What is Seaweed?

seaweed in seaweed salad

There are many types of seaweed on the market, which can make it overwhelming to figure out which edible seaweed to use for what purpose. In this article, we’ll break down what seaweed is, potential nutritional benefits, and recipes to help you incorporate seaweed into your diet.

What is seaweed?

Seaweed has become a very familiar term these days, but what is seaweed exactly? Seaweed is broad term that refers to numerous marine plants and large macroalgae. Seaweed is broken into categories by color; red (Rhodophyta), green (Chlorophyta) and brown (Phaeophyta). Brown seaweed includes some 1500 species, green 7000 species and red 4000 species. Unlike sea grasses and land plants seaweed does not have flowers, roots, or leaves - instead they have stipes (stem like) and blades (leaf like). Seaweed also produces its own food by utilizing sunlight and converting carbon dioxide and water into oxygen and sugar (known as photosynthesis). It can be found growing in oceans, rivers and lakes providing homes for many sea creatures. Many types of seaweed are edible, making them an abundant and sustainable food source for both marine and land dwellers alike.

Seaweed vs. Kelp

Seaweed vs Kelp is something of a misnomer. Kelp is a form of brown seaweed that grows in cooler, shallow waters often near the coastline. Giant kelp can grow up to 200 feet in its lifetime and like many other types of brown seaweed, often grows in groups or forests. By attaching itself to the substrate, kelp can stand fast against the currents and waves. Some familiar types of kelp are wakame, arame, and kombu. Kelp is often used in seaweed salads, seaweed snacks, mineral powders and even toothpaste!

Types of Seaweed

The main four types of seaweed you will encounter most often are wakame, arame, kombu, and nori. Each variety has classic ways that it is used and will be familiar to most. Arame, wakame, and kombu are all brown algae seaweeds and specifically a type of kelp. Nori is a form of red algae seaweed, popular for making sushi and seaweed snacks.


Wakame, also known as “Sea Mustard”, is a type of brown algae and a species of kelp. The dried version of this edible seaweed needs to be rehydrated prior to use and will expand 2 -3 times in size when hydrated. After it is rehydrated wakame turns a beautiful, brighter green color with a soft, silky, noodle-like texture. Wakame delivers an umami flavor with a salty, slightly sweet taste. Three popular recipes using wakame are the classic Japanese seaweed salad, miso soup and sunomono which is a cucumber and seaweed salad.


Arame, also known as "Sea Oak", is a species of kelp that has a mild, slightly sweet flavor making it easily adaptable to a variety of uses. Usually sold in a dried state it consists of dark brown strands with a firm texture. Rehydration is required for use in cooking which generally takes about five minutes. This nutritional powerhouse can be added to muffins, soups, and salads to name a few options. Arame is also used for fertilizer and harvested for alginate which is used in food production as a stabilizer or thickener.


Given the honor of being called the “King of Seaweed” Kombu is a form of brown algae and a species of kelp. It has a briny, deep umami flavor reminiscent of mushrooms! Commonly used as a base (called dashi) to make stock or added to dry beans when cooking in order to increase their digestibility. Because of its intense umami flavor, it is used like bay leaves to enhance the flavor of sauces and soups of any type. Kombu powder can also be used to make a face mask for your skin, often recommended for oily or acne prone skin due to its antimicrobial and antioxidant characteristics.


Nori is a type of red algae and the most well-known type of seaweed. Harvested, washed, shredded, dried and pressed into sheets this edible seaweed dresses up sushi all around the world. Chewy or crispy in texture, nori has a touch of salt and sweetness, but a powerhouse of umami flavor. Nori is used in many classic Japanese recipes; sushi, onigri, furikake, miso soup, and as an accompaniment to plain rice. You may also find nori used to make seaweed snacks, salad toppings, and as a powder to be added to everything from soup to popcorn.

Dried seaweed

Seaweed that is intended for consumption is often dried and packaged to prolong freshness. In order to maintain that freshness, it is recommended that you ensure it is in a sealed package and stored in a cool, dry, dark location. If you want to extend the life even further, it can be frozen or refrigerated in an airtight container. Watch for changes in color or texture to determine if it is still good for use.

Is seaweed good for you?

In recent years as seaweed has grown in popularity it has also found its way into potential applications for medical use. According to Today's Dietitian studies have been conducted indicating potential applications for cancer, Alzheimer’s disease, dementia, obesity, diabetes and hypertension.

In terms of dietary applications for health, seaweed is full of fiber, protein, essential fatty acids, antioxidants and high amounts of vitamins and minerals. This can be a double edged sword, as too much of a good thing is still too much. Being informed is always the first step. For example, individuals with certain health conditions or taking certain medications may need to take caution when introducing seaweed to their diet. Anyone taking blood thinners or suffering from an autoimmune disease should consult a medical professional prior to eating seaweeds as they can cause unwanted side effects or interfere with medications.

In addition to medical conditions there are some nutrients (these vary based on the type of seaweed) that are very high and not naturally eliminated by the body when in over abundance. Livestrong.com points out that iodine and sodium content for many seaweeds is very high in just a small amount. Iodine is an essential nutrient that must be consumed, but too much iodine can cause damage to your thyroid.

Seaweed, like many things, has great benefits when eaten as part of a balanced and varied diet. Staying mindful, balanced, connected to your body, and informed is the smart move.

Seaweed nutrients

High mineral content in seaweed includes calcium, iodine, iron, copper, and magnesium. Brown seaweeds are high in magnesium, one example is kombu which has 8 grams per serving which is over 50% of the daily recommended amount for an adult. Some red and green seaweeds are high in vitamin B12, nori contains 5mcg (2.4 mcg is the RDA) for an 8 gram portion. For those that grow in direct sunlight they are high in vitamin A, C, E and some forms of vitamin B (1,2,3,6,9,12). Lastly, the iron content in some cases can be very high – an 8 grams serving of dulse flakes has more iron than 3.5 ounces of lean beef.

There is a decent amount of variation in the different forms of seaweed and often the serving sizes are small, so reading the nutritional label can be a good place to start for specifics.

Seaweed for miso soup

Wakame is the seaweed most often used in miso soup, but any of the four main varieties can be used for miso soup. In a traditional Japanese dashi stock, both kombu and wakame are used to make the classic dish. Arame makes a lovely topping to any steaming bowl of soup, and adding a crispy, toasted slice of nori is great for dipping or floating on top.

Seaweed recipes

Seaweed snacks

If you are looking for a really simple way to elevate your meal, then try out these simple, healthy and delicious seaweed snack chips made with nori, almond butter and miso. 

Seaweed rolls

Seaweed rolls are an endlessly versatile way to enjoy sheets of seaweed such as nori, flat noodle-like wakame, crispy arame, or kombu powder for a nice umami bomb. Similar to seaweed rolls are nori rice balls, an equally delicious treat.

Seaweed wrap

It’s always a treat to find a new way to wrap up a bunch of delicious goodness. Nori is excellent for use as a wrap and is a great replacement for those looking to avoid gluten or limit carbohydrates.

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