Protein and Glycine in Allergens: Negative Correlation with Allergy Prevalence

Duan Ni

Credit: LinkedIn

There is a negative correlation between higher levels of protein/glycine in allergenic foods and corresponding prevalence of food allergy, according to new data, and carbohydrate and fat contents in such foods are not linked to prevalence.¹

These results were the conclusion of new research led by Duan Ni, a PhD candidate from Sydney Medical School Nepean at the University of Sydney in Australia. Ni and colleagues noted that prior research has evaluated the ways in which nutrients influence food allergy.²

However, they highlighted that the broader macronutrient context was neglected in these prior studies, citing the fat and carbohydrate components within food allergens, specifically, as well as their possible interactions.³

“Here, we systematically analysed the associations between the macronutrient profiles of common allergenic foods and their corresponding food allergy prevalence, harnessing comprehensive epidemiological and nutritional data,” Ni et al. wrote.¹

Trial Design and Findings

The research team reviewed data presented by the European Academy of Allergy and Clinical Immunology (EAACI), which provided a comprehensive overview of the epidemiological patterns linked to 8 commonly-observed and well-defined food allergies. The 8 food allergies were to egg, cow's milk, peanut, wheat, soy, fish, tree nuts, and shellfish.⁴

The team sought a more reliable evaluation of allergenic potential, so they looked into lifetime prevalence of food allergies—both self-reported and clinician-diagnosed—as opposed to point prevalence. This is due to the latter’s capture of information over a limited period of time and its consequent susceptibility to bias.

The investigators found that in 2023, the available data suggested the presence of a significant correlation between self-reported lifetime prevalence rates and clinician-diagnosed rates for food allergies (R² = 0.8858, P = .0005). Given the broader availability of their data, self-reported lifetime prevalence was prioritized by the team for the purposes of the evaluation.

Figures highlighting prevalence from 2014 - 2023 underwent logit transformation, with the research team making comparisons with the macronutrient profiles of the allergenic foods. These were sourced from the USDA.

With regard to allergens that involved multiple subtypes, such as tree nuts or fish, the investigative team implemented generalized categories such as "Nuts, not further specified (NFS)" and "Fish, NFS.”

The team’s analysis pointed to a negative correlation between the total protein content of foods considered to be allergenic and their overall lifetime prevalence of the allergy. They also found that other food components did not demonstrate associations of any significance.

Such a pattern was shown to be consistent across individual studies as well as meta-analyses. The investigators identified similar conclusions for prevalence that had been diagnosed by a clinician, except in the case of shellfish.

Additional analyses excluding milk, as the team noted the food product is particularly prone to reporting and diagnostic issues. Additional assessments looked at the role of amino acid composition in foods which are allergenic and their association with allergy prevalence.

In particular, the researchers found that glycine content was consistently negatively correlated with the prevalence of allergies to the aforementioned foods.

Conclusions

Overall, the research team determined that increased levels of total protein and glycine among the 8 allergenic foods highlighted by the EAACI were linked with lower prevalence of food allergy.

“It remains to be tested whether manipulating glycine content in foods could alter their allergenicity,” they wrote. "Together, our findings prompt future studies to unravel the mechanistic and pathophysiology of food allergies in broader nutritional contexts, which could guide food allergy managements and/or prevention.”¹

References

1. ^{Ni, D., Senior, A., Tan, J., Macia, L. and Nanan, R. (2024), Linking Macronutrient Composition of Common Allergenic Foods to European and North American Food Allergy Prevalence. Clin Exp Allergy. https://doi.org/10.1111/cea.14600.}
2. ^{H. Breiteneder and E. N. Mills, “Molecular Properties of Food Allergens,” Journal of Allergy and Clinical Immunology 115, no. 1 (2005): 14–23.}
3. ^{M. Bublin, T. Eiwegger, and H. Breiteneder, “Do Lipids Influence the Allergic Sensitization Process?,” Journal of Allergy and Clinical Immunology 134, no. 3 (2014): 521–529.}
4. ^{G. C. I. Spolidoro, M. M. Ali, Y. T. Amera, et al., “Prevalence Estimates of Eight Big Food Allergies in Europe: Updated Systematic Review and Meta-Analysis,” Allergy 78, no. 9 (2023): 2361–2417.}