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Just How Scary Is Saturated Fat?

Is your doctor's nutrition advice outmoded? Many physicians still warn against saturated fat, though they need a more nuanced message.

Have you ever heard the saying “you can’t teach an old dog new tricks”? It’s not true. Many old dogs learn new tricks with the right training and motivation. It turns out that it could be a lot harder to teach old docs new tricks, especially when it comes to nutrition. Even though medical schools taught very little nutrition science decades ago, some physicians just can’t let go of the lessons they learned. One of them was to cut back on fat in the diet, especially saturated fat.

What Did Doctors Learn About Nutrition?

During the middle of the 20th century, medical students were told that fat in general and saturated fat in particular raised cholesterol levels. It was seen as the driving force behind clogged arteries leading to heart attacks. Patients were urged to switch to margarine instead of butter, cut back on eggs and cheese and forego ice cream and burgers. After all, the thinking went, these foods are high in cholesterol and cholesterol is found in plaque in arteries.

Dietitians often recommended a “heart-healthy” breakfast of cornflakes with skim milk, toast with margarine and a glass of orange juice. Another option might be pancakes cooked on a nonstick griddle. The general advice was to stay away from any food with sat fat, especially dairy products such as cheese, butter, whole milk or ice cream. If people avoided saturated fat, they were told, they could reduce their risk of heart disease.

Margarine vs. Butter:

Before the century closed, nutrition science had found that margarine with its trans fats was actually causing more harm than butter. But health professionals have been reluctant to give up on fat as a dietary demon. That is why low-fat products like skim milk and non-fat yogurt dominate the dairy case. The American Heart Association still advises patients to limit saturated fat and select skim and low-fat dairy products.

EPIC Research Has Us Rethinking Heart-Healthy Nutrition:

A new report suggests that some foods rich in sat fat are indeed risky, while others are not (Journal of the American Heart Association, Nov. 19, 2021). The scientists analyzed data collected as part of a large epidemiological study of diet and health in Europe. (For the epidemiologists out there, it’s the EPIC study–European Prospective Investigation into Cancer and Nutrition.)

During the study, more than 10,000 participants in ten countries had heart attacks, strokes or other cardiovascular events. Investigators matched their records to those of 16,000 volunteers who remained healthy. All of the people in this study filled out detailed questionnaires on diet and lifestyle.

Overall, there was no link between saturated fat consumption and risk of cardiovascular disease. However, there were differences based on foods. People who ate more red meat and butter were more prone to heart disease. Those who ate more yogurt, cheese or fatty fish, on the other hand, had a lower risk. The researchers noted this specifically because these foods are also high in sat fat.

This research, published in the Journal of the American Heart Association, challenges decades of advice to avoid all saturated fat. However, previous studies had also been undermining that blanket recommendation.

Data from a PURE Nutrition Study:

The definition of healthy eating has been shifting, based on actual data. Recent research called the Prospective Urban Rural Epidemiology (PURE) study carefully collected dietary information from 135,000 people (Dehghan et al, The Lancet, online Aug. 29, 2017).  After seven years, almost 6,000 people had died, and more than 4,700 had suffered heart attacks or strokes.

High-Carb Diets Were More Dangerous:

Analysis showed that the people who had been eating a high-carbohydrate diet were more likely to end up among the deceased or diseased. Those whose diets were richer in fat were less likely to have died. One particular correlation stands out: those consuming more saturated fat were at lower risk for strokes.

Previous Studies on Saturated Fat:

This is not the first study to suggest that saturated fat is not our enemy. The Minnesota Coronary Experiment ran from 1968 till 1973. In this randomized controlled trial, 9,000 patients were served meals high in saturated fat or unsaturated vegetable oil. The corn oil lowered cholesterol but did not improve survival. If anything, those eating corn oil were somewhat more likely to die (Ramsden et al, BMJ, April 13, 2016).

Another classic trial had similar results. The Sydney Heart Study randomized 458 Australian heart attack survivors to continue on their usual 1960s diet high in saturated fat or to substitute safflower oil for sat fat. The data were not published at the time, but the men on the low sat fat diet were more likely to have heart attacks and die (Ramsden et al, BMJ, Feb. 5, 2013).

Rethinking Nutrition Dogma on Saturated Fat:

These findings led the investigators to question the diet-heart hypothesis so esteemed in nutrition circles. As new data (as well as new analysis of old data) demonstrate that old dietary beliefs were mistaken, health professionals need to rethink their advice. (Indeed, a few have begun to do so.) Sugar and other highly processed carbohydrates appear to be more hazardous to health than fat.

Learn More:

We have spoken with several physicians who have become convinced that we need to worry more about refined carbohydrates and sugar in our diets than about minimally processed fat. You can listen to our interviews with Dr. Robert Lustig, author of Fat Chance; Dr. Jacob Teitelbaum, author of The Complete Guide to Beating Sugar Addiction; and Dr. David Ludwig, author of Always Hungry. Our most recent interview with Dr. Ludwig is Show 1279: Challenging Dietary Dogma on Weight Gain.  For more from Dr. Lustig, listen to Show 1257: The Metabolical Results of the American Diet.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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  • Steur M et al, "Dietary Fatty Acids, Macronutrient Substitutions, Food Sources and Incidence of Coronary Heart Disease: Findings From the EPIC‐CVD Case‐Cohort Study Across Nine European Countries." Journal of the American Heart Association, Nov. 19, 2021. https://doi.org/10.1161/JAHA.120.019814
  • Dehghan M et al, "Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study." The Lancet, online Aug. 29, 2017. DOI:https://doi.org/10.1016/S0140-6736(17)32252-3
  • Ramsden CE et al, "Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73)." BMJ, April 13, 2016. doi: https://doi.org/10.1136/bmj.i1246
  • Ramsden CE et al, "Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis." BMJ, Feb. 5, 2013. doi: https://doi.org/10.1136/bmj.e8707
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