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All about Seaweed

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Nutritional value

  Raw kelp and kombu, 100 g Raw wakame, 100 g Dulse and dried nori, 10 g
Calories 43 45 21.7
Protein 1.7g 3.0g 3.6g
Carbohydrates 9.6g 9.1 g 2.4g
Fat 0.6g 0.6g 0.2g
Dietary fiber 1.3 g 0.5 g 0.2g
Glycemic load:    Not available
Antioxidant power  :  Not available

Sources  : Health Canada. Canadian Nutrient File, 2010.

The health benefits of seaweed

Seaweed is mainly consumed in Asia. In the West, they are used almost only in sushi or as condiments. However, the nutritional value of seaweed is exceptional and they have a refined taste. A new vegetable to discover.

Marine algae constitute a heterogeneous group comprising hundreds of plants living in fresh or salt water. You could say they are aquatic vegetables. Their size varies from less than a millimeter for  microscopic algae , to a few hundred meters for  giant laminaria .

Edible marine algae are usually classified by their color: green algae, brown algae and red algae. The most common commercially are the  sea lettuce , the  sea of hair , the  dulse  (seaweed dulse or small), the  Irish moss  (or carrageenan, which is pulled carrageenan), the  bean  or  sea spaghetti , the  nori  (or porphyry, used for  sushi ), the  wakame , the hijiki , the  kelp  and  kelp .

We know that regular consumption of vegetables (including algae) helps maintain good health and prevent a host of illnesses. The particular action of algae on cardiovascular diseases, diabetes, high cholesterol and hypertension is due, among other things, to the  antioxidants , fibers and phytosterols they contain.

The benefits of algae on cancer

Studies have shown that different algae or their compounds have the ability to counter the development of mammary tumors in animals 8 and induce the death of certain cancer cells in vitro , 19,20 . Algae, which tend to oppose estrogen, may be a protective factor in the development of hormone-dependent cancers such as breast or prostate cancer 13 , 21 . 

Epidemiological studies indicate that populations consuming an Asian-type diet have a lower incidence of these cancers, compared to populations consuming a North American-style diet 10-12 . This finding has been largely attributed to the high consumption of soybeans among Asians, but high consumption of algae among this population may also play a role. In addition, a deficiency of iodine and selenium, two nutrients abundant in algae, could play a role in the formation of breast cancer 14 . However, the real role of algae in the prevention of hormone-dependent cancers remains to be clarified.

An in vitro study   published in 2010 shows that fucoidan (a sugar found in brown marine algae) induces the death of human leukemia cells thanks, among other things, to the production of nitric oxide (NO) 19 . The authors note that fucoidan may increase the effectiveness of traditional chemotherapy agents in causing the death of cancer cells. In another in vitro study  , fucoidan destroyed cancerous breast cells 20 . According to the authors, fucoidan is a promising compound in the prevention of  breast cancer  and its therapeutic value deserves to be analyzed.

Seaweed, a powerful antioxidant

Several extracts of brown, red and green algae cultivated in Europe or Asia have demonstrated antioxidant activity in  vitro 1 . Their antioxidant composition and antioxidant capacity vary depending on several factors, such as the depth they grow in and their degree of exposure to ultraviolet (UV) rays. Algae contain various antioxidant compounds including carotenoids (lutein and zeaxanthin), flavonoids (catechins), phenolic acids (tannins) as well as certain vitamins (mainly vitamins C and E).

Seaweed to fill up on fiber

Seaweed contains interesting amounts of fiber, especially in soluble form 4 . Depending on the variety, a serving of fresh seaweed may contain up to 8% of the amount of fiber recommended daily 5 . The dried seaweed , in turn, contain from 35% to 50% of their weight in the form of fibers. In general, a diet rich in dietary fiber can help prevent cardiovascular disease, as well as control type 2 diabetes and appetite. The fiber in algae may be more effective in lowering blood cholesterol and hypertension than that in other sources .

