Effect of a formulation containing blackcurrant powder, L-theanine and pine bark extract on immune responses to influenza vaccine in older healthy adults

INTERVENTION: Freeze‐dried blackcurrants (with a minimum serve of 3.2 mg/kg anthocyanin) with 150 mg L‐theanine and 150 mg pine bark extract added. The formulations will be a powder which will be mixed with 250 ml water and will be given daily for 12 weeks. Participants will be asked to fill out a short daily health questionnaire during the intervention period asking if the intervention has been consumed, which will serve as a reminder to take their intervention. In addition a weekly SMS/E‐mail reminder will be sent. A one‐week wash‐out period will precede the intervention stage, where participants will be asked to avoid high‐polyphenolic contain foods, such as excessive caffeine or chocolate. A SMS/E‐mail reminder will be sent and a 3‐day diet record will be taken during this week to assess baseline diet. After 4 weeks of intervention participants will be vaccinated with the influenza vaccine developed according to World Health Organisation (WHO) guidelines for 2022 and approved by Medsafe, New Zealand. Vaccines will be administered intramuscularly in the deltoid region of the arm by a qualified nurse (Life Care Consultants, New Zealand) as part of this study. CONDITION: Immune response to influenza vaccine;Older age; ; Immune response to influenza vaccine ; Older age Infection ‐ Other infectious diseases Inflammatory and Immune System ‐ Normal development and function of the immune system PRIMARY OUTCOME: Cytokine production of ex‐vivo stimulated peripheral immune cells isolated from participants peripheral blood with influenza antigens.[0, 6, 8 (primary timepoint) and 12 weeks post initiation of intervention.] Specific T‐cell subset proliferation of ex‐vivo stimulated peripheral immune cells isolated from participants peripheral blood with influenza antigens.[0, 6, 8 (primary timepoint) and 12 weeks post initiation of intervention.] SECONDARY OUTCOME: Antigen specific immune response to the influenza vaccination as assessed by vaccine antigen‐specific plasma IgG1 concentration.[0, 6, 8 and 12 weeks post initiation of intervention.] Antigen specific immune response to the influenza vaccination as assessed by vaccine antigen‐specific plasma IgG3 concentration.[0, 6, 8 and 12 weeks post initiation of intervention.] Antigen specific immune response to the influenza vaccination assessed by vaccine antigen‐specific haemagglutination inhibition (HAI) in blood.[0, 6, 8 and 12 weeks post initiation of intervention.] Incidence of upper respiratory tract infection (URTI) to measure common illness and/or symptoms (e.g. coughs and colds) using the validated Wisconsin Upper Respiratory Symptom Survey – (WURSS‐24).[Daily over the 12 week intervention period.] Innate immune cell populations in participants peripheral blood such as plasma cells expressing IgM and IgG1, natural killer (NK) cells, monocytes, dendritic cells, macrophages, T cells including subsets cytotoxic T cells, T helper cells, NKT cells and regulatory T cells . In addition the expression of activation markers relevant to each population will be calculated. This is an exploratory outcome.[0, 6, 8 and 12 weeks post initiation of intervention.] Plasma primary and secondary metabolites. This is an exploratory outcome and metabolites that significantly change between placebo and active treatments will be the focus of this outcome.[0, 6, 8 and 12 weeks post initiation of intervention.] Plasma vitamin C concentrations.[0, 6, 8 and 12 weeks post initiation of intervention.] INCLUSION CRITERIA: Age: Aged over 50 years Sex: Any gender Body weight <120Kg Health: Healthy as gauged by self‐assessment and result on the General Health Questionnaire. Agreement: Participant having given written informed consent to comply with the conditions of the trial. No allergies to ingredients contained in the active or placebo treatment or the influenza vaccine, such as blackcurrant or egg products. Blood parameters which do not indicate clinically significant illness for albumin, alkaline phosphatase, alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea, calcium, chloride, creatinine, potassium, sodium, total bilirubin, total protein, glucose and HBA1c. . No previous severe reaction to the influenza vaccine Did not receive the influenza vaccine in 2021 and are willing to have the influenza vaccine as part of this study.