Beta-hydroxy-beta-methylbutyrate free acid (HMB-FA)

Tier 2 — promising · Muscle preservation · Recovery · Clinical nutrition

The free acid form of HMB absorbs faster and reaches higher blood levels than the calcium salt. A 2024 meta-analysis found HMB-FA (3 g/day) significantly reduces muscle damage markers after resistance exercise and preserves lean mass during caloric restriction. ISSN position stand supports its use for trained athletes during overreaching phases and for older adults at risk of muscle loss.

Dose: 3 g/day HMB free acid in 3 divided doses of 1 g; take 30–60 min before exercise