Hyaluronic acid (HA; hyaluronan) is a glycosaminoglycan found in skin, synovial fluid and other connective tissues. Oral HA has been studied primarily for skin hydration and visible skin-aging outcomes, and for knee discomfort or osteoarthritis symptoms, with smaller human datasets in safety and ocular-surface health. Human skin evidence is the strongest part of the oral-HA literature. A 2025 meta-analysis of seven randomized controlled trials found significant pooled effects on skin hydration, elasticity and wrinkle depth, while pooled effects on firmness, wrinkle volume and transepidermal water loss were not statistically significant. Individual trials have tested approximately 60–200 mg/day across molecular weights ranging from 2 kDa to 1.8 MDa as well as multi-molecular-weight and HA-matrix formulations. No single molecular weight has been established as universally superior. Joint evidence is promising but less certain. A 2024 systematic review identified 11 oral-HA or HA-containing studies involving 597 patients, but many used combination products, co-interventions or proprietary formulations. Direct trials of approximately 111–200 mg/day report some pain or discomfort benefits, alongside small samples, subgroup-dependent findings and inconsistent primary outcomes. The database also retains negative combination trials so positive studies are not considered in isolation. Published oral trials generally report few serious safety concerns, but long-term evidence in healthy supplement users remains limited. A small randomized dry-eye study also tested 240 mg/day oral sodium hyaluronate as an adjunct to topical HA. Industry involvement is common across the evidence base and is disclosed paper by paper. Mechanistic work suggests ingested HA is substantially processed by gut microbes rather than simply being absorbed intact. This Data Center separates meta-analyses, direct oral-HA randomized trials, HA-containing combination studies, narrative reviews, safety studies and mechanistic research so that biological plausibility, formulation-specific findings and clinical efficacy are not treated as equivalent evidence.
Randomized rehabilitation study with sustained pain/disability differences, but the oral intervention combined collagen peptides, vitamin C, sodium hyaluronate and minerals, so it cannot isolate HA.
Systematic review of 11 oral-HA rheumatology studies (597 patients), but attribution is limited because most studies used multi-ingredient products rather than isolated HA.
Prospectively registered double-blind placebo-controlled trial of direct sodium hyaluronate, but very small (31 participants) and manufacturer-linked.
Sourcedoi:10.3892/etm.2023.12352PMID 38234616PMC10792404 Trial registry
Year-long randomized double-blind placebo-controlled trial of near-pure oral HA, but the overall group difference was modest and clearer benefits appeared in a younger subgroup.
Randomized double-blind placebo-controlled knee-OA trial (n=60) with direct between-group pain findings, but short, exploratory and formulation-specific.
Multicenter randomized double-blind placebo-controlled OA trial, but tested FlexPro MD—a combination of krill oil, astaxanthin and 30 mg sodium hyaluronate—so efficacy cannot be attributed to HA alone.
Randomized double-blind placebo-controlled trial with significant WOMAC findings, but the active liquid combined 50 mg HA with glucosamine and chondroitin, preventing HA-specific attribution.
Sourcedoi:10.1097/MD.0000000000024252PMID 33592868PMC7870173 Trial registry
Randomized double-blind placebo-controlled combination trial and important null evidence; active formulation contained HA, glucosamine and chondroitin and did not significantly improve the prespecified symptom or quality-of-life scales versus placebo.
Sourcedoi:10.1097/MD.0000000000027405PMID 34622845PMC8500584
Randomized pilot with clinical and synovial-fluid biomarkers, but only 30 participants and a multi-ingredient preparation containing HA, chondroitin, collagen matrix and keratin.
Randomized comparative study without placebo; oral arm began with HA plus Boswellia before HA alone, so the study cannot isolate pure oral HA or establish superiority over placebo.
Randomized double-blind placebo-controlled adjunct trial after intra-articular HA, but the oral intervention was a multi-ingredient collagen/HA/chondroitin/MSM/mineral formulation and cannot isolate HA.
Randomized single-blind pilot with only 17 patients per arm and an HA product containing 100 mg Boswellia, so positive findings cannot be assigned to HA alone.
