There is an incredible amount of misinformation and misunderstanding in both the general public and the mainstream medical establishment regarding the role that red meat, fat, and cholesterol play in the development of cardiovascular disease. Medical dogma has been espousing the evils of red meat, fat, and dietary cholesterol for decades, but the latest scientific research is showing that the truth is not as simple as it was previously made out to be. There is very scanty evidence to support the claims that red meat, fat, and cholesterol cause cardiovascular disease, and even evidence drawing correlations is fairly weak. Here, I take a look at the most modern and up-to-date research regarding the role that diet plays in the development of cardiovascular disease, and discuss what the latest science says about the real contributing factors to heart disease. I will conclude with information on dietary recommendations for reducing one’s risk of developing cardiovascular disease.
Fat Phobia, the Diet-Heart Hypothesis, and the Makings of Medical Dogma
Since the mid-20th century, there developed a hypothesis (disseminated largely by Ancel Keys[i]) that a diet including red meat, saturated fat, and dietary cholesterol (essentially any animal food) promoted the development of atherosclerosis, hyperlipidemia, and increased the risk of heart attack. This hypothesis was based on four founding tenets: 1) dietary cholesterol is the main contributor to serum (blood) cholesterol levels; 2) high serum cholesterol is the main cause of arterial plaque build up, atherosclerosis, and clogged arteries; 3) saturated fat causes obesity and heart disease; 4) red meat and other animal products are high in saturated fat and cholesterol, therefore they cause heart disease.
As is discussed at length by Dr. Peter Attia[ii], from the beginning of the movement to link diet to risk of cardiovascular disease, the studies have been poorly designed and the evidence has been poorly interpreted by doctors, governments, and the media. What first began as a genuine scientific concern to figure out how to prevent the development of disease in the American public ended up becoming an exercise in how to legislate pseudoscience. Diet is certainly a significant contributor to the development of cardiovascular disease, however the dietary guidelines laid out by mainstream institutions such as the American Medical Association, the American Heart Association, and the U.S. Department of Agriculture pushed since the 1960’s have led to a precipitous rise in obesity and an exponential increase in type 2 diabetes[iii], both of which are risk factors for developing cardiovascular disease. Deaths from cardiovascular disease have declined since the late 1960’s, but this may largely be due to improvements in medical interventions (like heart surgeries) and reduced rates of smoking[iv]. It is, however, clear that the low-fat/high-carbohydrate diet promoted by the mainstream medical establishment has significantly contributed to the obesity and diabetes epidemics that plague us today. Since the 1960’s, consumption of fat and animal products has declined, yet carbohydrate consumption has increased dramatically, as well as total calorie intake (largely from carbohydrates)[v]. If the low-fat/high-carb diet works so well at preventing heart disease, obesity, and diabetes as the mainstream medical establishment would have us believe, then how is it that heart disease is still the leading cause of death in the U.S.? And why is it that many people who are put on low-fat/high-carb/low-cholesterol diets in order to lose weight, prevent or treat diabetes, and reduce their risk of cardiovascular disease often end up gaining weight, developing diabetes, and getting heart disease anyway?
Cholesterol
It has become an irrefutable conventional truth that a diet high in cholesterol causes heart disease. But that hypothesis is based on two unproven concepts: 1) increased dietary cholesterol leads to increased serum cholesterol; 2) serum cholesterol levels are directly correlated to rates of cardiovascular disease. Firstly, multiple studies in the last decade have shown that neither dietary cholesterol nor saturated fat intake have anything to do with serum cholesterol levels in at least 75% of Americans[vi]. In other words, studies have shown that eating foods high in cholesterol and/or saturated fat do not have either a causative or corollary relationship with the amount of cholesterol in the blood. This is because, on average, about 75% of the cholesterol in our bodies is made by endogenous production, that is, our body makes it in the liver and other tissues. About 25% of our bodily cholesterol comes from our food, and if we reduce our dietary intake of it, our body increases endogenous production to make up for the lack of ingestion[vii]. So foods that are said to trap dietary cholesterol in order to reduce their absorption into the blood (like plant fibers, especially of whole grains) are actually unimportant for the majority of people in regulation of serum cholesterol levels. Plant fibers are important to include in the diet, but for other reasons unrelated to cholesterol uptake, such as serving as prebiotic fodder for probiotic gut bacteria to ferment upon.
The body works very hard to ensure there is enough cholesterol in circulation because it is absolutely critical to the healthy functioning of many of our bodily processes and the integrity of our tissues. We need cholesterol to make many of our hormones and neurotransmitters, they are a critical part of the lipid membranes of all of our cells, and it makes up about 70% of the myelination of the neurons in our brains[i]. Low serum cholesterol is linked with increased risk of developing neurological disorders such as Parkinson’s disease, dementia, and Alzheimer’s, and an increase in overall risk of death[ii]. Cholesterol is also extremely important for proper neurological development in growing fetuses and children. The human body cannot survive without cholesterol, and to deprive it of such causes disease.
Secondly, serum cholesterol is not related to the development of heart disease in most people. A meta-review of studies does not shown any clear correlation between serum cholesterol levels and cardiovascular disease. There are four important statistics in the assessment of one’s “blood cholesterol”: low-density lipoprotein cholesterol (LDL-C), LDL particle number, high-density lipoprotein cholesterol (HDL-C), and HDL particle number. The most important of these measure to be aware of is the LDL particle number. This is because it’s the number of lipoproteins that ferry the cholesterol around that is actually indicative of one’s risk for developing heart disease, not the amount of cholesterol being ferried by these molecules. Higher numbers of LDL particles in the blood stream (regardless of whether they are ferrying cholesterol or something else, like fat) crowd and bump into each other and the endothelial linings of arteries, causing vessel damage and depositing cholesterol inside the vessel walls, forming the plaque that narrows vessels and eventually can clog arteries.
