What it is
Hyaluronic acid is a polysaccharide present in skin, synovial fluid and cartilage, where it holds water. Injected into the knee, it is a medical procedure; in a capsule, it is sodium hyaluronate drawn from rooster combs or from bacterial fermentation. People buy it to hydrate the skin, soften wrinkles and relieve the knee.
What the label does not say
- The trials are small, short and close to the manufacturers: the 2014 skin review (trials of 11 and 39 participants over 6 weeks) and the 2016 knee review (13 studies, 48 to 240 mg per day, 2 weeks to 12 months) are signed by the research division of a Japanese HA manufacturer; a 2025 knee trial is funded by the manufacturer of the product tested, with authors employed by the company.
- Molecular weight changes the product, and nobody yet knows which one to choose: the authors of the 2025 trial write that their results cannot establish the effect of molecular weight in humans and that data are lacking on the absorption and distribution of oral HA to the joints. Two bottles at 120 mg with different molecular weights are not the same product.
- On skin, the 2025 meta-analysis pools only 7 trials: hydration, elasticity and wrinkle depth significantly improved; firmness, wrinkle volume and transepidermal water loss not. The authors point to the small sample size and heterogeneity.
- In Canada, the accepted claim is limited to "helps to support joint health", at 48 to 120 mg per day (rooster comb) or 120 to 200 mg (fermentation). Nothing on skin, wrinkles or hydration.
The forms on the shelf
- Origin: rooster comb (Gallus gallus) or fermentation by Streptococcus equi, with different doses depending on the origin in the Canadian joint health products monograph.
- Molecular weight: from a few kDa (oligosaccharides) to more than 800 kDa. The 2016 review reports that in cell culture, HA above 100 kDa is rarely absorbed as is and that absorption increases as the weight drops to 70, 20 or 5 kDa; the skin trials used 300 kDa and 800 kDa.
- Blends with collagen, ceramides or vitamin C: without the milligrams of HA and its molecular weight, the label cannot be compared with any trial.
Published reference values
- Knee trial doses: 48 to 240 mg per day, from 2 weeks to 12 months (2016 review); 80 and 150 mg per day over 12 weeks in the 2025 trial.
- Skin trial doses: 120 and 240 mg per day over 6 weeks in the trials cited by the 2014 review, with no difference in effect between the two doses.
- Health Canada: 48 to 120 mg per day of rooster comb HA, 120 to 200 mg of fermentation HA, with no minimum duration or specific warning.
When
At any time. The trials measure the skin effect between 3 and 6 weeks and the joint effect at 8 to 12 weeks or more.
To mention to a professional
- Pregnancy and breastfeeding (general warning for joint health products): check with a health care professional. No drug interaction was found in the sources consulted, which reflects the scarcity of data more than established safety.
What it is sold for, and what the data show
Oral hyaluronic acid is sold as "hydration from the inside" and as a knee lubricant. The trials exist, but they are small, mostly Japanese, signed or funded by manufacturers; the only skin meta-analysis found counts 7 trials, and the effect of molecular weight, decisive for absorption, remains unestablished in humans. No NIH fact sheet is devoted to it. The promise outruns what these trials can carry.
Sources
- Health Canada, product monograph, Joint Health Products, Multiple Ingredient
- Oe et al., Oral hyaluronan relieves knee pain: a review, Nutrition Journal (2016, authors linked to a manufacturer)
- Kawada et al., Ingested hyaluronan moisturizes dry skin, Nutrition Journal (2014, authors linked to a manufacturer)
- Journal of Drugs in Dermatology, Oral Hyaluronic Acid Supplement: Efficacy in Skin Hydration, Elasticity, and Wrinkle Depth Reduction (meta-analysis, 2025)
Educational information, drawn from the sources above. It does not replace the advice of a health professional, who remains the reference for your situation, your medications, pregnancy or breastfeeding.