Vitamin C megadosage the airways as a result of vigorous exercise. EIB seems to be caused by the loss of water caused by increased ventilation, which may lead to the release of mediators such as histamine, prostaglandins and leukotrienes, all of which cause bronchoconstriction. Vitamin C participates in the metabolism of these mediators and might thereby influence EIB. A meta-analysis showed that 0.5 to 2 g/day of vitamin C before exercise decreased EIB by half. A meta-analysis showed a significant positive effect of vitamin C on endothelial function. Benefit was found of vitamin C in doses in the range from 0.5 to 4
Scurvy championing the cause of citrus juice, therefore, had no practical impact. Medical theory was based on the assumption that scurvy was a disease of internal putrefaction brought on by faulty digestion caused by the hardships of life at sea and the naval diet. Although this basic idea was given different emphases by successive theorists, the remedies they advocated (and which the navy accepted) amounted to little more than the consumption of 'fizzy drinks' to activate the digestive system, the most extreme of which was the regular consumption of 'elixir of vitriol' – sulphuric acid taken with spirits and barley water,