The thousand year ginseng was a present given to Guo Xiang for her 16th birthday by I-can't-remember-who. It is "claimed" to be able to eradicate various poisons and (most importantly) extend the life of the one who eats it.
What does everyone think happened to it?? If it really can do what is claimed to do, then it is possible for something like a 150 year old XLN running around in HSDS. Personally, I hope that didn't happen because it is just plain ridiculous. Maybe Z3F got it somehow, that's how he's able to walk around healthily when he's 110 or something.