What does the research show about beta-sitosterol?

Beta-sitosterol

A review of 4 short trials in 519 men with an enlarged prostate found symptom scores 4.9 points lower than placebo and no change in prostate size. Plant sterols as a class, which include beta-sitosterol, lower LDL cholesterol by 6% to 12% at 0.6 to 3.3 g a day. Whether blood sitosterol affects heart disease risk is disputed.

Add to Bio HackChecked 2026-11-09

Status: Dietary supplement in the US. Not approved by the FDA as a drug for any use.
Also called: β-sitosterol, sitosterol, plant sterols, phytosterols, sitosterolin
Taken for: prostate health, enlarged prostate, urinary symptoms, cholesterol, heart health

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help3

StrongShown to lower LDL by 6% to 12% at 0.6 to 3.3 g a day of plant sterols and stanols, rising with dose up to about 3 g.
ModerateShown to lower prostate symptom scores by about 5 points and raise urine flow in men with an enlarged prostate, in short trials.
ModerateShown to lower systolic blood pressure by about 1.6 mmHg for plant sterols and stanols as a class. HDL, blood sugar and weight did not change.

Reported risks1

LimitedLimited evidence: observational studies found no link between blood sitosterol and heart disease, while a genetic study linked higher levels to coronary disease. Neither tested supplements.

What people take it for, and what was found

Shown to help3

ModerateStudied in men

Urinary symptoms from an enlarged prostate

Shown to lower prostate symptom scores by about 5 points and raise urine flow in men with an enlarged prostate, in short trials.

The numbers and sources

Effect: In a systematic review of 4 double-blind RCTs (519 men, 4 to 26 weeks), beta-sitosterol lowered the International Prostate Symptom Score by 4.9 points against placebo (95% CI -6.3 to -3.5, 2 studies), raised peak urine flow by 3.91 mL/s (95% CI 0.91 to 6.90) and cut residual urine by 28.62 mL [1]. In one trial, 200 men given 20 mg three times a day for 6 months had IPSS fall 7.4 points against 2.1 on placebo, and peak flow rose from 9.9 to 15.2 mL/s [2].
Population: Men with symptomatic benign prostatic hyperplasia [1][2].
Sources: [1], [2]
Caveats: Trials were short and used preparations that were not standardized. Long-term effects are unknown [1].

Strong

LDL cholesterol

Shown to lower LDL by 6% to 12% at 0.6 to 3.3 g a day of plant sterols and stanols, rising with dose up to about 3 g.

The numbers and sources

Effect: In a meta-analysis of 124 studies, plant sterols and stanols at 0.6 to 3.3 g a day lowered LDL cholesterol by 6% to 12%, rising with dose up to about 3 g a day [3]. In 8 trials of sterol or stanol capsules and tablets at 1 to 3 g a day, LDL cholesterol fell 12 mg/dL (0.31 mmol/L, 95% CI -0.39 to -0.23) against placebo, the same as with enriched foods [4]. An umbrella review of 14 meta-analyses found LDL reductions of 0.26 to 0.36 mmol/L, with reductions of 0.2 mmol/L or more at 0.5 to 1 g a day. GRADE certainty for LDL was generally high [5].
Population: Adults in RCTs, mostly 4 to 6 weeks long in the capsule review [3][4]. Adults of mixed health status taking supplements or enriched foods [5].
Sources: [3], [4], [5]
Caveats: These reviews pooled plant sterols and stanols as a class, mostly in enriched foods, not beta-sitosterol alone [3]. They measured LDL cholesterol, not heart attacks or strokes.

Moderate

Blood pressure and other heart risk markers

Shown to lower systolic blood pressure by about 1.6 mmHg for plant sterols and stanols as a class. HDL, blood sugar and weight did not change.

