GSTM1 and inflammatory bowel disease: In two case series of IBD patients with mild-to-moderate IDA (n = 76, including 46 intolerant to ferrous sulfate), SI (30–60 mg/day for 2–3 months) was shown to be efficacious in increasing Hb concentrations (+0.6 g/dL), as well as ferritin and TSAT levels, with very few gastrointestinal side effects [98,99] (Supplementary Materials, Table S3).