Iron is a necessary mineral for the body because it functions in oxygen distribution to the cells as well as with the metabolism of nutrients. A 2001 "Journal of Nutrition" article describes iron deficiency as a notable problem in both developed and developing countries. It is treated most commonly with the medication, ferrous sulfate. This form of iron often causes constipation and its prescription is often met with hesitancy due to this common side effect. Other forms of iron have been developed that have reduced rates of constipation.
Heme Iron Supplement
Two broad categories of iron exist in foods and mineral supplements: Heme and non-heme iron. Heme iron is the more absorbable form of the two, with approximately 20 to 25 percent of the iron being absorbed from heme sources, which are the oxygen-carrying proteins in the flesh of animals. Heme iron is derived from meat, especially of the darker variety notes an article published in the "Journal of Nutrition" in 2001.
Heme iron is the only true form of iron that is non-constipating; it is considered organic. Beef liver is one of the absolute best sources of heme iron. On the contrary, iron that is found in vegetables, dairy products, other meats and mineral supplements is considered inorganic, has reduced absorbability and has an increased risk for causing constipation. A heme-iron supplement such as Energizing Iron by the Integrative Therapeutics nutritional company is considered highly absorbable and non-constipating. Energizing Iron uses predigested and concentrated liquid liver fractions from organically raised, pesticide and antibiotic free livestock from Argentina. The recommended dose for the supplement is two softgels, three times per day.
Ferrous gluconate is a synthetically derived non-heme type of iron. As a general rule, non-heme iron is considered less absorbable and more likely to cause constipation than heme iron. Ferrous gluconate, however is designed to be more recognizable by the body and thus easier to absorb and assimilate. The medical associates at Jackson Siegelbaum Gastroenterology note that because ferrous gluconate is better tolerated than ferrous sulfate, it often has a lower incidence of digestive complaints like constipation.
Ferrous glycinate is a form of iron that is produced by the combination of one molecule of ferrous iron bound to two molecules of the amino acid, glycine. Ferrous glycinate also goes by its trademarked name, Ferrochel®. Ferrous glycinate is noted by an International Programme on Chemical Safety document to be a very bio-available form of iron, even though it is of non-heme form. It describes ferrous glycinate as a very stable substance that maintains its availability even when exposed to variations in pH and the presence of substances that would otherwise inhibit iron absorption. The article further notes that significantly more iron is absorbed from the ferrous glycinate form of iron than from the conventional, ferrous sulfate form. Moreover, ferrous glycinate is regarded as a gentle form of iron because of its less negative effect on the digestive tract and reduced propensity over conventional iron to cause digestive disturbances such as constipation.