Andrew Huberman takes very small amounts of glutamine on a regular basis.

“Now, I've been taking glutamine as a supplement, gosh, since I was in college, mostly because I felt, either by superstition or by reality, that it protected me from various flus and colds, and things of that sort, because of the purported immune-enhancing effects. Again, those immune-enhancing effects have some data to support them, not a ton. However, I got into the habit of taking glutamine, and now that I've learned that glutamine seems to also have some cognitive-enhancing effects, possibly, it's a supplement that I continue to take.”