The numbers and sources

Effect: Plant sterols and stanols lowered systolic blood pressure by 1.55 mmHg (95% CI 0.42 to 2.67), diastolic by 0.84 mmHg, apoB by 0.06 g/L and hs-CRP by 0.25 mg/L. HDL cholesterol, fasting glucose, HbA1c, body weight, waist and fat mass did not change [5].
Population: Adults of mixed health status in trials pooled across 14 meta-analyses. Blood pressure came from one of them [5].
Sources: [5]
Caveats: Class-level evidence, not beta-sitosterol alone. These are risk markers, not heart attacks or strokes. Certainty was moderate to high for most outcomes, downgraded for inconsistency, imprecision or publication bias [5].

Doses studied

Prostate trials used 20 mg three times a day [2]. Cholesterol trials used 0.6 to 3.3 g a day of plant sterols or stanols [3], and 1 to 3 g a day as capsules or tablets with meals [4].

Risks

Mixed results1

Limited

Blood sitosterol levels and heart disease

Limited evidence: observational studies found no link between blood sitosterol and heart disease, while a genetic study linked higher levels to coronary disease. Neither tested supplements.

The numbers and sources

Effect: A meta-analysis of 17 observational studies (11,182 participants) found no association between blood sitosterol or campesterol levels and cardiovascular disease [6]. A genetic study of up to 9,758 people used Mendelian randomization and reported that higher blood sitosterol causally raised coronary artery disease risk, partly through cholesterol [7].
Population: Observational cohorts and case-control studies [6]. Genetic data from six studies [7].
Sources: [6], [7]
Caveats: Neither study tested beta-sitosterol supplements. The meta-analysis found signs of publication bias [6]. Both measured blood sterol levels, not intake.

Checked, no increase found1

ModerateStudied in men

Side effects in prostate trials

Withdrawals were about as common on beta-sitosterol as on placebo, 7.8% against 8.0%, in prostate trials.

The numbers and sources

Effect: Withdrawal rates were 7.8% on beta-sitosterol and 8.0% on placebo [1].
Population: 519 men in 4 RCTs [1].
Sources: [1]
Caveats: Long-term safety was not studied [1].

Claims tested and not found

That beta-sitosterol shrinks an enlarged prostate. Prostate size did not fall in the pooled trials [1] or in the 200-man trial [2].

Sources

Wilt TJ, MacDonald R, Ishani A. beta-sitosterol for the treatment of benign prostatic hyperplasia: a systematic review. BJU International. 1999. https://doi.org/10.1046/j.1464-410x.1999.00026.x
Berges RR, Windeler J, Trampisch HJ, et al. Randomised, placebo-controlled, double-blind clinical trial of beta-sitosterol in patients with benign prostatic hyperplasia. The Lancet. 1995. https://doi.org/10.1016/S0140-6736(95)91085-9
Ras RT, Geleijnse JM, Trautwein EA. LDL-cholesterol-lowering effect of plant sterols and stanols across different dose ranges: a meta-analysis of randomised controlled studies. British Journal of Nutrition. 2014. https://doi.org/10.1017/S0007114514000750
Amir Shaghaghi M, Abumweis SS, Jones PJH. Cholesterol-lowering efficacy of plant sterols/stanols provided in capsule and tablet formats: results of a systematic review and meta-analysis. Journal of the Academy of Nutrition and Dietetics. 2013. https://doi.org/10.1016/j.jand.2013.07.006
Zurbau A, Haintz L, Chen V, et al. Efficacy of phytosterols for reduction of cardiometabolic risk factors: An umbrella review of systematic reviews and meta-analyses and updated dose-response meta-analyses of randomized trials. Clinical Nutrition. 2026. https://doi.org/10.1016/j.clnu.2026.106698
Genser B, Silbernagel G, De Backer G, et al. Plant sterols and cardiovascular disease: a systematic review and meta-analysis. European Heart Journal. 2012. https://doi.org/10.1093/eurheartj/ehr441
Scholz M, Horn K, Pott J, et al. Genome-wide meta-analysis of phytosterols reveals five novel loci and a detrimental effect on coronary atherosclerosis. Nature Communications. 2022. https://doi.org/10.1038/s41467-021-27706-6

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