Cardiovascular (Heart) Risks and Benefits of Eating Grass-fed Beef Lawrence E. Widman, MD PhD
March 2019 (updated June 2020) Table of ContentsWhy are we talking about this? (Introduction)Setting the Stage (the short version) Setting the Stage (the longer version) Relationship between cholesterol and coronary atherosclerosis Relationships between diet, cholesterol, and coronary atherosclerosis Why do we need cholesterol anyway? What's with all the different types of cholesterol? Good? Bad? Give me a break! Why are there so many types of clinical studies? The obesity epidemic, or So what is wrong with not eating meat? What is the Healthy Mediterranean-Style Pattern? What is meant by "meat", and what is the difference between processed and unprocessed meat? Is processed meat good or bad for your heart health? Is unprocessed meat good or bad for your heart health? Is there a difference between unprocessed beef from animals fed grain compared with grass-fed cattle? Is there an advantage to Animal Welfare Approved meat? What does that mean, anyway? Is there an advantage to certified organic meat? What does that mean, anyway? If I eat certified organic, certified grass-fed beef, will I lose weight? Become healthy, wealthy, and wise? Supplemental material How the scientific method works A brief dictionary of terms we use here Ways to get confused by scientific studies References Why are we talking about this? (Introduction)For many decades, standard dietary advice in the United States has been to eat a diet rich in vegetable sources of protein and selected lipids (oils), while avoiding beef and other sources of animal proteins and fats (technically the type of fats known as lipids). New studies are showing that this advice may be wrong, and may have led to the rise in obesity and obesity-related disorders over this same period. In this article, I review the basis for the previously-standard advice, the available new data, and the conclusions that may be considered based on these new data. The audience for this review is the intelligent layman who wishes to understand the issues better. For this reader, citations to the primary and secondary literature are provided to facilitate further reading. Constructive comments and questions may be directed to review-article at leafycreekfarm.com. This article is long so details are hidden until you click on the text "click to show details" wherever more detail is available. Or, you can . Setting the Stage (the short version)The short story is that after World War II, the leading cause of death in the United States of America was coronary artery disease causing heart attacks. No one knew why it was happening, and the problem was getting worse. A great effort was made to find out why. Over the next decades, research studies identified the risk factors we know today: male sex, increasing age, use of cigarettes, high blood pressure, diabetes, and high cholesterol. Of the risk factors that could be changed, further effort was made to find out whether changing them made any difference. () Unfortunately, even though the studies of diet and cholesterol began in the same time period, the theory and practice of dietary control of cholesterol is not well understood, and what is thought to be true now appears to be changing. Setting the Stage (the longer version)The reasons for the transition from the decades-old emphasis on plant sources of food to emphasis on animal sources are complex but start with the fact that studies of diet are very hard to do. After all, people tend to eat what they want and a lot of studies just ask people what they ate. By contrast, for treatment of blood pressure, blood sugar, and cholesterol with medications, people just have to take the medications. Worse, the studies of diet and heart disease began just after the chaos of World War II and the rebuilding afterward. The majority of the scientists who worked on the problem then thought they found that eating animal protein was associated with more heart attacks than eating plant protein. They were so sure of this, despite protests from other scientists working on the same problem at the time, that this concept became accepted as Truth and became the basis of official dietary recommendations that have persisted for decades. Only recently have the original data been reexamined and found to be not as certain as was once thought. This is discussed in more detail below. Pertinent to this article, in particular, the original studies lumped together both processed meat such as salami and unprocessed meat such as raw beef and chicken. Newer studies show that processed meats are indeed not healthy, but that unprocessed meats not only are healthy but actually seem to be healthier than purely plant-based protein sources as measured by the effects on blood pressure, blood sugar (glucose), and blood cholesterol. Please see the detail in the sections on how the scientific method works, a brief dictionary of terms we use here, and ways to get confused by scientific studies for concepts and terms you may find unfamiliar in the more detailed discussion below. Relationship between cholesterol and coronary atherosclerosisThe reason we think there is a relationship between cholesterol and blockages in the arteries to the heart (coronary atherosclerosis) is that many studies, done as carefully as possible, have found that people who have high cholesterol levels are more likely to develop atherosclerosis. This is just an association and does not prove a causal relationship. However, when the level of cholesterol is reduced one way or another, the risk of developing atherosclerosis is also lowered. This proves causality (unless the methods used to reduce cholesterol