NutraBio uses Albion Minerals Ferrochel Iron (ferrous bisglycinate chelate) an advanced, more bioavailable and patented form of the essential mineral iron. While most iron supplements aren't easily absorbed and cause gastric upset, Ferrochel iron is chelated with the amino acid glycine to produce small, organic molecules that pass easily through the digestive tract and are gentler on the digestive system. Iron is needed to carry oxygen throughout the body. Additional Iron may be needed for menstruating women, individuals consuming limited animal protein, and vegetarians. NutraBio Iron Chelate is easily absorbed and gentler on the stomach than other iron supplements.