The Surprising Benefits of Sea Vegetables For Health, Climate, and More

Published on June 06, 2023

By Kristen Boye BS, Natural Health

Kristen Boye

Kristen Boye is a natural health expert, writer, copywriter, and editor. Kristen was raised on an organic farm in British Columbia which inspired her life’s work. She holds a Bachelor’s Degree in Natural Health, is a Certified Natural Foods Chef, co-owner of a medicinal herb farm, and is a natural foods and children’s health advocate. Kristen lives with her husband and two children on their medicinal herb farm in Western North Carolina.

Sea vegetables, also known as seaweed, have been dietary staples in traditional Asian and coastal cultures for thousands of years.

Thanks to growing awareness about their health benefits, certain varieties, such as nori, used in sushi or seaweed snacks, have also become common in North American homes.

However, did you know thousands of species of sea vegetables growing in our oceans possess a wealth of health benefits?

In this article, you’ll learn about several varieties of sea vegetables, their health benefits, and how to get more sea veggies into your diet.

What are Sea Vegetables?

Sea vegetables are edible seaweeds harvested from or cultivated in the ocean. 

Traditional coastal cultures have used various sea vegetables for millennia to flavor, add texture to foods, and provide essential nutrients.

Sea vegetables, such as nori and dulse, have also been part of the Western health food movement for decades.

Yet, until the twenty-first century, most North Americans were unfamiliar with sea vegetables.

That has changed in the last twenty years, with global seaweed/sea vegetable production (wild and cultivated) increasing three-fold from 2000 to 2019. REF#1854 

Thanks to a growing awareness about the benefits of eating sea vegetables, many varieties are now available in natural food stores and online.

They are also used in supplements for their naturally occurring bioavailable compounds, such as minerals and polysaccharides and polyphenols (types of antioxidant groups).REF#1855 REF#1856

Sea vegetables are also used as:REF#1857

  • Animal feed
  • Antioxidants
  • Biofertilizers
  • Natural insecticides
  • Traditional botanicals
  • And for promoting plant growth. 

Certain sea vegetables, such as brown seaweeds, also play an important role in the environmental monitoring and managing of coastal marine ecosystems. REF#1857 

Most seaweed production (97%) occurs in Asia, with China responsible for 56% of the world’s total seaweed production.REF#1858. 

With the seaweed industry valued at over 59 billion dollars,REF#1858. and the growing interest in sea vegetables for health, supplements, and environmental/climate purposes, now could be an opportune time for Western entrepreneurs and governments to claim their share of the global sea vegetable industry.

A List Of Common Edible Sea Vegetables

Most Americans are only familiar with a few sea vegetables like nori (found in sushi and seaweed snacks), wakame (the sea vegetable used in seaweed salads), and carrageenan (a common yet controversial food additive used in drinks and prepared foods to enhance texture). 

However, some of the less-known readily available sea vegetables include:

  • Agar agar
  • Arame
  • Bladderwrack
  • Brown seaweed
  • Dulse
  • Hijiki
  • Irish moss
  • Kombu
  • Marine algae
  • Rockweed 
  • Sea beans
  • Sea lettuce
  • Sea moss
  • Sea grapes
  • Wakame/Alaria

These sea vegetables are typically available at natural foods or health food stores, Asian markets, or online specialty stores.

The Benefits of Eating Sea Vegetables

For many people, especially those who didn’t grow up eating them, sea vegetables are an acquired taste.

Yet, they are steadily gaining popularity due to their vast array of nutrients and potential health benefits.

Here, we’ll explore seven health benefits of eating sea vegetables that may whet your appetite.

1: Sea Vegetables Are Nutrient-Dense

Sea vegetables are unique in that they all offer a tremendous array of nutrients not found in other vegetables.

For example, all edible sea vegetables contain:

  • Antioxidants: Such as polyphenols and polysaccharides (alginates) which, play a critical role in protecting cellsREF#1859
  • Essential fatty acids: Such as omega 3s, which support cardiovascular health and inflammatory response REF#1860
  • Fiber: This promotes digestive and heart health while nourishing the gut microbiomeREF#1861
  • Iodine: An essential nutrient lacking in many unfortified foods
  • Proteins not found in land-based foods: Such as specific lectins, phycobiliproteins, peptides, and amino acidsREF#1862
  • And other essential vitamins and minerals: Such as vitamins A, C, B vitamins, copper, and magnesium REF#1863

Certain varieties of sea vegetables also contain unique nutrients with specific health benefits.

No wonder sea vegetables have been prized in coastal cultures for centuries.

2. Sea Vegetables May Support Cognitive Function

Sea vegetables contain unique compounds that have been shown to support various aspects of cognitive function.