Double-blind randomized placebo-controlled trial with clinical and biomarker outcomes, but the intervention was Oralvisc, a HA-containing glycosaminoglycan mixture, so effects cannot be assigned to HA alone.
Very small pilot RCT (n=20) of a chicken-comb extract containing 60% HA; primary WOMAC pain did not differ between groups, so HA-specific efficacy remains uncertain.
Narrative review of oral-HA knee trials and mechanisms; useful historical synthesis but not a systematic review and authored in part by manufacturer researchers.
Prospective randomized controlled human trial of 240 mg/day oral HA, but all participants also used topical HA and the sample was small, so the study tests oral HA as an adjunct rather than standalone therapy.
Mechanistic animal study using isotope-labeled HA; informative for absorption and molecular-weight biology but not human efficacy evidence.
Prospective registered human safety pilot with laboratory and microbiome measurements, but only 20 healthy adults and seven days of dosing; not an efficacy trial.
Sourcedoi:10.3390/nu11051135PMID 31121841PMC6566413 Trial registry
Three-arm randomized, double-blind, placebo-controlled human trial with objective skin measurements; industry co-funding and a combination formula limit ingredient-specific interpretation.
Sourcedoi:10.3390/nu16121908PMID 38931263PMC11206740 Trial registry
Meta-analysis of seven randomized controlled trials; strongest synthesis for oral HA skin outcomes, though the underlying studies are small and heterogeneous.
Large randomized double-blind placebo-controlled dose-ranging trial (n=150), but manufacturer-funded and largely authored by company employees.
Sourcedoi:10.1038/s41598-025-32758-5PMID 41422283PMC12827323 Trial registry
Randomized double-blind placebo-controlled trial with instrumental skin outcomes, but the 60 mg Dermial ingredient is a matrix containing HA, sulfated glycosaminoglycans and collagen rather than isolated HA, and the study was manufacturer-funded.
Sourcedoi:10.1007/s13555-025-01447-6PMID 40498387PMC12256382 Trial registry
Randomized placebo-controlled four-arm study that includes an oral-only active comparison and a combined oral+topical arm; useful formulation evidence but proprietary full-spectrum HA products and company-affiliated investigators limit generalization.
Randomized double-blind dose-ranging human trial (n=129) with objective skin measures; interpretation is tempered by industry-affiliated authors and some within-group analyses.
Randomised, double-blind, placebo-controlled human trial (n=40) with 12 weeks of oral hyaluronan and instrumental skin endpoints. Directly relevant to oral HA efficacy, but small and manufacturer-funded with three authors employed by Kewpie Corporation.
Double-blind placebo-controlled human trial directly comparing two HA molecular weights, but small and heavily industry-affiliated.
Randomized double-blind placebo-controlled human trial with objective skin-moisture measures and two HA molecular weights; small and strongly industry-affiliated.
Randomized double-blind placebo-controlled skin trial using 200 mg/day full-spectrum HA, but short (28 days) and formulation-specific.
Older Japanese double-blind placebo-controlled trial of fermentation-derived HA; direct human evidence but small and accessible mainly through later reviews.
Older Japanese double-blind placebo-controlled skin-moisture trial; direct HA evidence but small, manufacturer-linked and less accessible than modern indexed RCTs.
Older Japanese double-blind placebo-controlled trial cited in later HA reviews; direct oral-HA evidence but small, older and not readily indexed in major databases.
Older Japanese double-blind placebo-controlled skin trial located through later peer-reviewed reviews; useful direct oral-HA evidence but limited by accessibility, small sample and older reporting standards.
Randomized single-blind placebo-controlled clinical component in an institutional journal; larger than several early skin trials but tested a low-MW chicken-comb preparation with a relatively low HA dose.
Small uncontrolled practice study in 20 women using a multi-ingredient HA solution; useful formulation evidence but no placebo and no ability to isolate HA from vitamin/mineral and food-concentrate components.
Peer-reviewed narrative review summarising six clinical trials of oral hyaluronan for dry skin. Useful for historical context and dose mapping, but it is not a systematic review or meta-analysis and several primary studies involved Kewpie-affiliated investigators or products.
Open-label uncontrolled pilot study of a multi-ingredient chicken cartilage matrix containing collagen, HA and chondroitin; cannot isolate HA efficacy.
