Glutamine (standalone, healthy adults)

Tier 3 — weak evidence · Gut health / Immunity

Has real evidence for helping critically ill and hospitalized patients recover. However, your body already makes about 80 g per day on its own, so supplements add little benefit for healthy people who eat enough protein. The one exception is post-infectious irritable bowel syndrome, where 15 g per day may help restore gut lining. Very safe.

Dose: 15 g/day for post-infectious IBS-D (best current application)