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The Health Benefits of Seaweed

Red seaweed is typically cultivated for food.

Red seaweed is typically cultivated for food.

Kelp forest, Otago peninsula

Kelp forest, Otago peninsula

What is Seaweed?

Seaweed, also called marine macroalgae (yes, it’s algae), is a plant-like organism typically found in the ocean, although some types can be found in fresh water. But not all seaweed is edible.

It can be used for many different things such as cosmetics, toothpaste, fertilizer, compost for landscaping, bioethanol and even paints. In fact, rotting seaweed produces large amounts of hydrogen sulfide, a toxic gas that can cause nausea and vomiting.

Edible Seaweed

Edible seaweed is used as food or for medicinal / herbal treatments and is divided into 3 different groups based on its color: red, green and brown. However, there are several varieties of seaweed. Probably the most well-known variety is kelp, also called Kombu (Saccharina japonica). Other common varieties include:

  • Nori (various species of the red algae Porphyra)
  • Dulse (Palmaria palmate)
  • Arame(Eisenia bicyclis)
  • Wakame (Undaria pinnatifida)
  • Irish Moss (Chondrus crispus)
  • Spirulina (Arthrospira platensis and Arthrospira maxima)
  • Sea Grapes, also called sea caviar (Caulerpa lentillifera)
Sea Grapes, aka Sea Caviar. It's easy to see why it's called sea caviar!

Sea Grapes, aka Sea Caviar. It's easy to see why it's called sea caviar!

Seaweed the Superfood

Because seaweed is found in the ocean, it is permeated by the essential and trace minerals found in sea water.

It has about ten times more calcium than cow’s milk and is almost identical in chemical composition to human blood plasma. Because of this, seaweed has the ability to alkalize our blood neutralizing the acidity caused by the consumption of animal products.

Seaweed also has a very high concentration of iodine, which is a trace element known to stimulate the thyroid gland. The thyroid is responsible for maintaining the body’s metabolism and aids in weight loss.

Iodine deficiency can lead to goiter, an enlargement of the thyroid gland that causes swelling of the neck and can lead to hypothyroidism, which can cause fatigue, weight gain and depression. Kelp is the most iodine-rich sea vegetable.

Kelp is the most abundant of the seaweeds and contains xylose, an essential sugar (polysaccharide) that is antibacterial, antifungal and helps prevent colon cancer. It also contains another essential sugar called fucose (not fructose), an antiviral that also supports long – term memory, and fights allergies.

Fucose also protects the lungs and can help alleviate cystic fibrosis, diabetes, cancer and herpes. Interestingly, research has failed to find these polysaccharides in the North American diet; however, it is quite plentiful in the Japanese diet, which has a high content of seaweed.

Kelp is also a rich source of several other vitamins and minerals including:

Codium fragile, also known as Dead Man's Fingers

Codium fragile, also known as Dead Man's Fingers

  • Potassium
  • Magnesium
  • Iron
  • Vitamin B6 (pyridoxine)
  • Riboflavin
  • Dietary Fiber
  • Glutamic Acid

Glutamic acid is responsible for a flavor the Japanese refer to as umami. It is one of the six basic tastes our tongue can sense (sweet, salty, bitter, sour and metallic). Umami is difficult to describe; however, a good example of a food high in umami is tomatoes.

Health Benefits of Eating Seaweed

As stated previously, seaweed is an excellent source of vitamins and minerals because of the constant bombardment of sea water to which it is subjected. It can be used to help prevent a number of different degenerative diseases including:

  • Obesity
  • Diabetes
  • Alzheimer’s Disease
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Seaweed with Sea Urchin Soup from Korea

Seaweed with Sea Urchin Soup from Korea

In fact, cultures that consume large amounts of seaweed (such as Japan and Korea) have a population with very few instances of these diseases.

One of the most coveted health benefits offered by seaweed is prevention of cancer. Lignans are the source of seaweed’s cancer fighting properties. They are polyphenolic structures and are derived from phenylalanine, an essential amino acid. Lignans are phytoestrogens that actively prevent angiogenesis (blood cell growth) by acting like antioxidants. This cuts off blood flow to would-be tumors. Lignans also prevent cancer from metastasizing.

Seaweed is also effective against stress and depression. It is a natural source of the B vitamins pyridoxine (B6) and pantothenic acid (B5). These are the energy vitamins; they keep the adrenal glands from becoming exhausted during times of stress. Without B vitamins, we become fatigued and we don't think as clearly.

