Phytosterols are plants’ equivalent of cholesterol. They are structurally similar, to animal cholesterol. At face value that makes consuming phytosterols sound like a counterproductive idea. However, the prevailing consensus view is that phytosterols reduce blood cholesterol, which in itself is considered favorable for CVD risk reduction. You can probably sense from my choice of wording that I’m a bit skeptical about the “lower cholesterol for reduced CVD risk” concept. I addressed this issue in an earlier article about statins.
Now, the EFSA and the FDA have endorsed phytosterol consumption (both on a petition by, you guessed it, Unilever).
EFSA allows the following claim: “Plant sterols have been shown to lower/reduce blood cholesterol. Blood cholesterol lowering may reduce the risk of coronary heart disease". As you can see, they sort of tap-dance around the issue. What they DO NOT say is that phytosterols reduce the risk of CHD. They only say that reduction of blood cholesterol reduces that risk (how could they say anything else when they explicitly endorse statin therapy for that purpose?).
When I look at such endorsements I always have the consumer in mind who is typically not sensitized to the granular meanings of lawyers’ formulations.
The FDA goes a step further and allows the formulation: “may reduce the risk of heart disease” (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr;sid=502078d8634923edc695b394a357d189;rgn=div8;view=text;node=21:2.0.1.1.2.5.1.14;idno=21;cc=ecfr)
Both agencies refer to studies that have shown that phytosterols indeed lower blood cholesterol by around 10%. But what interests us is: does this reduction go hand in hand with a reduction of disease endpoints? And here, the evidence is much less clear.
In fact, several studies in mouse models have shown that phytosterols actually promote atherosclerotic lesions, whereas others have found just the opposite effect. But these experiments may not translate to humans, as is more often than not the case.
What we are lacking is randomized clinical trials that look at phytosterol supplementation and relevant outcomes. Only those can convincingly show whether Dr. Mason has a point, in which case the FDA has to eat its own words, or not. To my knowledge, no such study is currently underway. And given the polarized diet discussion about vegetarian vs. animal-based nutrition, we need to be very careful about accepting either side’s arguments. I personally lean towards a healthy animal-based diet, and I’m skeptical about the promotion of vegetable oils as a cure-all.
