Have recent headlines made you believe that you can eat unlimited amounts of saturated fat in red meat and dairy products? I hope not. A recent study from Harvard School of Public Health shows that when people replace five percent of calories from saturated fats with the same amount of calories from:
• polyunsaturated fats, they gain a 25 percent reduction in heart disease,
• monounsaturated fats, they gain a 15 percent reduction in heart disease, and
• carbohydrates from whole grains, they gain a nine percent reduction in heart disease.
However, if they replace the saturated fats in meats and dairy products with refined carbohydrates in bakery products and sugar added foods and drinks, they still are at the same high risk for heart attacks (Journal of the American College of Cardiology, September 28, 2015).
The study reviewed data from 84,628 women in the Nurses’ Health Study and 42,908 men in the Health Professionals Follow-up Study, who were free of diabetes, heart disease, and cancer at the start of the study, and followed them every four years. There were 7,667 cases of heart attacks. Their analysis corrected for heart attack risk factors such as age, body mass index, smoking, and physical activity. The lead author, Dr. Frank Hu, says, “In terms of heart disease risk, saturated fat and refined carbohydrates appear to be similarly unhealthful.”
Why Are Red Meat and Dairy Products Still Associated with Heart Attack Risk?
Nobody has shown that red meat or whole-milk dairy products cause heart attacks, but drinking milk (JAMA Pediatrics, July 2013) and eating red meat (Am J Clin Nutr, August 2012;96(2):397-404) have been associated with increased risk for heart attacks and strokes. So even if saturated fat is not the problem, something else in red meat and dairy products is likely to be causing heart attacks. At this time the leading theories are TMAO, Neu5gc, and galactose.
TriMethylAmine Oxide (TMAO): TMAO is made by bacteria in the intestines from carnitine, choline, lecithin, creatine and creatinine, found in red meat, eggs, milk and dairy products, liver, poultry, shellfish, fish, sports supplements and protein drinks. Stanley Hazen at the Cleveland Clinic has shown that feeding humans carnitine can increase blood levels of TMAO (TriMethylAmine Oxide), a chemical that can punch holes in arteries and increase the formation of arteriosclerotic plaques (Nature Medicine, published online April 7, 2013 and N Engl J Med, 2013;368:1575-1584). Heart attacks are not caused by blockage of an artery by progressive narrowing of that artery. First, your immunity punches holes in the inner lining of an artery. This is called inflammation. Then plaques form over the holes. Then suddenly a plaque breaks off from the lining of the artery and travels down the ever-narrowing artery until it completely blocks blood flow through that artery leading to the heart muscle. That part of the heart muscle, unable to get its usual supply of blood, suffers from lack of oxygen which causes pain and eventually death to the part of the heart muscle starved of oxygen. More on TMAO
Neu5Gc: Ajit Varkey discovered Neu5Gc, a sugar chain that is found in meat from mammals but not in the cells of humans (Proceedings of the National Academy of Sciences, published online April 7, 2014). Your immunity attacks all cells that have different surface sugar proteins than you do. So when you eat red meat, you absorb Neu5Gc and your immunity attacks it just like it attacks germs that are trying to invade your body. These same antibodies and cytokines that are supposed to kill germs can stay active to cause inflammation that punches holes in arteries to start plaques forming there. More on Neu5gc
Galactose:The component in dairy products that may increase heart attack risk is a sugar called galactose. Whole milk, skim milk, butter and other non-fermented milk products contain galactose. High blood levels of sugars can cause cell damage. Only four sugars can be absorbed from your intestines into your bloodstream. Of the four, galactose appears to be the strongest cause of inflammation that punches holes in arteries to start plaques forming there. Fermenting milk breaks down galactose, so fermented dairy foods such as yogurt and cheese do not contain much galactose and therefore may be more healthful.
It really doesn’t make much difference whether or not saturated fat or cholesterol in foods increase heart attack risk. It appears that there is an association between heart attacks and both red meat (meat from mammals) and dairy products, so researchers are looking for other factors that may be the cause. I will continue to report on their work, and meanwhile, I recommend limiting or avoiding these foods and basing your healthful diet primarily on plants.