LOS ANGELES, June 22 (Xinhua) -- A new study by U.S. researchers suggested that daily use of a mushroom extract supported the immune system in clearing human papillomavirus (HPV) infections.

       The study, published Tuesday in Frontiers in Oncology, focused on women with a minimum two-year history of persistent high-risk HPV.

       In the randomized, double-blind, placebo-controlled Phase II study, patients in the treatment group received the supplement AHCC, a proprietary mushroom extract, for six months, followed by six months of a placebo.

       Patients in the placebo group received a placebo for 12 months.

       The study found that 14 of 22 patients, which is over 63 percent, in the treatment arm became HPV-negative.

       "Our results show that AHCC supplementation may help most patients eliminate their HPV infection and may decrease the long-term risk of HPV-related cancers," said Judith A. Smith, lead researcher on the study and professor in the Department of Obstetrics, Gynecology and Reproductive Sciences at UTHealth Houston.

       Every year, about 19,400 women and 12,100 men in the United States experience cancers caused by HPV, according to data from the U.S. Centers for Disease Control and Prevention.