by themselves reduce the risk). There are many ways to reduce cholesterol, starting with a very strict low-cholesterol diet, then progressing to losing weight for the obese, and then progressing to various medications. No single method works in everyone, but the fact that there are many methods suggests that the method is not the causal factor, and that lowering cholesterol is. Relationships between diet, cholesterol, and coronary atherosclerosisTo discuss the next topic, diet and cholesterol, we have to review some history. Up until World War II was over in 1945, coronary atherosclerosis was thought to be an inevitable consequence of aging. Very little was known about its causes. For example, the standard K rations issued to soldiers in that war included a pack of cigarettes with every ration. It was not known that diabetes and hypertension were strong risk factors. In fact, in the middle of a world war, these questions were not very important. Also, for interest, the scientist in charge of developing the K rations was Dr. Ancel Keys. However, after the war and into the 1950s, the death rate from heart disease was found to be high and rising. The rate of death from heart disease became so high that it was considered an urgent matter of public health to find out why. Several important projects were started:
Why do we need cholesterol anyway?We are all made of cells, and the outer walls (membranes) of all of our cells are made of ... cholesterol! We cannot live without it. In fact, if we eat less of it, our livers make more. What's with all the different types of cholesterol? Good? Bad? Give me a break!So, is there just one kind of cholesterol? Well, the part that is in the cells is the same. But hang onto your hat... When we talk about "cholesterol", we are usually referring to a combination of that molecule piggy-backed (or attached, if you will) to a carrier molecule that takes the cholesterol molecule from place to place in the body. The reason for this is that cholesterol, being a fat, does not mix well with blood, which is mostly water. The carrier molecule has a part that the cholesterol can stick to and a part that mixes well with water. There are a variety of these carriers. For our purposes, we can think just of the "good" cholesterol (cholesterol combined with "high density lipoprotein" or "HDL") and the "bad" cholesterol (cholesterol combined with "low density lipoprotein" or "LDL"). Each of these comes in several forms and there are other forms also. Additionally, the "bad" cholesterol can be small and dense, like a golf ball, or big and fluffy, sort of like a tennis ball. The small dense kind is worse than the big fluffy kind. To summarize, we have "good" cholesterol and "bad" cholesterol, by which we refer to the same cholesterol in cell membranes when it is combined with HDL or LDL. These combinations are called lipoproteins. The "good" HDL is returned to the liver for its cholesterol to be broken down into other molecules. The "bad" LDL travels out to the tissue to deliver cholesterol where it is needed and, as a side effect, to accumulate in the walls of blood vessels which narrows them and clogs them up. The reason this distinction is important is that we know from many studies that people with high levels of LDL have more heart attacks, those with high HDL have fewer, and treatments that lower the LDL do reduce the frequency of heart attacks and other complications of high cholesterol. () Thus, having a high LDL level is associated with an increased risk of coronary heart disease, higher levels are associated with greater risk, and lowering the LDL level even by mechanical means (apheresis) lowers the risk of coronary heart disease. We can accept therefore with good confidence that LDL is a treatable cause of coronary heart disease, and that lowering elevated levels by whatever means is a good thing to do. Why are there so many types of clinical studies?There are lots of types of studies. Some studies keep people locked up in rooms where everything they eat is monitored while others rely on people to eat only what they are given. Both of these types of studies are not common. When studies have tens of thousands of people being studied, they are often asked what they eat and whatever they answer is what goes into the study. This method is much less expensive but obviously not nearly as reliable. Some studies keep going for years to see how long people live and what kinds of diseases they get along the way. These are very expensive and, of course, take years to do. Some are short term and rely on blood tests for "surrogate" endpoints, such as changes in blood pressure, HDL, LDL, etc. () In the discussion below, you will see results based on mortality and morbidity (that is, death and serious illness) when they are available. Most of the time, though, you will see results based on the effect of diet on risk factors such as blood pressure, tendency toward developing diabetes, and lipoprotein levels (HDL and LDL). The obesity epidemic, or So what is wrong with not eating meat?The term "obesity epidemic" refers to the observation that the population in the United States of America and world-wide began to become obese in the late 1970's to early 1980's. This occurred after vigorous public health efforts began in the 1960's to convince people to abandon meat and substitute plant sources of protein. () The problem with obesity is that it causes a number of health problems that can be reversed if the excess weight is lost: diabetes mellitus, hypertension, elevated cholesterol, sleep apnea, and fatty liver disease. It has also been associated with certain cancers and with cognitive dysfunction. And, of course, the risk of