Barley is one of the gassier grains you can eat. It contains a combination of soluble fiber and fermentable sugars that your gut bacteria break down enthusiastically, producing gas in the process. If you’ve noticed more bloating or flatulence after eating barley soup, bread, or pearl barley as a side dish, the grain itself is a very likely culprit.
Why Barley Produces Gas
Two things in barley drive gas production: its high fiber content and a group of short-chain carbohydrates called FODMAPs. Both reach your large intestine largely undigested, where trillions of bacteria ferment them. That fermentation releases hydrogen, methane, and carbon dioxide, which is exactly what you feel as bloating and flatulence.
Barley’s fiber profile is unusually balanced between soluble and insoluble types. The soluble fibers, particularly beta-glucan and arabinoxylan, dissolve in water and form a gel-like substance in your gut. While they’re great for cholesterol and blood sugar, they also act as a feast for gut bacteria. Arabinoxylan in particular has strong prebiotic properties, meaning it actively encourages bacterial growth and, by extension, gas production. The insoluble fibers (cellulose and hemicellulose) move through your system more intact, but they still add bulk that can slow transit and give bacteria more time to ferment everything else.
Barley’s FODMAP Problem
Beyond fiber, barley is classified as a high-FODMAP food. FODMAPs are specific types of carbohydrates that are poorly absorbed in the small intestine. In barley, the main offenders are fructans, the same type of fermentable sugar found in wheat, rye, onions, and garlic. Barley and other cereals contain between 1.4 and 3.6 grams of fructo-oligosaccharides per 100 grams of dry weight, which is enough to trigger symptoms in sensitive people even at moderate serving sizes.
Fructans work a bit differently from regular fiber. They draw water into the intestine through osmotic activity while simultaneously being fermented by bacteria. This double action, fluid retention plus gas production, is why barley can cause not just flatulence but also that uncomfortable tight, distended feeling in your abdomen. For people with irritable bowel syndrome (IBS), even small amounts of fructan-rich foods can set off significant bloating, cramping, and changes in bowel habits.
It Might Be the Fructans, Not the Gluten
Barley contains gluten, and many people who react to it assume gluten is the problem. That’s sometimes true, particularly for people with celiac disease, where gluten triggers an immune response that damages the intestinal lining. But research has complicated this picture significantly.
In double-blind, placebo-controlled trials, people who believed they were sensitive to gluten did not show worsened symptoms when gluten was added to an otherwise low-FODMAP diet. Fructans, on the other hand, reliably triggered bloating, abdominal pain, and diarrhea in the same patients. Two separate crossover studies reached the same conclusion: for many people who think they react to gluten-containing grains, the fructans are the more likely trigger.
This distinction matters because it changes what you avoid and what you don’t. If fructans are your issue rather than gluten, you might tolerate sourdough wheat bread (where fermentation breaks down fructans) while still reacting to barley. It also means other high-fructan foods like onions and garlic could be bothering you too.
How Barley Compares to Other Grains
Among common grains, barley sits toward the gassier end of the spectrum. Wheat also contains fructans and produces significant fermentation gases, putting it in roughly the same category. White rice, by contrast, is one of the least gas-producing grains because it’s low in both fiber and FODMAPs. Oats contain beta-glucan like barley but lack the fructan load, making them a middle-ground option for most people.
The form of barley matters too. Hulled barley (the whole grain with only the outermost husk removed) retains the most fiber and will produce the most gas. Pearl barley has been polished to remove the bran layer, which reduces fiber content and may cause somewhat less bloating. Barley flour in baked goods can still trigger symptoms because the fructans remain intact through baking.
Reducing Gas From Barley
If you like barley but not the aftermath, a few strategies can help. The simplest is portion control. Many people tolerate small amounts of high-FODMAP foods without trouble. A quarter cup of cooked barley as part of a mixed dish is far less likely to cause problems than a full bowl of barley soup.
Soaking barley before cooking and discarding the soaking water can leach out some of the water-soluble fructans and oligosaccharides. This won’t eliminate them entirely, but it reduces the load your gut bacteria have to process. Cooking barley thoroughly also helps break down some of the resistant starches that contribute to fermentation.
Over-the-counter digestive enzyme supplements containing alpha-galactosidase (the active ingredient in products like Beano) can reduce gas from fermentable carbohydrates. In controlled studies, a higher dose of alpha-galactosidase taken with a meal rich in fermentable carbs significantly reduced both hydrogen production in the gut and the severity of flatulence. Lower doses still improved the overall symptom picture, just less dramatically. These enzymes work best when taken at the start of a meal rather than after symptoms have already begun.
Gradually increasing your barley intake over a couple of weeks, rather than going from none to a large serving, gives your gut microbiome time to adapt. The bacterial populations that ferment fiber do shift over time, and a more adapted microbiome tends to produce less noticeable gas from the same amount of food.
When Barley Gas Points to Something Else
Occasional gas after eating barley is normal and expected given its composition. But if barley consistently causes severe bloating, pain, diarrhea, or symptoms that last well beyond the meal, it’s worth considering whether something more specific is going on. Celiac disease affects roughly 1 in 100 people and causes an inflammatory reaction to the gluten proteins in barley, wheat, and rye. Symptoms go well beyond gas and can include fatigue, weight loss, nutrient deficiencies, and skin rashes.
People with IBS are particularly reactive to the fructans in barley. A low-FODMAP elimination diet, where you remove all high-FODMAP foods for several weeks and then reintroduce them one at a time, is the most reliable way to identify whether barley’s fructans are a specific trigger for you. This approach works best with guidance from a dietitian who specializes in digestive health, since FODMAPs appear in a wide range of foods that aren’t always obvious.