There are a number of causes for higher LDL particle numbers including metabolic syndrome (where the body uses an increasing number of LDL particles to ferry all of the fat that is created by the liver as a result of overconsumption of carbohydrates), hypothyroidism, infection (LDL particles are antimicrobial and are used to deactivate pathogens), leaky gut syndrome, and rare genetic mutations[iii]. The most common cause of elevated LDL particles is an inflammatory diet high in oxidized fats (which damage the endothelial linings of vessels through oxidation) and carbohydrates (particularly sugar); in other words, the Standard American Diet.
The Dangers of Statins
Statins are a class of pharmaceutical drug aimed at lowering serum cholesterol levels in the hopes that this will reduce an individual’s risk of heart disease. As it turns out, statins are not only completely ineffective for 96% of people studied, but they have huge side effect profiles that can predispose one to diabetes, muscle damage, cognitive decline, heart weakness, and heart failure[iv]. Statins work by inhibiting an enzyme that is involved in the conversion of acetyl-CoA into cholesterol. The problem is that there are other molecules essential to human health that are the products of this conversion cascade alongside cholesterol, namely coenzyme-Q-10 (CoQ10). CoQ10 is a vitally important molecule involved in cellular energy production, and without proper levels of it, cells (those with mitochondria) in many tissues of the body begin to suffer, most especially muscle cells. The heart is a muscle. Evidence has shown that statins weaken the heart muscle, which can increase one’s risk of heart failure[v]. By reducing the availability of cholesterol to brain cells, myelination of neurons can become damaged, resulting in cognitive impairment. Statins are very effective at lowering serum cholesterol levels, but as we’ve discussed, high serum cholesterol is not a significant contributor to heart disease. In some studies there was a very small benefit (2.6%) to those taking statins who had already had a heart attack[vi], but this is likely due to the reduction of the metabolite called mevalonate which makes endothelial smooth muscle cells more active and allows for the release of thromboxane which platelets use to form clots[vii]. A meta-analysis of studies has shown that statins provide almost no benefit to any other population besides males who have already had a heart attack[viii].
Red Meat
In the mid-20th century, all animal products were demonized as being major contributing factors to the diseases of modernity, especially heart disease and cancer; none more so than red meat. Eating red meat, which is high in saturated fat and cholesterol, was found in early epidemiological studies, like the China Study, to be correlated with increased rates of heart disease and cancer. But a reinterpretation of the data and more modern scientific research have shown there to be no clear correlation between any disease and meat eating[ix]. Humans have been eating meat since before our speciation, at least 1.3 million years ago, and many traditional human cultures throughout the world continue to eat diets heavy in animal products, especially meat, with few or no occurrences of the diseases of modernity that plague us today[x]. High quality red meat is one of the most nutrient-dense foods humans can consume, and contains many essential vitamins and minerals that we simply can’t live without. There are several observational studies that have linked red meat consumption with the development of heart disease in American populations, however this is most likely due to the fact that in the post-WWII time period, our modern culture has labeled red meat as “unhealthy”, so those who abstain from red meat may be engaging in other behaviors beneficial to one’s health, like eating enough vegetables and exercising regularly. Likewise, those who eat red meat (now that it is considered “unhealthy” by our culture) may engage in other unhealthy behaviors, such as smoking, drinking alcohol, and eating processed foods and sugar, all of which significantly increase one’s risk of heart disease.
Since saturated fat and cholesterol have been exonerated in recent scientific studies as potential causes of disease[xi], some scientists have searched for other possible reasons red meat might be correlated with modern diseases. One study found that an inflammatory metabolite of l-carnatine in red meat, called TMAO, contributed to the development of atherosclerosis[xii]. There is an association between an individual’s production of TMAO with certain kinds of bacteria that inhabit one’s gut microbiome, specifically Prevotella. However, Prevotella is more common in the guts of people who eat high carbohydrate diets, especially grains, than those who eat a lot of red meat, and in one sample Paleo dieter (who eats no grains but lots of red meat) there were no Prevotella and thus no TMAO production. Furthermore, there is a very weak link between the production of TMAO and atherosclerosis[xiii]. In fact, seafood, not red meat, is the type of food that results in the most TMAO production, yet seafood is considered one of the healthiest and most cardioprotective foods[xiv]. Thus, there is little evidence to suggest that fresh red meat (or saturated fat, or cholesterol) is harmful to the cardiovascular system on its own.
Although consumption of fresh red meat is not linked with development of disease, some studies have linked intake of processed meats (those that are cured and have added preservatives to them) with development of colon cancer and heart disease[i]. One study found that when red meat is consumed with oxidized vegetable oils (safflower oil), those that are so common in American cooking, the heme iron in the meat creates lipid peroxyl radicals that can damage and mutate DNA, causing colon cancer[ii]. The formation of lipid peroxyl radicals is not a problem in unprocessed oils that have not been oxidized because fresh-pressed, unrefined oils contain multiple antioxidant mechanisms that scavenge the radicals. This is further reason to avoid processed vegetable oils, and shows that red meat is not the culprit in causing disease unless there is a compounding factor from an unhealthy modern lifestyle, like consumption of rancid oils or sugar. In addition, eating charred or grill-blackened meats is linked with development of atherosclerosis due to the creation of advanced glycation end products that damage the linings of blood vessels[iii].
