foods and isolated nutrients, earlier assumptions fall away. What seemed like settled doctrine a generation ago now appears too simplistic. Rather than casting saturated fat as a universal threat, current evidence suggests a more nuanced approach — one that considers dietary patterns, food quality and individual metabolic responses.

We don’t claim to have the final word on saturated fat — and apparently, neither does nutrition science. But the weight of the evidence now suggests that the blanket warnings of the past were far too broad. Some foods rich in saturated fat may be problematic for certain individuals, while others appear surprisingly neutral or even beneficial.

Where does that leave us if we just want to know how to eat for health? The first step is to acknowledge that nutrition science is still a work in progress. Recent research demonstrates, for example, that common olive oil and extra-virgin olive oil have different impacts on heart health (American HePart Journal, Jan. 2026).

Twenty or thirty years ago, most researchers were not distinguishing between them. Twenty years from now, perhaps we will discriminate between butter from grass-fed cows and that from more confined dairies. For now, though, we can say that saturated fat may not be the dietary evil that we once thought it was.

How to Apply This Evolving Understanding

• Eat real foods. Cheese, full-fat yogurt and eggs are not automatically dangerous because they contain sat fat.
• Beware of sugary “low-fat” or “light” products. Replacing fat with sugar rarely improves health.
• Use extra-virgin olive oil generously. Evidence supports its cardiovascular and other benefits.
• Choose minimally processed fats. Butter or olive oil beats hydrogenated margarine or highly refined seed oils.
• Watch the whole plate. Vegetables, legumes and whole grains remain foundational.
• Respect individuality. People metabolize fats differently; what’s “healthy” isn’t identical for everyone.

FINAL, Final Words:

Are you rethinking saturated fat? Please share your eating habits in the comment section below. If you know someone who might find this article of value, please share it either via email or on social media. Just scroll to the top of the page and click on the appropriate icon. Why not encourage acquaintances to sign up for our free newsletter at this link? That way you won’t have to share such posts because they will get them automatically. If you can help support our work with a donation before the end of the year, we would be extremely grateful. Here is a link.