Quercetin appears to be an inhibitor of the Heat Shock Response, a response to heat exposure that results in activation of heat-shock and heat-response proteins   that can have wide-reaching effects such increasing intestinal permeability.  Specifically, Quercetin has shown inhibition at the level of phosporylation and trimerization in the cytosol    and downstream effects on promoter binding  and results of genetic signalling (mRNA expression and protein accumulation).  Through these effects, it may mitigate the anti-inflammatory effects of Heat-Shock Protein 70 (HSP70).  In humans, 30mg/kg quercetin a day (averaged to 2,000mg Quercetin daily) taken with exercise was shown to increase urinary lactulose on day 1, and increase both lactulose and serum endotoxin on day 7 after heat acclimatization should have occurred.  These results suggest impairment of intestinal permability acutely, and prevention of beneficial adaptations to heat over continual heat exposure associated with 2g Quercetin supplementation.