Evidence Level
Oral hyaluronic acid supplementation has been validated by multiple well-designed RCTs. Oe et al. (2017) conducted a landmark double-blind, placebo-controlled study showing that 120 mg/day of low-molecular-weight HA significantly increased skin moisture and reduced wrinkle depth in Japanese adults over 12 weeks. Kawada et al. (2014) similarly demonstrated improvements in skin elasticity and roughness with 240 mg/day. A systematic review by Hsu et al. (2021) concluded that oral HA supplementation consistently improves skin hydration across studies, with molecular weight being a key factor in absorption — low-molecular-weight forms (< 300 kDa) showing superior oral bioavailability. Isotope tracing studies have confirmed that ingested HA reaches the skin within 24 hours.