In this trial, approximately 81 children (mean age just under 10) were assigned to either the psyllium or placebo group, with the severity of symptoms assessed at baseline and after 4 weeks by the IBS severity scoring scale (IBS-SSS). Psyllium supplementation was shown to not only significantly reduce the mean IBS-SSS values but also substantially increase the number of children achieving remission, 43.9% vs. 9.7% with placebo. Also calculated was the number needed to treat (NNT), i.e., the number of children that would benefit per the number of children treated; with psyllium the NNT was only 3, a very impressive finding.
A previously published controlled trial with children (mean age 13) also found benefits to supplementation. After excluding children who experienced large symptom reduction from dietary restrictions (specific carbohydrate restriction), 84 children were given either psyllium or a placebo for 6 weeks. Those receiving psyllium had a reduction in the number of episodes of abdominal pain, without any change in breath hydrogen, methane production, gut permeability, or microbiome composition. In this trial, children ages 7-11 received 6g of psyllium per day while those ages 12-18 received 12g. For adults, it's generally recommended to take 20g of psyllium husk, along with a minimum of 500mL of water.