"moist fiber" = freshly grind up some flaxseeds and add a little (or a lot) of water to them and let them sit from 5-10 minutes. Drink it down. Fiber, O-3s, and no gluten.
I'd highly suggest that you tell him I suggested he get (at minimum) the "Stool Test for Gluten Sensitivity" at www.enterolab.com
. He can add other tests on to that as he wishes. Or if he'd like to take a chance with his PCP, have him ask to get the blood test "for celiac disease" (tissue transglutaminase). While the stool test shows issues much, much earlier, the blood test may be easier for him to swallow. He must know that a negative blood test doesn't mean he's not sensitive, it just means the issue hasn't gotten bad enough yet (it shows up in the stool first).
If you'd like to know which probiotics I recommend (which is first-line supplement therapy in my book for issues like this, along with dietary changes), shoot me a PM or check out my store.
Also, hemp protein (Nutiva or Nature's Way) has ~14g of fiber per serving, along with 11g of protein. Another option...