Vitamin C is water-soluble, and probably the most famous of all the vitamins. Even before its discovery in 1932, physicians recognised that there must be a compound in citrus fruits preventing scurvy, a disease that killed as many as 2 million sailors between 1500 and 1800. Later researchers discovered that man, other primates and the guinea pig depend on external sources to cover their Vitamin C requirements. Most other animals are able to synthesise Vitamin C from glucose and galactose in their body. The most prominent role of Vitamin C is its immune stimulating effect, which is important for the defence against infections such as common colds. It also acts as an inhibitor of histamine, a compound that is released during allergic reactions. As a powerful antioxidant it can neutralise harmful free radicals and aids in neutralising pollutants and toxins. Thus it is able to prevent the formation of potentially carcinogenic nitrosamines in the stomach (due to consumption of nitrite-containing foods, such as smoked meat). Importantly, Vitamin C is also able to regenerate other antioxidants such as Vitamin E. Vitamin C is required for the synthesis of collagen, the intercellular 'cement' substance which gives structure to muscles, vascular tissues, bones, tendons and ligaments. Due to these functions Vitamin C, especially in combination with zinc, is important for the healing of wounds. Vitamin C contributes to the health of teeth and gums, preventing haemorrhaging and bleeding. It also improves the absorption of iron from the diet, and is needed for the metabolism of bile acids, which may have implications for blood cholesterol levels and gallstones. In addition, Vitamin C plays an important role in the synthesis of several important peptide hormones and neurotransmitters and carnitine. Finally, Vitamin C is also a crucial factor in the eye's ability to deal with oxidative stress, and can delay the progression of advanced age-related macular degeneration (AMD) and vision-loss in combination with other antioxidant vitamins and zinc.

Lima de Ara?jo L, Maciel Barbosa J, Gomes Ribeiro AP, Oliveira Dos Santos AC, Pedrosa F. Nutritional status, dietary intake and serum levels of Vitamin C upon diagnosis of cancer in children and adolescents. 1. Nutr Hosp. 2012 Apr;27(2):496-503.

Introduction: The prevalence of malnutrition upon diagnosis, together with reduced food intake secondary to disease and treatment, make the periodic assessment of nutritional status (including the intake of antioxidant nutrients) of considerable importance to the follow up of patients with cancer. Objectives: Assess the nutritional status and frequency of inadequate Vitamin C levels among children and adolescents with cancer at the beginning of treatment and determine associated factors. Methods: A cross-sectional study was carried out with 30 patients under 18 years. Nutritional status was assessed using laboratory methods and anthropometric measurements. Vitamin C adequacy was assessed through its serum concentration and dietary intake. Results: In the sample, 10% were short for their age and 13.3% were underweight. The triceps skinfold measurement revealed fat depletion in 68% and the arm muscle circumference measurement revealed muscle depletion in 32.0%. Seventy percent of the patients had Vitamin C deficiency and had greater weight loss, lower Z scores for all anthropometric indicators analyzed, lower serum albumin and higher C-reactive protein than those without Vitamin C deficiency, but these differences were not statistically significant. Conclusions: children with cancer may have nutritional deficits upon diagnosis. Further studies are needed on the association between serum levels of antioxidant and nutritional status in order to offer safe, effective nutritional support.