Effect Of Microbial Fermentation On Content Os Statin, Gaba, And Polyphenols In Pu-Erh Tea
The Journal of Agricultural and Food Chemistry (2007)
A study conducted in Taiwan which isolated the micro-organisms that make aged Pu-erh tea taste good and measured their effect over time when introduced to new tea leaves. The study does not prove that drinking Pu-erh tea (new or aged) will improve your health but when combined with other references, supports the case that this is more likely to be true than not true.
Note the use of the term 'fermentation' in the context of its historic usage in the tea industry. The actual process being described is oxidization which is exactly the opposite process. For an explanation on this and other quirks of history, language and culture regarding Chinese tea, see our guide: How To Store Pu-Erh Tea by Daniel Lui.