You may have heard of them. You have no doubt eaten them. And if you want to lower your high cholesterol and protect your heart, you definitely need more of them. We’re talking about plant sterols. And it’s not just your vegetarians and health professionals that are singing the praises of plant sterols. Even the Food & Drug Administration (FDA) recognizes the overwhelming evidence of health benefits, allowing products that include .65 g per serving of plant sterols to feature the following health claim: “Foods containing at least 0.65 g per serving of plant sterol esters, eaten twice a day with meals for a daily total intake of at least 1.3 g, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.”
Check out some of the recent studies on plant sterols and their numerous health benefits:
LDL cholesterol: Numerous clinical trials have found that daily consumption of foods enriched with free or esterified forms of plant sterols or stanols lowers concentrations of serum total and LDL cholesterol (10, 32-35). A meta-analysis that combined the results of 18 controlled clinical trials found that the consumption of spreads providing an average of 2 g/day of plant sterols or stanols lowered serum LDL cholesterol concentrations by 9-14% (36). More recently, a meta-analysis that combined the results of 23 controlled clinical tri
als found that the consumption of plant foods providing an average of 3.4 g/day of plant sterols or stanols decreased LDL cholesterol concentrations by about 11% (37). Another meta-analysis examined the results of 23 clinical trials of plant sterol-enriched foods and 27 clinical trials of plant stanol-enriched foods, separately (11). At doses of at least 2 g/day, both plant sterols and stanols decreased LDL cholesterol concentrations by about 10%. Doses higher than 2 g/day did not substantially improve the cholesterol-lowering effects of plant sterols or stanols. Most recently, a meta-analysis that analyzed the results of 59 randomized controlled trials found that reductions in LDL cholesterol are greater in those with higher baseline levels of LDL cholesterol (38). The results of studies providing lower doses of plant sterols or stanols suggest that 0.8-1.0 g/day is the lowest dose that results in clinically significant LDL cholesterol reductions of at least 5% (39-43). In general, trials that have compared the cholesterol-lowering efficacy of plant sterols with that of stanols have found them to be equivalent (44-46). Few of these studies lasted longer than four weeks, but at least two studies have found that the cholesterol-lowering effects of plant sterols and stanols last for up to one year (26, 47). In addition to data from controlled clinical trials, a 5-year study that examined the customary use of phytosterol/-stanol enriched margarines under free-living conditions found beneficial effects on cholesterol levels (48). Recently, concerns have been raised that plant sterols are not as effective as stanols in maintaining long-term LDL-cholesterol reductions (49-51). Long-term trials that directly compare the efficacy of plant sterols and plant stanols are needed to address these concerns (11).
Coronary heart disease risk: The effect of long-term use of foods enriched with plant sterols or stanols on coronary heart disease (CHD) risk is not known. The results of numerous intervention trials suggest that a 10% reduction in LDL cholesterol induced by medication or diet modification could decrease the risk of CHD by as much as 20% (52). The National Cholesterol Education Program (NCEP) Adult Treatment Panel III has included the use of plant sterol or stanol esters (2 g/day) as a component of maximal dietary therapy for elevated LDL cholesterol (53). The addition of plant sterol- or stanol-enriched foods to a heart healthy diet that is low in saturated fat and rich in fruit and vegetables, whole grains, and fiber offers the potential for additive effects in CHD risk reduction. For example, following a diet that substituted monounsaturated and polyunsaturated fats for saturated fat resulted in a 9% reduction in serum LDL cholesterol after 30 days, but the addition of 1.7 g/day of plant sterols to the same diet resulted in a 24% reduction (54). More recently, one-month adherence to a diet providing a portfolio of cholesterol-lowering foods, including plant sterols (1 g/1,000 kcal), soy protein, almonds, and viscous fibers lowered serum LDL cholesterol concentrations by an average of 30%—a decrease that was not significantly different from that induced by statin (drugs that inhibit the enzyme, HMG-CoA reductase) therapy (55). However, analysis of individuals on such a cholesterol-lowering diet for one year found that the average LDL cholesterol reduction was only 13%, but almost a third of the participants experienced LDL cholesterol reductions >20% (56). Plant sterols are the major component in this diet responsible for the observed reductions in cholesterol concentrations (57). The US Food and Drug Administration (FDA) has authorized the use of health claims on food labels indicating that regular consumption of foods enriched with plant sterol or stanol esters may reduce the risk of heart disease (58).
Cancer: Limited data from animal studies suggest that very high intakes of phytosterols, particularly sitosterol, may inhibit the growth of breast and prostate cancer (65-67). Only a few epidemiological studies have examined associations between dietary phytosterol intakes and cancer risk in humans because databases providing information on the phytosterol content of commonly consumed foods have only recently been developed. A series of case-control studies in Uruguay found that dietary phytosterol intakes were lower in people diagnosed with stomach, lung, or breast cancer than in cancer-free control groups(68-70). Case-control studies in the US found that women diagnosed with breast or endometrial (uterine) cancer had lower dietary phytosterol intakes than women who did not have cancer (71, 72). In contrast, another case-control study in the US found that men diagnosed with prostate cancer had higher dietary campesterol intakes than men who did not have cancer, but total phytosterol consumption was not associated with prostate cancer risk (73). Although some epidemiological studies have found that higher intakes of plant foods containing phytosterols are associated with decreased cancer risk, it is not clear whether the protective factors are phytosterols or other compounds in plant foods.