Home Ingredients Beta-Sitosterol
CardiovascularProstate Health

Beta-Sitosterol

Evidence Level
Moderate
4 Clinical Trials
4 Documented Benefits
3/5 Evidence Score

Beta-sitosterol is one of the main plant sterols in the diet, a cholesterol-like compound found in vegetable oils, nuts, seeds, grains and legumes. It is studied at two very different doses. In men with urinary symptoms from an enlarged prostate, beta-sitosterol preparations were tested in short double-blind trials, the largest at 60 mg a day; a Cochrane review of four such trials (519 men) found better symptom scores and urine flow than placebo, with no change in prostate size. Those trials lasted 4 to 26 weeks and used varied preparations, and long-term effects are unknown. At gram doses, plant sterols as a group lower LDL cholesterol by about 6 to 12% by reducing cholesterol absorption from the gut, although no trial has shown fewer heart events. Urinary symptoms can have serious causes, so have them checked by a doctor before trying a supplement.

Studied Dose Urinary trials: 60 mg/day of beta-sitosterol, taken as 20 mg three times daily, for up to 6 months. LDL lowering: 0.6 to 3.3 g/day of total plant sterols or stanols, usually about 2 g/day, taken with meals.
Active Compound Beta-sitosterol (24-ethyl cholesterol)

Benefits

Urinary symptom scores and urinary flow in older men

A Cochrane review pooled 4 double-blind trials in 519 men with an enlarged prostate. Compared with placebo, beta-sitosterol improved the IPSS symptom score by about 4.9 points (2 trials) and peak urine flow by about 3.9 mL/s (4 trials). Prostate size did not shrink. The trials lasted only 4 to 26 weeks, and the one using a pure glucoside form showed no flow improvement.

Supported by Trial 2, Trial 1

Six-month trial: symptom scores and urine flow in 200 men

In a 6-month double-blind trial, 200 men with an enlarged prostate took 20 mg of beta-sitosterol three times daily or placebo. The main symptom score fell by 6.7 points versus 2.1 on placebo, and IPSS by 7.4 versus 2.1. Peak flow rose from 9.9 to 15.2 mL/s on beta-sitosterol and did not change on placebo. Prostate volume did not change in either group.

Supported by Trial 1, Trial 2

Results held at 18 months in men who kept taking it

In an open follow-up of the 6-month trial, 117 of the 200 men were re-examined at 18 months. The 38 who stayed on beta-sitosterol kept their gains, and 27 former placebo takers who switched to it improved to a similar degree. Men chose their own treatment, so this was not a blinded comparison, and the authors called for further trials.

Supported by Trial 3

LDL cholesterol lowering at gram doses (plant sterols as a group)

A meta-analysis of 124 studies found that plant sterols and stanols at 0.6 to 3.3 g a day lowered LDL cholesterol by about 6 to 12%, with the effect rising up to about 3 g. These studies tested plant sterol mixtures, not beta-sitosterol capsules at the 60 mg used in the urinary trials, which is far below these intakes.

Supported by Trial 4

Mechanism of action

1

Less cholesterol absorbed from the gut

At about 2 g a day, plant sterols and stanols partly block the absorption of cholesterol from the intestine, which lowers LDL cholesterol by roughly 8 to 10%, according to a European Atherosclerosis Society consensus review. This needs gram doses, far more than the amounts used in the prostate trials.

2

Urinary effects without prostate shrinkage

In the trials, urinary symptoms and flow improved while prostate size did not change, so any benefit does not come from shrinking the gland. The authors of the main trial noted that no precise mechanism of action has been described for plant-derived products like beta-sitosterol.

3

Proposed enzyme and anti-inflammatory effects (lab evidence)

Lab and animal studies have suggested that beta-sitosterol weakly inhibits 5-alpha-reductase, the enzyme that turns testosterone into DHT, and has anti-inflammatory activity. None of this was measured in the human trials, so these remain possible explanations rather than shown effects.

