Hyaluronic Acid

What Is Hyaluronic Acid?

Hyaluronic acid (HA), also called hyaluronan, is a glycosaminoglycan — a long, unbranched sugar chain found throughout the body's connective tissue, skin, eyes, and joints. Its defining property is water-binding: a single gram of HA can hold up to several litres of water, making it the body's principal dermal humectant.

About half of the body's HA is in the skin, where it keeps the dermis hydrated, plump, and resilient. Synovial fluid in the joints is rich in HA, where it provides lubrication and shock absorption.

Why It Declines — and Why That Matters

Dermal HA content falls progressively with age, accelerated by UV exposure. Less HA means less bound water in the dermis, which translates directly into the visible signs of skin ageing: reduced plumpness, dryness, fine lines, and loss of elasticity. Restoring HA — topically, orally, or by injection — targets that hydration deficit.

Three Different Things Called "Hyaluronic Acid"

This is where consumers get confused. The same molecule is delivered three very different ways:

• Injectable dermal fillers — cross-linked HA gel deposited locally by a clinician. Immediate, localised volume; this is a procedure, not a supplement, and is not what oral HA does.
• Topical HA — serums and creams. Larger molecules sit on the surface and draw water into the upper skin; smaller fractions penetrate somewhat. Useful for surface hydration, limited dermal reach.
• Oral HA — capsules/powder, the focus here. Low-molecular-weight HA is absorbed and distributed systemically, including to the skin.

The mechanism question for oral HA has long been "how does an ingested sugar polymer reach the skin?" Current evidence suggests low-molecular-weight HA is absorbed (partly broken into oligosaccharides), distributed to skin and connective tissue, and may also stimulate the body's own HA synthesis by fibroblasts.

The Evidence

• Skin hydration & wrinkles: Several randomised, placebo-controlled trials report that oral HA (typically 120-240 mg/day) improves skin moisture and reduces wrinkle appearance over 6-12 weeks. Low-molecular-weight forms tend to outperform high-molecular-weight in these trials. Effect sizes are modest and trials are often industry-funded — but the direction is consistent.
• Joints: Oral HA has supportive (mixed) evidence for knee osteoarthritis symptom relief; injectable intra-articular HA is a separate, clinically established use.
• Molecular weight matters: absorption and reported efficacy favour low-molecular-weight (often <50 kDa) HA. Product labels increasingly specify this.

Grade: B — reproducible but modest skin-hydration RCTs, with the usual caveats of small samples and industry funding.

Dosing

• Skin hydration: 120-240 mg/day of oral HA, once daily
• Prefer low-molecular-weight HA where specified — it shows the best absorption and trial outcomes
• Duration: 6-12 weeks before judging skin effects; HA hydration benefits are gradual, not acute
• Frequently co-formulated with collagen peptides and vitamin C in skin products

Who Might Consider It

• Skin hydration and fine-line support, especially in drier or more mature skin
• Part of a skin-longevity stack alongside collagen peptides and astaxanthin
• Joint comfort as an oral adjunct (with realistic expectations)

Oral vs Topical vs Filler — Pick by Goal

These are complementary, not competing — many people use oral plus topical, reserving fillers for targeted volume.

Related Research

• The Anti-Aging Skin Protocol: Collagen + Astaxanthin + GHK-Cu + Hyaluronic Acid
• Collagen Peptides Worth Taking: The 2026 Evidence Review
• GHK-Cu: Subcutaneous vs Topical — Which Form Works Better?