Similar results, including changes in microbiota and some immune parameters but not antibody level, were obtained in a population between 45 and 63 years old consuming 8 g day−1 of a mixture of short‐ and long‐chain inulin before receiving an influenza vaccine.[31, 32] Because an increase in HB titer could be observed in young adolescents in our previous study using an identical formulation and consumption regime,[22] we believe that the decreased responsiveness of the immune system in elderly is the reason for the absence of an effect in this study. The gene discussed is GSTM1; the disease is influenza.