Naturally grown,raw VC was collected from local clean area which uses natural growth without spray of insect-toxin drugs at Chiang Mai Province, Thailand. VC was washed four times and cut to small piece approximately one inch and heated until dry by an oven at 70 decree C. VC was then kept in a sterile bottle which contained a small bag of anti-moisture silica-gel pills. Each day for preparation, 20 grams of dry VC material and 3 cups of clean water (390 milliliter) was boiled in a traditional pot until water evaporated to 1 cup (130 milliliter). Condensed VC juice was then preserved in a clean bottle and was provided to subjects to drink prior to smoking each, three days per weeks for two months.