I want to admit my bias towards hydolysates up front: I think they are magical. My son has been on hypoallergenic formula since he was about 3 months old, and the difference between FC on breastmilk/regular formula/soy formula and the hypoallergenic formula we ultimately switched him to was astounding. It was like the kid had received a spontaneous lobotomy. He was miserable for the first 10 weeks of his life, with terrible skin rashes, gas, stomach issues, and a personality that can best be described as the Grinch meets Chairman Mao; within 24 hours of switching him to hypoallergenic formula, he could have starred as the “after” in a Harvey Karp instructional video. FC was truly the happiest baby on the block, thanks to Alimentum.
Still, I was concerned about the long-term safety of such a space-age, highly processed formula. The stuff smelled like regurgitated potatoes. (Although for some reason, FC loved it; up until a month ago, we still used a scoop of the stuff to flavor his hemp milk because he so adores the taste. But then again, he likes kiwi as well, and hates chocolate. I’m blaming FH’s taste genes.) And the whole “pre-digested” thing kind of skeeved me out. So, I did a little research, and the following is what I’ve found. Needless to say, I am by no means a doctor or have any background in science; this is just what I’ve gleaned from a layman’s perspective (with the slight advantage of a journalism background that focused on health issues), so take it all with a grain of salt. Or a grain of pre-digested protein. Your choice.
First, a definition: What are hydrolysates?
Basically, in kids who are allergic or sensitive to milk protein, the lower the molecular weight of a protein, the better. Casein hydrolysates like Similac Alimentum or Enfamil Nutramigen contain tiny, broken-down versions of milk protein, making it easier for milk-sensitive babies to digest. There’s another level of hypoallergenic-ness (yes, I made up that word, sue me) which you find in amino-acid based formula (Neocate); for some babies, even the infinitesimal amount of milk product in the hydrolysates is problematic. Since Neocate is only available by prescription, and the majority of kids with food sensitivities have success with the over-the-counter hydrolysates, we’re going to focus on these.
What are the nutritional differences?
Comparing nutritional labels, there doesn’t seem to be much difference between your average milk-based formula and a casein hydrolysate one. But a 2003 study in the American Journal of Clinical Nutrition did find that “the iron status of infants fed (casein hydrolysate formula) was lower than that of all other groups. The amounts of amino acids provided by hydrolysate formulas appear excessive compared with regular formula, which is reflected by high serum urea nitrogen… and high plasma amino acid concentrations.” The study authors suggest, in their conclusion, that a “reduced and more balanced amino acid content of hydrolysate formulas may be beneficial.” I’m not sure if the formula companies have changed the recipe since 2003, but I will look into it and get back to you.
The International Society of Infant Food Manufacturers has a good run down of the nutritional issues surrounding hydrolysates, but I’m well aware that there’s a bias against the formula organizations, so do with this what you will. They claim that “on the whole, available data suggest that there is no evidence that feeding (hydrolysate formula) impairs the growth and biochemical parameters of term infants. There is also no evidence of differences between infants fed (hydrolysates) and an adapted cow’s milk formula and/or human milk on growth parameters and biochemical parameters, except on indices of protein metabolism.”
What’s the deal on allergies?
A 2008 clinical report from the AAP suggested that hydrolysates may actually have a preventative effect against allergies:
The documented benefits of nutritional intervention that may prevent or delay the onset of atopic disease are largely limited to infants at high risk of developing allergy (ie, infants with at least 1 first-degree relative [parent or sibling] with allergic disease). Current evidence does not support a major role for maternal dietary restrictions during pregnancy or lactation. There is evidence that breastfeeding for at least 4 months, compared with feeding formula made with intact cow milk protein, prevents or delays the occurrence of atopic dermatitis, cow milk allergy, and wheezing in early childhood. In studies of infants at high risk of atopy and who are not exclusively breastfed for 4 to 6 months, there is modest evidence that the onset of atopic disease may be delayed or prevented by the use of hydrolyzed formulas compared with formula made with intact cow milk protein, particularly for atopic dermatitis.
It’s not clear in this synopsis, but reading through the entire study, it seems that both breastfeeding and use of hydrolysate formulas confer equal benefits in this particular case. Obviously, if you have a history of allergies and are able to breastfeed, it’s a no-brainer – why feed your kid expensive and atrociously smelly formula? But for those of us whose kids are unable to tolerate breastmilk due to severe allergies, or who cannot breastfeed for any other reason, but have a family history of allergies, the hydrolysates might be worth the cash.