Clinical trials

1
Six-month placebo-controlled trial in 200 men
PubMed

Randomized, double-blind, placebo-controlled multicentre trial of 20 mg beta-sitosterol three times daily for 6 months; primary outcome modified Boyarsky score (Berges et al. 1995, Lancet)

200 men with symptomatic benign prostatic hyperplasia, recruited between April and October 1993.

The modified Boyarsky score fell by 6.7 points versus 2.1 on placebo (p<0.01). IPSS fell by 7.4 versus 2.1, peak flow rose from 9.9 to 15.2 mL/s and residual urine fell from 65.8 to 30.4 mL on beta-sitosterol, with no change on placebo. Prostate volume did not change meaningfully in either group.

2
Cochrane review of beta-sitosterols for urinary symptoms
PubMed

Cochrane systematic review of randomized, placebo-controlled, double-blind trials lasting 4 to 26 weeks (Wilt et al. 2000, Cochrane Database Syst Rev)

519 men with benign prostatic hyperplasia in 4 trials.

Beta-sitosterols improved IPSS by 4.9 points (95% CI 3.5 to 6.3, 2 trials), peak urine flow by 3.91 mL/s (4 trials) and residual volume by 28.6 mL (4 trials) versus placebo. Prostate size did not shrink. Withdrawal rates were similar (7.8% vs 8.0%). The reviewers said long-term effectiveness and safety are not known.

3
18-month open follow-up
PubMed

Open extension of the 6-month double-blind trial, in which men chose their own further treatment (Berges et al. 2000, BJU Int)

117 of the original 200 men (59%) were re-evaluated at 18 months.

The 38 men who continued beta-sitosterol had stable scores and flow; the 41 who stopped had slightly worse symptom scores and residual urine. The 27 former placebo takers who started beta-sitosterol improved to a similar degree. The authors said further trials are needed before concluding it is effective.

4
Plant sterols and LDL cholesterol across doses
PubMed

Meta-analysis of randomized controlled studies grouped by dose (Ras et al. 2014, Br J Nutr)

124 studies (201 dose strata) of plant sterols, stanols or both; average intake 2.1 g/day.

Intakes of 0.6 to 3.3 g/day lowered LDL cholesterol by about 6 to 12%, with comparable dose responses for sterols and stanols and an average effect of about 12% near 3 g/day. Two of the three authors worked for Unilever.

Side effects and drug interactions

Common Potential side effects

Generally well tolerated in the trials; in the pooled prostate trials, withdrawal rates were 7.8% on beta-sitosterol and 8.0% on placebo.
At gram doses (about 2.5 g/day), plant sterols lowered blood beta-carotene by about 10 to 16% in a meta-analysis, while vitamin A (retinol) and vitamin D were unaffected and levels stayed in the normal range. The 60 mg doses used for urinary support are far lower.
People with sitosterolemia, an inherited condition in which plant sterols are absorbed and retained abnormally, are advised to avoid plant sterol-rich foods and should not take plant sterol supplements.

Important Drug interactions

Statins: at about 2 g/day, plant sterol LDL lowering adds to the effect of statins, according to a European Atherosclerosis Society consensus review. Tell your doctor if you combine them.
Ezetimibe and bile-acid binding resins (such as cholestyramine): these also act on cholesterol handling in the gut. Combined use was not studied in the cited trials, so discuss it with your prescriber.
Prostate medicines (alpha-blockers, 5-alpha-reductase inhibitors): no cited trial tested beta-sitosterol alongside them. Do not replace a prescribed medicine with a supplement.

