White kidney beans extract
Also known as: White kidney bean extract, WKBE, Phase 2, Glucosanol, Glycolite, PhaseLite, Starchlite, Phaseolus vulgaris L.
Overview
White kidney bean extract (WKBE) is a dietary supplement derived from Phaseolus vulgaris L., commonly known as the white kidney bean. Its primary active components are alpha-amylase inhibitors, proteins that interfere with the enzymatic breakdown of complex carbohydrates in the digestive tract. WKBE is primarily utilized for weight management, as it reduces the absorption of calories from starch by inhibiting alpha-amylase, the enzyme responsible for starch digestion. It is typically consumed before meals to minimize carbohydrate digestion and absorption. Research on WKBE is moderately extensive, with several randomized controlled trials (RCTs) and meta-analyses supporting its modest efficacy in weight management. The evidence quality is generally moderate, indicating that WKBE can be a useful adjunct in weight management strategies, particularly for individuals consuming carbohydrate-rich diets. While short-term studies are prevalent, long-term research is still limited.
Benefits
WKBE supplementation has demonstrated modest but statistically significant reductions in body weight and fat mass. A meta-analysis indicated an average weight loss of approximately 2.6 kg over 28 to 84 days when compared to placebo, especially when consumed alongside a high-carbohydrate diet. Another randomized controlled trial involving 81 overweight or obese subjects showed dose-dependent reductions in body weight, fat mass, BMI, waist, hip, and thigh circumference over 12 weeks with doses of 700 mg to 1000 mg taken three times daily before meals. These effects are most pronounced in overweight and moderately obese adults who consume carbohydrate-rich diets. While some studies suggest potential improvements in cardiometabolic markers such as blood glucose, triglycerides, cholesterol, and blood pressure, these effects are less consistently observed and require further investigation. The observed weight loss effects are generally small to moderate (around 2-3 kg), making WKBE a clinically meaningful adjunct to calorie restriction rather than a standalone solution. Benefits are typically noticeable within 4 to 12 weeks of consistent supplementation.
How it works
White kidney bean extract (WKBE) primarily functions by inhibiting alpha-amylase, an enzyme crucial for hydrolyzing starch into absorbable sugars within the digestive system. By blocking alpha-amylase activity, WKBE effectively reduces the digestion and subsequent absorption of complex carbohydrates, thereby decreasing the caloric uptake from starch-containing foods. The extract contains specific alpha-amylase inhibitor proteins with molecular weights ranging from 10–60 kDa. This inhibition leads to increased starch excretion and helps to mitigate postprandial blood glucose spikes. Additionally, some emerging evidence suggests that WKBE may influence the composition of gut microbiota, which could contribute to its broader metabolic effects.
Side effects
White kidney bean extract (WKBE) is generally well-tolerated and considered safe when used at typical clinical trial dosages, up to 3000 mg per day. The most common side effects, occurring in over 5% of users, are mild gastrointestinal symptoms such as bloating, gas, or diarrhea. These symptoms are typically a result of undigested starch fermenting in the colon. Uncommon side effects, reported in 1-5% of users, are not significant, and no serious adverse events have been linked to WKBE supplementation in documented studies. While no major drug interactions have been identified, caution is advised for individuals with diabetes due to WKBE's potential to influence blood glucose levels; close monitoring is recommended. WKBE is contraindicated for individuals with known legume allergies or those with digestive disorders that are sensitive to increased starch fermentation. Data on its use in pregnant or lactating women are limited, so it should be used with caution in these populations.
Dosage
For optimal efficacy, the recommended dosage of white kidney bean extract (WKBE) ranges from 700 mg to 1000 mg, taken three times daily, totaling 2100–3000 mg per day. Some studies have shown efficacy with a minimum effective dose of approximately 500 mg taken before meals. To maximize alpha-amylase inhibition, WKBE should be taken 15–30 minutes before carbohydrate-rich meals. The maximum safe dose observed in clinical studies is up to 3000 mg per day. It is crucial to use standardized extracts with verified alpha-amylase inhibitor activity, such as Phase 2. Due to the proteinaceous nature of the inhibitor, formulations may include enteric coatings or be consumed with food to protect against gastric degradation and ensure optimal absorption. No specific cofactors are identified as necessary for its action.
FAQs
Does WKBE cause weight loss on its own?
WKBE induces modest weight loss primarily by reducing carbohydrate absorption; it is most effective when combined with calorie restriction and a high-carbohydrate diet.
Is it safe to take long term?
Short- to medium-term use (up to 12 weeks) of WKBE is considered safe; however, data on its long-term safety beyond this period are currently limited.
Can it affect blood sugar?
Yes, WKBE may reduce postprandial blood glucose spikes by inhibiting carbohydrate digestion, so diabetic patients should monitor their glucose levels closely.
Are there any dietary restrictions?
WKBE is most effective when consumed with high-carbohydrate meals; its benefits may be diminished if you are following a low-carbohydrate diet.
Does it cause digestive discomfort?
Mild gastrointestinal symptoms like bloating, gas, or diarrhea can occur due to undigested starch, but these effects are usually transient and mild.
Research Sources
- https://www.nature.com/articles/s41598-024-63443-8 – This randomized controlled trial (RCT) with 81 overweight/moderately obese adults demonstrated that 700–1000 mg of WKBE taken three times daily led to dose-dependent reductions in body weight, fat mass, BMI, and various body circumferences over 12 weeks. The study was a high-quality RCT with placebo control and blinding, though it used a proprietary extract and involved calorie restriction as a co-intervention.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7284421/ – This systematic review analyzed multiple RCTs (n≥30 per group) over durations of 28–84 days, finding an average weight loss of approximately 2.6 kg with WKBE. It also noted improvements in metabolic markers and potential effects on gut microbiota. The review was of moderate quality, with consistent findings despite heterogeneity in study designs and short durations.
- https://pubmed.ncbi.nlm.nih.gov/29677119/ – This meta-analysis, encompassing multiple RCTs with a total of over 200 participants, found significant reductions in body weight and fat mass with Phase 2 WKBE supplementation over variable durations (4–12 weeks). The study was a high-quality meta-analysis supporting the efficacy of WKBE, though it noted variability in doses and formulations across the included smaller studies.
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