Alpha-galactosidase for gas and bloating

Alpha-galactosidase is the enzyme in products like Beano, marketed to reduce gas from beans, lentils, and other foods containing raffinose-family oligosaccharides — carbohydrates the human gut can't break down on its own, which get fermented by colon bacteria into gas instead.

What the evidence actually shows

The picture is genuinely mixed, not a clean yes or no:

  • A randomized, double-blind, placebo-controlled trial in children found alpha-galactosidase significantly reduced overall distress and the number of days with moderate-to-severe bloating compared to placebo.
  • A more recent randomized crossover trial in adults with irritable bowel syndrome (IBS) found alpha-galactosidase was not superior to placebo for reducing gas or other symptoms after a high-oligosaccharide meal.
  • Several of the earlier supportive trials were small, and much of the foundational research dates back to the 1990s — a real limitation when weighing how confident to be in the effect.

Put plainly: some people report real relief, some controlled trials support that, and at least one well-designed recent trial in IBS patients specifically did not find a benefit. This is a case where "it worked for me" and "the trial data is inconsistent" can both be true at once.

Who it's marketed to, and a reasonable read

Alpha-galactosidase is generally considered low-risk as an over-the-counter product, taken with the first bite of a gas-producing meal. Given the mixed trial results, it's reasonable to think of it as worth trying for occasional gas from specific foods (beans, cruciferous vegetables), rather than a guaranteed fix — and it isn't a treatment for IBS itself, which has other underlying mechanisms.

Not medical advice This page summarizes published trial results in general terms. It is not a diagnosis or a personal treatment recommendation. See our medical disclaimer.

Sources: Ohtsuka et al., "Efficacy and tolerability of α-galactosidase in treating gas-related symptoms in children: a randomized, double-blind, placebo controlled trial", PubMed 24063420; Böhn et al., "Acute effects of the enzyme α-galactosidase on gastrointestinal symptoms in irritable bowel syndrome patients", PubMed 33619835. Last reviewed: July 28, 2026.