Evidence Trace, complete trial record
In plain terms
In plain terms: Hyaluronic Acid (Oral) has some human trial evidence supporting it, but the evidence is not yet strong enough for EBL to call it established. It is worth knowing about and worth discussing with your clinician.
Hyaluronic Acid (Oral)
B
Supported: a good trial, backed by more
The endpoint this grade is based on: self_report, Graded by use. Skin hydration, elasticity and wrinkle depth: Grade B, several 12-week randomized trials and a 7-trial meta-analysis on instrument-measured surrogates, every trial run by or with a manufacturer, stated beside the letter. Knee symptoms: Grade C, one trend with an age-subgroup signal, one null primary, one self-rating without objective change. No trial measured cartilage or joint lubrication, and no human trial supports a gut-barrier claim.
The evidence as the record states it
Joints: Tashiro et al. (ScientificWorldJournal, 2012; PMID 23226979): 60 adults with knee osteoarthritis, 200 mg/day for 12 months with daily quadriceps exercise in both arms; symptom scores improved in both groups, with a trend favoring hyaluronic acid overall and significance only in those aged 70 or under at months 2 and 4; the hyaluronic acid was made by a manufacturer whose researcher is a co-author. Kalman et al. (Nutr J, 2008; PMID 18208600): 20 adults with knee osteoarthritis, 80 mg/day of a chicken-comb extract for 8 weeks; WOMAC pain, the primary endpoint, did not differ from placebo (p = 0.94). Sugiyama et al. (Exp Ther Med, 2024; PMID 38234616): healthy adults with knees graded 1 or less, 111 mg/day for 12 weeks; self-rated knee discomfort improved, objective mobility tests did not; the capsules were supplied by their manufacturer, whose employees are authors. Skin: Kawada et al. (J Clin Biochem Nutr, 2015; PMID 25834304): randomized skin-hydration trial of two of the same manufacturer's hyaluronans, run by its research division. Hsu et al. (Nutrients, 2021; PMID 34203487): 40 adults, 120 mg/day for 12 weeks; wrinkles, stratum corneum water content, water loss and elasticity better than placebo; three authors are the manufacturer's employees. Gao et al. (2023; PMID 38009035): randomized skin-condition trial with four authors employed by a second manufacturer. Dolečková et al. (Sci Rep, 2025; PMID 41422283): the largest skin trial, 150 adults, 60 or 120 mg/day for 12 weeks; hydration, elasticity, water loss and periorbital wrinkle depth better at 120 mg/day; run by a third manufacturer, with six of its employees as authors. Amin et al. (J Drugs Dermatol, 2025; PMID 40911749): meta-analysis of 7 randomized trials; hydration, elasticity and wrinkle depth improved, firmness and water loss not, with heterogeneity noted. Kawada et al. (Nutr J, 2014; PMID 25014997) is a review written by a manufacturer's employees, not a trial, and is background. Grade C: self-reported joint outcomes that are mixed, and instrument-measured skin surrogates that are consistent but manufacturer-run throughout. Funding: every trial behind the letter was run with a manufacturer's product and, in all but the null joint trial, with the manufacturer's researchers among the authors; none states an independent funder.
PMID 23226979 PMID 18208600 PMID 38234616 PMID 25834304 PMID 34203487 PMID 38009035 PMID 41422283 PMID 40911749 PMID 25014997
Evidence by specific use
Skin hydration, elasticity and wrinkle depth in adults
Grade B
Instrument-measured skin outcomes. Kawada et al. (J Clin Biochem Nutr, 2015; PMID 25834304): skin hydration trial of two of one manufacturer's hyaluronans, run by its research division. Hsu et al. (Nutrients, 2021; PMID 34203487): 40 adults, 120 mg/day for 12 weeks; wrinkles, stratum corneum water content, water loss and elasticity better than placebo; three authors are the manufacturer's employees. Gao et al. (2023; PMID 38009035): randomized skin-condition trial with four authors employed by a second manufacturer. Dolečková et al. (Sci Rep, 2025; PMID 41422283): 150 adults, 60 or 120 mg/day for 12 weeks; hydration, elasticity, water loss and periorbital wrinkle depth better at 120 mg/day; run by a third manufacturer with six employees as authors. Amin et al. (J Drugs Dermatol, 2025; PMID 40911749): meta-analysis of 7 randomized trials; hydration, elasticity and wrinkle depth improved. Replicated randomized evidence on instrument-measured surrogates is B; every trial was run by or with a hyaluronic acid manufacturer, which the replication funding rule counts and states beside the letter. Not A: skin hydration and elasticity are surrogate measures, not clinical outcomes or functions.
PMID 25834304 PMID 34203487 PMID 38009035 PMID 41422283 PMID 40911749
Knee symptoms in adults with knee osteoarthritis or knee discomfort
Grade C
Mixed and self-reported. Tashiro et al. (ScientificWorldJournal, 2012; PMID 23226979): 60 adults with knee osteoarthritis, 200 mg/day for 12 months with daily quadriceps exercise in both arms; a trend favoring hyaluronic acid overall and significance only in those aged 70 or under at months 2 and 4; the manufacturer's researcher is a co-author. Kalman et al. (Nutr J, 2008; PMID 18208600): 20 adults with knee osteoarthritis, 80 mg/day for 8 weeks; WOMAC pain, the primary endpoint, no different from placebo. Sugiyama et al. (Exp Ther Med, 2024; PMID 38234616): healthy adults with knee discomfort, 111 mg/day for 12 weeks; self-rated discomfort improved, objective mobility tests did not; the manufacturer's employees are authors. A trend, a null primary and a self-rating without objective change: C.
PMID 23226979 PMID 18208600 PMID 38234616
Why Grade B and not Grade A
Grade B reflects moderate human evidence -- typically a single strong trial, multiple smaller trials, or surrogate endpoint data without hard clinical outcome replication. To reach Grade A, Hyaluronic Acid (Oral) would require at least one additional independent randomized trial demonstrating a hard clinical endpoint or objectively measured functional outcome in a comparable population.
What this grade covers and what it does not
Grade B, the record's best use: skin hydration, elasticity and wrinkle depth, instrument-measured surrogates with several positive 12-week randomized trials (Hsu et al., 2021; PMID 34203487; Dolečková et al., 2025; PMID 41422283; Gao et al., 2023; PMID 38009035; Kawada et al., 2015; PMID 25834304) and a positive 7-trial meta-analysis (Amin et al., J Drugs Dermatol, 2025; PMID 40911749). Replicated randomized evidence on a surrogate is B, and the surrogate is what keeps it from A. Every skin trial was run by or with a hyaluronic acid manufacturer; under the replication funding rule those trials count and the funding is stated beside the letter. KNEE SYMPTOMS CARRY THEIR OWN C: a trend with an age-subgroup signal (Tashiro et al., 2012; PMID 23226979), a null primary (Kalman et al., 2008; PMID 18208600) and a self-rated improvement without objective change (Sugiyama et al., 2024; PMID 38234616). The record was divided from one bundled C in October 2026 by the written rule. WHAT THIS GRADE DOES NOT COVER: cartilage or joint lubrication, which no trial measured; a gut-barrier effect, which no human trial tested; injected hyaluronic acid, a different route; and any skin claim beyond hydration, elasticity and wrinkle depth at 60 to 120 mg/day for 12 weeks.
What would move this grade
An independent randomized trial demonstrating a hard clinical endpoint -- mortality, major adverse event, or objectively confirmed functional improvement -- in an adequately powered sample, with results independently replicated, would support Grade A.
How to track whether this is working
Skin hydration, skin elasticity, joint pain scores.