Is Red Meat Consumption a Significant Risk Factor For Cardiovascular Disease?

Progressive nutritional scientists recognize that total dietary saturated fat intake has little health effect or relevance as a target. Does that make red meat OK?

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 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 is become widely accepted by the nutritional scientific community that substituting refined carbohydrates for saturated fat doses 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. What follows is an updated form of that post.

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Saturated Fat: Traditionalists

Versus Progressives

Two editorials recently published in The Lancet show the widely varying opinions on the optimal diet for controlling obesity , diabetes and coronary heart disease that experts on nutrition, diabetes and heart disease hold.

The first paper contains what I would  consider the saturated fat "traditionalist" viewpoint. This is a modification of the misguided concept that was foisted on the American public in the 1980s and resulted in the widespread consumption of industrially produced trans-fats and high sugar junk food that was considered heart healthy.

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 five 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.

Darius Mozzafarian, a highly respected cardiologist and epidemiologist, who is dean of the School of Nutrition Science and Policy at Tufts, wrote the second editorial and is what I would term a saturated fatty acid (SFA) progressive. He makes the following points which are extremely important to understand and which I have covered in previous posts. I've included his supporting references which can be accessed here.

Fat Doesn't Make You Fat, Refined Starches And Sugar Do

Foods rich in refined starches and sugars—not fats—seem to be the primary culprits for weight gain and, in turn, risk of type 2 diabetes. To blame dietary fats, or even all  calories, is incorrect

Although any calorie is energetically equivalent for short-term weight loss, a food's long-term obesogenicity is modified by its complex effects on satiety, glucose–insulin responses, hepatic fat synthesis, adipocyte function, brain craving, the microbiome, and even metabolic expenditure Thus, foods rich in rapidly digestible, low-fibre carbohydrates promote long-term weight gain, whereas fruits, non-starchy vegetables, nuts, yoghurt, fish, and whole grains reduce   long-term weight gain.(1, 2, 3)

Overall, increases in refined starches, sugars, and other ultraprocessed foods; advances in food industry marketing; decreasing physical activity and increasing urbanisation in developing nations; and possibly maternal–fetal influences and reduced sleep may be the main drivers of obesity and diabetes worldwide".

There Are Many Different Kinds of Saturated Fats With Markedly Different Health Effects: It Makes No Sense to Lump Them All Together 

"SFAs are heterogeneous, ranging from six to 24 carbon atoms and having dissimilar biology. For example, palmitic acid (16:0) exhibits in vitro adverse metabolic effects, whereas medium-chain (6:0–12:0), odd-chain (15:0, 17:0), and very-long-chain (20:0–24:0) SFAs might have metabolic benefits.(4) This biological and metabolic diversity belies the wisdom of grouping of SFAs based on a single common chemical characteristic—the absence of double bonds. Even for any single SFA, physiological effects are complex: eg, compared with carbohydrate, 16:0 raises blood LDL cholesterol, while simultaneously raising HDL cholesterol, reducing triglyceride-rich lipoproteins and remnants, and having no appreciable effect on apolipoprotein B,  5 the most salient LDL-related characteristic. Based on triglyceride-lowering effects, 16:0 could also reduce apolipoprotein CIII, an important modifier of cardiovascular effects of LDL and HDL cholesterol. SFAs also reduce concentrations of lipoprotein(a) ,(6) an independent risk factor for coronary heart disease."

The Effects of Dietary Saturated Fats Depend on Complex Interactions With The Other Ingredients in Food

"Dietary SFAs are also obtained from diverse foods, including cheese, grain-based desserts, dairy desserts, chicken, processed meats, unprocessed red meat, milk, yoghurt, butter, vegetable oils, and nuts. Each food has, in addition to SFAs, many other ingredients and characteristics that modify the health effects of that food and perhaps even its fats. Judging the long-term health effects of foods or diets based on macronutrient composition is unsound, often creating paradoxical food choices and product formulations. Endogenous metabolism of SFAs provide further caution against oversimplified inference: for example, 14:0 and 16:0 in blood and tissues, where they are most relevant, are often synthesised endogenously from dietary carbohydrate and correlate more with intake of dietary starches and sugars than with intake of meats and dairy.(4)"

