The Science
Barley is high in fiber (3.8g/100g, 14% DV), which can be beneficial for some IBS subtypes (e.g., constipation-predominant) by promoting regular bowel movements, but for others (especially diarrhea-predominant or those with fructose/FODMAP sensitivity), the fiber and carbohydrates may trigger bloating, gas, and cramping. The moderate protein and mineral content (iron, magnesium, zinc) supports overall nutrition but does not directly address IBS symptoms. Individual tolerance varies widely, so it is not universally good or bad.
Recommendation
If you have IBS, start with a small portion (e.g., 1/4 cup cooked) and monitor symptoms; choose low-FODMAP grains like white rice or quinoa if barley causes discomfort.