The Nuance

Cheese, Eggs, Milk, and Meat: Solving the Mystery of Saturated Fat

A new theory could resolve long-standing contradictions in the saturated-fat research

Photo by Alexander Maasch on Unsplash

It’s a mystery that has confounded nutrition scientists.

People who have high levels of cholesterol in their blood — especially LDL cholesterol, a.k.a. the “bad” kind — are at elevated risk for cardiovascular disease.

Meanwhile, foods high in saturated fatty acids — including eggs, full-fat dairy products, and red meat — raise blood levels of cholesterol, including LDL cholesterol.

It stands to reason that eating these foods would increase a person’s risks for cardiovascular disease, which is the number-one cause of death in the U.S. and around the world. This logic has led both the World Health Organization and U.S. health authorities to recommend that people limit their intakes of saturated fat.

But there’s a problem: People who eat these foods don’t seem to develop cardiovascular disease at elevated rates (CVD).

A 2019 research analysis in the journal Nutrition Reviews looked at the findings of both observational studies and randomized controlled trials. It found no consistent associations between dietary intakes of saturated fat and heart disease — the most common and deadly form of CVD.

What explains this disconnect? A new hypothesis, published earlier this year in the American Journal of Clinical Nutrition, may provide the answer.

“I think we have been grossly wrong about saturated fats,” says Marit Kolby, first author of the AJCN paper and a nutritional biologist at Oslo New University College in Norway. “In my opinion, saturated fat has been blamed for what refined carbohydrates do.”

Kolby’s theory revolves around the normal operation of the body’s cells.

She explains that cholesterol can form up to 50% of a healthy cell’s membrane, which is the semi-permeable barrier that selectively allows nutrients, waste, and other stuff to pass in and out of the cell’s interior.

According to her hypothesis, which preliminary evidence supports, cells depend on cholesterol to…