Iron 36 mg Double Strength Veg Capsules - Essential Mineral Iron is an essential mineral that plays central roles in energy production, immune system function, and neurological health. Iron is an essential component of haemoglobin, a molecule that transports oxygen to the cells of the body, and myoglobin, which binds oxygen used in muscle tissues. NOW uses Ferrochel Iron Bisglycinate, which has clinically demonstrated superior absorption and is well tolerated because it is gentle and non-constipating. Natural color variations may occur in this product.