For example, the bioactive compounds known as alginates in brown seaweed have been shown to promote normal inflammatory processes within the brain by protecting mitochondrial membranes (the energy cells of the brain).REF#1864 

Although more research is needed, this is encouraging as science has found a link between inflammatory response, brain health, and brain aging.REF#1865 REF#1866 REF#1867 

As previously mentioned, sea vegetables are also good sources of iodine and essential fatty acids, which are critical for normal cognitive function.

Yet, the importance of iodine in brain development is often overlooked. 

Per the World Health Organization, “Iodine deficiency is the single most important preventable cause of brain damage” worldwide.REF#1868 

This is largely due to the impact of suboptimal maternal thyroid function on babies in-utero and the effects of iodine deficiency throughout a lifetime.REF#1869 

3: Seaweed May Support Healthy Thyroid Function

Thyroid disease affects an estimated 20 million Americans, with women at higher risk than men (although some experts believe that number is much higher).

Per the American Thyroid Association:REF#1870

  • More than 12% of the US population will develop thyroid disease in their lifetime.
  • Thyroid disease affects women five to eight times more than men (but men can get it too).
  • Up to 60% of people with thyroid disease are unaware they have it.
  • Undiagnosed thyroid disease may increase the risk of cardiovascular diseases, osteoporosis, and infertility.
  • The causes of thyroid problems are largely unknown.

Although many factors go into thyroid health issues, eating enough iodine-rich is often a good strategy to support overall thyroid health.

Research has shown iodine promotes healthy thyroid function, including normal levels of the thyroid hormones T4, T3, and TSH.

Research has also shown certain types of sea vegetables, such as the brown sea vegetable Sargassum, used in Traditional Chinese Medicine, may have an immunomodulating effect that may support thyroid health.REF#1871

However, some thyroid conditions do not respond well to additional dietary iodine. Always check with your doctor before increasing your iodine consumption.

Learn more about thyroid health in Thyroid Symptoms, Labs, And Supplements To Discuss With Your Doctor.

4. Sea Vegetables Are Excellent For Healthy, Flavorful, Plant-Based Cooking

Sea vegetables, when used correctly, can be a secret weapon in the kitchen.

They’re low-calorie, and their naturally salty, umami flavor lends itself to various savory dishes like stir fries, dressings, soups, noodles, and grains.

Dulse, for example, is a popular addition to low-salt seasoning blends because it adds a nice boost of flavor with less sodium than table salt.

The mild flavor and thickening action of dulse flakes make it an excellent superfood addition to smoothies.

And the sea vegetable agar agar can be used as a vegan substitute for gelatin.

We’ll share more culinary tips coming up.

5: Sea Vegetables Promote Healthy Digestive Functions

Research has shown sea vegetable extracts contain beneficial antioxidant polysaccharides known as alginates.

Alginates are rich in a plant compound known as mannuronic acid, which may have a protective effect on the gastrointestinal system.REF#1872 

Polysaccharides found in Algal, a type of algae, have also been shown to improve satiety and modulate gut microbiota.

And Laminaria japonica, a type of brown sea vegetable used in seaweed kimchi, has been shown to promote normal intestinal barrier function.REF#1873 

As previously mentioned, sea vegetables contain fiber and other digestive-supportive nutrients such as amino acids and magnesium.

Learn more about the gut microbiome and digestive health from a naturopath and medical herbalist in: Understanding The Microbiome & Tips To Maintain A Healthy Gut.

6: Sea Vegetables Support Immunity

Eating sea vegetables has many potential benefits for the immune system, including providing:

  • Essential nutrients, Such as iodine, vitamins C and A, are critical to various aspects of immune function.
  • Microbiome support: Since up to 80% of our immune system resides in the gut, eating a diverse diet of gut-supportive foods makes sense.
  • Inflammatory response support: This affects immunity, joint health, and more.

If you’re concerned about immunity, sea vegetables may be a healthy and functional addition to your diet.

7: Sea Vegetables May Promote Metabolic Health

Metabolic health refers to the health and function of various organs and systems involved in metabolism. 

This includes the thyroid, pancreas, cells, cardiovascular system, digestion, and others.

The nutrients and phytochemicals in sea vegetables have been shown to support metabolic health.

For example, per a 2020 study in the Journal Current Developments In Nutrition, the sea vegetable Algal contains polysaccharides, proteins, peptides, and phenolic fractions that support metabolic health by improving satiety, modulating gut microbiota, acting as antioxidants, and promoting normal inflammatory response, cholesterol levels, and sugar metabolism.REF#1874

Additional research has shown sea vegetables have the potential to support these aspects of metabolic health, including normal lipid levels and healthy weight management. REF#1875

These potential benefits are in addition to the positive effects of sea vegetables on thyroid function.