Dietary Saturated Fat Should Not Be a Target for Health Promotion

"These complexities clarify why total dietary SFA intake has little health effect or relevance as a target. Judging a food or an individual's diet as harmful because it contains more SFAs, or beneficial because it contains less, is intrinsically flawed. A wealth of high-quality cohort data show largely neutral cardiovascular and metabolic effects of overall SFA intake.(7) Among meats, those highest in processing and sodium, rather than SFAs, are most strongly linked to coronary heart disease.7Conversely, higher intake of all red meats, irrespective of SFA content, increases risk of weight gain and type 2 diabetes; the risk of the latter may be linked to the iron content of meats.(2, 8)  Cheese, a leading source of SFAs, is actually linked to no difference in or reduced risk of coronary heart disease and type 2 diabetes. (9, 10) Notably, based on correlations of SFA-rich food with other unhealthy lifestyle factors, residual confounding in these cohorts would lead to upward bias, causing overestimation of harms, not neutral effects or benefits. To summarise, these lines of evidence—no influence on apolipoprotein B, reductions in triglyceride-rich lipoproteins and lipoprotein(a), no relation of overall intake with coronary heart disease, and no observed cardiovascular harm for most major food sources—provide powerful and consistent evidence for absence of appreciable harms of SFAs."

Dietary Saturated Fats May Raise LDL cholesterol But This Is Not Important: Overall Effects On Obesity and Atherosclerosis Are What Matters

A common mistake made by SFA traditionalists is to consider only slices of data—for example, effects of SFAs on LDL cholesterol but not their other complex effects on lipids and lipoproteins; selected ecological trends; and expedient nutrient contrasts. Reductions in blood cholesterol concentrations in Western countries are invoked, yet without systematic quantification of whether such declines are explained by changes in dietary SFAs. For example, whereas blood total cholesterol fell similarly in the USA and France between 1980 and 2000, changes in dietary fats explain only about 20% of the decline in the US and virtually none of that which occurred in France.11Changes in dietary fats11 simply cannot explain most of the reductions in blood cholesterol in Western countries—even less so in view of the increasing prevalence of obesity. Medication use also can explain only a small part of the observed global trends in blood cholesterol and blood pressure. Whether decreases in these parameters are caused by changes in fetal nutrition, the microbiome, or other unknown pathways remains unclear, thus highlighting a crucial and greatly underappreciated area for further investigation."

Dietary Saturated Fats Are Neutral For Coronary heart Disease Risk

Finally, SFA traditionalists often compare the effects of SFAs only with those of vegetable polyunsaturated fats, one of the healthiest macronutrients. Total SFAs, carbohydrate, protein, and monounsaturated fat each seem to be relatively neutral for coronary heart disease risk, likely due to the biological heterogeneity of nutrients and foods within these macronutrient categories.(7) Comparisons of any of these broad macronutrient categories with healthy vegetable fats would show harm,(12) so why isolate SFAs? Indeed, compared with refined carbohydrates, SFAs seem to be beneficial.(7)

The overall evidence suggests that total SFAs are mostly neutral for health—neither a major nutrient of concern, nor a health-promoting priority for increased intake.

Focusing On Reducing Saturated Fats Leads To Unhealthy Dietary Choices

I've written about this a lot. The most baffling aspect of this is the promotion of low or non-fat dairy.

There is no evidence that low fat dairy products are  healthier than full fat dairy products.

Non-fat yogurt filled with sugar should be considered a dessert, not a healthy food.

"Continued focus on modifying intake of SFAs as a single group is misleading—for instance, US schools ban whole milk but allow sugar-sweetened skim milk; industry promotes low-fat foods filled with refined grains and sugars; and policy makers censure healthy nut-rich snacks because of SFA content.13"

It is extremely hard to change most people's opinions on dietary fat.

My patients have been hearing the SFA traditionalist dogma for decades and thus it has become entrenched in their minds.

When I present to them the new progressive and science-based approach to fat and saturated fat some find it so mind boggling that they become skeptical of the skeptical cardiologist!

Hopefully, in the next few years, the progressive SFA recommendations will become the norm and maybe , some day in the not too distant future, the inexplicable recommendations for low-fat or non fat dairy will disappear.

As more data accumulates we may become SFA enthusiasts!

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Although seven years have passed since those editorials, there has been only slight incremental improvement in nutritional messaging and the traditionalists are still in control of the American Heart Association and many other nutrition websites. I just checked what the AHA has to say about meat and dairy and it is still promoting outdated and unscientific 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 (as I mention in my lecture on the optimal diet to prevent atherosclerotic cardiovascular disease), Up-to-Date, the major online reference for physicians has this more progressive recommendation:

And, a “State of the Art Review” (Saturated Fats and Health: A Reassessment and Proposal for Food-based Recommendations: JACC State-of -the-Art Review) was published in 2020 in the Journal of the American College of Cardiology by a group of prominent nutritionists and provides substantial backing for the progressive SFA paradigm.

I encourage a full reading of the article but here is the abstract:

“across the board recommendation to limit dietary saturated fatty acid (SFA) intake has persisted despite mounting evidence to the contrary. 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 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, eggs 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.“

Saturatingly Yours,

-ACP

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.