Haven't really checked this out thoroughly yet but studies reportedly show that high cortisol levels make people more prone to catching colds. Kava probably lowers cortisol levels, making people less likely to catch a cold and more capable of dealing with it if they do. I haven't had a cold in years maybe Kava is the reason.
http://abcnews.go.com/Health/Coldan...eds-common-cold-study-finds/story?id=16054304
Stress makes the common cold more miserable and harder to kick by letting inflammation linger, a new study found.
Men and women who had chronic stress caused by work woes or marital strife were more likely to develop persistent cold symptoms after inhaling the cold virus than their stress-free counterparts. The culprit: cortisol, a stress hormone that serves as the off switch for the body's inflammatory response.
"The symptoms of a cold are not caused directly by the virus, they're caused by the inflammatory response to the infection," said Sheldon Cohen, a professor of psychology at Carnegie Mellon University in Pittsburgh and lead author of the study published today in the Proceedings of the National Academy of Sciences. "You want to produce enough of inflammation to fight off the infection, but not so much that you experience cold symptoms."
With chronic stress, cortisol is overproduced, and the immune system becomes resistant. In the absence of the off switch, inflammation lingers long after the cold virus is gone. "You have people whose immune cells are not responding to cortisol and, at the same time, they're exposed to a virus system creating an inflammatory response. But the body doesn't have the mechanism that allows it to turn off the inflammatory response, which manifests as cold symptoms," said Cohen.
http://www.ncbi.nlm.nih.gov/pubmed/11338315
A cohort study of stress and the common cold.
Takkouche B1, Regueira C, Gestal-Otero JJ.
Author information
Abstract
The common cold is one of the major causes of work absenteeism. Former studies, based on artificial inoculation of rhinovirus, implicated psychological stress in the occurrence of this syndrome, either by increasing susceptibility to the virus or by causing the subject to overrate the perception of the symptoms. Nevertheless, few studies on the effect of stress on the naturally acquired common cold have been conducted. We carried out a 1-year prospective cohort study among the faculty and staff of a Spanish university (N = 1,149). By means of standardized questionnaires, validated in a random sample of the population, we assessed the relation between the occurrence of common cold episodes and exposure to four dimensions of stress: stressful life events, negative affect, positive affect, and perceived stress. All four aspects of stress were related to the occurrence of the common cold. Subjects with a high (fourth quartile) index of negative affect showed an incidence rate ratio of 3.7 (95% confidence interval = 2.2-6.2). The incidence rate ratios for the fourth quartile were 2.5 (95% confidence interval = 1.5-4.1) and 1.9 (95% confidence interval = 1.1-3.2) for perceived stress and stressful events, respectively. A high index of positive affect was associated with an incidence rate ratio of 0.6 (95% confidence interval = 0.3-1.0). These findings suggest that psychological stress is a risk factor for the common cold.