The Environmental Benefits Of Sea Vegetables

Sea vegetables aren’t just good for humans; they play a critical role in environmental health.

Some of their environmental functions and benefits include: REF#1876 REF#1877 REF#1878 REF#1879 REF#1880 

  • Absorbing heavy metals and other toxins from the ocean
  • Acting as a carbon sink and sequestering agent. 
    • Per Time Magazine,REF#1876 researchers have found sea vegetables/seaweed is the most effective natural way of absorbing carbon from the atmosphere.
  • As a plant-based protein source
  • As habitats and food for marine life
  • Creating biofuel
  • Creating biodegradable plastics
  • Marine ecological regulation
  • Providing essential food for sea creatures
  • Phosphorus and nitrogen absorption
  • Regenerating marine ecosystems
  • Releasing oxygen into the water

In addition, a red algal species known as Asparagopsis taxiformis, can reduce methane production from beef cattle up to 99% when added to cattle feed.

This is not an exhaustive list of how different varieties of sea vegetables can benefit the planet, but it demonstrates their incredible potential and purposes.

How To Start Eating More Sea Vegetables

Many people are intrigued by sea vegetables' nutrients and health benefits but are unsure how to prepare them.

Fortunately, the newfound popularity of sea vegetables has made them easier to enjoy and prepare.

Here are some ways to get more sea vegetables into your diet:

    • Try seaweed snacks. These are sheets of nori cut into a uniform size and often flavored with salt, teriyaki, or wasabi. You can also buy large sheets of nori to tear off and eat.
  • Try nori or dulse crumbled up or sprinkled over various foods as a condiment. Nori is available in seaweed snacks or sheets, and dulse flakes can be found alone or in various seasoning blends.
    • Add sea veggies to soups. Dulse or noodle-like sea vegetables, such as arame, hijiki, or wakame, can make a tasty addition to miso soup or ramen bowls.
  • Sprinkle into grain bowls
  • Blend dulse or nori into sauces, dressings, and dips.
      • Culinary tip: Nori or dulse makes a good vegan substitute for anchovies in Caesar dressing.
    • Rehydrate and make into salads. There are many recipes for seaweed salads online. You can also add rehydrated, chopped seaweed to different types of salads for flavor and texture.
  • Make or buy sushi rolls.
  • Use agar agar in place of gelatin. The texture is slightly different, but it works just as well to create vegan gelatin-like desserts such as juice-based jellies, vegan pastry cream, ice cream, puddings, savory terrines or pates, and more.
  • Blend a tablespoon of dulse flakes into smoothies. It’s barely detectable and acts as a thickener if left to sit a few minutes.
  • Try your hand at Arame or Hijiki caviar as an appetizer. This may sound unusual, but this recipe can be made with arame or hijiki and is truly delicious served with vegan or traditional creme fraiche or sour cream on crackers, latkes, or flatbread. Your guests will love this unique appetizer.

    Who Shouldn’t Eat Sea Vegetables?

    Various types of sea vegetables have been consumed for thousands of years, with no serious indications of side effects from normal consumption.

    However, there are a few things to keep in mind when eating sea vegetables:

    • The iodine content: Not everyone will benefit from more iodine, and too much can cause the same symptoms as iodine deficiency. However, the National Institutes of Health states iodine intake from foods and supplements are unlikely to exceed the tolerable upper intake level in most people.REF#1877
      • The recommended daily allowance (RDA) of iodine for adult men and women 19+ years is 220 mcg and 290 mcg daily for pregnant and lactating women REF#1878
    • The Tolerable Upper-Intake Level (UL) of iodine for adults 19+ years and pregnant and lactating women is 1,100 mcg daily
    • Check with your doctor if you have a thyroid condition.
      • Possibility of heavy metals: Sea vegetables—especially red sea vegetables—may contain varying amounts of heavy metals. This is the same issue with fish and seafood. Consider eating sea vegetables in moderation and/or avoiding red sea vegetables.
    • Sodium content: Since sea vegetables absorb salt from the sea, they may not be appropriate for those on a very low-sodium diet.
    • Rare allergic reactions: These are unlikely but possible.

    Overall, sea vegetables are a healthful and beneficial food when eaten in moderation for most people.

    If you have concerns, check with your doctor or healthcare practitioner.

    Interested In Learning More About The Benefits Of Sea Vegetables?

    For more helpful information on the health benefits of sea vegetables and iodine, check out the following resources in our Herb Library & Seeds of Knowledge blog:


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