Page updated Feb 19, 2019.
First published Aug 12, 2013.
There are number of fat loss supplements available on the market. It is quite difficult to tell, however, which ones work and which don’t. Manufacturers and promoters will always make it sound as if their products work wonders. Sadly, that isn’t the case always.
White kidney bean extract is one such ingredient that promoters say will cause weight loss. Apparently, it works in a very different way to your run-of-the-mill fat burner. It decreases the absorption of carbohydrates – thus no more deposition of excess calorie fats in the body!
Sounds too good to be true?!
Well, there’s only one way to find out – to dig up some research, to see if it indeed causes weight loss.
What is Kidney Bean Extract?
White kidney bean extract is derived from the beans of the genus Phaseolus vulgaris (Carai et al., 2009). Anecdotal evidence suggests that extract derived from the beans of this genus is capable of causing reduction in body fat and body weight.
Some believe that it causes a fall in plasma blood level as well, which over time, affects diabetes and cardiovascular diseases favourably.
The genus P. vulgaris covers all different varieties of beans. However, white kidney bean extract is most efficient as an antiobeisty agent (more of it later).
Mechanism of Action White Kidney Bean Extract
Excess carbohydrate consumption (especially of refined ones) has been linked to the development of obesity.
During digestion carbohydrates are broken down into smaller fragments called monosaccharides – the human body absorbs carbohydrates only when it is present in this monosaccharide form. Two enzymes are responsible for causing this breakdown – alpha-amylase and alpha-glucosidase.
Opposing the action of these enzymes blocks the conversion of carbohydrate molecules into monosaccharides, decreases their absorption and conversion and storage as fats in the body, thus preventing obesity.
Drugs like Acarbose inhibit both the above mentioned enzymes (Barrett & Udani, 2011). Other drugs with similar action are miglitol and voglibose.
Plant constituents derived from raspberry, strawberries, green tea and black tea have similar enzyme-inhibiting properties (McDougall & Stewart, 2005). Likewise whole grains – wheat and rice (Tundis, Loizzo, & Menichini, 2010) – also contain these elements.
Glycoproteins obtained from kidney beans are however thought to be the most efficient in blocking enzymes responsible for breakdown of carbohydrates. No wonder then, these kidney bean glycoproteins are the ones that have been most extensively researched, especially the proprietary product – Phase 2 (Barrett & Udani, 2011).
White kidney bean extract helps fight obesity and other metabolic diseases. Some mechanisms by which it works are:
- Reduction in body weight
- Reduction in body fat
- Reduction in post-prandial (after meal) blood glucose levels (helpful in diabetes and cardiovascular disease)
- Reduction in blood and liver lipids, especially triglycerides (helps fight cardiovascular diseases)
Adverse Effects Associated With the Use of Kidney Bean Extract
Numerous studies have outlined the safety of consumption of kidney bean extract (Wu, |Xu, Shen, Perricone, & Preuss, 2010; Rothacker, 2003; Celleno, Tolaini, D’Amore, Perricone, & Preuss, 2007). Some researchers have reported initial gastrointestinal discomfort. However, these mild symptoms resolve completely over the next few days of supplementation (Boivin, Flourie, Rizza, Go, & DiMagno, 1988).
Some mild adverse effects of kidney bean extract are:
- Abdominal discomfort,
- Diarrhoea, and
- Flatulence (gases)
Effective Doses of Kidney Bean Extract
According to an estimate, there are about 200 brands containing Phase 2 (proprietary preparation of kidney bean extract) as one of the ingredients in their weight loss supplement (Barrett & Udani, 2011). Most companies recommend a dosage of 1-2 capsules containing 500mg taken before every meal – that makes it a maximum of 3000mg per day.
It might of interest to note that a study conducted by a safety panel concluded that the maximum daily dose of white kidney bean extract is 10,000mg (Bridgewater, 2007).
So, the doses suggested by supplements companies should be safe for you.
What Does Science Say About Kidney Bean Extract?
Proof that kidney bean extract works abounds in scientific literature.
- An increasing number of preclinical studies support the idea that kidney bean extract may help you lose weight (Pusztai et al., 1995; Grant, Dorward, Buchan, Armour, & Pusztai, 1995; Grant, Dorward, & Pusztai, 1993; Donatucci, Liener, & Gross, 1987; Maranesi, Barzanti, Biagi, Carenini, & Gentili, 1984; Maranesi, Carenini, & Gentili, 1984; Kakade & Evans, 1966).
- Some researchers have used the indirect method of hydrogen breath testing to prove the inhibitory effect of kidney bean extract on carbohydrate metabolism, and therefore reduction in absorption of carbohydrates and loss of body weight (Brummer, Karibe, & Stockbrugger, 1993; Strocchi, Corazza, Ellis, Gasbarrini, & Levitt, 1993; Strocchi et al., 1997).
Unbroken and unabsorbed carbohydrates pass as such into the large intestine where they are acted upon by colonic bacteria. These bacteria convert carbohydrates into organic acids, carbon dioxide and hydrogen. Some amount of this hydrogen in expelled through breath. Needless to say, more the hydrogen content in your breath, lesser the carbohydrate breakdown in your small intestines.
To conclude, if you are looking for a fat-burner to increase energy levels in addition to causing weight loss, this one is not for you. However, considering the ‘proven’ effectiveness of white kidney bean extract and its safety profile, we would recommend you definitely give it a try. But watch out for those ingredient amounts in your diet pill of choice and ensure there is sufficient to actually work!
