The idea that the iron in infant formula predisposes infants to constipation is perhaps the oldest urban legend kicking around pediatric offices.
The belief that iron in infant formula can create problems for babies may be an extension of the misery experienced by pregnant women when supplemented with iron. When they’ve experienced the effects of iron supplementation, new mothers will often take matters into their own hands. Pediatricians themselves desperate for relief from colicky parents will often gamble with the low-iron card. It’s estimated that low-iron formulas account for 9%-30% of elective infant formula sales in the United States.
So what are the facts? Let’s look at a typical 6 kilogram 3-month-old infant consuming an average of 28 ounces per day formula. An infant fed Enfamil Lipil low-iron receives 4.2 mg of iron per day. The same volume of standard Enfamil Lipil provides 10.1 mg of iron daily. It’s estimated that babies need about 1 mg of iron per kilogram of bodyweight. The baby in our example therefore requires 6 mg of iron daily. The Enfamil low-iron cuts our baby short.
For parents who like to live on the edge there’s Similac low-iron formula. It provides about one third of the iron available in Enfamil’s low-iron formula. In the case of our baby discussed above, Similac low-iron provides a meager 1.3 mg of iron per day.
So what’s the big deal? Iron happens to be very important for brain development. Studies have documented the long-lasting developmental effects of iron deficiency early in life. And what about the association between iron in formula and constipation? There isn’t one. This association was disproved in clinical studies some years back.
What’s important to take home here is the fact that standard infant formula contains appropriate levels of iron, not “extra” iron as is often assumed. Low-iron formula as you see from our example, puts babies at an unacceptably high risk for iron deficiency and should have no place in feeding babies.
It’s been suggested that low-iron formulas should be removed from the market. But so long as misconceptions about formula and constipation exist, there will be demand. And where there’s demand there’s a market.