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Written by OSEA Staff | Published August 6, 2025
Since 1996, we’ve harnessed the power of pure, potent seaweed to create clean, clinically tested skincare with powerful results. We formulate with seaweed—marine plants and algae—because it’s one of nature’s most incredible superfoods. But what is it that makes seaweed so powerful? Seaweed school is in session! Here are 14 things you need to know about seaweed in 2025.
1. Seaweed Isn’t a Plant—It’s Algae
While it may resemble plants, seaweed is technically marine algae. It doesn’t root in soil but anchors to rocks or other hard surfaces using a structure called a holdfast. Because it has no roots, seaweed takes the nutrients it needs from the sea.
2. There Are Over 600 Edible Varieties
Seaweed is incredibly diverse, with over 600 species used in food around the world. In addition to their culinary uses, many of these varieties are packed with beneficial compounds like proteins, essential amino acids, dietary fiber, healthy carbohydrates, and trace lipids, including omega-3 fatty acids.
3. Seaweed Is a Skin Superfood
Seaweed is rich in amino acids and antioxidants, which help protect against oxidative stress—a key factor in the skin aging process. When free radicals accumulate faster than the body can neutralize them, they can damage skin cells, leading to signs of premature aging such as wrinkles, fine lines, and loss of elasticity.
4. It’s Mineral Rich
Seaweed absorbs minerals from the ocean—including iodine, calcium, magnesium, potassium, zinc, and iron—and delivers them to the skin, leaving it soft, smooth, and naturally radiant.
5. It Helps Replenish Your Skin’s Moisture Barrier
Minerals like magnesium and zinc found in seaweed support the integrity of the skin barrier, which keep moisture locked in, and irritants out. The result is reduced sensitivity, improved moisture retention and smoother texture.
6. Seaweed Helps Draw Out Impurities
Compounds like fucoidan and alginate help draw out impurities to support the skin’s natural detox process.
7. Source Matters
We harvest seaweed from clean ecosystems around the world. Only the base of the stipe is collected, allowing the algae to regenerate naturally. We also harvest only during reproductive seasons and minimize water and energy use during processing.
8. Undaria Is a Skincare Superhero
Undaria seaweed (a type of brown kelp) is rich in antioxidants like fucoxanthin—a carotenoid with strong free-radical-fighting properties—and vitamins A, C, and E to help neutralize oxidative stress. It’s loaded with polysaccharides like fucoidan and alginates, which help lock in moisture, replenish the skin barrier, and prevent water loss.
Find it in: Undaria Algae™ Body Oil
9. Undaria Is an Invasive Species
By harvesting it responsibly from affected areas, we help reduce its ecological impact while creating effective skincare solutions.
10. Red Seaweed Has Ancient Roots
Red algae are among the oldest types of algae, with fossils dating back over a billion years! Our red seaweeds are packed with skin-loving bio-protective oligosaccharides and essential minerals. Some red algae known as coralline algae, even play a crucial role in building and maintaining coral reef structures.
Find it in: Dream Night Serum with Bio-Retinol
11. Brown Seaweed Visibly Firms Skin
Brown algae visibly firm, hydrate, boost skin elasticity and luminosity and reduce the look of oily shine. This super versatile seaweed is rich in polysaccharides, antioxidants, macro elements and trace elements.
Find it in: Anti-Aging Body Balm
12. One of Earth’s Fastest-Growing Organisms
Some species of brown seaweed, like giant kelp (Macrocystis pyrifera), can grow up to 2 feet per day and reach lengths of over 200 feet, forming vast underwater forests that provide habitats for marine life.
13. Japanese Miru Seaweed Is a Vegan Powerhouse
Also known as Codium fragile, Japanese Miru seaweed is rich in calcium and magnesium, and has more beta-carotene than fresh carrots. It helps replenish and balance the skin’s natural moisture levels.
Find it in: Hyaluronic Sea Serum
14. Seaweed Is a Natural Multitasker
From thickening sauces (thanks to alginates in brown seaweed) to supporting coral reefs (via calcium-secreting red algae), seaweed does it all—and we’re just scratching the surface. Dive deeper into the power of seaweed skincare here.