The brown marine algae ( laminaria longicruris ) found in the Gulf of St. Lawrence , more specifically in the Gaspé Peninsula, in Quebec, are particularly rich in two types of soluble fiber: laminaran (an indigestible sugar from the family of β-glucans) and fucans 22 . These compounds have several interesting biological properties 23 . Laminaran is thought to fight tumors and modulate the immune response. Fucans have anti- coagulant , anti-inflammatory and antiviral properties. A team of Quebec researchers has observed that the harvesting period of the algae had an influence on their laminaran and fucan contents 24 , 25 .

To fight against cholesterol

Wakame and nori contain phytosterols 6 . These compounds resemble cholesterol chemically and prevent it from being absorbed into the body. Consuming phytosterols could lower blood cholesterol levels, especially LDL cholesterol (bad cholesterol) 7 . On the other hand, to observe such effects, large quantities of dried algae should be consumed daily 6 , and no study has so far evaluated the impact of the consumption of phytosterols from algae on blood cholesterol.


Iodine is used to make thyroid hormones , which are necessary for the regulation of growth, development and metabolism. On the other hand, too high concentrations of iodine can cause problems with the functioning of the thyroid gland. Despite the relatively high quantities of iodine in nori, its usual consumption does not present any significant health risk. On the other hand, it is recommended that people consuming seaweed on a regular basis choose those containing the least iodine, for example sea lettuce, porphyry (Japanese nori) and dulse. One or two sheets of nori (equivalent to 8 to 15 sushi) are enough to meet daily iodine requirements.

Main vitamins and minerals

Excellent source Vitamin A The dulse and raw nori are excellent sources of vitamin A . The dulse and dried nori are excellent sources for women and good sources for humans.
Excellent source Vitamin B2
The dulse and raw and dried nori are excellent sources of vitamin B2. The raw wakame is an excellent source for the woman, but a good source for humans. The seaweed (kelp) and kombu wines are good sources.
Excellent source Vitamin B9 (Folate) The algae are all excellent sources of vitamin B9 (folate).
Excellent source Vitamin C The dulse and raw nori are excellent sources of vitamin C for the woman, but good sources for humans. The dulse and dried nori are good sources.
Excellent source Vitamin K All seaweed , except dried dulse and nori, are excellent sources of vitamin K.
Excellent source Copper The dulse , the nori and wakame wines are excellent sources of copper. The dulse and dried nori and the seaweed (kelp) and kombu wines are good sources.
Excellent source Iron The seaweed (kelp) , the kombu raw and raw wakame are excellent sources of iron for humans and a good source for women. The dulse and raw and dried nori are good sources of iron for humans and sources for the woman.
Excellent source Manganese The dulse and raw and dried nori and the raw wakame are excellent sources of manganese. The seaweed (kelp) and kombu wines are good sources for the woman and sources for humans.
Excellent source Magnesium The seaweed (kelp) , the kombu and raw wakame are excellent sources of magnesium.
Good source Vitamin B5
(pantothenic acid)
The raw wakame is a good source of vitamin B5 (pantothenic acid).
Good source Calcium The seaweed ( kelp) , the kombu and raw wakame are good sources of calcium.
Good source Phosphorus The raw wakame is a good source of phosphorus.
Good source Zinc The seaweed ( kelp) , the kombu , the dulse and nori wines are good sources of zinc for women.



Bioavailability of vitamin B12 from algae

Vitamin B12 found in algae is often considered to be inactive, and therefore cannot be assimilated by the body. However, researchers have shown that nori contains appreciable amounts of biologically active vitamin B12 15 . Rats with vitamin B12 deficiency received nori-enriched food for 20 days; researchers have observed an increase in vitamin B12 levels in their liver 16 . However, it should be noted that these results in animals are not necessarily transferable to humans. The absorption and metabolism of vitamin B12 from marine plants, such as seaweed, should be evaluated in humans.

