So how did everybody get the lipid hypothesis wrong?
It starts with Ancel. He lied. Well, he fudged data, which is pretty much the same as lying. He left off the countries, 15 out 22, that contradicted his theory. It turns out there was a relatively weak correlation between high fat diets and CVD. A better correlative was wealth which led to more sedentary lifestyles and, at least during the 50s, more smoking (see TV show Mad Men). But Ancel, like the mad scientist in the movie when his experiment goes horribly wrong, stuck to his theory and never fessed up to the cooking the books.
Part of the problem was the nature of consensus. Given acceptance of a theory that holds together well, even one based on bad data, it’s hard to change people’s minds, let alone whole industries. Research shows that when people have a strongly held conviction, data that makes contradicts their view point actually makes them stronger in their opinion and to reject the data and/or the source of the new information. A lot of the data refuting the Keys research has been out there for a while; it just took a lot of time to break down resistance.
Part of the problem was that there were many interests benefiting from the consensus: Doctors and scientists who were advocates of the high carb, low fat diets, pharmaceutical companies promoting statins, agribusiness, the USDA and any number of authors and experts who staked their reputations on the promotion of the lipid hypothesis.
But ultimately it comes down science: the scientific method will ultimately improve our knowledge but the process is by nature deliberate. It just took a while and improvements in technology, to get to the point where enough experts could stand up with data and say ‘No, the consensus is wrong.’ Now we know better.
What You Need to Know about cholesterol and eggs (with an assist from Hugo Gallo-Torres, M.D., PhD)
- The cholesterol in our blood streams is mostly produced by our liver; it is regulated by our bodies and diet has little effect on the overall level. There are is a small percentage of people +/-5% whose cholesterol levels may be significantly influenced by dietary cholesterol
- As a pivotal component of membranes, cholesterol is essential to life. Our bodies need cholesterol at a cellular level for, among other things maintenance and repair. Cholesterol is measured by the amount of lipoproteins in the blood. Lipoproteins are the carriers of cholesterol. Lowering the amount of lipoproteins (cholesterol count) generally is not healthy
- Low density lipoproteins (LDL) sometimes inaccurately labeled as bad cholesterol, carry cholesterol through the blood to cells to perform its jobs
- Animal fats, like those contained in egg, are composed of cholesterol and triglycerides. These are the main lipids we consume. Triglycerides are compounds consisting of three molecules of fatty acids esterified to glycerol and stored in adipose cell. On enzymatic hydrolysis, triglycerides released free fatty acids in the blood. Triglycerides are moved around the body through the blood stream just like cholesterol, giving tissues energy that they can be used and stored
- High levels of LDL or triglycerides can be an indicator that the body is producing or has too much cholesterol
- Cholesterol, if excessive, may build up in blood vessels and, through the formation of plaques, contribute to vascular damage (CVD)
- High density lipoproteins (HDL) carry cholesterol away from blood vessel back to the liver for processing. That is why is it called (again, mistakenly) good cholesterol. The amount of total fat in the blood is measured by adding total cholesterol (measured by adding HDL and LDL cholesterol) plus triglyceride counts in the blood and this is a reflection of what is going on in the liver and the adipose tissue. Too much triglyceride in the liver (“fatty liver”) or the adipose tissue (a cardinal sign of obesity) is not associated with good health, the consequence of inadequate metabolic functions. This is the main reason why merely lowering total cholesterol is not a good thing. It can alter the proper metabolic functions.
- While an egg is high in fat, only 27% of the fat is saturated, containing LDL, which has been the marker for coronary disease. The rest is mostly polyunsaturated fat, which contains HDL and has been shown in well-designed, well-executed studies to improve the ratio between HDL and LDL
- Finally, a very large 2007 study showed no correlation between 6 per week egg consumption and cardiovascular disease or strokes.