A compound in green tea has a powerful ability to increase the number of \"regulatory T cells\" that play a key role in immune function, U.S. researchers say. Principal investigator Emily Ho of the Linus Pauling Institute at Oregon State University says that may be one of the underlying mechanisms that make green tea beneficial in helping control inflammation, improve immune function and prevent cancer. Pharmaceutical drugs perform similar roles and have been the subject of much research, scientists say, but they have problems with toxicity, Ho says. \"This appears to be a natural, plant-derived compound that can affect the number of regulatory T cells, and in the process improve immune function,\" Ho says in a statement. \"When fully understood, this could provide an easy and safe way to help control autoimmune problems and address various diseases.\" In the study, the scientists experimented with a compound in green tea a polyphenol called EGCG which is believed to be responsible for much of its health benefits and has both anti-inflammatory and anti-cancer characteristics. The study, published in Immunology Letters, found the compound could cause a higher production of regulatory T cells and while its effects were not as potent as produced by prescription drugs it also had few concerns about long-term use or toxicity. \"EGCG may have health benefits through an epigenetic mechanism, meaning we aren\'t changing the underlying DNA codes, but just influencing what gets expressed, what cells get turned on,\" Ho says.