Probiotics and Influenza Vaccination Response

Inclusion Criteria: * Men and women * Age 16 - 65 y and healthy * Self-reported regular Dutch eating habits as assessed by questionnaire (3 main meals per day) * No influenza vaccination in 2022 * Non-smokers * BMI 18.5-28 * Adherence to habitual diet * no changes during study period * Signed informed consent Exclusion Criteria: * Recent vaccination * Acute or chronic illness (e.g., diabetes mellitus) * Gastrointestinal disorders (e.g., inflammatory bowel disease) * Acute gastroenteritis in the past 2 months * Immunodeficiency disorder * Use of immunosuppressive drugs (e.g. cyclosporine, azathioprine, systemic corticosteroids, antibodies) * Unexplained weight loss or weight gain of \> 3 kg in the 3 months prior to pre-study screening * Alcohol or drug abuse * Mental status that is incompatible with the proper conduct of the study * History of cancer * Use of immune boosting supplements within 4 weeks before screening To be extended \& specified in protocol phase