While sterols occur naturally in small quantities in food (nuts, vegetables, oils), food manufacturers are adding them to processed foods in order to earn a "heart healthy" claim.
The FDA approved a cholesterol-reducing indication for sterols , the American Heart Association recommends 200 mg per day as part of its Therapeutic Lifestyle Change diet, and WebMD gushes about the LDL-reducing benefits of sterols added to foods.
Sterols--the same substance that, when absorbed to high levels into the blood in a genetic disorder called "sitosterol emia"--causes extravagant atherosclerosis in young people .
The case against sterols, studies documenting its coronary disease- and valve disease-promoting effects, is building:
Higher blood levels of sterols increase cardiovascular events:
Plasma sitosterol elevations are associated with an increased incidence of coronary events in men: results of a nested case-control analysis of the Prospective Cardiovascular Münster (PROCAM) study.
Sterols can be recovered from diseased aortic valves:
Accumulation of cholesterol precursors and plant sterols in human stenotic aortic valves.
Sterols are incorporated into carotid atherosclerotic plaque:
Plant sterols in serum and in atherosclerotic plaques of patients undergoing carotid endarterectomy.
Though the data are mixed:
Moderately elevated plant sterol levels are associated with reduced cardiovascular risk--the LASA study.
No association between plasma levels of plant sterols and atherosclerosis in mice and men.
The food industry has vigorously pursued the sterol-as-heart-healthy strategy, based on studies conclusively demonstrating LDL-reducing effects. But do sterols that gain entry into the blood increase atherosclerosis regardless of LDL reduction? That's the huge unanswered question.
Despite the uncertainties, the list of sterol-supplemented foods is expanding rapidly:
Each Nature Valley Healthy Heart Bar contains 400 mg sterols.
HeartWise orange juice contains 1000 mg sterols per 8 oz serving.
Promise SuperShots contains 400 mg sterols per container.
Corozonas has an entire line of chips that contain added sterols, 400 mg per 1 oz serving.
MonaVie Acai juice, "Pulse," contains 400 mg sterols per 2 oz serving.
Kardea olive oil has 500 mg sterols per 14 gram serving.
WebMD has a table that they say can help you choose "foods" that are sterol-rich.
In my view, sterols should not have been approved without more extensive safety data. Just as Vioxx's potential for increasing heart attack did not become apparent until after FDA approval and widespread use, I fear the same may be ahead for sterols: dissemination throughout the processed food supply, people using large, unnatural quantities from multiple products, eventually . . . increased heart attacks, strokes, aortic valve disease.
Until there is clarification on this issue, I would urge everyone to avoid sterol-added "heart healthy" products .
Some more info on sterols in a previous Heart Scan Blog post: Are sterols the new trans fat? .