Many thanks!

This is a really common area of confusion. Most natural cheeses (cheddar, Swiss, mozzarella, Parmesan, brie, camembert, and most blue cheeses) are inherently gluten-free, and you’re right that the molds used today are typically grown on gluten-free media. The bigger risks tend to come from processed cheeses: shredded cheese (anti-caking agents), cheese spreads, beer-washed rinds, smoke-flavored cheeses, and anything with added seasonings or “natural flavors,” where cross-contact can happen. As for yeast, you’re also correct — yeast itself is gluten-free. The issue is the source: brewer’s yeast and yeast extracts can be derived from barley unless labeled gluten-free, while baker’s yeast is generally safe. When in doubt, sticking with whole, unprocessed cheeses and products specifically labeled gluten-free is the safest approach, especially if you’re highly sensitive.

Kirkland brand (at Costco) is gluten-free and is 2,000 IU.

Thanks a lot for your response! Can you maybe specify which kind of cheeses I should be cautious about? Camembert/Brie and blue cheeses (the molds of which are nowadays mostly grown on gluten-free media, though, so I've read, right?) or other ones as well? Also, I was under the impression that yeast is generally gluten-free if not declared otherwise. Is that false?

I agree with @trents, but thank you for bringing this up here!