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What Are Sea Greens?

Sea greens are, at their most basic level, edible plant life found in the ocean. Hence the name. Sea greens are typically low in calories, high in iodine, and depending on the variety may contain potassium, calcium and magnesium among other nutrients.

What Are Sea Greens?

What Are Sea Greens?

There are many different varieties including:

  • Kelp
  • Irish Moss
  • Salicornia
  • Dulse
  • Nori
  • Spirulina

Sea greens may grow or gather along the coastlines of nations around the world, but it’s some of the farthest-away (to America) places that seem to have adopted sea greens as a part of a national or cultural diet. Japan, Ireland, and many other countries have food traditions based around or including sea greens.

Different Types Of Sea Greens

There are many varieties, shapes, and sizes of sea greens to choose from and you will find many varieties in the wild. Some people encourage foraging of sea greens, but no matter which variety you need, informed foraging is the only way to approach these plants.

Why? Because if you gather sea greens that grow too close to sewage treatment facilities, farms, power plants, or similar operations you run the risk of foraging contaminated food.


Kelp is a large form of algae that can grow in dense populations near coastal areas and shorelines. There is no single variety of kelp; many varieties exist including wakame, kombu, and Alaria.

The two former varieties are used in Asian cooking while Alaria is eaten in Scotland, Iceland, and Ireland. Some kelp is strong, some varieties are mild, but in most cases kelp is used as an ingredient and not the main dish.


This sea vegetable is an algae that some sources say was used by NASA as a nutritional supplement for astronauts. This is one that seems to be more popular as a supplement than as an ingredient, but it’s easy to see why people want to take it like a vitamin–it tends toward being high in both protein and B vitamins. There are recipes that incorporate spirulina but many of these refer to the powdered variety.


Dulse has a salty flavor when dried. Fresh, it looks a bit like red lettuce, and as such makes a great addition to salads and side courses. You may find this works well as an added flavor for potatoes or rice. Some sources advise adding it to a bag of popcorn or over moist chocolate, as this sea green can sometimes taste a bit like bacon.


Not all sea vegetables grow directly in the ocean. Some grow in tidal areas, and Salicornia is one of these. Also known as sea beans, sea asparagus, sea beans, and sea pickle, Salicornia is said to be a summer vegetable with very particular growing conditions required.

Unlike some of the other sea greens in this list, Salicornia could make an excellent side dish when paired with Salmon or other seafood. These are not considered legumes, some sources describe them as herbs! That said, this sea vegetable has similar textures to some beans, asparagus, etc. Salicornia can taste salty, which is why it’s best to taste any dish using it before adding more.

Sea Purslane

Sea purslane is another variety of sea vegetable that lives along the coastline and not necessarily directly in the ocean. Some eat this raw, others prefer it cooked or even fermented. Some like to use this almost as a condiment due to its saltiness; you can add it to soups at the very end of the process or sprinkle it over rice or noodles. This sea vegetable is another fussy plant that requires specific conditions–the growing season for Sea Purslane is said to be very short.


Nori is typically discussed when talking about making maki sushi rolls–it’s the seaweed sheet that the rice and fish are rolled up into during prep. But nori is more than just a delivery system for seafood; this red algae was consumed in paste form in Japan until about the 1700s when the nori sheet was innovated, changing the utility of this sea-based food forever. Nori is great on salads, in soups, and over rice dishes of all kinds.

Irish Moss

There is no single species of the plant we know as Irish Moss. Multiple varieties exist in the oceans of the world from the North Atlantic (Chondrus crispus) to the Caribbean (Eucheumatopsis isiformis). Irish moss creates a jelly when it is cooked and that jelly in Caribbean recipes is used in ways you might not expect. One recipe calls for Irish Moss jelly to be mixed with cinnamon, vanilla, milk, and rum. There are Scottish and Irish varieties of this preparation and it is said to be good to consume when feeling unwell.

The Problem With Sea Greens

The “problem” here isn’t so much with the greens themselves (except in a few cases which we will explore below) but with the difficulty in finding reliable information about them. Sea greens have become a food fad, and that fad extends into dodgy (and not-so-dodgy) supplements which make all sorts of interesting claims.

There are plenty of less-than-reliable supplement sites out there touting the benefits of sea greens simply to promote a faddish “health” product. You’ll read all sorts of partially useful information, including the fact that seaweed and other sea greens are low in calories which according to some supplement retailers means you can use sea greens to lose weight.

Iodine, Kelp, and Supplements

But how much of those greens do you have to eat in order to get to that result? You may notice there are no supplement websites telling you how much to consume to approach the desired result.

That may be due in part to the fact that some sea greens are higher in iodine and should not be consumed in large quantities–and that goes for supplements as well as the fresh variety,

Kelp is a good example. The official site for the University of Rochester Medical Center reminds, “As a supplement, kelp is used as a natural source of iodine” but also notes that the average kelp-based supplement “might contain large amounts of iodine. This can cause decreased thyroid function (hypothyroidism) or increased thyroid function (hyperthyroidism).”

How To Consume Kelp?

Does this mean we should not cook with or consume kelp? No, it doesn’t. But it DOES mean you should take advice from nutritional supplement retailers with a grain of salt when they start talking about how high-fiber and low-calorie some sea vegetables are; remember that supplements are NOT regulated by the FDA.

Sea vegetables have their place at the table, it’s just not as a food replacement for high-calorie alternatives. Sea vegetables are, based on articles published by the James Beard Foundation, great as an ingredient in a larger dish. As a standalone, you might be hard pressed to find a recipe where the main ingredient is seaweed, kelp, etc.

Recipes Using Sea Greens

Sea Greens are becoming a popular food fad, and until now, have most commonly been seen in Asian cuisine in sushi, soups, salads, and rice dishes. Here is a list of recipes that use sea greens.

Seaweed Products To Try

Want to try to incorporate sea greens like seaweed into your diet? Here are a few products for you to try, including snacks and pre-made seaweed salads.

Monique McArthur
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