Seaweeds as Food and Medicine: The many nutritional and health benefits of kelp, dulse, Irish moss, and other seaweeds

Foods from the sea have long been prized by native populations. Sea vegetables—seaweeds like kelp and dulse— were often transported far inland by native people as commodities of trade. They have also been used as fertilizers and seaweeds and extracts from them are also used in cosmetics and industry.

Americans don’t eat a lot of sea vegetables, but the Japanese do, such as using nori to wrap sushi rolls. Studies have suggested there is a correlation between the Japanese intake of seaweed and the country’s lower rates of breast cancer, obesity, heart disease, respiratory disease, rheumatism and arthritis, high blood pressure, infectious disease, and constipation. This makes sense because there are several reasons why seaweeds are such powerful health-building foods.

Iodine and Other Minerals

Iodine is a relatively rare element (62nd in abundance on the earth) and especially rare in land plants. It is primarily found in foods from the sea, including ocean fish, shellfish, unrefined sea salt, and of course, sea vegetables. Iodine is essential not only for the thyroid but also for every cell in the human body.

But seaweeds don’t just supply iodine. They’re also rich sources of many other valuable minerals. The composition of minerals in seawater, like sodium, potassium, calcium, magnesium, and chlorine, is similar to the balance of these minerals in our own blood, suggesting our blood is like an internal ocean in which our cells live. Seaweed provides all these minerals, including major minerals like calcium, magnesium, and potassium, along with many trace minerals such as iron, copper, zinc, boron, silica, selenium, and chromium.

Other Health Benefits of Seaweeds

Holding SeaweedsSeaweeds are also sources of mucilaginous fibers. These water-soluble fibers absorb toxins, soothe irritated tissues, and act as bulk laxatives. They are very healing to the mucous membranes of the gastrointestinal tract. They are also soothing and moistening to the skin when used in baths, poultices, soaks, or other topical applications.

Seaweeds can also help the immune system. Many sea vegetables contain lignans, which are also found in flaxseeds and are known to bond to estrogen-receptor sites and inhibit estrogen-dependent cancers. Anti-cancer compounds have also been found in kelp, kombu, and wakame.

Ryan Drum, a professional herbalist and recognized expert on sea vegetables says that fucoidan, a compound found in kelp and bladderwrack, is “...extremely anti-proliferative against cancer cells. It interferes with every stage of a viral attack: cell attachment, cell penetration, and intracellular virion production.”

In TCM seaweeds are used when there is swelling or hardened masses in the body. It is used to soften the hard, swollen tissues, reduce the swelling, and get rid of the hardened tissue. Seaweeds are also used to loosen hardened phlegm or mucus.

Here’s more information on a few specific types of seaweeds and their health benefits.


Kelp Plant OceanKelp is one of the brown algae in the Laminariales order. Multiple species of this rapidly growing seaweed have been used for medicine, agriculture and manufacturing. Kelp grows in large underwater forests in cold, shallow parts of the ocean. These stands of kelp harbor many species of marine life.

Kelp contains over 30 minerals and is a good source of many essential vitamins. It has a naturally salty flavor and dried kelp can be sprinkled on food as a salt substitute.

Kelp also contains large amounts of algin, a mucilaginous fiber known to absorb heavy metals, including mercury, barium, cadmium, and lead, and the radioactive strontium 90. Algin also helps with acid reflux.

Kelp is particularly good for the thyroid. Not only does it supply iodine, but some research also suggests it actually contains small amounts of thyroid hormones, T4 and T3, as well as building blocks for these hormones, DIT and MIT (which are essentially T2 and T1). Kelp has been shown to help the body excrete dietary toxins such as dioxin and polychlorinated biphenyl (PCBs). These chemicals are known to disrupt thyroid and endocrine functions.

You can take kelp in capsules, six to twelve capsules per day. You can also use it like salt, sprinkling it in food.


Dried DulseAnother very valuable sea vegetable is dulse, a red seaweed that grows in cold waters along the northern coasts of the Atlantic and Pacific Oceans. Found growing on rocks, it is thick, lobed, and reaches 8-16” in length. It ranges in color from a deep rose to a reddish-purple.

Like kelp, duse is high in trace minerals It has a high protein content (about 1/3 of its dry weight) and is high in glutamic acid, the amino acid found in monosodium glutamate (MSG). This makes it a healthy alternative to MSG in enhancing the flavor of food. It’s also one of the richest plant sources of silica (next to horsetail), which aids the health of skin, hair, fingernails, bones, joints, and nerves.

In Chinese Medicine, dulse is called zicai where the cool, sweet, and salty taste is an indication that the herb can dispel heat, promote sweating and displace phlegm accumulation, particularly as it forms soft masses. It is used by Chinese and Western herbalists alike for treating edema, leg swellings, goiter, urinary infection, and sore throats.

Liquid dulse is a glycerin extract from seaweed. Liquid dulse is a great iodine and trace mineral supplement that tastes good. I used to give a little to my children. 15-20 drops of Liquid dulse will supply about 225 micrograms (mcg.) of natural iodine (regulate dose by taste). You can also sprinkle dulse powder in foods.

Irish Moss

Irish MossAnother great sea vegetable is Irish moss, a red algae found in the Atlantic Ocean off the coast of both North America and Europe. The common name carrageen moss comes from the word “carrageen,” which is Gaelic for "moss of the rock.”

Irish moss also supplies significant amounts of iodine, and other minerals, along with vitamins and a mucilage known as carrageenan. Carrageenan is also used as a thickening agent in commercial foods, such as whipped cream and milkshakes.

Besides being used to support the thyroid, Irish moss is also a great remedy for intestinal irritation. It can help heal ulcers and gastritis and has a mild bulk laxative action. It can reduce swelling in lymph nodes and ease dry, irritated lung conditions. It’s also a great herb to use in lotions for dry, irritated skin.

Other Seaweeds

Seaweed foodThere are many other useful seaweeds, including bladderwrack, agar, arame, kombu, nori, and wakame. You can find them in both regular grocery stores and in health food stores. You can even find chips for snacking made out of seaweed. If you have problems with low thyroid, dry skin, intestinal irritation or inflammation, constipation, sluggish lymphatics, and swollen lymph nodes, or you need minerals to strengthen your structural system, bones, teeth, hair, skin, and nails, I highly recommend taking seaweeds in capsules, adding them to foods, or otherwise incorporating them into your diet.


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