Impact of Diet and Lifestyle on Vaccine Efficacy in Adults Aged 55 and Older: A Review.

Context: Age-related declines in immune system function, including vaccine responsiveness, are well established. Dietary and lifestyle factors have been investigated in human clinical trials and observational studies for their effects on vaccine response. Objective: The review intended to assess dietary and lifestyle factors that can modulate vaccine response in a population aged 55 years or older or in a population with an average age of 55 years or older. Design: The research team performed a narrative review of studies occurring up until May 2021 by searching electronic PubMed databases. Results: The review findings suggest that two factors may have clinically relevant effects on vaccine response: regular aerobic exercise and psychological environmental stressors, in particular caregiving stress, which studies have consistently found can have a positive and negative effect or association, respectively. In addition, micronutrients used in combination as well as microbiome-targeted interventions show mostly promising results. Other factors may yet be relevant but very few studies have been done. Conclusions: Heterogeneity of study design, small sample sizes, and other challenges mean that strong conclusions remain elusive. Further study is needed as well as improvements in study design. However, there are indications that certain dietary and lifestyle factors influence vaccine effectiveness.