- Barrett, M. L. & Udani, J. K. (2011). A proprietary alpha-amylase inhibitor from white bean (Phaseolus vulgaris): a review of clinical studies on weight loss and glycemic control. Nutr.J, 10, 24. Online Resource
Boivin, M., Flourie, B., Rizza, R. A., Go, V. L., & DiMagno, E. P. (1988). Gastrointestinal and metabolic effects of amylase inhibition in diabetics. Gastroenterology, 94, 387-394. Online Resource
- Bridgewater, N. (2007). Evaluation of the Generally Recognized as Safe (GRAS) status of Phase 2 white bean (Phaseolus vulgaris) extract. NJ, Cantox Health Sciences International. Online Resource
- Brummer, R. J., Karibe, M., & Stockbrugger, R. W. (1993). Lactose malabsorption. Optimalization of investigational methods. Scand.J Gastroenterol.Suppl, 200, 65-69. Online Resource
- Carai, M. A., Fantini, N., Loi, B., Colombo, G., Riva, A., & Morazzoni, P. (2009). Potential efficacy of preparations derived from Phaseolus vulgaris in the control of appetite, energy intake, and carbohydrate metabolism. Diabetes Metab Syndr.Obes, 2, 145-153. Online Resource
- Celleno, L., Tolaini, M. V., D’Amore, A., Perricone, N. V., & Preuss, H. G. (2007). A Dietary supplement containing standardized Phaseolus vulgaris extract influences body composition of overweight men and women. Int J Med Sci., 4, 45-52. Online Resource
- Donatucci, D. A., Liener, I. E., & Gross, C. J. (1987). Binding of navy bean (Phaseolus vulgaris) lectin to the intestinal cells of the rat and its effect on the absorption of glucose. J Nutr., 117, 2154-2160. Online Resource
- Grant, G., Dorward, P. M., Buchan, W. C., Armour, J. C., & Pusztai, A. (1995). Consumption of diets containing raw soya beans (Glycine max), kidney beans (Phaseolus vulgaris), cowpeas (Vigna unguiculata) or lupin seeds (Lupinus angustifolius) by rats for up to 700 days: effects on body composition and organ weights. Br.J Nutr., 73, 17-29. Online Resource
- Grant, G., Dorward, P. M., & Pusztai, A. (1993). Pancreatic enlargement is evident in rats fed diets containing raw soybeans (Glycine max) or cowpeas (Vigna unguiculata) for 800 days but not in those fed diets based on kidney beans (Phaseolus vulgaris) or lupinseed (Lupinus angustifolius). J Nutr., 123, 2207-2215. Online Resource
- Kakade, M. L. & Evans, R. J. (1966). Growth inhibition of rats fed raw navy beans (Phaseolus vulgaris). J Nutr., 90, 191-198. Online Resource
- Maranesi, M., Barzanti, V., Biagi, P. L., Carenini, G., & Gentili, P. (1984). Nutritional studies on anti-alpha-amylase: II) Lipid metabolism investigation: fatty acid composition of organs and tissues. Acta Vitaminol.Enzymol., 6, 347-353. Online Resource
- Maranesi, M., Carenini, G., & Gentili, P. (1984). Nutritional studies on anti alpha-amylase: I) Influence on the growth rate, blood picture and biochemistry and histological parameters in rats. Acta Vitaminol.Enzymol., 6, 259-269. Online Resource
- McDougall, G. J. & Stewart, D. (2005). The inhibitory effects of berry polyphenols on digestive enzymes. Biofactors, 23, 189-195. Online Resource
- Pusztai, A., Grant, G., Duguid, T., Brown, D. S., Peumans, W. J., Van Damme, E. J. et al. (1995). Inhibition of starch digestion by alpha-amylase inhibitor reduces the efficiency of utilization of dietary proteins and lipids and retards the growth of rats. J Nutr., 125, 1554-1562. Online Resource
- Rothacker, D. (2003). Reduction in body weight with a starch blocking diet aid: StarchAway comparsion with placebo. Leiner Health Products. Online Resource
- Strocchi, A., Corazza, G., Ellis, C. J., Gasbarrini, G., & Levitt, M. D. (1993). Detection of malabsorption of low doses of carbohydrate: accuracy of various breath H2 criteria. Gastroenterology, 105, 1404-1410. Online Resource
- Strocchi, A., Corazza, G. R., Anania, C., Benati, G., Malservisi, S., Cherchi, M. V. et al. (1997). Quality control study of H2 breath testing for the diagnosis of carbohydrate malabsorption in Italy. The “Tenue Club” Group. Ital.J Gastroenterol.Hepatol., 29, 122-127. Online Resource
- Tundis, R., Loizzo, M. R., & Menichini, F. (2010). Natural products as alpha-amylase and alpha-glucosidase inhibitors and their hypoglycaemic potential in the treatment of diabetes: an update. Mini.Rev Med Chem., 10, 315-331. Online Resource
- Wu, X., |Xu, X., Shen, J., Perricone, N., & Preuss, H. (2010). Enhanced weight loss from a dietary supplement containing standardized Phaseolus vulgaris extract in overweight men and women. Journal of Applied Research, 73-79. Online Resource
About the author: Rachel Butler
Rachel has been with us since we launched back in 2012.
Rachel has reviewed countless products over the years, and has written many articles offering sound advice. Her professional opinions are widely respected.
Rachel graduated a BSc in Clinical Science from the University of Leicester, U.K.
She lives in York with her husband and young daughter and their dog, a little terrier named Betsy.
Disclaimer: Our reviews and investigations are based on extensive research from the information publicly available to us and consumers at the time of first publishing the post. Information is based on our personal opinion and whilst we endeavour to ensure information is up-to-date, manufacturers do from time to time change their products and future research may disagree with our findings. If you feel any of the information is inaccurate, please contact us and we will review the information provided.
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