Featured in these supplement guides

High Cholesterol→

More Cardiovascular Ingredients

Cardiovascular
Omega-3 Fatty Acids
Omega-3 fatty acids are polyunsaturated fats. EPA and DHA come from fish, krill and algae…
Cardiovascular
CoEnzyme Q10
Coenzyme Q10 (CoQ10) is a fat-soluble compound the body makes for itself. It carries elect…
Cardiovascular
Beetroot
Beetroot (Beta vulgaris) is a root vegetable sold as juice, concentrated shots and powder,…
Cardiovascular
Potassium
Potassium is the main mineral inside the body's cells and an essential nutrient for the el…

Related articles from our blog

📝 Article
The 7 Best Prostate Supplements of 2026
Walk the men's-health aisle and every prostate bottle promises comfortable nights and a healthy prostate. The honest rea…
September 18, 2026
📝 Article
Plant Sterols for Cholesterol: What a 2026 Study Found
Most supplements live in a gray zone of hopeful, small, and mixed studies. Plant sterols are one of the few exceptions.…
July 11, 2026
📝 Article
Supplements for Prostate Health: The Honest Evidence on BPH
The prostate supplement market is enormous, and it is also one of the clearest examples of marketing outrunning evidence…
July 1, 2026

Frequently asked questions about Beta-Sitosterol

What is beta-sitosterol used for?

Beta-sitosterol is a plant sterol studied for two separate goals: urinary comfort in men with an enlarged prostate, at about 60 mg a day, and healthy LDL cholesterol, where plant sterol mixtures are used at about 2 g a day. It is found naturally in nuts, seeds and vegetable oils.

Does beta-sitosterol help the prostate?

In short trials of men with an enlarged prostate, beta-sitosterol improved urinary symptom scores and urine flow compared with placebo, but it did not shrink the prostate, and long-term effects are unknown. Urinary symptoms can have other causes, including prostate cancer, so have them evaluated by a doctor.

How much beta-sitosterol should I take?

The main prostate trial used 20 mg three times a day (60 mg daily). LDL cholesterol studies used much larger plant sterol intakes, about 0.6 to 3.3 grams a day with meals. Follow product labeling.

Is beta-sitosterol safe?

It was well tolerated in the trials. At gram doses, plant sterols slightly lower blood levels of beta-carotene and some other carotenoids, while vitamin A and vitamin D levels were unaffected. People with the inherited condition sitosterolemia should avoid plant sterol supplements.

What is Beta-Sitosterol?

Beta-sitosterol is one of the main plant sterols in the diet, a cholesterol-like compound found in vegetable oils, nuts, seeds, grains and legumes. It is studied at two very different doses.

Does Beta-Sitosterol interact with any medications?

Possible interactions include: Statins: at about 2 g/day, plant sterol LDL lowering adds to the effect of statins, according to a European Atherosclerosis Society consensus review. Tell your doctor if you combine them. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Beta-Sitosterol?

