Selenium fortification of infant formulas: does selenium form matter?

Selenium is a trace element essential for the health and development of the growing infant. It is a necessary component of proteins and enzymes required for a variety of functions, including antioxidant defense, modulation of the inflammatory response, and production of thyroid hormones. In breast-fed infants, selenium stores depend on the selenium content of the mother's diet. In formula-fed infants, selenium levels are correlated to the residual selenium stores accumulated in utero and the level and type of selenium fortification used in the formula. Today, the United States Food and Drug Administration (FDA) recommends that infant formulas contain selenium at levels between 2.0 and 7.0 μg per 100 kcal. While the US FDA does not recommend a particular selenium form for fortification, evidence indicates that organically bound selenium forms (e.g., selenomethionine and selenium-enriched yeast) are better absorbed and retained than inorganic forms (e.g., selenite and selenate). Preliminary data from studies in adults do suggest that fortification with standardized selenium-enriched yeast may offer benefits compared to fortification with other organically bound selenium forms. However, because most studies evaluating the impact of selenium fortification of infant formula have assessed inorganic selenium supplements, additional research into the bioavailability and outcomes associated with the use of selenium-enriched yeast in infants is needed.