Kelp

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What Is Kelp in Skincare?

Kelp is a group of large brown seaweeds (the order Laminariales) that grow in cold, nutrient-rich coastal waters. In skincare, kelp is used as an extract or powder for its moisture-binding sugars, minerals, and antioxidant compounds, and it shows up in masks, toners, serums, and moisturizers aimed at soft, hydrated, smooth-looking skin.

EWG Skin Deep score for Kelp EWG Skin Deep rating for Kelp

The most useful compounds in brown seaweeds for skin are their polysaccharides (alginates, laminarin, and fucoidan) and their polyphenols (phlorotannins). These are what most of the research on seaweed skincare has measured.

Quick Facts

INCI names Laminaria Digitata Extract, Laminaria Japonica Extract, Macrocystis Pyrifera (Kelp) Extract, Undaria Pinnatifida Extract; often supplied as Glycerin (and) Laminaria Digitata Extract
Common names Kelp, sea kelp, oarweed, kombu (Laminaria), giant kelp (Macrocystis), wakame (Undaria)
Not the same as Bladderwrack (Fucus vesiculosus), a related brown seaweed in a different order, often confused with kelp
Source Wild-harvested or farmed brown seaweed, North Atlantic and Pacific coasts
Form Liquid extract (often in glycerin), or green-brown powder
Solubility Water soluble extracts; powders disperse in water
Typical usage rate Glycerin kelp extract: 5% to 10% (supplier range)
Key compounds Alginates, laminarin, fucoidan, phlorotannins, amino acids, minerals including iodine
Skin types Normal, dry, combination, and mature skin

How Kelp Works on the Skin

Hydration and a soft film

Alginates and other seaweed polysaccharides are long sugar chains that hold water and form a thin, flexible film on the skin's surface. That film helps the skin feel smooth and hydrated, which is why seaweed shows up in peel-off and rinse-off masks and in light gel moisturizers.

Antioxidant and protective compounds

Brown seaweeds contain phlorotannins, polyphenols unique to brown algae, and fucoidan, a sulfated polysaccharide. In lab tests these compounds show antioxidant activity and inhibit enzymes that break down elastin and collagen.

What the research measured

  • In a 2015 paper in the journal Cosmetics (Fitton and colleagues), a fucoidan-rich extract of wakame (Undaria pinnatifida, a true kelp) and a fucoidan and polyphenol extract of bladderwrack were tested in the lab and in people. In a placebo-controlled study with 25 participants, gels containing 0.3% of the extracts reduced transepidermal water loss (TEWL) and visible redness after a controlled UV exposure. In a separate 60-day half-face study with 20 participants, a cream with 0.3% bladderwrack extract improved dermatologist ratings for the look of age spots, brightness, and wrinkles compared with placebo. The study was funded by the extract's manufacturer.
  • In a 2002 study in the Journal of Cosmetic Science (Fujimura and colleagues), 10 women applied a gel with a 1% bladderwrack extract to one cheek and a placebo gel to the other twice daily for five weeks. Skin elasticity, measured with a Cutometer, improved significantly on the extract side.

Most published human studies on brown seaweed skincare use these specific, standardized extracts. Results from those studies do not automatically apply to any kelp powder or extract, so look for products that name the seaweed species and the extract type.

How to Use Kelp in DIY Formulas

  • Liquid extracts go into the water phase or the cool-down phase below 40°C (104°F). Use glycerin-based kelp extract at up to 10%, the top of the supplier range.
  • Powders work best in rinse-off masks. Mix kelp powder with a clay and a liquid (aloe, floral water, or plain water) just before use, apply for 10 to 15 minutes, and rinse.
  • Thickening. Seaweed polysaccharides add body. Expect a slightly thicker gel or lotion and adjust your gum or emulsifier accordingly.
  • Scent and color. Powders bring an ocean scent and a green-brown tint. Liquid extracts are usually close to colorless.
  • Preserve and store. Kelp extracts are often sold without preservatives. Use a broad-spectrum preservative in the finished product, and keep powders sealed, dry, and away from light.

Pair kelp with other marine ingredients such as marine plankton or with mask bases from our facial clays guide.

Who Kelp Suits

Kelp extracts suit normal, dry, combination, and mature skin, and seaweed masks are popular for skin that looks dull or feels dehydrated. Kelp is naturally rich in iodine, so people who are sensitive or allergic to iodine or seafood-derived ingredients should avoid it or ask their doctor first. If you have sensitive skin, patch test first on the inner arm for 24 hours and start at the lowest rate of the range (5% for glycerin extract), then work up.

Frequently Asked Questions

What does kelp do for your skin?

Kelp extracts supply alginates and other polysaccharides that hold water and leave a soft film, plus antioxidant polyphenols and minerals. Skin feels smoother and more hydrated, and masks leave it feeling fresh and clean. In studies, specific brown seaweed extracts improved measured hydration and elasticity.

Is kelp good for oily or blemish-prone skin?

Kelp extracts are light and water based, so they suit oily and combination skin in toners, gels, and masks. A kelp and clay mask absorbs surface oil and leaves skin feeling clean. Patch test first, as with any botanical.

Is bladderwrack the same as kelp?

No. Both are brown seaweeds, but bladderwrack (Fucus vesiculosus) belongs to the order Fucales and kelp belongs to Laminariales. They share compounds such as fucoidan and phlorotannins, which is why they are often grouped together.

Can kelp tighten skin?

Seaweed polysaccharides form a film that can make skin feel temporarily smoother and tauter as a mask dries. In one five-week study, a 1% bladderwrack gel improved measured elasticity. Results depend on the specific extract.

Is kelp safe for sensitive skin?

Kelp extracts are generally well tolerated. Kelp is naturally rich in iodine, so people sensitive or allergic to iodine or seafood-derived ingredients should avoid it or ask their doctor first. Patch test on the inner arm for 24 hours before regular use.

What is the difference between kelp and other algae in skincare?

Kelp is a brown macroalga. Green microalgae such as chlorella and red seaweeds have different compounds and textures. See our algae glossary entry for the wider family.

Shop and Learn More

The facial mist that once appeared in this collection has been retired. For a full guide to ocean-derived actives, read our Marine Ingredient Skin Guide.

Sources

  • Fitton JH, Dell'Acqua G, Gardiner VA, Karpiniec SS, Stringer DN, Davis E. Topical Benefits of Two Fucoidan-Rich Extracts from Marine Macroalgae. Cosmetics. 2015;2(2):66-81. doi:10.3390/cosmetics2020066. MDPI
  • Fujimura T, Tsukahara K, Moriwaki S, Kitahara T, Sano T, Takema Y. Treatment of human skin with an extract of Fucus vesiculosus changes its thickness and mechanical properties. J Cosmet Sci. 2002;53(1):1-9. Journal of Cosmetic Science

These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

About the Author
Written by Kari Thomas, cosmetic formulator and founder of Skin Perfection.