In a small 1994 study, researchers served 19 volunteers a bowl of meatless chili on two occasions, a week apart. With one meal, the volunteers took eight drops of an enzyme called alpha-galactosidase. With the other, a placebo. Then they recorded every time they passed gas over the next six hours.
It sounds like the setup for a joke, but it was a serious question, and it still is for anyone who loves beans and doesn't love what happens afterward. Here's what that study and later ones found.
Why beans cause gas in the first place
Beans, lentils and chickpeas contain carbohydrates called galacto-oligosaccharides, or GOS. Their sugars are joined by a bond that human digestive enzymes can't break. So they travel intact to the colon, where gut bacteria ferment them and produce gas (Hillilä et al., 2016).
GOS belong to the same family of fast-fermenting carbohydrates, known as FODMAPs, as inulin. Here's why that family matters for bloating. Alpha-galactosidase is the enzyme that can break the bond in GOS. Taken with food, the idea is that it digests some of these sugars before bacteria get to them.
What the studies found
The chili study. With the enzyme, volunteers had significantly fewer episodes of flatulence per hour over the six hours. There was no difference in bloating or pain (Ganiats et al., 1994).
A big bean meal with breath testing. In a double-blind study, 8 healthy volunteers ate 420 grams of cooked beans with 300 GalU or 1,200 GalU of alpha-galactosidase, or a placebo. The higher dose significantly reduced hydrogen in the breath, a marker of fermentation, as well as the severity of flatulence. Both doses significantly reduced the total symptom score (Di Stefano et al., 2007).
People with IBS who react to GOS. In a double-blind crossover trial, 31 people with IBS followed a low-FODMAP diet and then ate foods high in GOS for three days, with a full dose of the enzyme (300 GALU), a half dose or a placebo. Twenty-one of them reacted to GOS with a clear rise in symptoms. In that group, the full dose significantly reduced overall symptoms and bloating. Breath hydrogen, however, didn't differ between the full dose and placebo (Tuck et al., 2018).
Daily use for IBS over 12 weeks. A trial gave 125 people with IBS and bloating or flatulence the enzyme or a placebo with meals for 12 weeks. The enzyme showed only a trend toward improvement, and the authors found no evidence to support routine use in IBS. More people dropped out of the enzyme group (18 versus 7), often citing abdominal pain or diarrhea (Hillilä et al., 2016).
What this adds up to
It targets one thing. Alpha-galactosidase breaks down GOS. It isn't designed to help with gas from lactose, inulin or sugar alcohols.
It looks best meal by meal. The positive studies tested the enzyme with specific GOS-rich meals, not as a general daily treatment for IBS.
Dose matters. In the bean study, only the higher dose significantly reduced breath hydrogen and flatulence severity (Di Stefano et al., 2007).
The studies are small. Two of the four trials had fewer than 20 people. Treat the results as promising, not settled.
Beans may bother you less than you expect
There's another encouraging finding. In three feeding studies where adults ate half a cup of beans a day for 8 or 12 weeks, fewer than half reported more flatulence from pinto or baked beans in the first week, and only 19% did with black-eyed peas. Between 3% and 11% reported more gas even on control diets without beans. The authors concluded that concerns about gas from beans may be exaggerated, and that responses vary by person and bean type (Winham and Hutchins, 2011).
Starting with small portions and building up slowly is a reasonable, low-risk approach either way.
How to test it yourself
Pick one GOS-rich meal that reliably bothers you, such as chili, hummus or lentil soup.
Take the enzyme with your first bites, following the label dose.
On another day, eat the same meal without it.
Rate gas and bloating from 0 to 10 about four hours after each meal, and repeat the comparison at least twice.
Product labels list strength in GalU or similar units, which makes doses easier to compare. One option is Meal Enzymes from noonlife, which includes alpha-galactosidase along with protease, amylase, lipase and lactase.
A few cautions
Alpha-galactosidase products commonly carry label warnings for people with galactosemia, and advise people with diabetes to check with a doctor first.
If bloating is new and happens most days, especially with pelvic pain, early fullness or urinary urgency, see a doctor rather than treating it yourself.
Blood in the stool, weight loss you can't explain or anemia always need a medical check.
Sources
Ganiats TG, Norcross WA, Halverson AL, Burford PA, Palinkas LA. Does Beano prevent gas? A double-blind crossover study of oral alpha-galactosidase to treat dietary oligosaccharide intolerance. J Fam Pract. 1994;39(5):441-5. PMID 7964541
Di Stefano M, Miceli E, Gotti S, Missanelli A, Mazzocchi S, Corazza GR. The effect of oral alpha-galactosidase on intestinal gas production and gas-related symptoms. Dig Dis Sci. 2007;52(1):78-83. PMID 17151807
Tuck CJ, Taylor KM, Gibson PR, Barrett JS, Muir JG. Increasing symptoms in irritable bowel symptoms with ingestion of galacto-oligosaccharides are mitigated by α-galactosidase treatment. Am J Gastroenterol. 2018;113(1):124-134. PMID 28809383
Hillilä M, Färkkilä MA, Sipponen T, Rajala J, Koskenpato J. Does oral α-galactosidase relieve irritable bowel symptoms? Scand J Gastroenterol. 2016;51(1):16-21. PMID 26133538
Winham DM, Hutchins AM. Perceptions of flatulence from bean consumption among adults in 3 feeding studies. Nutr J. 2011;10:128. PMID 22104320
This article is for general information and isn't medical advice. Talk to your healthcare provider before using an enzyme supplement if you have diabetes, galactosemia or another medical condition.
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