Inflammation and Sugar: The Real Causes of Heart Disease
Inflammation is now understood to be a major contributing factor to the development of atherosclerosis. Inflammation can be caused by a number of different variables including smoking, exposure to environmental toxins and pollution, infection, stress, and an unhealthy diet. Sugar consumption in particular is very harmful to cardiovascular health. Modern research has shown refined sugar to be an inflammatory substance, especially to the endothelial cells of the blood vessels. A meta-analysis of multiple studies showed a significant association between consumption of sugar (primarily from sugary drinks) and development of heart disease[xv]. Even the American Heart Association (which is always behind on the latest research) has recognized the significant impact that sugar has on the cardiovascular system![xvi] In addition, blood sugar disregulation and metabolic syndrome significantly increases one’s risk of developing heart disease[xvii].
A diet high in sugar and carbohydrates causes the liver to convert excess carbohydrates into lipids in order to store that energy in the body fat. Excess carbohydrate intake is the major cause of weight gain, not fat intake. An increased rate of conversion of sugar to fat will likewise increase the amount of fat moving through the blood vessels (called blood lipids or triglycerides) from the liver to the adipose tissue. Higher blood triglycerides are associated with an increased risk of heart disease[xviii]. Furthermore, the more sugar that travels through the blood vessels, the more it begins to glycate their endothelial linings. Glycation of endothelial cells in arteries starts an inflammatory cascade that results in oxidation and tissue damage in the vessels, which leads to the development of arterial plaques that scarify and narrow the vessels. Vessels narrowed by plaques are at greater risk of getting clogged by materials moving through the blood, such as triglycerides or LDL particles, which can cause heart attacks (if plaques block arteries close to the heart) or blockages that damage circulation.
Glycation of endothelial cells can begin in as little time as a week in a hyperglycemic environment[xix]. Prolonged hyperglycemia, as in the case of metabolic syndrome or diabetes, begins to glycate endothelial vessels to the point that blood flow in the highly vascularized tissues of the body becomes damaged, such as in the kidneys, eyes, and capillaries of the toes and fingers. Eventually the nerves become glycated and can cause diabetic neuropathy. Reduced blood flow to these areas causes tissue death and increased susceptibility to infection. Sometimes tissue infections become so intractable in uncontrolled diabetes that limbs must be amputated. Hyperglycemia caused by excessive carbohydrate intake (in the case of type 2 diabetes) is extremely dangerous due to its tissue damaging effects and its ability to cause atherosclerosis. But hyperglycemia and endothelial glycation can happen even without being diagnosed with diabetes or a metabolic disease. Thus, it is my view that those who are concerned about developing atherosclerosis should control their carbohydrate intake and keep a sharp eye on their hemoglobin A1c, which is the measure of how much glycation is happening to the hemoglobin protein in the blood (and thus may be indicative of glycation in the vessels at large).
In addition to sugar, refined and oxidized vegetable oils such as soy, corn, industrial sunflower seed, safflower, canola, and low-quality olive oil cause inflammation in the gut and blood vessels that further contribute to endothelial oxidation and vessel damage, which contribute to atherosclerosis[xx]. Together, rancid refined vegetable oils and sugar are a deadly combination for the cardiovascular system, and yet the Standard American Diet is laden with them.
Dietary Recommendations for Heart Disease
Now that we understand that dietary cholesterol, saturated fat, and red meat are not harmful to cardiovascular health in general, what is it that makes up a healthy diet for those that want to prevent or reverse cardiovascular disease? As discussed, excessive carbohydrate intake is a key ingredient in the development of atherosclerosis, as is the ingestion of inflammatory foods such as rancid vegetable oils. In 2008, a two-year trial compared the effects of a low-fat versus a low-carb versus a Mediterranean diet on various measures of cardiovascular health, blood sugar control, and inflammation in 322 obese individuals. The low-carb diet (based on the Atkins diet) reduced body weight, blood triglycerides, C-reactive protein (a measure of systemic inflammation), hemoglobin A1c, and the ratio of total cholesterol to HDL the most out of all three diets, with the Mediterranean diet coming in second. The low fat diet (based on American Heart Association guidelines) was the least beneficial in all measures compared to the others[xxi]. Based on what we’ve learned from this and similar studies we can conclude that for those with diabetes, obesity, and/or a high risk of developing heart disease, a low-carb diet is likely the healthiest choice.
In particular, a heart-healthy diet may have the following characteristics: be low in carbohydrates of all kinds (even from whole grains), ideally less than 100g per day, depending on the severity of disease markers; completely free from sodas and sugar/refined sweeteners; free from refined vegetable oils and trans fats; free from charred/grilled and processed meats; be high in healthy fats such as unrefined coconut oil, grass-fed butter, fats from grass-fed animals, real cold-pressed unrefined extra-virgin olive oil; include plenty of high-quality meats, eggs, and milk from grass-fed and/or pastured animals; include plenty of seafood and fatty fish; include plenty of fresh vegetables, especially those with dark or vibrant colors and lots of fiber; include a moderate amount of fruits (which should be factored into total daily carbohydrate intake); and plenty of nuts, seeds, and legumes. Some experts have posited that wheat has several negative influences on cardiovascular health, and that a truly heart-healthy diet must be wheat- or gluten-free. Cardiologist Dr. William Davis suspects that for certain people, atherosclerosis may be induced by an autoimmune mechanism triggered by ingestion of wheat, and that dysbiosis can lead to hyperlipidemia[xxiii].
There are several specific foods and supplements that may enhance the effectiveness of a heart-healthy diet. It is a good idea for those with heart disease or at risk of developing heart disease to increase the diet’s ratio of omega-3 fatty acids to omega-6’s by taking a high-quality, sustainably-harvested fish oil supplement, in addition to eating grass-fed animal products and fatty fish high in omega-3’s. Seeds high in omega-3 fats such as flax and chia (when soaked raw and blended) can be added to smoothies or cold drinks. In addition, eating fermented vegetables or probiotic dairy products (e.g. yogurt, kefir) may be helpful in correcting any underlying dysbiosis that may be contributing to inflammation and cardiovascular disease. In order to support blood vessel integrity and reduce oxidation, it is very important to eat plenty of low-carb, high-fiber berries that are high in anthocyanins, like blueberries, billberries, cranberries, black currants, raspberries, blackberries, and goji berries. A simple and powerful herbal remedy for improving and protecting blood vessel integrity and heart health is the hawthorn berry. This can be made into jams, tinctures, decoctions, or powdered and added to foods or put into capsules.
