Ingredient review

Sacrum Exopolysaccharides

INCI: Aphanothece Sacrum Exopolysaccharides

A unique, jelly-like polysaccharide from a rare algae that helps hydrate and soothe skin while forming a protective film.

beautyskincarehumectantfilm-former

In plain English

This ingredient is a natural gooey substance made by a special type of algae (cyanobacteria) found in Japan. In skincare, it acts like a sponge to hold water on your skin, keeping it hydrated, and also creates a thin, invisible film that helps protect your skin from drying out or getting irritated. Think of it as a gentle, plant-based jelly that locks in moisture and calms your skin.

Quick decision guide

Useful, but context matters

Sacrum Exopolysaccharides is generally a lower-concern ingredient when the full formula suits your skin.

Plain-English read

Treat this as a practical screening step before you compare products that contain this ingredient.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging Sacrum Exopolysaccharides.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.

Score terms in plain English

Irritation risk

low

Less likely to sting, burn, or bother most users, though sensitive skin can still react.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

emerging

The ingredient may be promising, but claims should be treated more cautiously.

What it is

A high-molecular-weight exopolysaccharide (a type of complex sugar) produced by the cyanobacterium Aphanothece sacrum, also known as Suizenji-nori, a traditional Japanese food. It is harvested and purified for use in cosmetics.

How it works

It forms a flexible, hydrating film on the skin's surface that reduces water loss (transepidermal water loss, or TEWL), while its sugar chains attract and hold moisture from the environment. This dual action helps keep the skin plump, smooth, and protected from external stressors.

Pros

Deep hydration without oil

It holds many times its weight in water, providing lasting moisture without adding greasiness, making it ideal for oily or combination skin types.

Calms irritation

The film it creates can help shield sensitive skin from environmental irritants, reducing redness and discomfort over time.

Cons and cautions

Can feel sticky

At higher concentrations or in certain formulations, it may leave a tacky or slightly jelly-like feel on the skin, which some people dislike.

Limited research

Most evidence comes from lab studies or traditional use; large-scale human trials on its cosmetic benefits are still scarce.

Best for

  • People with dry or dehydrated skin
  • Those with sensitive or easily irritated skin
  • Anyone looking for a gentle, natural hydrator

Use caution if

  • Individuals with known allergies to cyanobacteria or algae (rare)
  • Those who prefer very lightweight, non-film-forming textures

Usage tips

Apply to damp skin to help the polysaccharide spread evenly and lock in extra moisture.
Layer it under a richer moisturizer if you have very dry skin, or use it alone in humid weather for lightweight hydration.
Patch test first if you have a history of algae allergies.

Safety summary

Considered safe for topical use with a very low irritation and comedogenic risk. No significant safety concerns have been reported in cosmetic applications.

Research notes

Early research suggests strong water-binding and film-forming abilities, with potential anti-inflammatory effects. More human studies are needed to confirm long-term benefits.

Common label clues

Typical concentration
0.1% to 2%
Regulatory status
Generally recognized as safe for cosmetic use in the US, EU, and Japan. No specific restrictions noted.
Common uses
Serums, Moisturizers, Masks, Eye creams
Environmental note
The cyanobacterium is cultivated in controlled environments, but large-scale production and its ecological footprint are not well-documented publicly.

Good to know

  • Aphanothece sacrum is a traditional Japanese food, and its exopolysaccharides are sometimes called 'sacran'.
  • This ingredient is often used in K-beauty and J-beauty products for its soothing, jelly-like texture.

Common questions

What is Sacrum Exopolysaccharides in beauty products?

This ingredient is a natural gooey substance made by a special type of algae (cyanobacteria) found in Japan. In skincare, it acts like a sponge to hold water on your skin, keeping it hydrated, and also creates a thin, invisible film that helps protect your skin from drying out or getting irritated. Think of it as a gentle, plant-based jelly that locks in moisture and calms your skin.

What does Sacrum Exopolysaccharides do in a beauty product?

It forms a flexible, hydrating film on the skin's surface that reduces water loss (transepidermal water loss, or TEWL), while its sugar chains attract and hold moisture from the environment. This dual action helps keep the skin plump, smooth, and protected from external stressors.

Is Sacrum Exopolysaccharides safe for most people?

Considered safe for topical use with a very low irritation and comedogenic risk. No significant safety concerns have been reported in cosmetic applications.

Who should be careful with Sacrum Exopolysaccharides?

Individuals with known allergies to cyanobacteria or algae (rare) Those who prefer very lightweight, non-film-forming textures

Research sources

Cosmetic Ingredient Review (CIR) - Safety Assessment of PolysaccharidesOpenPubMed - Study on Aphanothece sacrum polysaccharidesOpenINCIDecoder - Ingredient ProfileOpen

Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.