Hi @Tannin, in general mushrooms haven't been on the radar as a gluten threat, so I am not sure why you seem to be so concerned with commercial mushrooms like button or Portabella varieties?  While I appreciate the detailed perspective from a cultivation standpoint, I think it's important to clarify that the core concern you're describing—substrate contamination—is an extremely niche risk for the vast majority of celiacs. For anyone buying standard commercial mushrooms like cremini or portobella from a grocery store, the mushroom itself is inherently and safely gluten-free; it's a fungus, not a grain.  The real, practical risk of gluten exposure doesn't come from the remote chance of rye berry residue on a fresh mushroom cap, but from much more likely sources like pre-sliced packaging facilities, canned products with added flavorings, or restaurant preparation where shared equipment and sauces are the true culprits. Focusing on peeling mushrooms seems to address a theoretical problem rather than the actual ones, which are handled by simply buying whole, fresh mushrooms and preparing them in a clean environment. For most people with gluten sensitivity, this is a non-issue, and the warning might create unnecessary alarm about an otherwise safe and healthy whole food.

I was diagnosed with Celiac Disease abput 10 years ago. When I was initially diagnosed my only "symptom" was persistently low iron (that occasionally dipped into anemia). After diagnosis,  over time, I started to develop symptoms when exposed to gluten--they have been overall relatively minor, but have increased over time (and yes, I realize my guts are likely being wrecked regardless of the symptoms) on the rare occasions I've been exposed to gluten. I had COVID19 last week (now testing negative) and was glutened last night (never trust anything labeled gluten-free in a mixed environment). I had my traditional symptoms (sharp gas pains, burping, nausea, stomach ache) but they were accompanied by new, more intense symptoms (muscle cramps all over my body--feet, calves, biceps, neck, shoulders, jaw, abdomen, I'm still sore today and cold sweats). I spent about 6 hours writhing before I felt well enough to get up.  I have been told by my allergist that COVID19 can cause your immune system to hyper react. I'm wondering if that's what happened here.   Has anyone else had experience getting glutened post COVID19? Relatively shortly after recovering from COVID19? Was it a more extreme reaction or same? I can't seem to find any articles on this, so I thought I'd ask the community.  Thank you!

I love mushrooms. I can tell you from a home cultivation point of reference that what is used to grow  the mycelium (building blocks of fungus) that eventually produces fungal colonies that make mushrooms varies wildly depending on the variety. I prefer raising varieties that don’t require rye berries or millet. However, that’s not always financially plausible- I just am careful with how I harvest and prepare those and haven’t had a contamination issue to my knowledge. I raise mushrooms  in sealed tubs far away from where I store and prepare food. Mushrooms themselves are primarily made of chitin. Chitin has zero gluten in it to my knowledge. The issue is contamination. If you find yourself paralyzed about potential contamination of commercial farm fresh mushrooms like Button or Portabella, you can actually peel the outer layers off of the caps and foot chopping off the bottom most portion of the foot. I personally get tested every year to see how my antibody levels are doing. I seem to be doing fine without basing my diet exclusively around food with official Gluten Free labeling. Where this matters most is *pre prepared foods*. Fresh mushrooms I prep myself no problem. If I were to buy prepared mushrooms, I’d scrutinize labels. In restaurants that’s a whole other ballgame. Hope this helps.  

A friend of mine is in the bar trade most of his life and has never heard of lines being mixed for different type of beers and ciders. Better to stick with cans.

Thanks very much for confirming my suspicion @Scott Adams! That helps a lot because I'm really trying to track down and get rid of these sources of cross-contact and so I'm going to just rule out the draft ciders and hope that helps. Also @Rogol72 its nice to hear you haven't had a problem on that side of the pond - draft cider lines being used for cider only certainly sounds like the right way to do it, but I think that must not always be practiced over here!