Conclusion
In conclusion, there is a significant amount of misinformation and outdated science that one has to wade through in the search for what dietary factors help or hurt cardiovascular health. We now know that inflammation via excessive carbohydrate intake is a much more significant contributor to the development of cardiovascular disease than the oft-maligned trinity of cholesterol, saturated fat, and red meat. Diets that focus on eating whole foods, especially with lots of vegetables and certain fruits, high-quality meats and seafood, and enough high-quality saturated fats are the foundation of a heart-healthy lifestyle. Of course, regular exercise and reduction of risk factors such as smoking and exposure to environmental toxins are also important facets of a healthy lifestyle. Overall, cardiovascular disease (and its related afflictions, diabetes and obesity) are consequences of the modern lifestyle, and by returning to the dietary and lifestyle traditions of our ancestors, we can live longer, healthier lives.
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[i] Keys, Ancel. “The Seven Countries Study”. <http://sevencountriesstudy.com/about-the-study>
[ii] Attia, Peter. “The limits of scientific evidence and the ethics of dietary guidelines: sixty years of ambiguity”. University of California at San Diego, Medical School. San Diego, CA. June 20, 2012. Lecture. <https://vimeo.com/45485034>
[iii] Ibid.
[iv] Unal, Belgin, Julia Alison Critchley, and Simon Capewell. "Explaining the decline in coronary heart disease mortality in England and Wales between 1981 and 2000." Circulation 109.9 (2004): 1101-1107.
[v] Attia, Peter. 2012.
[vi] Kresser, Chris. The Diet-Heart Myth. 2012.
[vii] Attia, Peter. “The straight dope of cholesterol – Part I”. April 25, 2012. <http://eatingacademy.com/nutrition/the-straight-dope-on-cholesterol-part-i>
[i] Björkhem, Ingemar, and Steve Meaney. "Brain cholesterol: long secret life behind a barrier." Arteriosclerosis, thrombosis, and vascular biology 24.5 (2004): 806-815.
[ii] Kresser, Chris. 2012.
[iii] Ibid.
[iv] Ibid.
[v] Enig, Mary; Fallon, Sally. “Dangers of Statin Drugs: What You Haven’t Been Told About Popular Cholesterol-Lowering Medicines”. The Weston A. Price Foundation. June 14, 2004. <http://www.westonaprice.org/modern-diseases/dangers-of-statin-drugs-what-you-havent-been-told-about-popular-cholesterol-lowering-medicines/>
[vi] Kresser, Chris. 2012.
[vii] Enig, Mary, et al. 2004.
[viii] Kresser, Chris. 2012.
[ix] Minger, Denise. “One year later: the China Study, Revisited and Re-Bashed”. 2011. <http://rawfoodsos.com/2011/07/31/one-year-later-the-china-study-revisited-and-re-bashed/>
[x] Price, Weston A. Nutrition and physical degeneration. Price-Pottenger Nutrition Foundation, 2003.
[xi] Bittman, Mark. "Butter is back." The New York Times (2014).
[xii] Koeth, Robert A., et al. "Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis." Nature medicine 19.5 (2013): 576-585.
[xiii] Leach, Jeff. “From Meat to Microbes to Main street: is it time to trade in your George Foreman Grill?”. Human Food Project: Anthropology of Microbes. April 15, 2003.
[xiv] Kresser, Chris. “RHR: Heart Attacks and Red Meat—Correlation or Causation?” Revolution Health Radio. December 18, 2014. <http://chriskresser.com/heart-attacks-and-red-meat-correlation-or-causation>
[i] Geddes, Linda. “What’s the beef?”. New Scientist. January 24-30, 2015: 30-35. Print.
[ii] Sawa, Tomohiro, et al. "Lipid peroxyl radicals from oxidized oils and heme-iron: implication of a high-fat diet in colon carcinogenesis." Cancer Epidemiology Biomarkers & Prevention 7.11 (1998): 1007-1012.
[iii] Goldin, Alison, et al. "Advanced glycation end products sparking the development of diabetic vascular injury." Circulation 114.6 (2006): 597-605.
[xv] Huang, Chen, et al. "Sugar sweetened beverages consumption and risk of coronary heart disease: a meta-analysis of prospective studies." Atherosclerosis 234.1 (2014): 11-16.
[xvi] American Heart Association. “Added Sugars Add to Your Risk of Dying from Heart Disease”. December 2, 2014. <http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/Added-Sugars-Add-to-Your-Risk-of-Dying-from-Heart-Disease_UCM_460319_Article.jsp>
[xvii] Malik, Shaista, et al. "Impact of the metabolic syndrome on mortality from coronary heart disease, cardiovascular disease, and all causes in United States adults." Circulation 110.10 (2004): 1245-1250.
[xviii] Corliss, Julie. “Eating too much added sugar increases the risk of dying with heart disease”. Harvard Health Blog. February 6, 2014. <http://www.health.harvard.edu/blog/eating-too-much-added-sugar-increases-the-risk-of-dying-with-heart-disease-201402067021>
[xix] Goldin, Alison, et al. "Advanced glycation end products sparking the development of diabetic vascular injury." Circulation 114.6 (2006): 597-605.
