CanPrev Iron Bis-Glycinate - 25 mg - An iron supplement that contains the preferred bisglycinate form, a chelated iron that is easy to absorb, gentle on the stomach and doesn’t cause gastrointestinal upset. Some iron supplements may cause uncomfortable side effects like constipation, diarrhea, stomach upset and nausea. CanPrev’s Iron Bis-Glycinate 25 boosts iron and lets the body stay upset free.