Phytosterols, or just "sterols" to its friends and neighbors, are a group of cholesterol-like compounds that are abundant in the plant world. Lately, however, sterols have proliferated in the processed food supply, thanks to the observation that sterols reduce LDL cholesterol when ingested by humans.
This must mean that sterols are good for you.
Uh oh. Wait a minute: There is a rare disease called sitosterolemia in which there is unimpeded intestinal absorption of all sterols ingested through diet. They must have really low LDL cholesterols! Nope. They develop coronary disease--heart attacks, angina, etc.--in their late teens and 20s. In other words, if sterols gain access to your bloodstream, they are bad. Very bad.
Conventional thinking is that only a modest quantity of dietary sterols gain access to the bloodstream. But there are two potentially fatal flaws in this overly simplistic line of thinking
1) What happens when you load up your diet with "heart healthy" sterols, such as those in "heart healthy" margarines, mayonnaise, and yogurt, effectively increasing sterol intake 10-fold?
2) What happens in people with the genetic pattern, apo E4, that is carried by 25% of the general population that permits much greater intestinal absorption of sterols?
My prediction: Despite the fact that sterols reduce LDL, they may, in certain genetically-susceptible people, such as those with apo E4, increase risk for heart disease: heart unhealthy.