NutraSmarts rates the evidence for Beta-Sitosterol as Moderate (3 out of 5). It is backed by 4 study summaries and 8 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(8 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Wilt TJ, MacDonald R, Ishani A. beta-sitosterol for the treatment of benign prostatic hyperplasia: a systematic review. BJU Int. 1999;83(9):976-83. doi: 10.1046/j.1464-410x.1999.00026.x.PubMedUsed to support: Systematic review of 4 double-blind trials (519 men, 4 to 26 weeks): beta-sitosterol improved urinary symptom scores (IPSS by 4.9 points in 2 trials) and flow measures (peak flow 3.91 mL/s) versus placebo but did not reduce prostate size; the trial of pure beta-sitosterol glucoside showed no flow improvement. The authors noted short trials and unstandardized preparations.
  2. Berges RR, Windeler J, Trampisch HJ, Senge T. Randomised, placebo-controlled, double-blind clinical trial of beta-sitosterol in patients with benign prostatic hyperplasia. Beta-sitosterol Study Group. Lancet. 1995;345(8964):1529-32. doi: 10.1016/s0140-6736(95)91085-9.PubMedUsed to support: 6-month multicentre RCT in 200 men taking 20 mg beta-sitosterol three times daily: the modified Boyarsky score (primary outcome) fell 6.7 versus 2.1 points on placebo, IPSS fell 7.4 versus 2.1, and peak flow and residual urine improved, with no relevant change in prostate volume.
  3. Berges RR, Kassen A, Senge T. Treatment of symptomatic benign prostatic hyperplasia with beta-sitosterol: an 18-month follow-up. BJU Int. 2000;85(7):842-6. doi: 10.1046/j.1464-410x.2000.00672.x.PubMedUsed to support: Open 18-month follow-up of the Lancet trial (117 of 200 men re-evaluated): men who continued beta-sitosterol kept their improvements and former placebo takers who switched improved similarly; men chose their own treatment, and the authors called for further trials.
  4. 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. Br J Nutr. 2014;112(2):214-9. doi: 10.1017/S0007114514000750.PubMedUsed to support: Meta-analysis of 124 studies: plant sterol or stanol intakes of 0.6 to 3.3 g/day lowered LDL cholesterol by about 6 to 12%, rising with dose up to about 3 g/day. This is evidence for plant sterols as a class at gram doses, not for low-dose beta-sitosterol capsules.
  5. Wilt T, Ishani A, MacDonald R, Stark G, Mulrow C, Lau J. Beta-sitosterols for benign prostatic hyperplasia. Cochrane Database Syst Rev. 2000;1999(2):CD001043. doi: 10.1002/14651858.CD001043.PubMedUsed to support: Cochrane review of 4 randomized, placebo-controlled, double-blind trials in 519 men: beta-sitosterols improved IPSS (by 4.9 points), peak urine flow (by 3.91 mL/s) and residual volume versus placebo, without reducing prostate size; long-term effectiveness and safety are unknown.
  6. Gylling H, Plat J, Turley S, Ginsberg HN, Ellegård L, Jessup W, Jones PJ, Lütjohann D, Maerz W, Masana L, Silbernagel G, Staels B, Borén J, Catapano AL, De Backer G, Deanfield J, Descamps OS, Kovanen PT, Riccardi G, Tokgözoglu L, Chapman MJ, European Atherosclerosis Society Consensus Panel on Phytosterols. Plant sterols and plant stanols in the management of dyslipidaemia and prevention of cardiovascular disease. Atherosclerosis. 2014;232(2):346-60. doi: 10.1016/j.atherosclerosis.2013.11.043.PubMedUsed to support: European Atherosclerosis Society consensus: at 2 g/day, plant sterols and stanols inhibit cholesterol absorption and lower LDL cholesterol by 8 to 10%, adding to the effect of statins; the panel noted there are no randomized trials with hard clinical end points showing fewer cardiovascular events.
  7. Baumgartner S, Ras RT, Trautwein EA, Mensink RP, Plat J. Plasma fat-soluble vitamin and carotenoid concentrations after plant sterol and plant stanol consumption: a meta-analysis of randomized controlled trials. Eur J Nutr. 2017;56(3):909-923. doi: 10.1007/s00394-016-1289-7.PubMedUsed to support: Meta-analysis of randomized trials (average intake 2.5 g/day): plant sterols and stanols lowered blood beta-carotene by about 16% (10% after adjusting for cholesterol) and some other carotenoids, did not change cholesterol-adjusted tocopherol, and did not affect retinol or vitamin D; levels stayed within normal ranges.
  8. Tada H, Nomura A, Ogura M, Ikewaki K, Ishigaki Y, Inagaki K, Tsukamoto K, Dobashi K, Nakamura K, Hori M, Matsuki K, Yamashita S, Yokoyama S, Kawashiri MA, Harada-Shiba M. Diagnosis and Management of Sitosterolemia 2021. J Atheroscler Thromb. 2021;28(8):791-801. doi: 10.5551/jat.RV17052.PubMedUsed to support: Review of sitosterolemia, an inherited disorder of ABCG5 or ABCG8 in which plant sterols are absorbed and retained abnormally: patients are advised to restrict plant sterol-rich foods, and the condition may be more common than once thought.