“For the love of all that is dairy, why are we still eating low-fat?” asked Bon Appetit last year. “Science has come around on full-fat dairy. Why haven’t we listened?”
The science has come around, according to Bon Appetit, because “better designed studies found that saturated fat increased both good and bad cholesterol,” and “when both were raised, the net effect is zero.”
Simple? Yes. Correct? No.
Four recent studies randomly assigned people to eat diets that were either high or low in saturated fat, largely from dairy (see here, here, here, and here). The results: LDL (bad) cholesterol was higher—and HDL (good) cholesterol didn’t budge—in people who ate more dairy fat.
“Dairy fat is high in palmitic acid, a saturated fat that has potent LDL-raising effects,” says Frank Hu, who chairs the nutrition department at the Harvard T.H. Chan School of Public Health.
And there’s no question that a higher LDL puts the heart at risk.
“LDL is a major cause of heart disease, and lowering it with diet or drugs prevents heart disease,” says Frank Sacks, professor of cardiovascular disease prevention at the Harvard T.H. Chan School of Public Health.
“LDL isn’t just a marker for a higher risk. It’s the real deal.”
Dairy fat doesn’t raise LDL in some industry-funded studies, but there’s usually a reason why.
For example, one study—funded by the Australian, Canadian, Danish, Dutch, French, and U.S. dairy industries—reported no difference in LDL when people were randomly assigned to eat regular versus lower-fat cheese.
But the study was “underpowered”—that is, too small to see a difference from the change in sat fat—noted Jan Pedersen of the University of Oslo in a letter to the journal’s editor.
A second industry-funded study reported no higher LDL on a high-cheese or high-meat diet than on a lower-fat, higher-carb diet.
No surprise there.
“The cheese and meat diets were enriched with foods rich in polyunsaturated fats such as nuts, canola oil, and sunflower oil, which are known to lower LDL cholesterol,” wrote Peter Marckmann of the Roskilde Hospital in Denmark in a letter to the editor. “The diets were apparently designed so that the possibly desired conclusion could be drawn.”
That said, butter may raise LDL slightly more than cheese.
In the largest study—funded by the Canadian dairy industry—LDL was 4 points higher when people ate about 10 pats of butter than when they ate about 3 ounces of cheese a day. (The two foods supplied the same amount of sat fat.)
However, the researchers reported much bigger differences in LDL when they switched people from butter to polyunsaturated fat (18 points lower), monounsaturated fat (10 points lower), or carbs (7 points lower).
“It’s conceivable that fermentation may mitigate the LDL-raising effect of the palmitic acid in cheese,” says Hu. “By how much, it’s hard to know.”
“But that doesn’t exonerate the palmitic acid and other saturated fats in cheese. It just means that when it comes to raising LDL, cheese is the lesser of two evils, and they’re both worse than unsaturated fats.”
That fits with studies that ask people what they eat and wait years to see who gets heart disease.
“There’s certainly no good evidence that high-fat dairy is better than low-fat,” says Hu. And pushing high-fat dairy could also lead to worse diets.
“We eat much of our dairy in foods like cheeseburgers and pizza,” notes Hu.
“Promoting high-fat dairy would do more harm than good because when we eat those foods, we get not only saturated dairy fat but also processed meats, refined carbs, and sodium.”
Bottom Line: Dairy fat hasn’t earned a clean bill of health for your heart.
The information in this post first appeared in the September 2019 issue of Nutrition Action Healthletter.
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