[xx] Fallon, Sally; Enig, Mary. “The Skinny on Fats”. The Weston A. Price Foundation. January 1, 2000. <http://www.westonaprice.org/health-topics/the-skinny-on-fats/>
[xxi] Shai, Iris, et al. "Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet." New England Journal of Medicine 359.3 (2008): 229-241.
[xxiii] Davis, William. “Wheat and Heart Disease”. The Gluten Summit. November 2013. Webinar.
Since the mid-20th century, there developed a hypothesis (disseminated largely by Ancel Keys[i]) that a diet including red meat, saturated fat, and dietary cholesterol (essentially any animal food) promoted the development of atherosclerosis, hyperlipidemia, and increased the risk of heart attack. This hypothesis was based on four founding tenets: 1) dietary cholesterol is the main contributor to serum (blood) cholesterol levels; 2) high serum cholesterol is the main cause of arterial plaque build up, atherosclerosis, and clogged arteries; 3) saturated fat causes obesity and heart disease; 4) red meat and other animal products are high in saturated fat and cholesterol, therefore they cause heart disease.
As is discussed at length by Dr. Peter Attia[ii], from the beginning of the movement to link diet to risk of cardiovascular disease, the studies have been poorly designed and the evidence has been poorly interpreted by doctors, governments, and the media. What first began as a genuine scientific concern to figure out how to prevent the development of disease in the American public ended up becoming an exercise in how to legislate pseudoscience. Diet is certainly a significant contributor to the development of cardiovascular disease, however the dietary guidelines laid out by mainstream institutions such as the American Medical Association, the American Heart Association, and the U.S. Department of Agriculture pushed since the 1960’s have led to a precipitous rise in obesity and an exponential increase in type 2 diabetes[iii], both of which are risk factors for developing cardiovascular disease. Deaths from cardiovascular disease have declined since the late 1960’s, but this may largely be due to improvements in medical interventions (like heart surgeries) and reduced rates of smoking[iv]. It is, however, clear that the low-fat/high-carbohydrate diet promoted by the mainstream medical establishment has significantly contributed to the obesity and diabetes epidemics that plague us today. Since the 1960’s, consumption of fat and animal products has declined, yet carbohydrate consumption has increased dramatically, as well as total calorie intake (largely from carbohydrates)[v]. If the low-fat/high-carb diet works so well at preventing heart disease, obesity, and diabetes as the mainstream medical establishment would have us believe, then how is it that heart disease is still the leading cause of death in the U.S.? And why is it that many people who are put on low-fat/high-carb/low-cholesterol diets in order to lose weight, prevent or treat diabetes, and reduce their risk of cardiovascular disease often end up gaining weight, developing diabetes, and getting heart disease anyway?
Cholesterol
It has become an irrefutable conventional truth that a diet high in cholesterol causes heart disease. But that hypothesis is based on two unproven concepts: 1) increased dietary cholesterol leads to increased serum cholesterol; 2) serum cholesterol levels are directly correlated to rates of cardiovascular disease. Firstly, multiple studies in the last decade have shown that neither dietary cholesterol nor saturated fat intake have anything to do with serum cholesterol levels in at least 75% of Americans[vi]. In other words, studies have shown that eating foods high in cholesterol and/or saturated fat do not have either a causative or corollary relationship with the amount of cholesterol in the blood. This is because, on average, about 75% of the cholesterol in our bodies is made by endogenous production, that is, our body makes it in the liver and other tissues. About 25% of our bodily cholesterol comes from our food, and if we reduce our dietary intake of it, our body increases endogenous production to make up for the lack of ingestion[vii]. So foods that are said to trap dietary cholesterol in order to reduce their absorption into the blood (like plant fibers, especially of whole grains) are actually unimportant for the majority of people in regulation of serum cholesterol levels. Plant fibers are important to include in the diet, but for other reasons unrelated to cholesterol uptake, such as serving as prebiotic fodder for probiotic gut bacteria to ferment upon.
The body works very hard to ensure there is enough cholesterol in circulation because it is absolutely critical to the healthy functioning of many of our bodily processes and the integrity of our tissues. We need cholesterol to make many of our hormones and neurotransmitters, they are a critical part of the lipid membranes of all of our cells, and it makes up about 70% of the myelination of the neurons in our brains[i]. Low serum cholesterol is linked with increased risk of developing neurological disorders such as Parkinson’s disease, dementia, and Alzheimer’s, and an increase in overall risk of death[ii]. Cholesterol is also extremely important for proper neurological development in growing fetuses and children. The human body cannot survive without cholesterol, and to deprive it of such causes disease.
Secondly, serum cholesterol is not related to the development of heart disease in most people. A meta-review of studies does not shown any clear correlation between serum cholesterol levels and cardiovascular disease. There are four important statistics in the assessment of one’s “blood cholesterol”: low-density lipoprotein cholesterol (LDL-C), LDL particle number, high-density lipoprotein cholesterol (HDL-C), and HDL particle number. The most important of these measure to be aware of is the LDL particle number. This is because it’s the number of lipoproteins that ferry the cholesterol around that is actually indicative of one’s risk for developing heart disease, not the amount of cholesterol being ferried by these molecules. Higher numbers of LDL particles in the blood stream (regardless of whether they are ferrying cholesterol or something else, like fat) crowd and bump into each other and the endothelial linings of arteries, causing vessel damage and depositing cholesterol inside the vessel walls, forming the plaque that narrows vessels and eventually can clog arteries.
There are a number of causes for higher LDL particle numbers including metabolic syndrome (where the body uses an increasing number of LDL particles to ferry all of the fat that is created by the liver as a result of overconsumption of carbohydrates), hypothyroidism, infection (LDL particles are antimicrobial and are used to deactivate pathogens), leaky gut syndrome, and rare genetic mutations[iii]. The most common cause of elevated LDL particles is an inflammatory diet high in oxidized fats (which damage the endothelial linings of vessels through oxidation) and carbohydrates (particularly sugar); in other words, the Standard American Diet.
