Legumes, more commonly known as beans -- such as garbanzo, pinto, and kidney beans -- are a great source of low-fat protein. Legumes are also rich in nutrients such as iron and folate, and because they are high in soluble fiber, legumes are known to reduce cholesterol levels. Unfortunately, every rose has a thorn, and for legumes the thorn is both painful and embarrassing -- substantial gas and bloating. If you would like to enjoy legumes in your diet, there are ways to reduce the gassy side effect.
Double Trouble -- Sugar & Fiber
Legumes contain a high concentration of a complex sugar called raffinose. Other gas-producing foods that contain raffinose in smaller amounts include cabbage, cauliflower, Brussels sprouts, broccoli, and asparagus. In addition to their high concentration of raffinose, legumes are also an excellent source of soluble fiber, which may also increase gas.
A Lack of Enzymes
Humans produce specific digestive enzymes which help break down foods into absorbable nutrients. Unfortunately, humans are not able to produce the enzyme needed to break down fiber, nor do they produce the enzyme alpha-galactosidase, which is necessary to break down raffinose. Dietary fiber and raffinose are not broken down during digestion, and instead are delivered intact to the large intestine. This is when the discomfort of fermentation begins.
Some People Have More Gas
Because legumes have high levels of both raffinose and soluble fiber, they cause a large increase in colonic fermentation which produces copious gas for many individuals. But not everyone experiences increased gas when they eat legumes. One theory is that the type and amount of bacteria in your gut affects how much fermentation takes place. In a 2008 report in "BMC Microbiology," researchers found that when they fermented soy milk with a certain strain of lactobacillus, rats fed the fermented soy milk had a significant reduction in gas emissions when compared to rats fed soy milk without the lactobacillus. This research suggests that certain strains of bacteria may be able to reduce the gas-causing effects of legumes; however, more research needs to be done.
Strategies to Reduce Flatulence
Try one or more of these strategies to reduce gas caused from beans. Soak dried beans overnight, rinse thoroughly and cook them in fresh water to reduce raffinose levels. If you eat canned beans, rinse the beans thoroughly before eating them. Try a dietary enzyme containing alpha-galactosidase, such as Beano or Bean-zyme when eating foods high in raffinose. If you suspect a food may cause gas, eat it in small amounts. Finally, according to an UpToDate patient information guide for gas and bloating, if you experience unpleasant smelly gas due to sulfur, try taking bismuth-subsalicylate (Peptol-Bismol). Always read the dosage recommendations and warnings on over-the-counter medication; if you have questions check with your pharmacist or doctor.
References
- NIDDK: Gas in the Digestive Tract
- UpToDate: Patient Information -- Gas & Bloating
- "BMC Microbiology"; Ability of Lactovacillus Fermentum to Overcome Host Alpha-galactosidase Deficiency, as Evidenced by Reduction of Hydrogen Excretion in Rats Consuming Soy Alpha-galacto-oligosaccharides; Le Blanc et al; 2008
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