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Discover Seaweed: The Essential Ingredient of the Japanese Diet

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    Explore the varieties of edible seaweed used in Japanese cooking, the health benefits and how to cook with these sea vegetables.

    Various kinds of seaweed presented on the table, including nori, wakame, hijiki, and kombu.

    Hailed as the superfood of Japanese cuisine, seaweeds have long been an indispensable part of Japanese diet and other East Asian cultures like China, Korea and Taiwan.

    Japanese consume seaweeds for both its nutritional properties and culinary values. Today we will explore the varieties of edible seaweed used in Japanese cooking, their remarkable health benefits and how you can incorporate these sea vegetables in your diet.

    What Is Seaweed?

    Seaweed, or marine plants and algae, are plant-like organisms that grow in the ocean, rivers, lakes and other water bodies.

    The edible seaweeds are also known as sea vegetables, where they have been used in traditional medicine, farming and healthy diets in different parts of cultures, from Asia to the Western worlds such as Scotland, Ireland and Iceland.

    What Are the Different Types of Seaweed?

    As vast as the ocean, the varieties of seaweed reflect its complex biodiversity with over 10,000 species. They are often categorized based on their cell structures, pigments, ecology and uses. The 3 common varieties are: red algae (nori and dulse), brown algae (wakame, kelp, kombu), and green algae (spirulina and chlorella).

    Edible Seaweed that are commonly used in Japanese cuisine

    Seaweeds are an integral part of the Japanese diet and you can find different varieties of seaweeds being used in cooking. From eating fresh to adding it to salads to using as a natural flavoring, the roles of seaweeds are just as multi-faceted. Here we feature 5 most common seaweeds in the Japanese cuisine:

    Nori 海苔 Seaweed | Pantry | Easy Japanese Recipes at

    Nori 海苔

    Comes in paper-thin dark green sheets, nori is the most prominently known and most consumed seaweed worldwide. Used mainly as an ingredient of wrapping sushi, nori is made by shredding and drying seaweed before pressing it into thin layer – a method adopted from the paper making process.

    Aside from sushi and onigiri rice balls, nori is also used as delicious garnish for noodles, rice bowls (donburi) and soups. When chopped into small fine pieces, nori is mixed in with ingredients such as sesame seeds, chili pepper, salt and sugar as a table seasoning.

    You can find nori being sold toasted or non-toasted. Nori snack (a.k.a nori chips or seaweed snacks) is another popular product of toasted nori that are simply roasted and seasoned with salt and enjoyed as a delicious savory snack. In Japan, nori no tsukudani (海苔の佃煮) is another classic way to enjoy the seaweed, where it is flavored with soy sauce, dashi, sake and mirin and made into a paste-like accompaniment for steamed rice.

    Delicious Recipes with Nori

    Temaki Sushi (Hand Roll) |

    Kombu 昆布 Seaweed Pantry | Easy Japanese Recipes at

    Kombu Kelp 昆布

    Dark green with thick leather-like texture, Kombu, also known as kelp, is the quintessential ingredient in Japanese pantry.  Japanese kombu is cultivated mainly in Hokkaido (北海道) which has long-standing methods of kelp harvesting.  There are more than ten species of kombu kelp and each has its own characteristic of taste and flavor. The highest quality kombu kelp is Ma-Kombu, which are shaped like thick wide leaves. Known for its refined sweetness and deep flavor, this kombu is a chef’s choice for producing clear, delicious stock.

    Ma-Kombu from Hokkaido

    In Japanese cuisine, kombu is used most extensively in making dashi, the umami-packed Japanese soup stock. The high glutamate content presented in kombu makes it a sought-after natural flavor enhancer.  Most kombu are sold in dried form. You can also find kombu pickled in vinegar or eaten fresh in sashimi.

    For those who consume large amount of beans, you can add strips of kombu into dried beans as you cook. This magical ingredient will help to tenderize the beans and reduce the gas-producing properties. A great solution for bean eaters!

    Delicious Recipes with Kombu

    Kombu Dashi | Easy Japanese Recipes at

    Wakame わかめ Seaweed | Pantry | Easy Japanese Recipes at

    Wakame わかめ

    Grown in cool and mineral rich arctic currents, wakame have been harvested in Japan for generations since the Nara period. The taste is briny and salty, much like a mild anchovy with a subtle sweet flavor. It has a unique tenderness that comes with a light crunch.

    Wakame is commonly used in soups like miso soup and salads like tofu salad, as well as a side dish to vegetables, like cucumber. To prepare, the leaves should be cut into small pieces as they will expand during cooking.

    Wakame is low in calorie and known for its ability to aid in weight loss and to boost energy levels. You will find dishes featuring wakame are typically dressed with simple vinegar and soy sauce. One of the most trendy wakame dishes is Goma Wakame, where the seaweed salad is lightly dressed with roasted sesame seeds, soy sauce and vinegar.

    Delicious Recipes with Wakame

    Sunomono (Cucumber Salad) | Easy Japanese Recipes at

    Dried Hijiki seawweed in a bag.

