Supplement analysis backed by scientific evidence · PT

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Limited evidenceWeight management

White Kidney Bean Extract

White kidney bean extract really does inhibit starch-digesting amylase, but the weight effect in humans is small and the trial base is weak: an early meta-analysis found no significant weight difference versus placebo, and a more recent one found about 1.6 kg — from short, mostly small studies.

What the science says

  • Short-term weight loss Limited evidence

    A 2026 meta-analysis reported reductions in body weight (-1.62 kg; 95% CI -1.99 to -1.25), BMI (-0.58 kg/m²), fat mass (-1.17 kg) and waist circumference (-1.58 cm) versus placebo. An earlier meta-analysis of 6 RCTs found no significant weight difference (-1.77 kg; 95% CI -3.33 to 0.33) and judged that every included trial had serious methodological flaws. The direction is consistent; the certainty is not.

  • Reduces body fat Limited evidence

    The 2011 pooled analysis did find a significant fat-mass reduction favouring Phaseolus vulgaris (-1.86 kg; 95% CI -3.39 to -0.32), echoed by the 2026 analysis. Heterogeneity was evident in both, and body composition was rarely the primary endpoint.

  • Blocks starch digestion Moderate evidence

    Phaseolamin is a genuine alpha-amylase inhibitor and reduces the post-meal glucose spike after a starch load in acute human studies. However, the fraction of dietary starch actually blocked in a normal mixed meal is far smaller than "carb blocker" marketing implies, and inhibition does not extend to sugars or fat.

  • Product potency varies enormously Limited evidence

    Amylase-inhibiting activity per gram differs by an order of magnitude between commercial extracts, and few products declare inhibitor units. Two products at the same milligram dose can deliver very different biological activity, which is a major source of the inconsistency between trials.

Dosage & safety

Studied doseTrials used roughly 445-3,000 mg/day of standardised Phaseolus vulgaris extract, most commonly 1,000-3,000 mg/day, taken immediately before starch-containing meals, for 4-12 weeks. Timing matters: taken away from a meal it has nothing to act on.
SafetyThe predictable effects come from undigested starch reaching the colon: flatulence, bloating, abdominal cramping and loose stools, which are dose-related and often improve with a lower starting dose. Only properly processed commercial extracts should be used — raw or under-processed kidney bean material contains phytohaemagglutinin, a lectin that causes severe vomiting and diarrhoea. There is no safety data beyond about 12 weeks. People taking diabetes medication should monitor glucose, since blunting postprandial glucose can compound drug effects. Avoid in pregnancy and breastfeeding for lack of data, and in anyone with a history of intestinal obstruction or significant malabsorption.

Scientific references

Where to buy

Nutricost, White Kidney Bean, 120 Capsules (650 mg per Capsule)

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