Explore the varieties of edible seaweed used in Japanese cooking, the health benefits, and how to cook with these sea vegetables.
Hailed as the superfood of Japanese cuisine, seaweeds have long been an indispensable part of the Japanese diet and other East Asian cultures like China, Korea, and Taiwan.
Japanese consume seaweed 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 into your diet.
Table of Contents
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, and 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.
5 Types of Edible Seaweed Used in Japanese Cuisine
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).
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 it as a natural flavoring, the roles of seaweeds are just as multi-faceted. Here we feature 5 most common seaweeds in Japanese cuisine:
1. Nori
Comes in paper-thin dark green sheets, nori (海苔) is the most prominently known and most consumed seaweed worldwide. Used mainly as an ingredient for wrapping sushi, nori is made by shredding and drying seaweed before pressing it into a thin layer – a method adopted from the paper-making process.
Aside from sushi and onigiri rice balls, nori is also used as a 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 seaweed, where it is flavored with soy sauce, dashi, sake, and mirin and made into a paste-like accompaniment for steamed rice.
Nori Recipes
2. Kombu Kelp
Dark green with a thick leather-like texture, kombu (昆布), also known as kelp, is the quintessential ingredient in the 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.
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 is sold in dried form. You can also find kombu pickled in vinegar or eaten fresh in sashimi.
For those who consume large amounts of beans, you can add strips of kombu to dried beans as you cook. This magical ingredient will help to tenderize the beans and reduce their gas-producing properties. A great solution for bean eaters!
Kombu Recipes
- Kombu Dashi
- Vegan Dashi
- Kombu Tsukudani (Simmered Kombu)
- Hot Tofu (Yudofu)
- Kenchinjiru (Vegetable Soup)
- Clam Miso Soup
3. Wakame
Grown in cool and mineral-rich arctic currents, wakame (わかめ) has 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 for vegetables, like cucumber. To prepare, the leaves should be cut into small pieces as they will expand during cooking.
Wakame is low in calories and known for its ability to aid in weight loss and boost energy levels. You will find dishes featuring wakame that 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.
Wakame Recipes
4. Hijiki
A brown variety of seaweed, hijiki (ひじき) 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, the Japanese strongly believe 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 and then cooked with soy sauce, sugar, or other seasonings.
Hijiki Recipes
5. Mozuku
Mozuku (もずく) is one of the secret ingredients of the longevity of Okinawans, along with other superfoods such as tofu, turmeric, local greens, and goya (bitter gourd). Surrounded by shallow clean water and a 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.
It has a unique, slimy, 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 the 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:
Antioxidants
Many studies have shown that seaweeds are an extraordinary source of antioxidants, which is vital to prevent inflammations. In Japan’s medical field, seaweeds are recommended to be included in the diet to help protect against chronic diseases such as cancer, stroke, and 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 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.
Iodine
Another outstanding health benefit of seaweed is iodine. Iodine plays a major role in the 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 offer the best support for cardiovascular and cognitive health.
Good-for-Your Gut Probiotics and Fibre
A terrific source of probiotics and dietary fiber, seaweeds can aid digestion and weight loss since they are low in calories. Its complex enzymes and carbohydrates can help to break down sugars that are normally indigestible to the human gut.
Where to Buy Seaweeds
If you live near a Japanese grocery or a well Asian market, you should be able to find assorted seaweeds mentioned above. Most 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 proven 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 a 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.
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[…] read Discover Seaweed: The Essential Ingredient of the Japanese Diet about the different types of […]
I like fresh salted seaweed, sold in the refregerated section. I reconstitute it before adding to miso soup. My question is, can I use it in a salad after rinsing/rehydrating? Or do I need to boil it first? Thanks!
Hi Bernice – Are you referring to Korean salted seaweed? If yes, the texture might be tough if you add it directly to a salad without cooking. You do want to saute it lightly first. For Japanese salads, we recommend using wakame. It has a tender texture after rehydration and you can toss it into salad directly without cooking.
Where do I purchase the Japanese miso soup bowls?
Hi Doti – If you’re located in the US, you can check MTC kitchen, or our SHOP page:
https://www.amazon.com/shop/justonecookbook
If you live outside of the US, I recommend reading this post. We have a list of online shops that may ship internationally:
https://www.justonecookbook.com/the-ultimate-guide-to-japanese-tableware/
Great to hear about the benefits of seaweed. Not to mention the yummy recipes. Thanks for mentioning Scotland as we have a long tradition of using seaweed not only in food but also to fertilise the garden or farm fields. It certainly isn’t as varied or delicious as Japan though. For those in the UK who want to think eco and save air miles,Mara Seaweed in Edinburgh sell a seaweed range,also other Irish and Scottish companies produce them too. Beautiful to think Scotland and Japan can inspire each other.
