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White Kidney Bean Extract (Phaseolus vulgaris)
A bean-derived alpha-amylase inhibitor sold as a 'carb blocker.' The mechanism is real (it slows starch digestion), but the human evidence is thin: a meta-analysis found NO statistically significant weight loss versus placebo, and the positive trials are small, short, and often industry-linked.
What the evidence says
White Kidney Bean Extract doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from high-quality meta-analyses and randomised trials published 2007–2026.
Based on 6 studies · 2 meta-analyses · 4 RCTs
Confidence
High confidenceBy outcome
The amylase-inhibiting mechanism is real, but a meta-analysis found no significant weight loss versus placebo and rated every trial as seriously flawed, keeping the score low.
4 trials ongoing or recruiting · 8 completed on ClinicalTrials.gov
Registered trials show research momentum for White Kidney Bean Extract, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Oct 2026
White kidney bean extract (Phaseolus vulgaris) contains a glycoprotein that inhibits pancreatic alpha-amylase, the enzyme that breaks dietary starch into absorbable sugars. The marketing pitch — block carbs, lose weight — has a plausible mechanism, but the clinical evidence does not hold up well.
The most rigorous synthesis (Onakpoya 2011) pooled six trials and found a statistically NON-significant difference in weight loss versus placebo, with all included RCTs carrying 'serious methodological flaws'; it found a significant but heterogeneous body-fat reduction and concluded that larger, better trials are needed before any firm claim can be made.
Individual positive trials exist (e.g. Celleno 2007, Grube 2014), but they are short (30 days to 12 weeks), small, use proprietary extracts, and several involve authors affiliated with supplement interests. So the honest read is: a real enzyme effect, weak and inconsistent clinical proof of meaningful weight loss.
A bean glycoprotein inhibits pancreatic alpha-amylase, slowing the breakdown of starch into absorbable glucose so some carbohydrate passes undigested.
Undigested starch may act like resistant starch in the lower gut — proposed to reduce caloric availability and feed gut bacteria.
How White Kidney Bean Extract works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Use caution and monitor blood glucose — additive glucose-lowering is possible.
Not established as safe — avoid.
By slowing carbohydrate absorption, it could add to the glucose-lowering effect of antidiabetic drugs (especially other alpha-glucosidase/amylase inhibitors) — monitor for hypoglycemia.
Tip: Reduce dose; undigested starch fermenting in the gut is the cause
Tip: Take with smaller starch portions
White Kidney Bean Extract has an evidence score of 3/10 — emerging evidence based on 6 indexed studies, including 1 meta-analysis. A bean-derived alpha-amylase inhibitor sold as a 'carb blocker.' The mechanism is real (it slows starch digestion), but the human evidence is thin: a meta-analysis found NO statistically significant weight loss versus placebo, and the positive trials are small, short, and often industry-linked. Representative study: PMID 22844674.
The commonly studied dose of White Kidney Bean Extract is 445 mg of standardized Phaseolus vulgaris extract before starch-containing meals, the dose of the one cited trial that states one. Label products go up to 1,500 mg, above that dose. Proprietary extracts differ in potency and there is no consensus efficacy dose. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
The best time to take White Kidney Bean Extract is with meals. Take it with food. Must be taken shortly before a starch-rich meal to inhibit amylase acting on that meal's carbohydrate.
White Kidney Bean Extract has a safety rating of "moderate". That is a category, not a measure of individual risk, and there are precautions worth knowing. Reported side effects include flatulence, bloating, loose stools, abdominal discomfort. How often they occur is not established for all of them. Use caution if any of these apply to you: Pregnancy/breastfeeding (not established as safe).
Smoking status: not checked. AREDS2 Formula: what these mean for you changes depending on whether you smoke or used to, and you have not told us. That check was skipped.
Berberine
Likely helpsActivates AMPK to regulate blood sugar, improve insulin sensitivity, and support lipid metabolism. Its only head-to-head trial with metformin cited here was a 36-person pilot, which does not show it can replace metformin.
Caffeine
Probably helpsBlocks adenosine receptors to boost alertness, reaction time, and endurance — an umbrella review of 21 meta-analyses found it ergogenic for endurance, strength and power.
Alpha Lipoic Acid
Likely helpsUniversal antioxidant that works in both water and fat, supporting blood sugar control, nerve health, and cellular energy.
AREDS2 Formula
Too few graded studiesThe one supplement formula with randomised-trial evidence for slowing age-related macular degeneration — but only in people who already have intermediate AMD or advanced AMD in one eye. It does not prevent AMD, and it does not restore vision that has been lost. AREDS2's own contribution was to swap beta-carotene out, because beta-carotene raises lung cancer risk in smokers and former smokers.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 6 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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