Hi Caveeater,
I have always used green tea extract, and I was wondering about white tea. I saw at
https://en.wikipedia.org/wiki/White_tea#Composition that white and green tea have similar catechins content, depending on varieties and place of origin. Overall, they both contains polyphenolic antioxidants, like catechins. Those antioxidants are believed to be the cause of theses teas health benefits. You are right when saying that these teas have antioxidants properties, they contain excellent antioxidants. This is part of why they are mast cells stabilizers (
http://www.sciencedirect.com/science/article/pii/S2314459914000088 )
I do not tolerate caffeine at all, it causes me stomach irritation, and anxiety secondary to too much adrenal stimulation. But green tea has been one of the first allied I have found, around 20 years ago, against POIS. Like for you, it helps me a lot with fatigue, and has been a life saver ewhen I had to go to work and get through the day, while in POIS. It has also a good effect on my hypotension ( when in POIS without any prevention method, I have marked and sustained low blood pressure, making very difficult any effort or even normal activity.
I have refined my green tea source, through the years. In the beginning, it was cheap, commercial, full-of-sugar iced tea beverage. Now, I use all-natural, caffeine-free capsules of green tea extract with standardized polyphenols and EGCG ( Jamieson's brand, a high quality Canadian brand of natural products) .
Did you noticed any low blood pressure when you are in POIS, caveeater ?