Seaweed protects against heart disease as well. Because of its high content of folic acid and magnesium, seaweed has been shown to prevent myocardial infarction (heart attacks) and hypertension (high blood pressure).

Other Medicinal Uses of Seaweed

Although not technically medicinal, seaweed has a large role in microbiology. Agar, the primary medium for growing cultures is made from seaweed.

Seaweed may be beneficial when used against tuberculosis, worm infestations, arthritis, and influenza. It is also used as an ingredient in some diet pills since it has a “filling” effect on the stomach. In Japan, Nori (the seaweed wrapped around sushi) is thought to be a remedy for radiation poisoning.

How Much Seaweed is Too Much

As with anything, too much of a good thing can be bad. This applies to superfoods as well. The table below shows the dosages of seaweed for specific medical conditions that have been tested in clinical trials. You should always talk with your doctor before starting any new herbal supplement.

Seaweed Dosages

Recommended Dosage of Seaweed for Specific Medicinal Uses

Medical Use/TreatmentSeaweed Treatment Dosage

High Cholesterol

5 g per day (powder)


12 g per day

Metabolic Syndrome

4 to 6 g dried seaweed daily for 2 months

Effects on Estrogen

5 g per day for 7 weeks


2,400 mg a day as a mineral supplement for 12 weeks

How to Eat Seaweed

Depending on the type of seaweed used, it can be added to just about anything. For example, spirulina usually comes in a powder. I have a wonderful recipe for Spirulina – and – Chocolate Balls that I found in a book by David Wolfe called Superfoods.

But seaweed can be used in salads, salad dressings, soups, sushi, guacamole, salsa, cookies and my personal favorite: Smoothies!! Experiment with it and find your favorite way to use it.

© Copyright 2012 -2015 by Melissa "Daughter of Maat" Flagg ALL RIGHTS RESERVED

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.


Mel Flagg COA OSC (author) from Rural Central Florida on November 20, 2012:

@Dim Flaxenwick Thank you! You're too kind!

Dim Flaxenwick from Great Britain on November 20, 2012:

Magnificent article, covering all points possible.

I grew up in South Wales ., close to Swansea, where kelp was always fresh, sold at the swansea market.

Thank you for reminding me of the benefits of seaweed.

Mel Flagg COA OSC (author) from Rural Central Florida on November 12, 2012:

@Dr. Mark, of course I run into opposition for Vit C, it's too good for too many things lol

I'll have to go check out your hub, we do a lot of composting, and I'm always up for reading more on the subject. :D Plus I love your writing!

Mark dos Anjos DVM from The Atlantic Rain Forest, Brazil on November 12, 2012:

I wrote a hub on that about 4 months ago! (PLEASE read it-no one else has!) It is one of the few I have that are not related to my dog (although my dog does go out to the beach with me and helps me collect on the beach.)

Good point about the Vitamin C. I bet you run into all sorts of naysayers when you try to talk about megadoses, even though it has been well known for so many years.

Mel Flagg COA OSC (author) from Rural Central Florida on November 11, 2012:

@DrMark Actually you are absolutely right. Most MDs will tell patients not to take any herbal remedies. They'll tell you that taking vitamin C isn't worth it as well. My current physician has a little experience with herbs and vitamins, although he usually tells me "just research it like you always do before you take it." lol At least he's open-minded. Thank you for the suggestion, I'll change it today.

I never thought about adding seaweed to my compost, but that's a great idea!

Mark dos Anjos DVM from The Atlantic Rain Forest, Brazil on November 09, 2012:

This was a really well done article but I do have one comment that you may not care for. You mentioned "before starting any herbal supplement talk to your doctor" but in the vast majority of cases, in my experience (and probably yours) the MD is going to recommend you not take the herbal supplement because it is a waste of money and will do you absolutely no good. I think the sentence should read "before starting any herbal therapy talk to a physician that has experiences in herbal therapy".

Personally I only use seaweed for my compost, but the suggestions you make are really good.

Mel Flagg COA OSC (author) from Rural Central Florida on November 03, 2012:

@Pamela like phoenix said, it is an acquired taste, but I think it's delicious! Let me know if you give it a try! I hope you enjoy it, the health benefits are almost too good to pass up!