heart attack goes up rapidly when one develops diabetes mellitus, hypertension, and elevated cholesterol. We have now set the stage for a discussion of the risks and benefits of eating lean, unprocessed meat such as grass-fed cattle. We have seen that diet is only one part of optimizing the reader's cardiovascular risk profile, that the dictum that "beef is bad for you" is no longer acceptable scientifically, and that there may be advantages to eating a lot of meat if you are overweight and/or have diabetes. (Of course, any medical questions must be discussed with your own physician before you act on anything you read or do not read here.) We have also seen that we have to use "surrogate endpoints" like LDL levels, blood pressure, and blood sugar responses to experimental changes in diet because we simply do not have, and are not likely to get soon, sufficiently large randomized clinical trials of various types of diet with endpoints like total mortality. So now let's look at the key questions. The scientific statements labeled DGA below are taken from the U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015-2020 Dietary Guidelines for Americans. 8th Edition. What is the Healthy Mediterranean-Style Pattern?From DGA page
83: "USDA Food Patterns: Healthy Mediterranean-Style Eating Pattern": The key statement in this official description is:
What is meant by "meat", and what is the difference between processed and unprocessed meat?From the DGA, page 25:"Meat, also known as red meat, includes all forms of beef, pork, lamb, veal, goat, and non-bird game (e.g., venison, bison, and elk). Poultry includes all forms of chicken, turkey, duck, geese, guineas, and game birds (e.g., quail and pheasant)." "Meats and poultry vary in fat content and include both fresh and processed forms." "Lean meats and poultry contain less than 10 g of fat, 4.5 g or less of saturated fats, and less than 95 mg of cholesterol per 100 g and per labeled serving size (e.g., 95% lean ground beef, pork tenderloin, and skinless chicken or turkey breast)." "Processed meats and processed poultry (e.g., sausages, luncheon meats, bacon, and beef jerky) are products preserved by smoking, curing, salting, and/or the addition of chemical preservatives." Is processed meat good or bad for your heart health?From the DGA, page 25: "About Meats & Poultry": "Strong evidence from mostly prospective cohort studies but also randomized controlled trials has shown that eating patterns that include lower intake of meats as well as processed meats and processed poultry are associated with reduced risk of CVD in adults. Moderate evidence indicates that these eating patterns are associated with reduced risk of obesity, type 2 diabetes, and some types of cancer in adults. As described earlier, eating patterns consist of multiple, interacting food components, and the relationships to health exist for the overall eating pattern, not necessarily to an isolated aspect of the diet. Much of this research on eating patterns has grouped together all meats and poultry, regardless of fat content or processing, though some evidence has identified lean meats and lean poultry in healthy eating patterns. The key statements in this official advice are:
From DGA page 57: "About Meats & Poultry": The key statements in this official advice are:
It is important to know something about the substances added to processed meat in the processes of "smoking, curing, salting, and/or the addition of chemical preservatives". Salting of course means adding large quantities of salt. But what do smoking, curing, and chemical preservatives refer to? Nitrites, nitrates, and nitrosamines. And sometimes smoke. A review from 2017 of the hazards of eating red meat comments in detail on the various compounds that are found in both processed and unprocessed meats, and how these are transformed in the cooking process. () And another review article is more clear that the problem is with processed meats, not red (unprocessed) meats: Renata Micha, RD, PhD; Sarah K. Wallace, BA; Dariush Mozaffarian. "Red and Processed Meat Consumption and Risk of Incident Coronary Heart Disease, Stroke, and Diabetes Mellitus A Systematic Review and Meta-Analysis." Circulation. 2010;121:2271-2283."Consumption of processed meats, but not red meats, is associated with higher incidence of CHD and diabetes mellitus. These results highlight the need for better understanding of potential mechanisms of effects and for particular focus on processed meats for dietary and policy recommendations." Is unprocessed meat good or bad for your heart health?From DGA page 25: "About Meats & Poultry": The key statement in this official advice is:
The review discussed in the previous section presented data showing that unprocessed meat is either not a health risk or is only mildly so. Please note the bias revealed by the author against consumption of red meat in the Conclusions of that article. Please press the "click to show details" link to display it. Now, at last, we get to the new experimental data comparing the standard Mediterranean-Style diet to modifications including addition of more protein and especially of lean unprocessed meat. Maki KC, Van Elswyk ME, Alexander DD, et al. "A meta-analysis of randomized controlled trials that compare the lipid effects of beef versus poultry and/or fish consumption." Journal of Clinical Lipidology 6(4):352-61 · July 2012() Changes in the fasting lipid profile were not significantly different with beef consumption compared with those with poultry and/or fish consumption. Inclusion of lean beef in the diet increases the variety of available food choices, which may improve long-term adherence with dietary recommendations for lipid management."In other words, the findings with beef were statistically the same as for poultry and/or fish as measured by improvement in total cholesterol, LDL and HDL cholesterol, and triglycerides. Among the 8 studies analyzed, the blood tests were compared with the measurements made while the patients were eating whatever their usual diet was. Maki KC, Wilcox ML, Dicklin MR et al. "Substituting Lean Beef for Carbohydrate in a Healthy Dietary Pattern Does Not Adversely Affect the Cardiometabolic Risk Factor Profile in Men and Women at Risk for Type 2 Diabetes." The Journal of Nutrition. 