Due to similarities in symptoms, lactose intolerance is often confused with cows’ milk allergy (CMA). This can lead to incorrect diagnosis and treatment, which ultimately means continued discomfort for the child.
Intolerance vs allergy
Food intolerance and allergy are both examples of ‘food hypersensitivity’. This is the umbrella term for non-toxic adverse reactions to foods1.
Food allergy occurs when a food protein interacts with the immune system to cause an allergic response, whereas food intolerance does not involve food proteins and is a non-immune reaction2.
Food intolerance can be caused by either an enzyme deficiency or a pharmacological reaction2.
Enzyme deficiency
This is when a person doesn’t produce enough of an enzyme that breaks down a particular food, leaving them unable to digest that food properly.
Pharmacological reaction
Some substances found in foods can cause a pharmacological reaction, e.g. vasoactive amines, caffeine and alcohol.
Causes of lactose intolerance and CMA
Lactose intolerance is caused by the inability to completely digest lactose – the sugar found in all mammalian milk – due to the absence or deficiency of the enzyme lactase in the gut3,4.
The cause of CMA is an immunologic hypersensitivity to one or more of the proteins found in milk5. This means CMA is an allergic reaction, involving the body’s immune system; lactose intolerance does not involve the immune system3,4.
In addition, unlike CMA, where just a tiny amount of milk protein can trigger a reaction, most people with primary lactose intolerance are able to tolerate small amounts of lactose6,7.
Similarities and differences in symptoms
It can be difficult to differentiate between delayed CMA and lactose intolerance, as some symptoms overlap and the terminology used in the literature and in relation to products is inconsistent.
So it is important to be aware that there are other symptoms that can occur with CMA, but not with lactose intolerance.
With lactose intolerance, the symptoms are purely gastrointestinal, e.g. abdominal pain, diarrhea and bloating2,7. But with CMA, symptoms can be gastrointestinal or they can be respiratory (e.g. wheezing, rhinitis) or skin-related (urticaria/hives) and, in some cases, can lead to anaphylaxis8. Therefore, symptoms from two or more of these organ systems is suggestive of CMA rather than lactose intolerance9.
Although lactose intolerance and CMA can share some similar symptoms, their actual causes are very different. By understanding the differences between food intolerance and allergy, and being aware of CMA-specific symptoms, healthcare professionals can be better prepared in diagnosing and treating these conditions more accurately.
References
- Johansson, S. G. O., et al. “Revised nomenclature for allergy for global use: Report of the Nomenclature Review Committee of the World Allergy Organization, October 2003.” Journal of allergy and clinical immunology 113.5 (2004): 832-836.
- Venter, Carina. “Cow’s milk protein allergy and other food hypersensitivities in infants.” J Fam Health Care 19.4 (2009): 128-34.
- Wright T, Meyer R. Milk and eggs. In: Venter, Carina. “Cow’s milk protein allergy and other food hypersensitivities in infants.” J Fam Health Care 19.4 (2009): 128-34.
- Heyman, Melvin B. “Lactose intolerance in infants, children, and adolescents.” Pediatrics 118.3 (2006): 1279-1286.
- Hill, D. J., et al. “Manifestations of milk allergy in infancy: clinical and immunologic findings.” The Journal of pediatrics 109.2 (1986): 270-276.
- EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). “Scientific Opinion on lactose thresholds in lactose intolerance and galactosaemia.” EFSA Journal 8.9 (2010): 1777.
- NHS Choices. Lactose intolerance [Online]. 2011. Available at: https://www.nhs.uk/conditions/lactose-intolerance/ [Accessed: December 2019]
- Bahna, Sami L. “Cow’s milk allergy versus cow milk intolerance.” Annals of Allergy, Asthma & Immunology 89.6 (2002): 56-60.
- NICE. CG116 Food allergy in children and young people: full guideline. London: NICE, 2011.
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