Weak immune defenses during seasonal exposure – Cetebe® DEFENSE plus with vitamin C, vitamin D3 and zinc, Deficiency of vitamin C, D3, or zinc affecting immunity – Cetebe® DEFENSE plus with vitamin C, vitamin D3 and zinc, Oxidative stress weakening the immune system – Cetebe® DEFENSE plus with vitamin C, vitamin D3 and zinc, Need for gradual, long-lasting vitamin C release – Cetebe® DEFENSE plus with vitamin C, vitamin D3 and zinc