[hirvi74]

This is the first I have ever read about fiber causing issues with medications.

What effects does fiber have on certain medications and why? Does it slow the absorption rate due to the medication being dispersed in the fiber?

[eurasiantiger]

It’s not the fiber. Grapefruit contains furanocoumarins which inhibit the action of the liver enzyme CYP3A4. That particular enzyme breaks down most medications.