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.

Dashti-Khavidaki S, Talasaz AH, Tabeefar H, Hajimahmoodi M, Moghaddam G, Khalili H, Lessan-Pezeshki M, Jahanmardi A. Plasma Vitamin C concentrations in patients on routine hemodialysis and its relationship to patients' morbidity and mortality. 1. Int J Vitam Nutr Res. 2011 Jul;81(4):197-203.

BACKGROUND: Some studies have hypothesized the protective role of Vitamin C against cardiovascular disorders (CVD) in patients with end-stage renal disease (ESRD). This study was designed to assess plasma Vitamin C concentration and its relationship to hemodialysis (HD) patients' morbidity and mortality. METHODS: Plasma Vitamin C concentrations were assessed in HD patients using spectrophotometry and subjects were prospectively followed for up eighteen months for all-cause mortality. Any association between Vitamin C concentration and patients' demographic data, co-morbidities, or the cause of ESRD were investigated using the Chi-square test. RESULTS: Ninety-one patients with a mean age of 56.7 ? 15.7 years were included in this study. The most frequent cause of ESRD was simultaneous hypertension and diabetes in 30 % of patients, followed by hypertension in 25.6 %, and diabetes in 11.1 %, respectively. About 34 % of patients had CVD as the most prevalent co-morbidity. Forty-nine patients (53.8 %) had low levels of Vitamin C concentration. There was a significant relationship between Vitamin C insufficiency and presence of any co-morbidity in HD patients (p < 0.05). There was a significant difference in Vitamin C concentrations between patients without co-morbidities and those with cardiovascular ones (F[2,88]=3.447, p = 0.036). Twenty-two (24.2 %) patients died over a median duration of 227 days. There was a significant difference in time to death of patients with and without low levels of Vitamin C concentration (p = 0.04). CONCLUSIONS: The results showed lower plasma Vitamin C levels in HD patients who suffered any co-morbidity and sooner time to death in these patients.