Do Take Control and Benecol have a place in your diet? Johns Hopkins cardiologist Christopher Sibley, M.D. looks at the data.
Can reducing your cholesterol be as easy and painless as spreading a pat or two of heart-healthy margarine on your toast or veggies every day? Well, there is fairly convincing evidence that food spreads containing plant additives called sterols or stanols, substances that inhibit the absorption of cholesterol in the intestine, can indeed lower your LDL (“bad”) cholesterol. Recent studies, however, have raised some potential concerns about the safety and efficacy of margarines based on plant sterols—but not stanols.
How Sterols and Stanols Work to Lower Cholesterol
In 2000, the U.S. Food and Drug Administration approved two cholesterol-lowering margarines: Take Control, which contains plant sterol esters extracted from soybeans, and Benecol, which incorporates plant stanol esters derived from pine tree wood pulp. Plant stanols and sterols, which are found naturally in many foods, have been included in several other products in addition to margarine.
Dietary plant sterols and stanols lower LDL cholesterol levels by about 6% to 20%, with considerable individual variation. They produce the greatest reduction of LDL cholesterol at a dosage of about 2 g/day; their effectiveness does not increase at higher dosages. The additives do not alter the levels of HDL (“good”) cholesterol or triglycerides.
Although dietary plant sterols and stanols produce comparable reductions in LDL cholesterol, several recent studies have found some significant differences between the two compounds. For example, research reported in the American Journal of Cardiology indicates that the cholesterol-lowering effects of plant sterols diminish after about two months. At this point, the LDL cholesterol levels of people consuming dietary plant sterols did not differ significantly from baseline. The level of plant sterols in the blood also rose after two months. In addition, the synthesis of bile acids declined significantly, which is believed to impair the cholesterol-lowering effect of the plant sterols. Other recent studies have shown that statins increase the blood levels of plant sterols several-fold and that the given in combination with statins also declines with time.
By contrast, plant stanols maintain their efficacy in reducing LDL cholesterol levels over the long term, whether given alone or in combination with a statin. In addition, stanols lower the blood levels of plant sterols and do not affect the synthesis of bile acids. In a study published in the Journal of the American College of Cardiology, researchers measured the levels of plant sterols and cholesterol in the blood and in fatty deposits removed from the carotid arteries during endarterectomy (an artery-clearing procedure that reduces the risk of stroke). They found that as the ratio of plant sterols to cholesterol in the blood increased, so did the proportion of plant sterols in the fatty deposits removed from the arteries. This discovery raises questions about the possible role of dietary plant sterols in plaque formation.
The Bottom Line on Sterols and Stanols
There are potential concerns about the efficacy and safety of plant sterols: With time, their LDL cholesterol-lowering effect diminishes, and their level in the blood increases. And plant sterols have now been found in atherosclerotic plaques.
These findings are rather worrisome, but according to Johns Hopkins cardiologist Christopher Sibley, M.D., “There is no need for people currently consuming plant sterol margarines to panic. Plant sterols may simply be innocent bystanders, and we don’t yet know whether their presence in plaques actively predisposes to heart attack and stroke. At this point, it remains an open question whether plant sterols wear a white hat or a black hat with regard to atherosclerosis.”
Plant stanols, by contrast, seem more likely to “wear white hats.” The LDL-lowering effect of the stanols does not decline with time, levels of stanols in the blood do not rise, and they have the added benefit of lowering plant sterol blood levels.
