Already in this user's V stack daily stack at 500 mg Cognizin. Best-evidenced and cleanest-safety-profile chronic choline donor for a 20yo brain-priority MMA athlete with subconcussive impact exposure — A-tier replicated trials in healthy adults (attention, working memory, processing speed) plus a large stroke-recovery evidence base, no Korean-style cardiovascular signal, and the cytidine-uridine bonus citicoline uniquely delivers makes it the ideal chronic baseline cholinergic substrate. Verdict would only change if 23andMe shows something unexpected or if a major safety signal emerges.

Already in this user's V stack stack at 1200 mg/day (Swanson NAC, 2 caps). Massive A-tier evidence base — FDA-approved indication for paracetamol overdose, A-tier psychiatric (OCD, BFRB/trichotillomania), B-tier addiction + glutamate-toxicity rationale. Cheap, daily-safe, BBB-penetrant. For an MMA athlete with daily subconcussive impact, the glutamate-modulation + glutathione-precursor combination is mechanistically near-perfect — no other single supplement covers both lanes as well. Verdict would only weaken if a credible chronic-toxicity signal emerged at 1200-2400 mg/day (none currently exists after 30+ years of clinical use).

A-tier evidence for cleaner cognition when paired with caffeine; A-tier subjective sleep onset support; B-tier acute anxiolytic. Cheap, daily-safe, minimal tolerance, stack-clean with everything in V4. Already in V4 at Suntheanine 200 mg/day. Verdict would only change if a credible chronic-toxicity signal emerged (none does) or if the 2025 sleep meta-analysis "subjective-only, not objective" finding hardens into "placebo-equivalent on PSG" — at which point it stays A-tier for caffeine pairing but becomes B-tier (not A) for sleep onset.