Differentiating milk allergy (IgE and non-IgE mediated) from lactose intolerance: understanding the underlying mechanisms and presentations

Lactose intolerance (LI) is often confused with cow’s milk protein allergy (CMPA), however it is distinctly different; being non-immune mediated and related to malabsorption of lactose,¹ whereas CMPA is immune mediated.² Gastrointestinal symptoms are common in non-Immunoglobulin E (IgE) mediated CMPA and include diarrhoea, abdominal pain and vomiting and some of these symptoms overlap with LI.^1;2

In the absence of breast milk a hypoallergenic formula is recommended in CMPA, which in the past were lactose free, but the addition of lactose has become possible in recent years.³ The use of lactose containing formulas in non-IgE-mediated CMPA remains highly debated because of concerns related to brush border damage in children with cow’s milk associated enteropathy. Guidelines have suggested that a hypoallergenic formula without lactose might be useful until normal absorptive function of the mucosa was regained.⁴ As the prevalence of concomitant lactose intolerance in non-IgE mediated CMPA has never been studied, we set out to establish this.

A  multicentre prospective observational study was conducted through the National Institute for Health Research network in the United Kingdom. All children below 2 years of age, with symptoms of non-IgE mediated CMPA affecting the gastrointestinal tract were eligible for the study. The symptom score from Chebar Lozinsky et al.⁵ was used to establish the diagnosis and only data of children, who demonstrated symptom improvement after 4 weeks on a cow’s milk elimination diet were included. All eligible children had a lactose loading dose (1g/kg) administered prior to commencing their elimination diet. The first stool that was produced after lactose loading was collected and frozen at -18⁰C. Stool chromatography was performed at Great Ormond Street Hospital NHS Trust using a standard accepted procedure.

Twenty patients (Table 1) were recruited for the study, but only 8 stool samples were obtained within the protocol specifications). Lactose was not detected in any stool sample of children in this study.

*p<0.001

Although numbers were low, this study suggests that LI is not common in non-IgE mediated CMPA and that hypoallergenic formulas containing lactose, in the absence of breast milk should be considered, especially as lactose has other benefits.

References

1.  De Koker CE, Shah N, Meyer R. The differences between lactose intolerance and cow's milk protein allergy. J Fam Health Care 2014; 24(1):14-8, 20.
2.  Fiocchi A, Brozek J, Schunemann H, et al. World Allergy Organization (WAO) Diagnosis and Rationale for Action against Cow's Milk Allergy (DRACMA) Guidelines. Pediatr Allergy Immunol 2010; 21 Suppl 21:1-125.
3.  Niggemann B, von Berg A., Bollrath C, et al. Safety and efficacy of a new extensively hydrolyzed formula for infants with cow's milk protein allergy. Pediatr Allergy Immunol 2008; 19(4):348-54.
4.  Host A, Koletzko B, Dreborg S, et al. Dietary products used in infants for treatment and prevention of food allergy. Joint Statement of the European Society for Paediatric Allergology and Clinical Immunology (ESPACI) Committee on Hypoallergenic Formulas and the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) Committee on Nutrition. Arch Dis Child 1999; 81(1):80-4.
5.  Chebar LA, Meyer R, De KC, et al. Time to symptom improvement using elimination diets in non-IgE mediated gastrointestinal food allergies. Pediatr Allergy Immunol 2015; 11.