— Not on the basis of increased dietary saturated fat, the Skeptical Cardiologist finds
Anthony Pearson, MD
December 3, 2022
When the Skeptical Cardiologist was training as a cardiologist in the late 1980s there were two (unproven) concepts that had emerged from epidemiological research that I accepted as proven.
The first was that consumption of saturated fatty acids (SFAs) of any type and in any food increased the risk of atherosclerotic cardiovascular disease (ASCVD). The second was that consumption of meat increased the risk of cardiovascular disease and that the higher the SFA content of the meat, the higher the risk of ASCVD.
In 2013, I was challenged to look at the scientific bases of the first concept and started writing the Skeptical Cardiologist. Very quickly, I discovered that there was no scientific basis to recommend substituting no or low-fat dairy products for the unprocessed full fat forms of yogurt, milk, and cheese despite the reduction in saturated fat intake associated with this substitution.
In fact, in the last decade it has become widely accepted by the nutritional scientific community that substituting refined carbohydrates for saturated fat does not lower the risk of cardiovascular disease, lower your risk for diabetes, or aid in weight management.
Despite this, highly respected sources for dietary advice on lowering cardiovascular risk continue to spread misinformation and conflate “healthy” protein sources with foods that are low in saturated fat.
In 2015 I described the conflict occurring in the nutritional scientific community between the old guard traditionalists and more scientifically open-minded progressives. An excerpt from that post:
The traditionalists have shifted from condemning all fats to vilifying only saturated and trans fats. They would like to explain at least part of the reduction in coronary heart mortality as due to lower saturated fat consumption and the accompanying lowering of LDL (“bad”) cholesterol. The SFA traditionalists fortunately are in decline and more and more in the last 5 years, prominent thinkers, researchers and scientists working on the connection between diet and the heart believe saturated fats are neutral but sugar and refined carbohydrates are harmful in the diet.
Although 7 years have passed since that post, there has been only slight incremental improvement in messaging and the traditionalists are still in control of the American Heart Association (AHA) and many other nutrition websites. I just checked what the AHA has to say about meat and dairy, and it is still promulgating the outdated, traditional concepts:
The American Heart Association recommends choosing healthy sources of proteins, mostly from plant sources; regularly eating fish and seafood; substituting nonfat and low-fat dairy products in place of full-fat versions; and for people who eat meat or poultry, choosing those that are lean and unprocessed.
In general, red meats (such as beef, pork and lamb) have more saturated fat than skinless chicken, fish and plant proteins. Saturated fats can raise your blood cholesterol and increase your risk of heart disease. If you eat poultry, pork, beef or other meats, choose lean meat, skinless poultry, and unprocessed forms.
However, on the bright side, Up-to-Date, the major online reference for physicians, has this more progressive recommendation for patients who do not require special diets for existing diseases:
Do not focus on trying to restrict total fat intake; instead, increase consumption of minimally processed, bioactive-rich foods like fruits, nuts, seeds, vegetables, legumes, whole-grain products, plant oils, yogurt, and seafood, which are linked to lower risk of cardiovascular diseases, diabetes, and obesity. Reduce consumption of processed meats and carbohydrate-rich foods high in refined starch, added sugars, trans fat, or sodium. Cheese, milk, eggs, poultry, and unprocessed red meats may be added in moderation.
Do not assume that low-fat or “fat-free” varieties of packaged and processed foods (e.g., snack foods, salad dressings) are more healthful or better for weight control. These foods are often rich in refined starches and added sugars, which have been associated with higher triglyceride-rich lipoproteins and lower high-density lipoprotein (HDL) cholesterol levels, a possible increase in the incidence of type 2 diabetes and obesity, and failure to gain the benefits of more healthful alternatives.
And, a review by a group of prominent nutritionists, published in 2020 in the Journal of the American College of Cardiology, provides substantial backing for the progressive SFA paradigm. I encourage a full reading of the article but here is the abstract:
Most recent meta-analyses of randomized trials and observational studies found no beneficial effects of reducing SFA intake on cardiovascular disease (CVD) and total mortality, and instead found protective effects against stroke. Although SFAs increase low-density lipoprotein (LDL) cholesterol, in most individuals, this is not due to increasing levels of small, dense LDL particles, but rather larger LDL particles, which are much less strongly related to CVD risk. It is also apparent that the health effects of foods cannot be predicted by their content in any nutrient group without considering the overall macronutrient distribution. Whole-fat dairy, unprocessed meat, and dark chocolate are SFA-rich foods with a complex matrix that are not associated with increased risk of CVD. The totality of available evidence does not support further limiting the intake of such foods.
N.B. In the last 3 years, multiple studies/organizations have concluded that the association between unprocessed red meat consumption and colorectal cancer, breast cancer, type 2 diabetes and ischemic heart disease is very weak. If we stop making dietary decisions based on macronutrient content (e.g., lower SFA content) are there other reasons to eliminate or reduce meat consumption?
A decision to eliminate or minimize meat consumption for many individuals is driven by environmental and ethical concerns. I’ll examine this issue in a subsequent post.
Anthony C. Pearson, MD, is a noninvasive cardiologist and professor of medicine at St. Louis University School of Medicine. He blogs on nutrition, cardiac testing, quackery, and other things worthy of skepticism at The Skeptical Cardiologist, where a version of this post first appeared.