The Dangers of Statins
Statins are a class of pharmaceutical drug aimed at lowering serum cholesterol levels in the hopes that this will reduce an individual’s risk of heart disease. As it turns out, statins are not only completely ineffective for 96% of people studied, but they have huge side effect profiles that can predispose one to diabetes, muscle damage, cognitive decline, heart weakness, and heart failure[iv]. Statins work by inhibiting an enzyme that is involved in the conversion of acetyl-CoA into cholesterol. The problem is that there are other molecules essential to human health that are the products of this conversion cascade alongside cholesterol, namely coenzyme-Q-10 (CoQ10). CoQ10 is a vitally important molecule involved in cellular energy production, and without proper levels of it, cells (those with mitochondria) in many tissues of the body begin to suffer, most especially muscle cells. The heart is a muscle. Evidence has shown that statins weaken the heart muscle, which can increase one’s risk of heart failure[v]. By reducing the availability of cholesterol to brain cells, myelination of neurons can become damaged, resulting in cognitive impairment. Statins are very effective at lowering serum cholesterol levels, but as we’ve discussed, high serum cholesterol is not a significant contributor to heart disease. In some studies there was a very small benefit (2.6%) to those taking statins who had already had a heart attack[vi], but this is likely due to the reduction of the metabolite called mevalonate which makes endothelial smooth muscle cells more active and allows for the release of thromboxane which platelets use to form clots[vii]. A meta-analysis of studies has shown that statins provide almost no benefit to any other population besides males who have already had a heart attack[viii].
Red Meat
In the mid-20th century, all animal products were demonized as being major contributing factors to the diseases of modernity, especially heart disease and cancer; none more so than red meat. Eating red meat, which is high in saturated fat and cholesterol, was found in early epidemiological studies, like the China Study, to be correlated with increased rates of heart disease and cancer. But a reinterpretation of the data and more modern scientific research have shown there to be no clear correlation between any disease and meat eating[ix]. Humans have been eating meat since before our speciation, at least 1.3 million years ago, and many traditional human cultures throughout the world continue to eat diets heavy in animal products, especially meat, with few or no occurrences of the diseases of modernity that plague us today[x]. High quality red meat is one of the most nutrient-dense foods humans can consume, and contains many essential vitamins and minerals that we simply can’t live without. There are several observational studies that have linked red meat consumption with the development of heart disease in American populations, however this is most likely due to the fact that in the post-WWII time period, our modern culture has labeled red meat as “unhealthy”, so those who abstain from red meat may be engaging in other behaviors beneficial to one’s health, like eating enough vegetables and exercising regularly. Likewise, those who eat red meat (now that it is considered “unhealthy” by our culture) may engage in other unhealthy behaviors, such as smoking, drinking alcohol, and eating processed foods and sugar, all of which significantly increase one’s risk of heart disease.
Since saturated fat and cholesterol have been exonerated in recent scientific studies as potential causes of disease[xi], some scientists have searched for other possible reasons red meat might be correlated with modern diseases. One study found that an inflammatory metabolite of l-carnatine in red meat, called TMAO, contributed to the development of atherosclerosis[xii]. There is an association between an individual’s production of TMAO with certain kinds of bacteria that inhabit one’s gut microbiome, specifically Prevotella. However, Prevotella is more common in the guts of people who eat high carbohydrate diets, especially grains, than those who eat a lot of red meat, and in one sample Paleo dieter (who eats no grains but lots of red meat) there were no Prevotella and thus no TMAO production. Furthermore, there is a very weak link between the production of TMAO and atherosclerosis[xiii]. In fact, seafood, not red meat, is the type of food that results in the most TMAO production, yet seafood is considered one of the healthiest and most cardioprotective foods[xiv]. Thus, there is little evidence to suggest that fresh red meat (or saturated fat, or cholesterol) is harmful to the cardiovascular system on its own.
Although consumption of fresh red meat is not linked with development of disease, some studies have linked intake of processed meats (those that are cured and have added preservatives to them) with development of colon cancer and heart disease[i]. One study found that when red meat is consumed with oxidized vegetable oils (safflower oil), those that are so common in American cooking, the heme iron in the meat creates lipid peroxyl radicals that can damage and mutate DNA, causing colon cancer[ii]. The formation of lipid peroxyl radicals is not a problem in unprocessed oils that have not been oxidized because fresh-pressed, unrefined oils contain multiple antioxidant mechanisms that scavenge the radicals. This is further reason to avoid processed vegetable oils, and shows that red meat is not the culprit in causing disease unless there is a compounding factor from an unhealthy modern lifestyle, like consumption of rancid oils or sugar. In addition, eating charred or grill-blackened meats is linked with development of atherosclerosis due to the creation of advanced glycation end products that damage the linings of blood vessels[iii].
Inflammation and Sugar: The Real Causes of Heart Disease
Inflammation is now understood to be a major contributing factor to the development of atherosclerosis. Inflammation can be caused by a number of different variables including smoking, exposure to environmental toxins and pollution, infection, stress, and an unhealthy diet. Sugar consumption in particular is very harmful to cardiovascular health. Modern research has shown refined sugar to be an inflammatory substance, especially to the endothelial cells of the blood vessels. A meta-analysis of multiple studies showed a significant association between consumption of sugar (primarily from sugary drinks) and development of heart disease[xv]. Even the American Heart Association (which is always behind on the latest research) has recognized the significant impact that sugar has on the cardiovascular system![xvi] In addition, blood sugar disregulation and metabolic syndrome significantly increases one’s risk of developing heart disease[xvii].
