LDL, Saturated Fat, and Heart Disease: Should We Worry?
A tale of two competing paradigms and why I hope my diet isn't killing me.
Ever since the heady days of the Atkins diet in the early 1970s, the cosmic joke about ketogenic diets has been that, regardless of their efficacy for reducing weight and treating chronic diseases—and they might be uniquely effective—they’re commonly rich in saturated fat and can raise LDL cholesterol, a combination that is considered the ultimate offense to the conventional concept of heart-healthy eating.
That’s why the American Medical Association went after the Atkins diet in 1973, declaring that it was “deeply concerned about about any diet that advocates an `unlimited’ intake of saturated fat and cholesterol-rich foods.” Hence, all too likely to increase the “risk of coronary artery disease and other clinical manifestations of atherosclerosis… particularly if the diet is maintained over a long period.”
This perspective is slowly eroding as clinical trials demonstrate keto's efficacy, but it’s not going away. I suspect it never will. The clinical trials are inevitably short-term, from a few months to a year or two. Heart disease develops over decades, so it’s easy for establishment doctors, dietitians (and health reporters) to assume that any short-term benefits are transient while the long-term consequences of elevated LDL may be inevitable. When the Times ran an article this past week on the use of the ketogenic diet for mental health—depression, bipolar disorder, and schizophrenia—the reporter still felt the need to suggest that the diet would raise heart disease risk (albeit letting a psychiatry professor, Gia Merlo, say it for her1).
Popular versions of the keto diet also tend to be high in saturated fats, like from red meat, and low in fiber, which may increase the risk of health conditions like cardiovascular disease and some types of cancer, Dr. [Gia] Merlo added.
So here’s the cosmic joke circa 2026: we have an eating pattern that can reduce body weight without restricting calories, can put type 2 diabetes into remission, and maybe even cognitive disorders such as schizophrenia and bipolar depression, as the Times was reporting, It can improve every major risk factor for all those chronic diseases that associate with obesity and diabetes—including heart disease, stroke, and even cancer—and yet physicians (and psychiatrists) and nutrition writers still fear it will kill us prematurely because it can elevate LDL cholesterol.
Moreover, the implication is that we should consider that possibility more important than the remission of whatever chronic disease happens to ail us, even if it’s as debilitating as schizophrenia or these other mental health disorders.
RFK Jr might have said that "the war against saturated fat is over,” but, regrettably (and perhaps habitually), he was over-interpreting the evidence. Eleven health organizations—led by the American Heart Association and the American College of Cardiology—just published new guidelines on “the management of dyslipidemia,” advocating ever-lower LDL cholesterol levels at ever-younger ages and regular cholesterol testing beginning as early as age 10.
The idea is that the sooner we catch LDL cholesterol going up, the sooner we can act on it, which, as The New York Times reported, “could markedly reduce heart attacks and strokes.” And, of course, step one is diet.
The first approach for lowering LDL levels should be lifestyle: diet and exercise. While most people cannot make a significant difference in their LDL level with this approach, Dr. Blumenthal said, for some it turns out to be all they need..
And the diet recommended in the guidelines is the conventional healthy diet we’ve been reading about for decades: rich in fruits, vegetables, whole grains, and legumes, with olive oil or other plant oils instead of butter, and lean proteins, if not, preferably plant sources of protein.
The section in the guidelines discussing dietary intervention is, perhaps not surprisingly, a lengthy, paragraph-long encapsulation of the last 60 years of conventional thinking on diet and disease:
I have allies in my world who question all of this science, beginning with the LDL→heart disease link. They might be right, but I don’t know that literature well enough to judge.2
For this post, I’m going to accept that it’s true that lowering LDL with drugs will reduce heart disease risk and even make us live longer, and then strictly discuss what that should or should not tell us about a heart-healthy diet.
Should we worry about saturated fat in our diets and about the elevated LDL of ketogenic diets, in particular? I’ve been living with this question since the turn of the century, when I first reviewed the evidence for a year-long (award-winning) investigation in the journal Science. What follows is how I now think about the saturated fat/LDL issue, why I disagree with conventional medicine on this—and the decisions I’ve made considering what I know about my own LDL on a ketogenic diet.
This is, once again, a story about the history of medical science and what happens when physicians and their funding agencies commit to a hypothesis before conducting experiments to test it. It’s another tale of two competing paradigms. But if you don’t know the history, you can’t understand the context for the conventional wisdom.