    Hijiki ひじき

    A brown variety of seaweed, hijiki grows wild on the rocky coastlines of Japan, China, and Korea. Hijiki may be a lesser known seaweed of Japanese cuisine, but it is a favorite sea vegetable prepared at Japanese homes. Aside from its many health benefits, Japanese strongly believes that consuming moderate amounts of hijiki can give you beautiful, black lustrous hair.

    Comes in sprig-like dried form, hijiki almost resembles of dried black tea leaves. To prepare for cooking, the seaweed needs to be first rehydrated then cooked with soy sauce, sugar or other seasonings.

    Delicious Recipe with Hijiki

    Hijiki Salad | Just One Cookbook

    Mozuku もずく Seaweed | Pantry | Easy Japanese Recipes at

    Mozuku もずく

    This seaweed is one of the secret ingredients of longevity of Okinawans, along with other superfoods such as tofu, turmeric, local greens, and goya (bitter gourd). Surrounded by shallow clean water and temperate climate, Okinawa is Japan’s largest producer of mozuku where it accounts for over 90% of output nationwide. The harvest season is from March to May and it is almost entirely farmed by the locals, and then distributed to the mainland of Japan. 


    Mozuku has a unique, slimy and long stringy texture. While the most common way to eat mozuku is from the packages that have been dressed with vinegar seasoning, the seaweed is more versatile than one can imagine. Some creative home chefs in Okinawa even use mozuku in dishes such as crispy tempura, gyoza, chilled soup, stir fry, omelette and so on. 

    To learn more about mozuku and its relationship with the Okinawan people, you can read this article published by the Okinawa Institute of Science and Technology. 

    Health Benefits of Seaweed

    Recognized for their contribution to overall robust health of the Japanese people, the unique health properties of seaweed are substantial and vary from plant to plant. According to Doctors Seibin and Teruko Arasaki, Japanese scientists and authors of Vegetables from the Sea, report that all of the minerals required by human beings are present in sufficient amounts in sea vegetables. In general, the health benefits of seaweeds include the following:


    Many studies have shown that seaweeds are extraordinary source of antioxidants, which is vital to prevent inflammations. In Japan medical field, seaweeds are recommended to be included in the diet to help protect against chronic diseases such as cancer, stroke, arthritis and lifestyle-related illnesses such as obesity and high blood pressure. 

    A paper published by Dr Jane Teas of Harvard University shows that kelp consumption might be a factor in the lower rates of breast cancer in Japan.

    Vitamins and Minerals

    Rich in vitamins A, C, E and K, seaweeds are accredited for improving skin and hair health. They are also high in Vitamin D, which helps the absorption of calcium for healthy bones.

    Amongst the vegetables, seaweeds are an incredible source of minerals, most notably calcium, copper, zinc, magnesium and iron. For example, hijiki alone contains far more calcium than milk.


    Another outstanding health benefit of seaweed is iodine. Iodine plays a major role for strong metabolism of cells, which is essential to convert food into energy. It is also needed to maintain a healthy thyroid and the balance of our hormones.

    DHA and EPA omega-3 fatty acids

    For vegetarians and vegans, seaweeds provide a great source of omega-3 fatty acids DHA and EPA, which are often missing in other plant foods. Omega-3 fatty acids offers the best support for cardiovascular and cognitive health.

    Good-for-Your Gut Probiotics and Fibre

    A terrific source of probiotics and dietary fibre, seaweeds can aid digestion and weight loss since they are low in calorie. Its complex enzymes and carbohydrates can help to breakdown sugars that are normally indigestible to the human gut.

    Where Can You Buy Seaweeds from

    If you live near a Japanese grocery or a well Asian market, you should be able to find assorted seaweeds mentioned above. Most of the natural food stores also carry them these days. With the gaining popularity, you can even find packages of seaweeds sold at Whole Foods or online from a number of sources such as Amazon or iHerb.

    Enjoy in Moderation

    While the benefits of seaweeds for our health are proved to be abundant, there are some potential concerns with regard to consuming seaweeds. Due to the high level of iodine, those with thyroid disease or susceptible to it should enjoy seaweed with caution. If you are advised to be on a low-sodium diet, you want to be careful with certain types of seaweeds which may have higher level of sodium.

    To reap the benefits of these sea vegetables, seaweed should be enjoyed in moderation along with a well-balanced diet just like the Japanese belief that moderate eating keeps the doctor away. 

    Did You Enjoy Learning about Seaweed?

    We hope you get to incorporate more seaweeds into your daily diet and enjoy a strong, healthy life. 

    Sign up for the free Just One Cookbook newsletter delivered to your inbox! And stay in touch with me on FacebookPinterest, YouTube, and Instagram for all the latest updates.

    Author Reese

    Originally from Penang, Malaysia, Reese lives in Minnesota with her husband and their baby boy. She previously ran an Asian spice shop, and also worked on UNESCO Heritage projects in Penang in the areas of performing arts, history, and arts education. Reese loves spending time with her family, listening to podcasts, and reading up on art & design. And of course dreaming of another trip to Japan to hike mountain trails and eat her favorite street food Okonomiyaki. More from Reese →

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