As early as in the year 1999, during the meeting of the American Chemical Society it was said that vitamin C lowers the level of cortisol, while discussing the research carried out on rats and speculating that a similar influence may also be visible on humans.
Both in animals and in people, adrenal glands react to stress by releasing corticosteroids, such as cortisol and corticosterone. These and other hormones provoke the “fight or run” reaction, the aim of which is to enable taking defensive action in the circumstances of danger.
However, these hormones also suppress the immune system, the first defense line of the organism against diseases.
P. Samuel Campbell, the chairman of the faculty of biological sciences at the University of Alabama, along with his colleagues, stressed laboratory rats by immobilizing them for one hour a day for the period of three weeks. When stressed rats were administered 200mg of vitamin C (the equivalent of a few grams in humans) the level of stress hormones in blood of the rats was reduced.
Also other indicators of physical and emotional stress were reduced: weight loss, adrenals enlargement, decreased size of thymus and spleen.
Vitamin C therapy also increased the level of IgG antibodies in the organism, being the main defense against the systemic infection.
In the control group of rats, which were not exposed to stress, vitamin C increased the production of IgG antibodies to a little higher level, as it took place in the case of stressed rats. This suggests that stress causes vitamin C tolerance. Therefore animals – and probably also people – who are under the influence of emotional stress, may need higher doses of vitamin C in order to protects their immune system.
P. Samuel Campbell concluded that his research help to throw light on other evidence of vitamin C effectiveness in the protection of the immune system. For example, in other studies, vitamin C increased the immunity in the tested group of elderly women. It also reduced the occurrence frequency of the upper respiratory tract infections among marathon runners.