When the skeptical cardiologist was training as a cardiologist in the late 1980s, two (unproven) concepts emerged from epidemiological research that I accepted as proven.
The first was that the 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 meat consumption increased the risk of cardiovascular disease, and the higher the SFA content of meat, the higher the risk of ASCVD.
In 2013, I was challenged to examine the scientific basis of the first concept and started writing The Skeptical Cardiologist. Very quickly, I discovered that there was no scientific basis for recommending replacing fat-free or low-fat dairy products with unprocessed forms of yogurt, milk and cheese, despite the reduction in saturated fat intake associated with this substitution.
In fact, over the past decade it has become widely accepted by the nutritional science community that replacing refined carbohydrates with saturated fats does not reduce the risk of cardiovascular disease, decrease the risk of diabetes, or help not weight management.
Despite this, highly respected sources of cardiovascular risk reduction dietary advice continue to spread misinformation and confuse “healthy” protein sources with foods low in saturated fat.
In 2015, I described the conflict taking place in the nutritional science community between old-guard traditionalists and more scientifically open progressives. An excerpt from this post:
Traditionalists have gone 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 disease mortality as being due to reduced consumption of saturated fat and the concomitant lowering of LDL (“bad”) cholesterol. SFA traditionalists are thankfully in decline and increasingly over the past 5 years leading thinkers, researchers and scientists working on the link between diet and the heart believe that saturated fat is neutral but the sugar and refined carbohydrates are harmful in the diet.
Although 7 years have passed since that post, there has only been a slight incremental improvement in messaging and traditionalists still control the American Heart Association (AHA) and many other nutrition websites. I just checked what the AHA has to say about meat and dairy, and they still promulgate the outdated traditional concepts:
The American Heart Association recommends choosing healthy sources of protein, primarily from plant sources. regularly eat fish and seafood; replace fat-free and low-fat dairy products with non-fat versions; and for people who eat meat or poultry, choose those that are lean and unprocessed.
In general, red meats (such as beef, pork, and lamb) contain more saturated fat than skinless chicken, fish, and vegetable protein. Saturated fats can raise your blood cholesterol levels 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 leading online reference for doctors, has this more gradual recommendation for patients who don’t need special diets for existing conditions:
Don’t focus on limiting total fat intake; instead, increase intake of minimally processed, bioactive-rich foods like fruits, nuts, seeds, vegetables, legumes, whole-grain products, vegetable oils, yogurts, and seafood , which are linked to a lower risk of cardiovascular disease, diabetes and obesity. Reduce the consumption of processed meats and carbohydrate-rich foods that are high in refined starch, added sugars, trans fats, or sodium. Cheese, milk, eggs, poultry and unprocessed red meats can be added in moderation.
Don’t assume that low-fat or “fat-free” varieties of packaged and processed foods (eg, snack foods, salad dressings) are healthier or better for weight control. These foods are often high in refined starches and added sugars, which have been linked to higher triglyceride-rich lipoproteins and lower high-density lipoprotein (HDL) cholesterol levels, possible increased incidence of type 2 diabetes and obesity, and an inability to reap the benefits of healthier alternatives.
And, a review by a group of eminent nutritionists, published in 2020 in the Journal of the American College of Cardiology, provides substantial support for the progressive AFS paradigm. I encourage a full reading of the article but here is the summary:
The 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 effects protectors against strokes. Although SFAs increase low-density lipoprotein (LDL) cholesterol, in most individuals this is not due to increased levels of small dense LDL particles, but rather larger LDL particles. , which are much less strongly related to CVD risk. It is also evident that the health effects of foods cannot be predicted by their content in any nutrient group without considering the overall macronutrient distribution. Whole dairy products, unprocessed meat, and dark chocolate are SFA-rich foods with a complex matrix that are not associated with an increased risk of CVD. The totality of available evidence does not support further limiting the consumption of these foods.
NB Over the past 3 years, several 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?
The decision to eliminate or minimize meat consumption for many people is driven by environmental and ethical concerns. I will examine this problem in a future post.
Anthony C. Pearson, MD, is a noninvasive cardiologist and professor of medicine at St. Louis University School of Medicine. He blogs about nutrition, heart tests, quackery and other things worthy of skepticism on The Skeptical Cardiologist, where a version of this post first appeared.