The method of drying the algae could probably influence the bioavailability of this vitamin. Air drying would make vitamin B12 “inactive”, while freeze-drying (cold drying) would not have this effect 16 . In light of these studies and given the different varieties of algae consumed, it is advisable not to rely on algae to meet our daily vitamin B12 needs. The vegetarians , whose intake of this vitamin is often deficient, will have to turn to other foods (especially foods fortified with the vitamin, such as soy milk) to meet their needs.

Precautions for consumption of seaweed

Hijiki and arsenic

The Canadian Food Inspection Agency advised to avoid the consumption of seaweed hijiki (black seaweed, slightly bitter, sold dried ) 18 . The inorganic arsenic content of it could exceed acceptable daily rates, even when consumed in small amounts. Among several algae samples analyzed, including dulse, porphyry and Japanese kelp (kombu), only the hijiki variety contained a high content of inorganic arsenic. Exposure to high concentrations of inorganic arsenic has been associated with gastrointestinal disturbances, anemia, and liver damage.

Anticoagulants and vitamin K

Seaweed contains large amounts of vitamin K, which is necessary, among other things, for blood clotting. People taking blood thinners (eg Coumadin®, Warfilone® and Sintrom®) should eat a diet in which the vitamin K content is relatively stable from day to day. For these people, seaweed should not be eaten as a main dish (a sushi meal, for example). People on anticoagulation therapy are advised to consult a dietitian-nutritionist or a doctor in order to know the food sources of vitamin K to ensure the most stable daily intake possible.

Recipe ideas

with seaweed

To access other recipes, you can go to the kitchen recipe site, which offers, among other things, the following recipes : seaweed recipes , seaweed for maki , seaweed for sushi

Seaweed can be tasted barely cooked and still crunchy ; or cooked very long and almost melted in the dish. Although they generally accompany fish , there is nothing to prevent them from being cooked with poultry or meat .


Rehydrate the dried algae. The algae rehydration time varies according to the type. Sea hair, sea lettuce, porphyry and dulse take only a few minutes; sea ​​spaghetti and hijikis will take 15 minutes; kelp, wakame and laminaria from 30 to 60 minutes. You can use a liquid other than water to rehydrate them: white wine, vinegar, beer, etc. Avoid, however, red wine or red wine vinegar, the tannin of which reacts with iodine.

Nori can be dry roasted by passing it over the flame of a gas stove or by placing it on an electric hob. In Japan, it is a common technique for making sushi, preparing fine omelets, or for other culinary uses of this seaweed.

