system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: what makes a leaf of lettuce more digestible than other leaves?

It's clear that our stomachs can't break down most greenery around us, like ruminants with 4 stomachs can. But what makes one leaf digestible to us and another not?
gpt
Cellulose. Humans lack the enzyme cellulase thus leaving us unable to digest plants that are high in cellulose. However, a plant like lettuce has a relatively low amount of cellulose compared to other natural greens and leaves, and contains a higher amount of digestible material and our body just filters the cellulose through the stomach undigested which it is able to do since the amount is low.