Hyaluronic Acid vs Polyglutamic Acid: Which Hydrating Ingredient Wins?
Hyaluronic Acid vs. Polyglutamic Acid: The Hydration Comparison
Hyaluronic acid has been the hydration benchmark in skincare for decades. Polyglutamic acid (PGA) — a fermentation-derived ingredient prominent in Korean skincare — is newer and is often marketed as outperforming it.
Here's what the evidence actually says.
Hyaluronic Acid: What It Is
Hyaluronic acid (HA) is a glycosaminoglycan naturally found in the skin. As a skincare ingredient, it functions as a humectant — drawing water from the environment and deeper skin layers toward the surface [1].
Key nuances:
- Different molecular weights perform differently: lower molecular weight HA penetrates deeper; high molecular weight stays on the surface and forms a film [1]
- Works best on damp skin — in a very dry environment on dry skin, a strong humectant can pull moisture from the skin
- Effects are maintained with daily use; it doesn't permanently increase the skin's own HA production at cosmetic concentrations [1]
Polyglutamic Acid: What It Is
PGA is a naturally occurring biopolymer produced through fermentation (typically by Bacillus subtilis). It has deep roots in Korean and Japanese fermented-food culture (it's found in natto).
Key properties:
- Holds a large amount of water — studies commonly cite around 1,000 times its weight for standard PGA. The frequently quoted "5,000x" figure refers to cross-linked PGA hydrogels, not the PGA in typical serums
- Larger molecule than most HA — stays on the skin surface, creating a film
- Can inhibit hyaluronidase (the enzyme that breaks down HA) in lab studies, which may help preserve the skin's own HA
- Provides longer-lasting surface hydration than HA alone in some comparisons
Head-to-Head
| Factor | Hyaluronic Acid | Polyglutamic Acid |
|---|---|---|
| Water-holding capacity | ~500–1,000x its weight | ~1,000x (cross-linked hydrogels much higher) |
| Penetration depth | Varies by MW (some deep, some surface) | Surface only |
| Duration of effect | Hours | Longer — forms a surface film |
| HA preservation | No | May inhibit hyaluronidase (in vitro) |
| Best used on | Damp skin | Any skin |
| Works for | All skin types | All skin types |
The Winner?
They're complementary, not competitive. HA draws water in at different depths; PGA keeps water at the surface longer and may help preserve the skin's own HA. Using both — HA serum followed by PGA, or a product combining both — provides broader, more durable hydration than either alone [1][3].
Korean brands increasingly combine both: TONYMOLY, Dr. Jart+, and SKIN1004 offer HA/PGA combinations.
Bottom Line
HA is the baseline hydrator for good reason — it's versatile and well-studied. PGA is a meaningful complement, particularly for dry skin and for maximizing a plumped, well-hydrated appearance. Use HA first (on damp skin), then PGA to seal — or choose a product that combines both and skip the deliberation.
This article reflects current dermatological consensus and is not a substitute for personalized advice from a licensed dermatologist.