system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can humans eat leafy greens like spinach and its extremely beneficial, but cant eat generic grass for any nutritional value?

I ask this as I munch on spinach like a cow.
gpt
Greens like spinach have much thinner cell walls than grass. It's like the difference between tearing through a garbage bag and a brick wall. Cows can do it by chewing, swallowing, regurgitating, chewing again...