However I never heard of quercitin being a problem. Nevertheless I usually just eat an apple or two a day instead. I will meanwhile try out regular flushing niacin. Its very possible my wonderful inositol hexaniacinate has been causing me problems with increased dif. sleeping at night with terrible jerking legs. Thanks for the tip!! Also found out recenlty not all vit. C is made the same. The only one I seem to tolerate is made from sago palm...