Effect of zinc or zinc plus arginine supplementation on antibody titre andlymphocyte subsets after influenza vaccination in elderly subjects: a randomized controlled trial

Objective: to evaluate whether oral supplementation with zinc or zinc/argin ine increases the antibody response to influenza vaccine or modulates the l ymphocyte phenotype in elderly subjects. Design: a randomized controlled trial with two supplemented groups and one control group. Setting: a community nursing home. Participants: 384 subjects aged 64-100 (mean age 82 years) examined in thre e separate studies. Intervention: oral supplementation with zinc (400 mg/day) or zinc plus argi nine (4 g/day) for 60 days starting 15 days before influenza vaccination. T he control groups received vaccine only. Measurements: haematological and nutritional indices, antibody titre agains t influenza viral antigens, lymphocyte phenotype. Results: supplementation with title or zinc plus arginine increased zinc pl asma concentrations restoring the age-related impairment in zinc concentrat ions to values found in younger people. The antibody titre against influenz a viral antigens was not increased in zinc or zinc/arginine supplemented gr oups in comparison with subjects receiving vaccine alone. The number of CD3 , CD4 or CD8 lymphocytes was not affected by zinc or zinc/arginine suppleme ntation. Conclusion: prolonged supplementation with zinc or zinc/arginine restores z inc plasma concentrations but is ineffective in inducing or ameliorating th e antibody response after influenza vaccination in elderly subjects.