A diet high in sugar and carbohydrates causes the liver to convert excess carbohydrates into lipids in order to store that energy in the body fat. Excess carbohydrate intake is the major cause of weight gain, not fat intake. An increased rate of conversion of sugar to fat will likewise increase the amount of fat moving through the blood vessels (called blood lipids or triglycerides) from the liver to the adipose tissue. Higher blood triglycerides are associated with an increased risk of heart disease[xviii]. Furthermore, the more sugar that travels through the blood vessels, the more it begins to glycate their endothelial linings. Glycation of endothelial cells in arteries starts an inflammatory cascade that results in oxidation and tissue damage in the vessels, which leads to the development of arterial plaques that scarify and narrow the vessels. Vessels narrowed by plaques are at greater risk of getting clogged by materials moving through the blood, such as triglycerides or LDL particles, which can cause heart attacks (if plaques block arteries close to the heart) or blockages that damage circulation.
Glycation of endothelial cells can begin in as little time as a week in a hyperglycemic environment[xix]. Prolonged hyperglycemia, as in the case of metabolic syndrome or diabetes, begins to glycate endothelial vessels to the point that blood flow in the highly vascularized tissues of the body becomes damaged, such as in the kidneys, eyes, and capillaries of the toes and fingers. Eventually the nerves become glycated and can cause diabetic neuropathy. Reduced blood flow to these areas causes tissue death and increased susceptibility to infection. Sometimes tissue infections become so intractable in uncontrolled diabetes that limbs must be amputated. Hyperglycemia caused by excessive carbohydrate intake (in the case of type 2 diabetes) is extremely dangerous due to its tissue damaging effects and its ability to cause atherosclerosis. But hyperglycemia and endothelial glycation can happen even without being diagnosed with diabetes or a metabolic disease. Thus, it is my view that those who are concerned about developing atherosclerosis should control their carbohydrate intake and keep a sharp eye on their hemoglobin A1c, which is the measure of how much glycation is happening to the hemoglobin protein in the blood (and thus may be indicative of glycation in the vessels at large).
In addition to sugar, refined and oxidized vegetable oils such as soy, corn, industrial sunflower seed, safflower, canola, and low-quality olive oil cause inflammation in the gut and blood vessels that further contribute to endothelial oxidation and vessel damage, which contribute to atherosclerosis[xx]. Together, rancid refined vegetable oils and sugar are a deadly combination for the cardiovascular system, and yet the Standard American Diet is laden with them.
Dietary Recommendations for Heart Disease
Now that we understand that dietary cholesterol, saturated fat, and red meat are not harmful to cardiovascular health in general, what is it that makes up a healthy diet for those that want to prevent or reverse cardiovascular disease? As discussed, excessive carbohydrate intake is a key ingredient in the development of atherosclerosis, as is the ingestion of inflammatory foods such as rancid vegetable oils. In 2008, a two-year trial compared the effects of a low-fat versus a low-carb versus a Mediterranean diet on various measures of cardiovascular health, blood sugar control, and inflammation in 322 obese individuals. The low-carb diet (based on the Atkins diet) reduced body weight, blood triglycerides, C-reactive protein (a measure of systemic inflammation), hemoglobin A1c, and the ratio of total cholesterol to HDL the most out of all three diets, with the Mediterranean diet coming in second. The low fat diet (based on American Heart Association guidelines) was the least beneficial in all measures compared to the others[xxi]. Based on what we’ve learned from this and similar studies we can conclude that for those with diabetes, obesity, and/or a high risk of developing heart disease, a low-carb diet is likely the healthiest choice.
In particular, a heart-healthy diet may have the following characteristics: be low in carbohydrates of all kinds (even from whole grains), ideally less than 100g per day, depending on the severity of disease markers; completely free from sodas and sugar/refined sweeteners; free from refined vegetable oils and trans fats; free from charred/grilled and processed meats; be high in healthy fats such as unrefined coconut oil, grass-fed butter, fats from grass-fed animals, real cold-pressed unrefined extra-virgin olive oil; include plenty of high-quality meats, eggs, and milk from grass-fed and/or pastured animals; include plenty of seafood and fatty fish; include plenty of fresh vegetables, especially those with dark or vibrant colors and lots of fiber; include a moderate amount of fruits (which should be factored into total daily carbohydrate intake); and plenty of nuts, seeds, and legumes. Some experts have posited that wheat has several negative influences on cardiovascular health, and that a truly heart-healthy diet must be wheat- or gluten-free. Cardiologist Dr. William Davis suspects that for certain people, atherosclerosis may be induced by an autoimmune mechanism triggered by ingestion of wheat, and that dysbiosis can lead to hyperlipidemia[xxiii].
There are several specific foods and supplements that may enhance the effectiveness of a heart-healthy diet. It is a good idea for those with heart disease or at risk of developing heart disease to increase the diet’s ratio of omega-3 fatty acids to omega-6’s by taking a high-quality, sustainably-harvested fish oil supplement, in addition to eating grass-fed animal products and fatty fish high in omega-3’s. Seeds high in omega-3 fats such as flax and chia (when soaked raw and blended) can be added to smoothies or cold drinks. In addition, eating fermented vegetables or probiotic dairy products (e.g. yogurt, kefir) may be helpful in correcting any underlying dysbiosis that may be contributing to inflammation and cardiovascular disease. In order to support blood vessel integrity and reduce oxidation, it is very important to eat plenty of low-carb, high-fiber berries that are high in anthocyanins, like blueberries, billberries, cranberries, black currants, raspberries, blackberries, and goji berries. A simple and powerful herbal remedy for improving and protecting blood vessel integrity and heart health is the hawthorn berry. This can be made into jams, tinctures, decoctions, or powdered and added to foods or put into capsules.
