Does fiber push through medication?

Can food sit undigested (or partially) in our GI tract, and then be pushed through with fiber/oatmeal or detox, i.e. such that nutrients in the food that never got processed then do when the food is pushed through? If so, can this be true for medication, e.g. psychiatric meds? Sometimes I swear I can feel the effect of the previous day’s medication, even when it was an instant-release and should only have lasted 4 hours, especially when I eat a lot of oatmeal… Thanks for any thoughts!

Digestion starts as soon as you put food into your mouth, but presumably you’re talking about the absorption of food components, nutrients, and medications that takes place in the small intestine. The chopped-up watery slush in the intestines, called chyme, moves through at a regular pace produced by peristalsis. The large intestine mostly takes excess water out of the chyme, although it is possible that the last tiny traces of medicines may be absorbed there. Nothing that happens in the large intestine (colon) should have any noticeable effect on meds, though.

Nothing ever sits around waiting, except for a true intestinal blockage. If you had one you’d be in the hospital. All fiber does is regulate the water content of the residue in the large intestine. A more watery feces moves through more easily.

If you take a fiber supplement with medication, vitamins, etc, it is possible that the fiber will absorb these items, and you won’t receive the benefit of them.

and no, you don’t have 10-15 lbs of undigested meat stuck in your intestines. if you did, that would be a legitimate, immediate medical emergency.

This thread is grosser when paired with the OP’s name.


Fiber may reduce the absorption of a small selection of medications:

That’s definitely not connected to anything in the OP. It’s also not quite the case that fiber absorbs these medications. The more likely mechanism is that the fiber alters the viscosity of the chyme, slowing the rate of absorption or causing more rapid passage.