  • Add seaweed at the end of cooking in soups, cooked vegetables, legumes, rice, pasta.
  • Season the seafood pizzas .
  • You can add it to butter sauces , mayonnaise, salad dressings, mustard.
  • Native American corn : season the creamed corn with seaweed powder.
  • Cut the algae into thin strips, grill them and add them to a coleslaw or cooked and cooled soba noodles . Serve the noodle salad with chopped chives, Japanese mustard and an accompanying sauce.
  • Shrimp, cucumber and wakame salad: cut a cucumber lengthwise, remove the seeds and cut it into thin slices. Put it to disgorge with a little salt in a colander, rinse with water and drain. Soak the algae for ten minutes in cold water, drain them, then mix them with the cucumber slices, cooked shrimp and thin strips of ginger. Season with rice vinegar sauce, dashi, soy sauce, honey and mirin.
Antiflatulence algae!
Added to legumes while they are cooking, algae have the property of reducing their cooking time, and making them more digestible (reducing flatulence) while refining their taste and texture. This action would be attributable to their richness in glutamates.
  • Add 1 tsp. algae ground in an omelet preparation or, for a more elaborate dish, prepare a Japanese omelet, made up of a few layers of eggs interspersed with nori.
  • Incorporate seaweed in bread , cookie, pancake and, why not, cake and muffin preparations . Some do not hesitate to make ice creams and sorbets, especially since they have a gelling power which allows the preparation to “take”.
  • Rehydrate a dry seaweed, wrap it around a fish and bake or steam. Or stuff the fish with seaweed. Or, marinate it for 30 minutes in lemon juice with a few spoonfuls of seaweed powder, before cooking it.
  • Shrimps and scallops can be steamed, wrapped in a piece of rehydrated seaweed.
  • You can also cook a whole fish stew after placing it on a kelp leaf in a saucepan. Add a little water, cover and simmer over the heat for about twenty minutes.
  • Dashi: this essential broth of Japanese cuisine is used in the composition of a multitude of dishes, whether soups, stews or sauces. There is a snapshot of it, just diluted in water, but it is very easy to prepare it yourself. For 2 l of water, about 40 g of kelp and 60 g of bonito flakes are needed(preparation based on a fish from the tuna family found in Asian grocery stores). Wipe the kelp with a damp cloth and put it on the fire in a pan with water. As soon as the first bubbles appear, check the texture of the kelp by pushing the thickest part of the thumbnail. If it penetrates easily, it is because the kelp is perfect. Otherwise, simmer for a few minutes without boiling. Reserve the kelp. Add half a cup of cold water to lower the broth temperature, add the bonito flakes, bring to a boil and remove from the heat. Let the bonito flakes settle on the bottom, then pass without pressing.
  • Consumed with tofu and wakame algae: rehydrate the algae by putting them for ten minutes in cold water, drain them and cut them into coarse strips, removing, if necessary, the hard ribs. Slice the tofu, then cut it into cubes or rectangles. Place the seaweed and tofu in the bowls, cover with warmed dashi broth seasoned with soy sauce and sake, and garnish with thin strips of lemon zest.
  • You can prepare algae in tempura like other vegetables. The Japanese also use it as decoration  : they wrap thin strips around the shrimp tails or around a packet of soba noodles to make pretty little bundles that will be fried with vegetables or fish.
  • Marine quiche: brown a shallot in butter or oil, add pieces of rehydrated seaweed, cook for a few minutes, then put this preparation in a shortcrust pastry. Cover with a mixture of beaten eggs with a little cream and sprinkle with grated Parmesan cheese or garnish with thin slices of salmon. Bake in the oven.

Seaweed condiments. Here are some classics of Japanese cuisine.

Taming algae
It sometimes takes a while for the body to get used to algae, the laxative effects of which are very real. It is recommended to include them gradually in your diet. Eventually, they could constitute up to 10% of the food ration, as is the case in Japan.
  • Mix equal parts table salt and seaweed powder.
  • You can simply grill the wakame or the dulse and reduce them to powder, which you can add to the dish of your choice.
  • Boil several sheets of nori in ½ cup of water and cook over low heat until most of the water is absorbed, to obtain a thick puree . Add a little tamari, cook for a few more minutes and serve with rice or vegetables.
  • Grill wakame in an oven set at 180 ° C (350 ° F) for 10 to 15 minutes. Let cool and reduce to powder. Toast dry sesame seeds in a pan and grind them with seaweed powder until 80% of the seeds are sprayed. The proportion of wakame and sesame seeds can vary from 1 to 1 to 1 to 5, depending on the use you want to make of it.

Choice and conservation

To choose

The market for fresh algae is not very established in North America, there is practically none. However, there is a growing supply of dulse or wakame salad , offered in certain fishmongers or certain sushi restaurants . They are usually garnished with sesame seeds and chili peppers.

The fresh algae must be well rinsed to the desalinate .

The dried algae are sold in sheets, ribbons, molded pieces or powder.

You can find, in specialized shops, seaweed in brine or canned . The appearance and texture of canned seaweed is reminiscent of that of spinach puree.


Fresh seaweed: a few days in the refrigerator.

Dried seaweed: in an airtight container, away from heat and light. The shelf life of packaged products is generally 2 years , although in Japan they are kept much longer because the algae improve over time.

The little story of seaweed

Common names: seaweed, sea vegetables.