Conclusion
In conclusion, there is a significant amount of misinformation and outdated science that one has to wade through in the search for what dietary factors help or hurt cardiovascular health. We now know that inflammation via excessive carbohydrate intake is a much more significant contributor to the development of cardiovascular disease than the oft-maligned trinity of cholesterol, saturated fat, and red meat. Diets that focus on eating whole foods, especially with lots of vegetables and certain fruits, high-quality meats and seafood, and enough high-quality saturated fats are the foundation of a heart-healthy lifestyle. Of course, regular exercise and reduction of risk factors such as smoking and exposure to environmental toxins are also important facets of a healthy lifestyle. Overall, cardiovascular disease (and its related afflictions, diabetes and obesity) are consequences of the modern lifestyle, and by returning to the dietary and lifestyle traditions of our ancestors, we can live longer, healthier lives.
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[i] Keys, Ancel. “The Seven Countries Study”. <http://sevencountriesstudy.com/about-the-study>
[ii] Attia, Peter. “The limits of scientific evidence and the ethics of dietary guidelines: sixty years of ambiguity”. University of California at San Diego, Medical School. San Diego, CA. June 20, 2012. Lecture. <https://vimeo.com/45485034>
[iii] Ibid.
[iv] Unal, Belgin, Julia Alison Critchley, and Simon Capewell. "Explaining the decline in coronary heart disease mortality in England and Wales between 1981 and 2000." Circulation 109.9 (2004): 1101-1107.
[v] Attia, Peter. 2012.
[vi] Kresser, Chris. The Diet-Heart Myth. 2012.
[vii] Attia, Peter. “The straight dope of cholesterol – Part I”. April 25, 2012. <http://eatingacademy.com/nutrition/the-straight-dope-on-cholesterol-part-i>
[i] Björkhem, Ingemar, and Steve Meaney. "Brain cholesterol: long secret life behind a barrier." Arteriosclerosis, thrombosis, and vascular biology 24.5 (2004): 806-815.
[ii] Kresser, Chris. 2012.
[iii] Ibid.
[iv] Ibid.
[v] Enig, Mary; Fallon, Sally. “Dangers of Statin Drugs: What You Haven’t Been Told About Popular Cholesterol-Lowering Medicines”. The Weston A. Price Foundation. June 14, 2004. <http://www.westonaprice.org/modern-diseases/dangers-of-statin-drugs-what-you-havent-been-told-about-popular-cholesterol-lowering-medicines/>
[vi] Kresser, Chris. 2012.
[vii] Enig, Mary, et al. 2004.
[viii] Kresser, Chris. 2012.
[ix] Minger, Denise. “One year later: the China Study, Revisited and Re-Bashed”. 2011. <http://rawfoodsos.com/2011/07/31/one-year-later-the-china-study-revisited-and-re-bashed/>
[x] Price, Weston A. Nutrition and physical degeneration. Price-Pottenger Nutrition Foundation, 2003.
[xi] Bittman, Mark. "Butter is back." The New York Times (2014).
[xii] Koeth, Robert A., et al. "Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis." Nature medicine 19.5 (2013): 576-585.
[xiii] Leach, Jeff. “From Meat to Microbes to Main street: is it time to trade in your George Foreman Grill?”. Human Food Project: Anthropology of Microbes. April 15, 2003.
[xiv] Kresser, Chris. “RHR: Heart Attacks and Red Meat—Correlation or Causation?” Revolution Health Radio. December 18, 2014. <http://chriskresser.com/heart-attacks-and-red-meat-correlation-or-causation>
[i] Geddes, Linda. “What’s the beef?”. New Scientist. January 24-30, 2015: 30-35. Print.
[ii] Sawa, Tomohiro, et al. "Lipid peroxyl radicals from oxidized oils and heme-iron: implication of a high-fat diet in colon carcinogenesis." Cancer Epidemiology Biomarkers & Prevention 7.11 (1998): 1007-1012.
[iii] Goldin, Alison, et al. "Advanced glycation end products sparking the development of diabetic vascular injury." Circulation 114.6 (2006): 597-605.
[xv] Huang, Chen, et al. "Sugar sweetened beverages consumption and risk of coronary heart disease: a meta-analysis of prospective studies." Atherosclerosis 234.1 (2014): 11-16.
[xvi] American Heart Association. “Added Sugars Add to Your Risk of Dying from Heart Disease”. December 2, 2014. <http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/Added-Sugars-Add-to-Your-Risk-of-Dying-from-Heart-Disease_UCM_460319_Article.jsp>
[xvii] Malik, Shaista, et al. "Impact of the metabolic syndrome on mortality from coronary heart disease, cardiovascular disease, and all causes in United States adults." Circulation 110.10 (2004): 1245-1250.
[xviii] Corliss, Julie. “Eating too much added sugar increases the risk of dying with heart disease”. Harvard Health Blog. February 6, 2014. <http://www.health.harvard.edu/blog/eating-too-much-added-sugar-increases-the-risk-of-dying-with-heart-disease-201402067021>
[xix] Goldin, Alison, et al. "Advanced glycation end products sparking the development of diabetic vascular injury." Circulation 114.6 (2006): 597-605.
[xx] Fallon, Sally; Enig, Mary. “The Skinny on Fats”. The Weston A. Price Foundation. January 1, 2000. <http://www.westonaprice.org/health-topics/the-skinny-on-fats/>
[xxi] Shai, Iris, et al. "Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet." New England Journal of Medicine 359.3 (2008): 229-241.
[xxiii] Davis, William. “Wheat and Heart Disease”. The Gluten Summit. November 2013. Webinar.
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