Horsetail (Equisetum)

Tier 3 — weak evidence · Hair · Nails · Silica

A prehistoric plant and natural silica source marketed for hair, nails, and bones. One small RCT found improved nail brittleness after 6 months. Hair evidence is mostly anecdotal. Contains thiaminase, which destroys vitamin B1 — long-term use without B1 supplementation can cause deficiency. Not recommended for extended use without added B1.

Dose: 300 mg/day standardised horsetail extract; supplement B1 if using long-term; limited evidence