Thanks for sharing your knowledge with us, Laura! It has to show that many world cuisines are influenced by each other:)
Where can I buy mozuku? I’m in Colorado.
Hi Carol – you should be able to find mozuku in Japanese or Korean grocery stores in Colorado. We have a Grocery Stores Directory and online shopping page that you will find helpful. Check these out:
https://www.justonecookbook.com/japanese-grocery-stores-around-the-world/
https://www.justonecookbook.com/online-shops-for-asian-ingredients-goods/
How long does an unopened package of wakame stay edible? The package is 1-2 years. There isn’t an expiration date on the package. Thanks!
Hi Jennifer, Dried wakame can last a long time, but we still recommend using it within a year or two within the year of purchase. Like dried spices, you can use them as long as they are stored well in dark cool places. The best bet would be checking for any molds or smells if it’s been stored for too long.
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Hi,
Thank you for the informative article! I was just wondering if there are any concerns associated with consuming any of these types of seaweed because of ocean or water pollution? Are there huge differences in quality and hygiene, depending on where you are buying and in what form ie. fresh or dried? Any hints on where I could get this type of infomation would be much appreciated.
Hi Aly – Glad that you found this article useful. You brought up a legitimate concern about consuming seaweed. There are some quality Japanese seaweeds available. You can look out for the organic label. If you’re in the US, what I’d suggest is to buy seaweed from places like Maine & Northern California. Good news is with the rise of plant-based diets, we’re seeing some dedicated seaweed farmers in the US advocating for sustainable and environmentally friendly ocean kelp farming. As for fresh or dried, both are fine depending on what’s available (although they are typically available in dried or powdered). Read the ingredients to make sure it’s minimally processed.
Here are a few seaweed companies that carry sustainably harvested and certified organic seaweeds:
1. Eden Seaweed
2. Maine Coast Sea Vegetables
3. Maine Seaweed
4. Atlantic HoldFast Seaweed
5. Salt Point Seaweed
6. Ironbound Island Seaweed
You can visit the companies websites or find some of the brands available at Whole Foods/ local co-ops or Amazon.
If you’re interested to learn more, 60 Minutes on CBS featured a story on seaweed farming a while ago:
https://www.cbs.com/shows/60_minutes/video/mR3viZvYerRqEMqy0QrX5xBhMXLxEluN/seaweed-farming-and-its-surprising-benefits/
Hope this helps!
Reese
I wanted to make some seaweed dishes that my grandchildren will eat but I’m wondering if it’s safe for them. They are six and nine years old
Hi Robin – it is safe for your grandchildren to eat seaweed dishes. All Japanese and Asian families let their children eat seaweed dishes starting a young age. Everything in moderation of course. You can always start with the safe ones like kelp and nori.
[…] a read of this article to learn more about different types of seaweeds used in Japanese cuisine and their health […]
Hi, can you use the kombu kelp in any way after preparing dashi with it?
Absolutely! The easiest way to repurpose kombu kelp is to make furikake (the versatile Japanese seasoning) with it. You can mix kombu with chopped nori/ dulse, sesame seeds and combined with the usual seasoning. Furikake makes a delicious topping on rice and noodles! Here’s the recipe you can refer (feel free to adapt):
https://www.justonecookbook.com/homemade-furikake-rice-seasoning/
Great post. I’ve only had a few of these. Aonori and hijiki are something I want to find and use.
Happy that you enjoyed the post! Definitely give both aonori and hijiki a try. They have unique texture, but so good for you:)
Have learnt such a great deal from the article on seaweed. Altho’ I have been to Asia many times and eaten seaweeds both there and at home there were many facts I did not know. Had never heard od ‘hijiki’ for instance 🙂 ! Now: would you know whether the green sea vegetable we call ‘samphire’ here in Australia is also counted as a seaweed in Japan or indeed is it known there?
Thank you so much for taking the time to leave a comment here, Eha! So glad that you found the article useful. Yeah, the varieties of seaweed is aplenty! Don’t even get me started on the seaweeds that are used in Chinese cuisine:) Not aware that samphire is used in Japan. Probably mostly used in England, Australia, Ireland and western countries? We will need to find out.