MicronutrientsRationale and impact of vitamin C in clinical nutritionMcGregor, Gerard Pa; Biesalski, Hans Kb Author Information aInstitute of Physiology, Faculty of Medicine, Philipps University of Marburg, Marburg, Germany bDepartment of Biological Chemistry and Nutrition, University Hohenheim, Stuttgart, Germany Correspondence to Hans K. Biesalski MD, PhD, Department of Biological Chemistry and Nutrition, Garbenstrasse 30, University Hohenheim, 70599 Stuttgart, Germany Tel: +49 711 4594112; fax: +49 711 4593822; e-mail: [email protected] Current Opinion in Clinical Nutrition and Metabolic Care: November 2006 - Volume 9 - Issue 6 - p 697-703 doi: 10.1097/01.mco.0000247478.79779.8f Buy Metrics Abstract Purpose of review The impact of vitamin C on oxidative stress-related diseases is moderate because of its limited oral bioavailability and rapid clearance. Parenteral administration can increase the benefit of vitamin C supplementation as is evident in critically ill patients. The aim here is to assess recent evidence of the clinical benefit and underlying effects of parenteral vitamin C in conditions of oxidative stress. Recent findings In critically ill patients and after severe burns, the rapid restoration of depleted ascorbate levels with high-dose parenteral vitamin C may reduce circulatory shock, fluid requirements and oedema. Summary Oxidative stress is associated with reduced ascorbate levels. Ascorbate is particularly effective in protecting the vascular endothelium, which is especially vulnerable to oxidative stress. The restoration of ascorbate levels may have therapeutic effects in diseases involving oxidative stress. The rapid replenishment of ascorbate is of special clinical significance in critically ill patients who experience drastic reductions in ascorbate levels, which may be a causal factor in the development of circulatory shock. Supraphysiological levels of ascorbate, which can only be achieved by the parenteral and not by the oral administration of vitamin C, may facilitate the restoration of vascular function in the critically ill patient. © 2006 Lippincott Williams & Wilkins, Inc.