Too much animal-based protein poses increased AD risk

Frequent intake of high-protein foods in diets, especially those derived from animals, appears to be associated with an increased risk of atopic dermatitis (AD) and allergic sensitization to common house dust mites, according to a study.

Data from 11,494 young Chinese adults in Singapore and Malaysia showed that the risk of AD was elevated among those with high dietary protein score (adjusted odds ratio [OR], 1.397, 95 percent confidence interval [CI], 1.133–1.724; p<0.003) and those with high animal protein score specifically (adjusted OR, 1.353, 95 percent CI, 1.106–1.682; p<0.003). [JID Innov 2023;3:100224]

“Interestingly, synergy factor analysis revealed that a higher intake of plant proteins than animal proteins in diets significantly reduced overall associated risks of atopic dermatitis and allergic sensitization but not those of intrinsic eczema,” the investigators said. “Most importantly, these associations are independent of dietary fat intake.”

In the study cohort, the prevalence of AD was higher than that of intrinsic eczema (13.5 percent vs 4.45 percent), and the majority of the participants tested positive for skin prick test (69.0 percent). The mean age was largely similar in the AD and intrinsic eczema groups (range 21.92–23.26 years) as was the mean body mass index (BMI; range 20.96–21.04 kg/m²), with 61.48 percent women.

More participants with AD than nonallergic noneczema controls had a high dietary protein score (29.5 percent vs 22.0 percent), indicating a greater intake frequency of high-protein foods in diets in the AD group. When looking at protein sources, a higher proportion of participants in the AD group had an elevated animal protein score (37.9 percent vs 30.4 percent), while more controls had a high plant protein score (33.7 percent vs 35.7 percent).

Protein-modulated inflammation

Several studies have shown that a high intake of animal protein can trigger inflammation throughout the body. For example, eating a meal with added animal protein led to the surge of the inflammatory protein CCL5 in the blood, while diets high in chicken protein contributed to increased levels of the inflammatory proteins IL-1β, IL-6, and TNF-ɑ in the brain. [Nutr J 2011;10:115; J Nutr Biochem 2020;85:108487]

In contrast, eating a plant-based diet has been linked to a lower risk of chronic diseases associated with inflammation. This, according to the investigators, is because plant-based diets can lower levels of inflammatory markers in the blood and reduce inflammation throughout the body. One study found that eating a high plant protein diet for 6 weeks helped reduce the levels of the inflammatory proteins TGF-β1, chemerin, and progranulin in the blood. [Adv Nutr 2019;10:433-451; Clin Nutr 2020;39:862-869]

Evidence from the previous studies mentioned may partly explain the protective effect of frequent intake of high plant-based protein foods on the risk of AD, according to the investigators. “These data provide some valuable insights into how plant-based protein diets can be considered for nutritional treatment and clinical intervention in those with an allergic background and AD disease.”