Cow’s Milk Allergies are the most common food allergy in children, affecting 2-3% of these individuals in developed countries (Høst 2002). In most cases 45-50% of those affected by milk allergies will naturally resolve their allergies by their 1st year of age (Høst 2002). Milk allergies are associated with hives wheezing and or coughing immediately after consumption and symptoms such as cramps, itching, and diarrhea which take time to develop. A true milk allergy differs from lactose intolerance in that a milk allergy will involve actual immune system response whereas intolerance does not. The reasoning for allergy resolution is quite unclear but Bunyavanich et al. uses her study to connect allergy resolution to microbiome composition. To better understand this work,we can look at allergic responses and digestive issues as a response or the inability of the living microorganisms in the human body’s inability to process these allergens (Round & Mazmanian 2009).
The study of the gut microbiome is a relatively new, developing field that can be used to better understand human health through host-bacterial interactions (Round & Mazmanian 2009). In their study to potentially explain or better understand the resolution of milk allergies in children, Bunyanavich et al. examines the development of the gut microbiome of children in relation to the milk allergies. The scientific journal article, “Early-life gut microbiome composition and milk allergy resolution,” examines the early age human gut microbiome in hopes to find associations between the microbiome and a person’s allergies to milk (Bunyavanich et al. 2016). This study examines the gut microbiome through the fecal samples of 226 children with milk allergies at the intervals: 6 months after initial observation, 12 months after initial observation, and yearly afterwards until age 8 to examine changes in their microbiome and whether or not their milk allergies resolve. For analysis, data is collected on the subjects including sex, race, and status on breastfeeding, mode of delivery at birth, whether the subject is eating solid food, and whether the subjects were taking antibiotics.
Presence of Bacteria may be key to Allergy Resolution
In the study stool samples were collected from the group of participants and were split into age groups of 3-6 months old, 7-12 months old, and 13-16 months old at initial sampling, using subjects from study conducted by Consortium of Food Allergy Research. The researchers used next generation sequencing to identify presence of specific organisms, in this case, the type of bacteria in the gut microbiome. Only the samples from the 3-6 month old age group showed a significant difference in microbiome composition between those who would resolve their milk allergy later on and those who would not (Bunyavanich et al. 2016). The results show that children from the 3-6 month group that would eventually resolve their milk allergy possessed greater levels of Clostridia and Firmicutes, and lower levels of Bacteriodetes. This can potentially serve as a consistent indicator of milk allergy resolution if not a way of manipulating a milk allergy to resolve. One provided interpretation of why an indicator is only shown in the 3-6 month group is that the early infancy stage (3-6 months old) serves as a specific window in which the gut microbiota shapes itself in particular regards to food allergies (Bunyavanich et al. 2016). An alternative explanation is that the gut is shaped over the course of various age stages but is obscured in samples older than 6 months (Bunyavanich et al. 2016).
Metabolism of Fatty Acids
Results from this study showing a difference in the microbiome can indicate whether or not the milk allergy will be resolved brings up a question. Does the composition of the gut bacteria manipulate the resolution of the milk allergy or whether the transition towards resolving a milk allergy changes the environment so that different bacteria thrive? Evident from functions of the significant bacteria, the resolution of the milk allergy may at least partially be affected by the bacteria.
In an analysis of the bacteria present in the 3-6 month old group of children, the gut bacteria were mainly found to be associated with decreased fatty acid metabolism (Bunyavanich et al. 2016). This could mean that lowered fatty acid metabolism in the gut microbiome may help in reducing long-term allergy risk. Supporting this idea, lipids are known to help assist the transport of food allergens into the intestinal lining (Bublin et al. 2014). A decrease of fatty acid metabolism would mean less transport of fatty acids into the intestinal lining and therefore less allergens. An attempt to include Clostridia and Firmicutes into probiotic supplements may serve as a viable future option to reduce milk allergies in children but would require some research to see if such a plan can work.
Does Milk in Baked Goods Act Differently?
Bunyanavich et al. expresses interest in the analysis of the gut microbiota associated with the tolerance of baked milk at the end of this study because the ability to consume milk baked into other products serves as an indicator of faster resolution of milk allergies (Kim et al. 2011). Such a study may reveal a mechanism as to why a milk allergy would be resolved faster due to the consumption of baked milk, if the consumption of baked milk really does have an effect that is. Baking milk likely changes the allergens protein structure reducing its severity to a point where some individuals are less affected (Thomas et al. 2007). The effect of baked milk on the gut microbiome can serve as a tool to investigate effect of chemically altered allergens on the gut microbiome.
We Should look at more Allergens
The major significance of the study relates to the bacterial mechanism of fatty acid digestion associated with the 3-6 month individuals who would come to resolve their milk allergies. Such a finding should be verified with studies of increased size and expanded upon by investigating allergens beyond milk. This is a first attempt at this type of an investigation on milk allergies and will benefit from a larger, diverse study if only to replicate the findings.
Expanding beyond milk, if the increase in bacteria in this study is associated with fatty acid digestion, which may prevent the transport of allergens through the gut lining, wouldn’t it be possible that similar associations can be found in relation to other food allergens? Does an increase in these Clostridia and Firmicutes relate to an overall reduced allergen reactivity? I would love to see these interesting results verified and expanded on with more microbiome research in the near future.
- For Basic Info on milk allergies, take a look at the Mayo Clinic profile on milk alllergies.
- If you are interested in reading more, view the main article.
Bublin, M., Eiwegger, T., & Breiteneder, H. (2014). Do lipids influence the allergic sensitization process? Journal of Allergy and Clinical Immunology, 134(3), 521-529. doi:10.1016/j.jaci.2014.04.015
Bunyavanich, S., Shen, N., Grishin, A., Wood, R., Burks, W., Dawson, P., Clemente, J. C. (2016). Early-life gut microbiome composition and milk allergy resolution. Journal of Allergy and Clinical Immunology, 138(4), 1122-1130. doi:10.1016/j.jaci.2016.03.041
Caffarelli, C., Baldi, F., Bendandi, B., Calzone, L., Marani, M., Pasquinelli, P., & Ewgpag, O. B. (2010, January 15). Cow’s milk protein allergy in children: A practical guide. Ital J Pediatr Italian Journal of Pediatrics, 36(1), 5. doi:10.1186/1824-7288-36-5
Høst, A. (2002). Frequency of cow’s milk allergy in childhood. Annals of Allergy, Asthma & Immunology, 89(6), 33-37. doi:10.1016/s1081-1206(10)62120-5
Kim, J. S., Nowak-Węgrzyn, A., Sicherer, S. H., Noone, S., Moshier, E. L., & Sampson, H. A. (2011). Dietary baked milk accelerates the resolution of cow’s milk allergy in children. Journal of Allergy and Clinical Immunology, 128(1). doi:10.1016/j.jaci.2011.04.036
Mayo Clinic Staff. (n.d.). Milk allergy. Retrieved November 22, 2016, from http://www.mayoclinic.org/diseases-conditions/milk-allergy/basics/definition/con-20032147
Round, J. L., & Mazmanian, S. K. (2009). The gut microbiota shapes intestinal immune responses during health and disease. Nature Reviews Immunology, 9(8), 600-600. doi:10.1038/nri2614
Thomas, K., Herouet-Guicheney, C., Ladics, G., Bannon, G., Cockburn, A., Crevel, R., Vieths, S. (2007, July). Evaluating the effect of food processing on the potential human allergenicity of novel proteins: International workshop report. Food and Chemical Toxicology, 45(7), 1116-1122. doi:10.1016/j.fct.2006.12.016