Are supplements with amino acid chelated minerals better than those with other forms of minerals?

Answer:

Minerals, like magnesium and iron, are metal ions that like to attach to other compounds.  The compounds to which they attach can affect how well they are absorbed and how available they are  for use in the body.  A "chelate" is a compound in which a metal is attached by two bonds to an organic compound such as an amino acid (e.g., methionine) or a dicarboxylic acid (e.g., citric acid). There is evidence that some, but not necessarily all, chelated compounds may improve mineral absorption.  Salt forms of minerals, in which the metal is attached by a single bond to a compound (like iron bound to sulfur to make ferrous sulfate) help stabilize the mineral so that it is non-reactive until you take it and the mineral is released, but salts generally do not enhance absorption like chelates.

Selenomethionine, a chelate of selenium and the amino acid methionine, is a very popular form of selenium and there is evidence that it is slightly better absorbed than sodium selenite and sodium selenate (Schrauzer, J Am Coll Nutr 2001, FAO 2002).

A chelate of iron and the amino acid glycine (forming iron bis-glycine chelate or Ferrochel) was shown to be absorbed two to four times better than ferrous sulfate (a common "salt" form of supplemental iron rather than a "chelate") when given with food (Layrisse, J Nutr 2000), although it was not absorbed better than ferrous ascorbate when given only with water (Olivares, Arch Latinoam Nutr 2001).

A small, preliminary study found that magnesium diglycinate, a chelate of magnesium and glycine, was better absorbed than magnesium oxide in surgical patients who had impaired magnesium absorption due to intestinal resection. (Schuette, JPEN J Parenter Enteral Nutr 1994). Chelated magnesium in the aspartate and taurate forms, as well as non-amino acid chelates such as magnesium lactate, citrate, glycerophosphate, and gluconate, also show good absorption, and some of these chelated forms — including magnesium diglycinate — may reduce the laxative effects of magnesium.

Another small, preliminary study found that an amino acid chelate of zinc (zinc bis-glycinate) increased the bioavailability of zinc by 43% when compared to zinc gluconate (Gandia, Int J Vitam Nutr Res 2007). Zinc methionine, another amino acid chelate form of zinc, seems to be absorbed better than zinc sulfate when taken without food, but not when taken with food (Rosado, Nutr Res 1993). However, zinc picolinate, which is not an amino acid chelate, also seems to be well absorbed, showing greater absorption than zinc citrate and zinc gluconate (Barrie, Agents Action 1987).

You can also learn more about forms of calcium, magnesium, iron, zinc and other minerals in ConsumerLab.com's reviews of these supplements, and in the Review of Multivitamin and Multimineral Supplements.