Polygala tenuifolia (Yuan Zhi)

Tier 3 — weak evidence · TCM nootropic · Memory · Neuroprotection

A TCM herb classified as a Shen (spirit) calming and intelligence-boosting remedy for over 2,000 years. Contains tenuifolin and onjisaponins that cross the blood-brain barrier and enhance BDNF expression in animal models. A 2024 small RCT found 100 mg/day improved verbal memory in healthy older adults. May cause GI irritation at higher doses. Traditional formulas pair it with Acorus and Poria.

Dose: 100–300 mg/day root extract standardised to tenuifolin; traditional decoction 3–9 g/day