to the editor: I have a billion-dollar question for the author of this article, assuming the following: 4 million babies born each year in the United States; one half with formula provided by the Women, Infants, and Children (WIC) Program, the other one half out of pocket; a difference of 11 cents between an ounce of whole milk and an ounce of formula; and the period between six and 12 months of age as the issue.

In Figure 1, an algorithm for selection of formula for term infants, the author recommends formula in the latter half of the infant's first year. As a disciple of evidence-based medicine, I have been unable to find data to support this advice. I remember that the American Academy of Pediatrics (AAP) lost a lawsuit in Ohio over this recommendation because they were portrayed as being in cahoots with the formula manufacturers.

I have always assumed that the American Academy of Family Physicians just went along with the AAP. I continue to recommend to my mothers that when their child is consuming meats and vegetables, whole milk is sufficient and cheaper by approximately $100 per month. That's a lot of money for young families to throw away, unless there is a sound medical reason. I would be happy to be corrected, but I find no data one way or the other in the references provided with this article.

in reply: I appreciate Dr. Yuan's further discussion of primary lactase deficiency. As he correctly explains, it is always preferable to counsel parents against unwarranted changes in formula. Unfortunately, some parents insist on trying alternative formulas despite education that lactose intolerance is rare before two years of age. In these cases, lactose-free formula might be offered as a last resort because it is associated with fewer safety concerns than soy formula.

In response to Dr. Iliff's question, there are several compelling reasons to avoid whole cow's milk before one year of age. Cow's milk has a much lower iron content than iron-fortified formula.¹ It was originally hoped that iron-fortified cereals could compensate for this difference, but multiple nutritional surveys have demonstrated that infants do not consume sufficient quantities of cereal to meet their iron requirements.² Furthermore, cow's milk (which is high in calcium and low in vitamin C) appears to decrease the bioavailability of iron from dietary sources.²

Infants who are fed cow's milk can lose additional iron through occult gastrointestinal blood loss.^3,4 Most infants lose very little blood, but occasionally infants have significant occult blood loss. It is impossible to predict which infants will be most affected, and the blood loss is too subtle for parents to detect in the diaper.

In 1983, the AAP issued a statement supporting the use of whole cow's milk instead of formula for infants older than six months who consumed at least one third of their calories from supplemental food.² We now know that even mild iron deficiency (insufficient to cause anemia) can adversely impact cognitive development in children.⁵ In light of growing evidence linking cow's milk to iron deficiency, the AAP issued a new statement in 1992 reversing their earlier position; iron-fortified formula is recommended for all non-breastfed infants until one year of age.²