2020;00:1-10() "Conclusions: Substituting lean, unprocessed beef for carbohydrate in a Healthy US-Style Eating Pattern resulted in a shift toward larger, more buoyant LDL subfractions, but otherwise had no significant effects on the cardiometabolic risk factor profile in men and women with prediabetes and/or metabolic syndrome. This trial was registered at clinicaltrials.gov as NCT03202680."Compared with a standard healthy diet, substituting lean beef protein for carbohydrate actually improved the lipid profile by shifting the LDL particle size from the small dense size thought to worsen atherogenesis to the "light fluffy" size thought to be less atherogenic, and did not change estimated cardiovascular risk in patients at increased risk for developing coronary artery disease. Thus, in this carefully done study, adding protein to the standard "healthy" diet did not made it less healthy and may have made it more healthy. Lauren E O’Connor, Douglas Paddon-Jones, Amy J Wright, and Wayne W Campbell. "A Mediterranean-style eating pattern with lean, unprocessed red meat has cardiometabolic benefits for adults who are overweight or obese in a randomized, crossover, controlled feeding trial." Am J Clin Nutr 2018;108:33–40.() "In conclusion, adults who are overweight or obese can consume typical US intake quantities of red meat (∼70 g/d) as lean and unprocessed beef and pork when adopting a Mediterranean Pattern to improve cardiometabolic disease risk factors. Our results support previous observational and experimental evidence which shows that unprocessed and/or lean red meat consumption does not increase the risk of developing cardiovascular disease (11) or impair associated risk factors (13)."In other words, the group that ate more red meat had better outcomes than the standard Mediterranean Pattern diet group as measured by total cholesterol and LDL. The other parameters measured did not worsen in the group that ate more red meat. Appel LJ, Sacks FM, VJ Carey, et al. "Effects of Protein, Monounsaturated Fat, and Carbohydrate Intake on Blood Pressure and Serum Lipids. Results of the OmniHeart Randomized Trial" JAMA, November 16, 2005—Vol 294, No. 19 2455-2464.() "Conclusion: In the setting of a healthful diet, partial substitution of carbohydrate with either protein or monounsaturated fat can further lower blood pressure, improve lipid levels, and reduce estimated cardiovascular risk."Compared with a standard healthy diet, substituting protein (half from plants and the rest from chicken and fish, with about the same amount of beef in all three diets) or unsaturated fat for carbohydrate actually improved blood pressure and lipid levels, and reduced estimated cardiovascular risk. Thus, in this carefully done study, adding protein to the standard "healthy" diet actually made it more healthy. O'Connor LE, Kim JE, and WW Campbell. "Total red meat intake of ≥0.5 servings/d does not negatively influence cardiovascular disease risk factors: a systemically searched meta-analysis of randomized controlled trials." Am J Clin Nutr 2017;105:57–69() "Conclusions: The results from this systematically searched meta-analysis of RCTs support the idea that the consumption of ≥0.5 servings of total red meat/d [per day] does not influence blood lipids and lipoproteins or blood pressures."Is there a difference between unprocessed beef from animals fed grain compared with grass-fed cattle?A physician at The Mayo Clinic opined that grass-fed beef may be better. Let's look at some data: () Is there an advantage to Animal Welfare Approved meat? What does that mean, anyway?() There are many other aspects to raising cattle humanely, and there are several third-party organizations that audit and certify operations like ours. Of these, according to Consumer Reports, the best is A Greener World. We were certified by them in 2018 and elected to terminate our certification in 2020 because they do not allow kosher slaughter, which we feel is humane. We continue to operate our farm exactly as we did while we were under their certification. Is there an advantage to certified organic meat? What does that mean, anyway?The National Organic Program is a legal standard of the government of the United States of America. It regulates use of the term Certified Organic for all products that can carry that label. The standards are complex in detail but basically very simple: certified products may not come in contact in any way with any forbidden substances, and pretty much all synthetic substances are forbidden. For crops, this means no pesticides, no synthetic fertilizers, no hormones, no use of genetically modified seed, and so forth. For livestock, this means no antibiotics, no hormones, no growth stimulants, and no food that is not itself certified organic. It also means that animal byproducts are never used. How important are these standards? Opinions of course vary, but we suggest consideration of residues of antibiotics and of pesticides. () If I eat certified organic, certified grass-fed beef, will I lose weight? Become healthy, wealthy, and wise?
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