Associations between food consumption with T cell activation and antibody responses following SARS-CoV-2 mRNA vaccination

COVID-19 mRNA vaccines induce protective immunity, but the factors influencing individual immune responses remain incompletely understood. This study investigated associations between dietary habits, T cell activation, and antibody responses to SARS-CoV-2 vaccination. We analyzed peripheral blood mononuclear cells following spike protein stimulation and measured anti-SARS-CoV-2 S protein antibody levels. We found significant positive correlations between CD4⁺ activation-induced marker (AIM)⁺ T cells, CD4⁺ CD69⁺ T cells, and anti-SARS-CoV-2 S protein antibody levels. Among various food items, yogurt and bread consumption frequencies showed significant positive correlations with immune parameters. Participants with high yogurt consumption (daily or more) demonstrated significantly higher levels of CD4⁺ AIM⁺ T cells, CD4⁺ CD69⁺ T cells, and antibody levels compared to low consumption groups. Similar patterns were observed for bread consumption. These associations remained significant after adjusting for age, sex, vaccination count, and prior infection history. Additionally, we observed correlations between serum and fecal anti-SARS-CoV-2 antibodies, with distinct gut microbiota and metabolite profiles associated with antibody levels. Our findings suggest that regular consumption of specific foods may influence vaccine-induced immune responses, potentially through interactions with the gut environment. These results provide a foundation for investigating dietary approaches to optimize vaccine responses.