I recently discovered The International Network of Cholesterol Skeptics (THINCS). Their website states that they are a “steadily growing group of scientists, physicians, other academicians and science writers” who oppose the notion that animal fat and high cholesterol cause atherosclerosis and cardiovascular disease. I also recently discovered the medical literature on oxidized cholesterol and thought that THINCS may have a point. The problem may not be cholesterol and animal fat; it may be oxidized cholesterol.
Atherosclerosis, commonly known as clogged arteries, is the most common disease on Earth. It is the most common underlying cause of a wide range of health outcomes that include high blood pressure, erectile dysfunction, and heart attacks. Atherosclerosis may also be the most researched, and the most confusing, disease for health professionals and the public.
There are many reasons for the confusion about atherosclerosis. Some of it is cognitive dissonance because scientific evidence about the cause of atherosclerosis conflicts with core beliefs about cholesterol-containing foods. Some of the confusion is deliberate, as Upton Sinclair said: “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” Industries on both sides of the cholesterol-atherosclerosis stand-off profit from confusion and misinformation.
Regardless of the reason, the consequences of this confusion are deadly. Atherosclerosis is THE most common cause of death worldwide. If we don’t get clarity about this disease and control it, millions of people will continue to suffer and die each year from an entirely preventable disease.
So, what do we know with certainty about cholesterol and atherosclerosis?
- Cholesterol is a waxy fat that is essential for normal life. It is in the cell membrane of every cell in our body and can be made by every animal cell. It can also be made by some plants in minute amounts that are only now detectable with modern analytic techniques. Extracting oils from these plants concentrates and oxidizes the cholesterol.
- Cholesterol is carried through the bloodstream by protein carriers. High density lipoproteins (HDL) carry cholesterol to the liver. Low density lipoproteins (LDL) carry cholesterol to cells. LDL have been demonized as “bad,” but in fact LDL carrying native cholesterol (NC) circulates in harmony with the immune system and does not cause inflammation or atherosclerosis. We know this with certainty from experimental animal studies and from epidemiological and post-mortem studies of people who eat little or no cholesterol-containing foods. Their cholesterol levels are rarely above 150 mg/dl and their arteries are clear with no signs of atherosclerosis.
- Cholesterol in food is easily oxidized by exposure to air, heating, processing, and digestion to form a group of compounds called cholesterol oxidation products (ChOP). We know this with certainty because we can measure it. Raw chicken has about 2.8 to 4.5ug/g of lipids. Grilled and roasted chicken has 92.5 and 88.6 µg/g, respectively, after storage. Fresh raw meat has trace amounts of ChOP, cooked meat has 180 to 1900 µg/g, depending on the cooking method.
- ChOP from food are absorbed through the intestines and also carried by LDL. The combination can be called oxidized LDL (Ox-LDL) or LDL-ChOP. The endothelial cells that line arteries recognize LDL-ChOP as damaged molecules and send out inflammatory signals to attract immune cells to come and get rid of it. Macrophages are immune cells that gobble up anything that could be toxic. Macrophages gobble up LDL-ChOP to become foam cells, so called because they look foamy when they are filled with fat. We know this with certainty because when LDL-NC is incubated with macrophages nothing happens. When LDL-ChOP are incubated with macrophages they form foam cells.
- Foam cells accumulate under the endothelial cell surface of arteries to form fatty streaks that grow larger to form atherosclerotic plaques. “Athero” is the fatty pustular core of the plaque that forms when immune cells and foam cells die and release their lipids. “Sclerosis” is the scar tissue that forms around the fatty necrotic pustular core.
- Atherosclerosis can be reversed by eliminating cholesterol-containing foods from the diet. We know this with certainty because we have pictures of plaque regression on oil-free plant-based diets.
- Exposure to dietary cholesterol/ChOP is the only factor necessary to produce atherosclerosis in experimental animals. Saturated fat is inseparable from cholesterol/ChOP in meat, milk and eggs. Saturated fat does not cause atherosclerosis in the absence of ChOP. There is no known mechanism by which saturated fat causes atherosclerosis by itself. In some studies “cholesterol-free” vegetable oils/saturated fats such as coconut oil produced atherosclerotic lesions in rabbits. What the researchers did not know at the time was that these oils contain minute amounts of ChOP. Beef tallow was used in some studies as an example of a saturated fat that caused atherosclerosis. Beef tallow contains high levels of ChOP.
This information about ChOP is not breaking news. The toxic effects of oxidized cholesterol have been well documented since the 1980s. You may not have heard about it because it was not part of the marketing of any products. We learned about LDL and HDL from the marketing of statin medications. We may start hearing more about Ox-LDL now because a blood test is available.
What we don’t know with certainty is the level of ChOP that is safe to eat. Even if we knew this, it would not be useful information because it is not possible to accurately know how much ChOP are in a given food.
It depends on how long it was exposed to air and how it was cooked. The only way to avoid exposure to ChOP is to eat an oil-free plant-based diet.
In preventive medicine/lifestyle medicine we need clear consistent, and accurate messages to promote healthy behavior changes. The medical literature on Ox-LDL is confusing because the focus is on drug development not dietary advice. Human and animal research that focus on dietary ChOP strongly support the view that atherosclerosis is essentially a foodborne illness.
This blog is a very simplified overview of the role of dietary ChOP in causing atherosclerosis. My fervent hope is that members of THINCS and members of the medical establishment will take the time to learn about ChOP. Cholesterol-free plant based diets will prevent and reverse atherosclerosis.
Preventing and reversing atherosclerosis will prevent the suffering and untimely deaths of millions of people around the world.
Dr. Jennifer Rooke is an Assistant Professor in the Department of Community Health and Preventive Medicine at Morehouse School of Medicine. She recently joined the faculty at Morehouse to start a lifestyle medicine clinic. Lifestyle Medicine is the use of interventions such as evidenced-based nutrition, physical activity and stress management to treat disease. Dr. Rooke has practiced medicine for over 27 years and is board certified in both Occupational Medicine and Public Health/Preventive Medicine. Dr. Rooke is a fellow of both the American College of Occupational and Environmental Medicine, and the American College of Preventive Medicine. Dr. Rooke serves as adjunct faculty in the Department of Family and Preventive Medicine at Emory University. Contact the author or visit her website www.advancedlifestylemedicine.com