Right alongside the saturated fat myth is the cholesterol myth that suggests that dietary cholesterol causes cardiovascular disease. As a result, many people forgo eggs, liver, and other high-cholesterol foods, thinking they are doing the “heart healthy” thing. But is it true?
To begin with, there are two aspects to the theory. First, there is the idea that dietary cholesterol increases blood cholesterol, which is of primary concern to us in this discussion. But then there is the second matter, which is the idea that blood cholesterol levels determine risk for cardiovascular disease. While we’re at it, we might as well debunk them both
To begin with, the notion that dietary cholesterol increases blood cholesterol has absolutely no basis in reality. In fact, even Ancel Keys, the “grandfather of the diet-heart theory,” said in 1997 that “there’s no connection whatsoever between the cholesterol in food and cholesterol in the blood.
And we’ve known that all along.” (Bowden & Sinatra, 2012) So despite the fact that we’ve been told to avoid eggs, it turns out that eating eggs, liver, or other high-cholesterol foods has essentially no impact on blood cholesterol levels.
The theory of dietary cholesterol causing atherosclerosis originated, perhaps, from some rabbit studies in which the researchers fed (oxidized) cholesterol to rabbits and demonstrated increases in health problems in the rabbits.
Consider for a moment that rabbits are naturally herbivores. Adding cholesterol to an herbivore’s diet is likely to produce health problems. Add substantial oxidized cholesterol to anyone’s diet and it’s probably going to cause problems. But does this translate to humans eating actual food? No, it does not.
The Framingham Heart Study demonstrated that dietary cholesterol has no impact on rates of cardiovascular disease. Furthermore, the overwhelming evidence of the studies measuring the effects of lowering blood cholesterol levels indicates that it is not an effective way to reduce cardiovascular disease.
In fact, there is considerable evidence that lowering blood cholesterol levels leads to increased risk of a variety of diseases. This has been concluded by a number of studies, including the Framingham Heart Study, the Honolulu Heart Program, and the Japanese Lipid Intervention Trial. (Thanks to Chris Kresser for bringing these studies to attention.)
In conclusion, there is no evidence that dietary cholesterol leads to cardiovascular disease. And there is even evidence that lowering blood cholesterol (through drugs or other means) is a bad idea that not only doesn’t improve cardiovascular health, but actually worsens health overall. Then again, if you’re a rabbit, you may want to lay off the pure oxidized cholesterol.