Although it's been a while since Zhang Yanhang needed something to restore Life Value, it's clear that he doesn't actually need this kind of thing. Instead of items that can restore Life Value, he actually wants something that can restore Physical Strength.
After all, the Green Medicine Grass obtained early on in Raccoon City could still be used because of the Hundred Taboos. However, that thing couldn't even recover during his Second Tier phase, let alone now when he's at the Fourth Tier.
While it can indeed be used, the Green Medicine Grass that can only restore a tiny bit of Physical Strength is like a drop in the bucket for Zhang Yanhang, whose Physical Strength has surged by more than a thousand times, even if he eats all of it, it would only recover a bit.