Milk Allergies and Constipation

Dr. Greene`s Answer:

A cranky, unhappy toddler may well be responding to physical discomfort. Tummy troubles of one type or another can make anyone feel miserable. Milk is a major part of most children’s diets. If a child is intolerant to milk, this can affect how he feels every single day of his life. Nausea, cramps, and pain can squelch the normal joys of discovery and mastery.

Symptoms of Milk Allergies

But the classic symptoms of milk intolerance are diarrhea, spitting up, or abdominal pain. Many kids with milk intolerance also wheeze, especially when they get a cold. They can also have the dry, sensitive skin of eczema and their noses always seem to be running. Ear infections are also more common than in other kids. Constipation, however, has not been typically associated with milk intolerance — until now.

The observation that constipation might sometimes be caused by milk intolerance has appeared in the medical literature from time to time, dating back as far as 1954. But only recently has there been a well-designed study published showing that this is indeed the case. The results of this study have helped many children to enjoy the exuberance of childhood without pain.

Studying Milk Allergies and Constipation

Researchers at the University of Palermo in Italy worked with 65 children with chronic constipation. All of these children had been treated with laxatives when dietary measures had failed. Even with the medical treatment, these children were still constipated, having hard, painful stools only every 3 to 15 days. Forty-nine of their little bottoms had fissures and redness or swelling from the hard plugs of stool.

Each child received either cow’s milk or soymilk for 2 weeks, with no one knowing which was which. Next, they had a week during which they could eat and drink anything they wanted to wash out the effects of the first 2 weeks. Then they switched sides for 2 weeks and got the milk that they didn’t get the first time. Careful recordings of the bowel habits were made.

When the secret code was broken at the end of the study, they found status quo constipation for each child while he or she was on cow’s milk. But while they were taking soymilk (which causes firmer stools in most kids), 68% of these kids were no longer constipated! The redness, swelling, and fissures on their bottoms healed. How wonderful to finally have relief after diet and medicines hadn’t worked for so long!

The results were most dramatic in kids who also had frequent runny noses, eczema, or wheezing. Nevertheless, sometimes constipation can be the only symptom of cow’s milk intolerance.

Treating Milk Allergic Kids and Constipation

This has broad implications. The children in this study were those with severe chronic constipation that was unresponsive to medications. I am convinced that they are only the tip of the iceberg. There must be a much larger group of mildly allergic children whose constipation improves with laxatives. Time may prove that it is better for these children to avoid the offending protein by switching milks rather than being treated with laxatives.

Presumably, swelling of the intestinal lining causes the constipation. Whatever the exact mechanism, the problem is likely with the protein in cow’s milk, not with the fat or lactose (the sugar). Skim milk or lactose-free milk will not help with this one. Switching to soymilk and other soy products might transform the life of your son in only a couple of weeks!

These same ideas also apply to infants who may be experiencing constipation related to their milk-based formulas. In the past, low iron formulas had been recommended for constipation. However, starting in 1999, the American Academy of Pediatrics (AAP) Committee on Nutrition declared that constipation is not a contraindication to iron-fortified formulas and that, in fact, lowering the iron content causes more harm than benefits.  

First, let’s address the iron in formula and constipation question. Some people will (or have) told you that the iron is the problem and that switching to a low-iron formula will help. It makes sense, because when adults take iron supplements, we get constipated as a side effect. But there was a study done concerning the formula and constipation question in babies. Half got low iron, half got regular (not knowing which was which) and the rate of constipation was the same in both groups. For most kids, that does not make a difference, and the iron is very important for growing babies.

The constipation can be formula-related, though. Allergies to some of the proteins in the formula could cause the discomfort. Sometimes switching to another brand will help (the milk-based formulas are not all the same). Sometimes switching to soy will help (just as we saw in the study above). All other things being equal, soy makes stools firmer; but for kids with an isolated allergy to milk protein, the constipation may dramatically clear up on soy.

Unfortunately, some children are also soy protein intolerant. As it happens, this is more common in kids who are allergic to cow’s milk protein. If you don’t get good results within two weeks, I suggest also eliminating soy from the diet and trying Alimentum or Nutramigen (protein hydrolysate infant formulas) for two weeks. Because the proteins in these formulas are broken down, your son is less likely to be allergic to them. If they work, you can then experiment with other sources of calcium, protein, and fat for the future (perhaps fortified rice milk). 

It’s not that common for simple changes to relieve relentless, longstanding problems. But when a child is made miserable by an allergy, removing the source can result in a rapid, dramatic improvement in the quality of life. I hope, Shannon, that this turns out to be the case with your son and that this next season his smiles double to make up for those he has missed.

Resources and References

Committee on Nutrition. Iron fortification of infant formulas. Pediatrics. July 1999, 104 (1) 119-123.

Dehghani SM, Ahmadpour B, et al.  The role of cow’s milk allergy in pediatric chronic constipation: a randomized clinical trial. Iran J Pediatr. 2012;22(4):468-474.

Iacono, G, et al.  Intolerance of cow’s milk and chronic constipation in children.  New England Journal of Medicine. 1998; 339:1100-1104.

Melvin B. Heyman, for the Committee on Nutrition; Lactose Intolerance in Infants, Children, and Adolescents. Pediatrics September 2006; 118 (3): 1279–1286.