Fair warning: This video shows open-heart surgery and some may find it disturbing.
I was shown this video recently and I felt like it was as good a time as any to try and explain the myth of “artery clogging saturated fats.” We hear this term and this idea all the time: if you eat fat, especially saturated fat, it will fill your arteries with a thick greasy coating of fat, or harden and get lodged in your veins, forming plaque.
That video ignores the mechanisms behind how plaque forms. The next video actually does a good job of describing how plaque is made. It is much more complicated than just grease lining your blood vessels like the drain in your sink. Unfortunately it doesn’t explain why LDL and HDL are good or bad. We’ll get to that, but first let’s explore why this idea is so prevalent in our society.
I heard a nutrition teacher say just the other day, and I quote: “Animal fats clog your arteries.” Fat and cholesterol get grouped together mainly because they are both in animal meat, which has been deemed by some as the direct cause of heart disease and obesity. There is definitely a higher risk of heart attack when a person is fat. Unfortunately the word “fat” perpetuates the idea that eating fat makes someone fat. Since fat does have more calories than carbohydrates or protein, consuming too much fat could cause excess caloric intake, which can eventually cause weigh gain. Animal fat doesn’t just find its way out of your system and latch onto other fat cells in your hips or belly, or clog your arteries. It’s hard to fight this idea when it’s repeated everywhere, and we are “taught” this myth over and over again.
For a very thorough history of the whole situation, read Good Calories, Bad Calories by Gary Taubes. Here I’ll give you a short synopsis. Three events occurred around the same time. First, during World War I when meat was saved for the soldiers, more folks grew vegetables in their own “victory gardens.” Second, some experiments were done on rabbits. Adding cholesterol to a rabbit’s diet caused these rabbits heart disease. Scientist selected rabbits because “the rabbit exhibits hypercholesterolemia within a few days of an administration of a high cholesterol diet…”(1). Third,new techniques were becoming available to determine the cause of death in people. The electrocardiogram was invented in 1918 and helped cardiology become a medical specialty. They were able to figure out who died from heart attacks and soon after that, exactly what kind of heart attack. Before the 1910’s anyone past middle age was deemed to have died from natural causes. It’s likely a lack of proper diagnosis, rather than a lack of heart attacks affected the number of heart attack deaths. You may be asking how victory gardens, rabbits and the infancy of cardiology could be related. On their own they don’t mean much, but when you put them all together you can paint the picture we’ve all come to believe as the truth.
Before 1910 no one kept track of what people ate. During World War I it became useful to track, but the numbers weren’t very accurate, so the USDA did a bit of estimation. So when the government started keeping track of food consumption, meat was scarce and vegetable consumption was high, which may have been a dramatic change from the way people ate just a few years before the war. It really wasn’t until after World War II that the USDA had more reliable information about food consumption, and the numbers they did have for meat were most likely artificially low.
Then there’s the rabbit model. The thinking behind this is if rabbits get clogged arteries like humans, and if rabbit arteries get clogged on a high cholesterol diet, it follows that human arteries must do the same. The idea is reasonable if you accept the idea that rabbits and humans are similar. We share many characteristics, but diet and the ability to process cholesterol in food is not one of them. Rabbits never naturally eat cholesterol, and their digestive systems are similar to humans’ but far from exact.
Rabbits developed plaque when they ate cholesterol, the population began eating more meat and cholesterol after WWI ended (up from the artificial low) and there was an increase in deaths from heart attack (due to better diagnosis). When scientists looked at this data in the 1940’s, they could easily argue that the dramatic increase in heart attacks coincided with an increase in meat consumption. Combined with the rabbit model to site as evidence, they could “prove” that cholesterol (and therefore meat) was the cause of heart disease. The time frame matches but there is no science linking the two. The rabbit model simply proves rabbits shouldn’t eat cholesterol.
When Ancel Keys shared this information, along with his “7 Countries Study,” (which had many flaws we won’t get into now) it was hard to argue that cholesterol may be bad for human longevity. Eventually, he convinced the USDA to recommend a lower cholesterol diet for people at “high-risk.” High risk was defined as men who had already had heart attacks. Ultimately that suggestion trickled down to include the rest of the population too, because if reducing cholesterol helps prevent heart attacks in high-risk men, then why wouldn’t it help everyone? It’s pretty easy to see why this is now accepted as “common knowledge” but the science never really proved any of it.
There is a correlation between countries of affluence and an increase in chronic diseases like coronary heart disease, and high blood pressure. And it’s true that countries of affluence eat more meat, particularly here in the USA. At the same time, we also eat more added sugar, more preservatives, more hydrogenated oils, and lots of poor quality, nutrient scarce foods. The meats we eat are, more often than not, unnaturally fattened with corn and soy affecting their omega-3/6 ratios (2)(3). The oils we use are heated, pressed, damaged, genetically modified, or all of the above. All of these foods contribute to heart disease (4),(5), but it’s hard to definitively identify which of these is the biggest culprit.
Another argument is that eating more saturated fat will raise your cholesterol. The idea may be based on the fact that if you eat more animal fat, you are most likely eating more cholesterol because of the meat accompanying that fat. When measured in humans though, dietary saturated fat intake made no difference in blood cholesterol. (6) Your liver makes cholesterol by taking lipids (fats) you eat and transforming it into cholesterol. It may make logical sense that the more fat you eat, the more cholesterol you’d make, but the body is smarter than that. We’ll talk about how cholesterol is made and what it does in the next segment, and then how to prevent heart disease the right way. Thanks for reading and stay tuned for the next installment of the artery clogging myth.
Ref. (1) http://la.rsmjournals.com/content/38/3/246.full.pdf
Ref. (2) http://www.eatwild.com/healthbenefits.htm
Ref. (3) http://www.mercola.com/beef/omega3_oil.htm
Ref. (4) http://news.health.com/2010/04/20/added-sugars-diet-threaten-heart-health/
Ref. (5) http://www.sciencedaily.com/releases/2005/06/050617065306.htm
Ref. (6) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2123482/?page=3