Mel Flagg COA OSC (author) from Rural Central Florida on November 03, 2012:

@phoenix, I've only had seaweed on wrapped around the vegan sushi my hubby makes, and I LOVE it! But I can see how it would be an acquired taste, kind of like iced coffee (which I much prefer over hot coffee, but I'll take a cup of Lady Grey tea over all of it!) Next time we go to the store, I'll be picking up some seaweed, because I didn't realize how healthy it was until I researched it! (Blame hubby for that one lol)

Mel Flagg COA OSC (author) from Rural Central Florida on November 03, 2012:

@Carol Thank you! I love walks on the beach, unfortunately I don't live as close as I used to, so it's not something I get to do. Arizona must be quite a change!

Pamela Oglesby from Sunny Florida on October 30, 2012:

I haven't tried seaweed but this is an interesting hub and I am open to the idea. I have heard before that it is good for you but just haven't come across it. Interesting hub.

Zulma Burgos-Dudgeon from United Kingdom on October 29, 2012:

I'm quite fond of seaweed. It is an acquired taste and I'm the only one in the family who has acquired it. I never realised it had such health benefits. I just think it's quite tasty.

carol stanley from Arizona on October 28, 2012:

When we lived in Oregon on the coast we saw seaweed on our walks on the beach. I kept promising to pick some up and use it...Now thatI am back in Arizona ..too late. Great hub with some excellent information.

Mel Flagg COA OSC (author) from Rural Central Florida on October 28, 2012:

@Janine, I KNOW!!! While I was doing the research, I too was astounded. I got the idea from some copywriting I did earlier in the week. Of course I went further in depth, and some of the chemistry behind how it works was just fascinating. Thank you for sharing!!! :D I finally got a chance to read your blog today! Granted it was only two posts, but I did it! :D I was beginning to think I might forget how to read with all the writing I've been doing lol

Mel Flagg COA OSC (author) from Rural Central Florida on October 28, 2012:

@Susan, ah you're the other great mind that thinks like mine does! lol :D Glad I'm in good company! I'll have to go check your hub out! :D

Mel Flagg COA OSC (author) from Rural Central Florida on October 28, 2012:

lol :D tee hee

Mel Flagg COA OSC (author) from Rural Central Florida on October 28, 2012:

@Cathy, I've never tried pignoli nuts! But I will next time I make pesto!! Yum!

Janine Huldie from New York, New York on October 28, 2012:

Mel, I seriously I never would have thought that seaweed had so many wonderful benefits. Not sure I could wrap my brain around ingesting it, but seriously some of the benefits you speak of are truly intriguing to say the least. Have of course voted and shared all over!!

Susan Zutautas from Ontario, Canada on October 28, 2012:

I'm the guilty one.... mine is on Kelp. Thanks Bill :)

Bill Holland from Olympia, WA on October 28, 2012:

That may be the highest form of flattery. :)

Ms. Immortal from NJ on October 28, 2012:

It's awesome! pignoli nuts.

Mel Flagg COA OSC (author) from Rural Central Florida on October 28, 2012:

@billybuc lol YAY!! :D Ok, I won't tell anyone! It is really weird though, and especially since it's the second time its happened! Yikes!

Mel Flagg COA OSC (author) from Rural Central Florida on October 28, 2012:

@Cathy Oh that sounds yummy!! I'll have to try that. What nuts do you use in your pesto? :D Now I have to check and see how much basil I have lol.

Bill Holland from Olympia, WA on October 28, 2012:

Who would have ever guessed it was possible that two about seaweed would pop up on the same weekend! I'm as surprised as you are! LOL Don't tell a soul but I liked yours better. :)

Mel Flagg COA OSC (author) from Rural Central Florida on October 28, 2012:

@Billybuc, ok who is this person that keeps writing about the same topics I do? First the chronic fatigue, now seaweed?? Ugh!! And I thought I picked truly unique topics lol

We use Nori seaweed when my hubby makes our vegan sushi. I LOVE it! It's really nor that bad. :D

Ms. Immortal from NJ on October 28, 2012:

I love seaweed. Thanks, I will check out the chocolate ball recipe, I'm very curious.

I make a basil pesto and brush it on nori sheets and dehydrate for a few hours. The results are delicious chips. There yummi.

Bill Holland from Olympia, WA on October 28, 2012:

So weird! In ten months I never read a hub on seaweed, and now two in two days. This is something I have never considered eating, but after this hub, and the one yesterday, at the very least I would consider it. Great information on the good health benefits.

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