Sitosterol

Beta-sitosterol/Nutrient Depletion:

  • AcarboseAcarbose: A controlled clinical trial investigated the impact of starch malabsorption on colon carcinogenesis and found that the alpha-glucosidase inhibitor acarbose decreases fecal concentration of beta-sitosterol by approximately 40%, indicating that absorption may be increased (21).
  • Activated charcoalActivated charcoal: Data from clinical trials indicated that activated charcoal (8g given three times a day) slightly decreases serum levels of beta-sitosterol (180).
  • Alpha-tocopherol (vitamin E)Alpha-tocopherol (vitamin E): In clinical trials, the bioavailability of alpha-tocopherol decreased with concurrent administration of plant sterols (230).
  • Beta-caroteneBeta-carotene: In human clinical trials, plant sterols, including beta-sitosterol, given in doses of up to 9g daily reduced beta-carotene blood levels (131; 232; 44; 45; 48; 190; 191; 178; 54). This is thought to be a result of reductions in LDL-C, which carries beta-carotene, by beta-sitosterol. (23). Randomized controlled trials indicate that the lowering of beta-carotene is counterbalanced by consuming an additional daily serving of a high-carotenoid vegetable or fruit when consuming spreads containing sterol or stanol esters (50).
  • Blood sugarBlood sugar: In animal research, beta-sitosterol had hypoglycemic effects (71). Two human clinical trials have shown either a lowering of HbA1C or a lack of effect of plant sterols in diabetic subjects (94; 95). Also, in an animal study, fractions obtained from the leaves of Morus insignis, a source of beta-sitosterol, demonstrated hypoglycemic effects (71).
  • Carotenoids (other)Carotenoids (other): Clinical trials demonstrated that beta-sitosterol in doses of up to 1.5g daily reduced blood levels of lutein and lycopene (131).
  • CholestyramineCholestyramine: Cholestyramine doses of up to 32g per day reduced beta-sitosterol concentrations in patients with sitosterolemia (162; 168; 154).
  • EzetimibeEzetimibe: Ezetimibe has been shown in reviews, randomized controlled trials, and observational clinical trials to decrease sitosterol concentrations in children and adults with sitosterolemia, hyperlipidemic individuals, and individuals with and without type 2 diabetes (208; 209; 210; 211; 212; 213; 214; 215; 216). Doses of 40mg daily of ezetimibe have been shown to have greater effects on reducing plasma plant sterol concentrations in individuals with sitosterolemia compared to doses of 10mg daily (217). The effects of ezetimibe on sitosterol levels are significantly more potent in individuals with the CC genotype of the sterol regulatory binding protein-1c (SREBP-1c) polymorphism than the G allele-carriers (218). The effects of ezetimibe on sitosterol levels are increased with co-administration of rifampin (219).
  • Fat-soluble vitamins (other)Fat-soluble vitamins (other): Clinical trials demonstrate a lack of effect of plant sterols, including beta-sitosterol, in doses of up to 9g daily on blood levels of fat-soluble vitamins (Vitamins D and A [retinol]) (44; 45; 32; 51).
  • LifibrolLifibrol: Lifibrol, a lipid-lowering drug for the therapy of hypercholesterolemia, has been shown in clinical trials to reduce sterols including lanosterol, lathosterol, beta-sitosterol and campesterol (221).
  • LipidsLipids: Plant sterols, including beta-sitosterol, have been shown to lower TC as well as LDL-C in randomized controlled trials (RCTs) (43; 183; 44; 45; 46; 47; 184; 177; 129; 185; 186; 32; 158; 49; 18; 89; 187; 54; 90; 188; 132; 189). Plant sterols, including beta-sitosterol, have been shown to lower TC as well as LDL-C in randomized controlled trials (RCTs) (43; 183; 44; 45; 46; 47; 184; 177; 129; 185; 186; 32; 158; 49; 18; 89; 187; 54; 90; 188; 132; 189). HDL-C has been shown in clinical trials to be increased by about 5% with supplementation of plant sterols, including beta-sitosterol, in the diet (45; 189). Data from other clinical trials contradict this and suggest that a lack of effect of beta-sitosterol on HDL-C (46; 47; 185; 190; 18; 191; 178; 192; 54; 89). In children with familial hypercholesterolemia, there was a 15% reduction in HDL-C with treatment with beta-sitosterol (90).
  • Lutein/zeaxanthineLutein/zeaxanthine: In human trials, plant sterol functional foods altered lutein and zeaxanthine concentrations (249).
  • OlestraOlestra: Olestra, a nonabsorbable fat substitute comprised of long-chain fatty acid esters of sucrose, has been shown in clinical trials to decrease the amount of beta-sitosterol in stools (233).
  • Soluble fiberSoluble fiber: In a randomized clinical trial, 25g daily of soluble fiber intake in individuals on lipid-lowering therapy reduced phytosterolemia as measured by beta-sitosterol (237).
  • Trans fatty acidsTrans fatty acids: In randomized controlled trials, diets high in trans fatty acids have significantly decreased beta-sitosterol in healthy young men (106).