A molecule the body already makes, sold as a prescription medicine in several countries and as a supplement elsewhere. The strongest human signal is memory in adults whose recall has slipped with age, from small, short, often poor-quality studies. Side effects are mild and uncommon. Much of the supporting literature comes from the companies that sell it. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Plasma free choline | 8–12 µmol/L | Shows whether supplemental choline is needed at all |
| Homocysteine | < 8 µmol/L | Choline and folate share the methylation pathway that clears it |
| Trimethylamine N-oxide | < 5 µmol/L | Tracks gut conversion of choline into a clot-promoting metabolite |
| Blood pressure | < 120/80 mmHg | Detects the hypotension reported at high doses |
| Resting heart rate | 55–70 bpm | Detects the bradycardia reported with high-dose injected use |
| Alanine aminotransferase | 10–26 U/L (men), 8–22 U/L (women) | Choline adequacy protects against fat accumulation in the liver |
| Computerised cognitive battery composite | No established target; track change from the individual's own baseline | Gives an objective read on whether memory is actually responding |
Cadence: Blood pressure and pulse at baseline and 4 weeks, cognitive battery at 12 weeks, full fasting panel at 6 to 12 months thereafter