Beveridge, S.

Hornig, D.

Maggini, S.

Wintergerst, E.S.

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1st International Immunonutrition Workshop, Valencia, 3–5 October 2007, Valencia, SpainImmune-enhancing role of vitamin C and zinc and effect onclinical conditionsS. Beveridge1, E. S. Wintergerst2, S. Maggini1 and D. Hornig31Bayer Consumer Care, Basel, 2Bayer Diabetes Care, Basel, Switzerland and 3 Bayer Diabetes Care, Reinach, SwitzerlandThe present paper is intended to give an overview on the roles of vitamin C and Zn in immune functions. Vitamin C concentrations in theplasma and leucocytes rapidly decline during infections and stress. Supplementation of vitamin C improves components of the humanimmune system such as antimicrobial and natural killer (NK) cell activities, lymphocyte proliferation, chemotaxis and delayed-typehypersensitivity. Vitamin C contributes to maintaining the redox integrity of cells and thereby protects them against reactive oxygenspecies generated during the respiratory burst and in the inflammatory response. Similarly, Zn deficiency impairs cellular mediators ofinnate immunity such as phagocytosis, NK cell activity, and the generation of oxidative burst. Thus, both nutrients play important andcomplementary roles in immune function and the modulation of host resistance to infectious agents, reducing the risk, severity andduration of infectious diseases. A deficiency in one of these essential nutrients weakens immunity since vitamin C is crucial for cellularimmunity and Zn for the production of antibodies.A large number of randomized controlled intervention trials with intakes of £1 gvitamin C and £30 mg Zn are available. These trials show that adequate intakes of vitamin C and Zn ameliorate symptoms and shorten theduration of respiratory tract infections including the common cold. Natural defences can only provide full protection when the body hassufficient Zn, as well as high levels of vitamin C.The physiological effects of vitamin C provide clear evidence and rationale for a numberof ways in which it might help to protect against infection. This evidence is termed mechanistic evidence because it stems fromknowledge of the chemical reactions and biochemical processes in which vitamin C is known to play an important role (Table). Theactions of Zn not only complement the actions of vitamin C to provide ‘double protection’ (Table), but may even have a synergistic effect.Like vitamin C, in recent years research has proved that Zn is essential for effective immune defence at several different levels.Table. Summary of the role of vitamin C and Zn in body defences(1,2,3)Defence Vitamin C ZnSkin and mucosal barriers Collagen synthesisImproved strengthCellular proliferationMaintains thicknessNeutrophils and macrophages Improved motility and chemotaxisEnhanced killingOverall improvement in phagocytosisLymphocytes Proliferation of stem cellsB- and T-cell differentiationB- and T-cell interactionB lymphocytes Antibody productionT lymphocytes Proliferation Proliferation and appropriate responseDestruction of infected tissue cells and tumoursInterferon Production enhancedAdequate intakes of vitamin C and Zn are essential for health.This is of special importance in populations in which insufficient intake ofthese nutrients is prevalent. The current belief is that regular prophylactic intakes of vitamin C at doses of ‡ 200 mg daily have no effecton the incidence of the common cold, but may be beneficial in the reduction of the severity and duration of the symptoms, suggesting thatvitamin C plays some role in the respiratory defence mechanisms. However, the elderly, who have been shown to have a lowered vitaminC status and may therefore be more prone to infections, individuals exposed to continuous oxidative stress, such as chronic smokers, andindividuals exposed to heavy physical exercise and/or cold environment may benefit from a moderate continuous vitamin C intake. Othervulnerable population groups include children. As a result of the high prevalence of Zn deficiency, especially in children in developingcountries, and the impaired immune status, susceptibility to infectious diarrhoea, malaria and pneumonia is found to be substantiallyincreased. Large intervention trials with daily intakes of 10–30 mg Zn have shown that Zn supplementation could be an importantadjuvant therapy for treating these infectious diseases in children in developing countries. Given that both vitamin C and Zn havean important and synergistic effect on immune function and the modulation of host resistance to infectious agents it is hence appropriateand beneficial to combine the trace element Zn with a high dose of vitamin C in one supplement.1. Wintergerst ES, Maggini S & Hornig DH (2006) Ann Nutr Met 50, 85–94.2. Wintergerst ES, Maggini S & Hornig DH (2007) Ann Nutr Met 51, 301–323.3. Maggini S, Wintergerst ES, Beveridge S & Hornig DH (2007) Br J Nutr 98, Suppl. 1, S29–S35.Proceedings of the Nutrition Society (2008), 67 (OCE), E83 doi:10.1017/S0029665108006927https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S0029665108006927Downloaded from https:/www.cambridge.org/core. University of Basel Library, on 11 Jul 2017 at 09:32:27, subject to the Cambridge Core terms of use, available at

Immune-enhancing role of vitamin C and zinc and effect on clinical conditions

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