Pectin?
Like in canning?
Yes, but probably treated to make it a lot easier to absorb. Pectin is a fiber easily extracted from citrus peel, fruit and seed.
You can make enough pectin to set a batch of jelly by putting 2 tablespoons of crushed citrus seed in cheesecloth and dropping it in fruit juice or something acidic like vinegar and simmering it.
Or use the peels.