Scientific names: Porphyra spp., Palmaria spp., Undaria spp., Laminaria spp., Etc.
Families: fucaceae, laminariaceae, ulvaceae, himanthaliaceae, etc.

The term ”  seaweed  “, which appeared in 1551, comes from the Latin alga .

There is no doubt that algae have been known and consumed by Homo sapiens since its appearance on the planet. It is even thought that its predecessor, Homo erectus , was already consuming it. These marine plants are part of the culinary traditions of the coastal populations of China, Japan, Polynesia, Hawaii, the United Kingdom, Iceland and Siberia.

Chinese texts dating from the VI th  century BC show varieties of seaweed fine enough taste to be at the Kings menu . In Japan, from the XIII th  century, is commonly consumed in 8 species, which number is now down to 21. X th  century, dulse (or dulse) was fairly common in the Icelandic diet for that we regulate the harvest.

Village on algae
In the Prince of Wales archipelago, located in south-eastern Alaska, there is a village to which the Haida-Kaiganis, the first inhabitants of the region, had given the name of Sukkwan, word for the Tlingit language which literally means “village on the beautiful underwater grass”, by allusion to the edible algae which grow in the coastal waters.

Native American and Inuit culinary traditions also place a great deal of importance on seaweed. On the Arctic coast, they have always been an important resource during times of scarcity. We also know that the Inuit consumed the stomach contents of the whales they fished, which consisted mainly of microscopic algae . In addition, the Amerindians collected the eggs that the females of various species of fish deposited on the kelp, and cooked eggs and kelp together . This dish is also highly prized by the Japanese, who pay the high price to import it from Canada or the United States.

Knowing the nutritional richness of algae, it is surprising that Europeans, if we exclude those from the North, and North Americans, have consumed them so little or not at all. For example, in Brittany, a seafaring country where 600 species have been listed, there is only one traditional dish (a kind of blank) made from these plants. Anyway, this situation is changing under the influence of Japanese cuisine which is spread all over the world. In the East as in the West, the chefs compete in creativity to put them on the menu, sushi being the most common example.

Grow algae

By the end of the XVII th  century, the Japanese began to cultivate some species in the brackish waters of Tokyo Bay. Since then, seaweed farming has greatly developed since 90% of all seaweed sold in the trade is cultivated. The main producing countries are China, Japan and Korea. The simplest method is to install supports in the marine environment to which they cling, as is done for mussels. However, cultivation on land, in basins filled with purified seawater, is changing rapidly. This method has only recently been practiced in Nova Scotia. For the future, the industry is looking into the possibility of producing genetically modified varieties in a closed fermenter type environment where all environmental factors will be controlled.

Ecology and environment

In France, researchers from the National Center for Scientific Research have been conducting research for several years on what is known as the “vaccination” of crop plants with seaweed. The initial hypothesis is that seaweed has molecules that have the effect of provoking an immune response in plants and allowing them to protect themselves against diseases . These molecules cause a series of reactions in plant cells, such as the formation of real plant antibiotics, called “phytoalexins”, or defense proteins ( Pathogenesis related proteins ).

As in vertebrates, “plant  vaccination  ” requires only very small amounts of the active agent. In fact, when a certain threshold is exceeded, the effect is less. The protection lasts about 6 to 8 weeks, after which the treatment must be resumed, if necessary. However, it is essential that the treatment is applied before the onset of the disease. This type of prophylaxis does not entirely eliminate the use of fungicides (agents that fight fungi), but considerably reduces the quantities required.

Note that algae have long been used in organic farming, both to stimulate plant growth and to protect them from disease . Coastal potato producers used to put potatoes in plantation furrows. Subsequently, we learned how to make a liquid manure by soaking them in water. Filtered, this liquid manure was applied to plants. Today, the practice is generalized in organic farming, with the difference that one usually uses extracts prepared industrially.

These extracts, whether based on algae or terrestrial plants, are a natural alternative to synthetic pesticides and the controversial GMOs.

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