Why you should eat seaweed: sustainability and health benefits

In this first post on the relationship between ethical consumerism and health I’m going to take a look at the sustainability and health benefits of… seaweed!

First I’ll cover the sustainability of seaweed and then the health benefits – and one health benefit in particular that made science headlines this month.

Seaweed sustainability and nutrition. The left image shows the red seaweed dulse growing in blue ocean water. The right image shows crispy dulse on a wooden board.
Dulse (Palmaria palmata) growing in the ocean (left) and ready to eat (right). Dulse crisps up and smells like bacon after your fry it – and can be used to make a nutritious DLT sandwich (that’s right: dulse, lettuce, and tomato).

Sustainability of seaweed

I touched upon seaweed before, in a post on potato chips and related snacks. You’re probably already aware of some of the environmental benefits of seaweed so I’ll summarize the key points. Here they are, in the form of a generalized Green Stars review for seaweed (similar to this review that I wrote on Ocean’s Halo seaweed chips):

Seaweed can heal our planet! (5/5 green stars)

  • Seaweed does not compete for land space, providing a great way to feed the population without putting stress on our forests.
  • There’s also no need for fresh water, fertilizer, or pesticides. Each of these three items is a massive burden on our planet, so seaweed, a crop that can be grown without them, should be a much larger part of our diet.
  • Seaweed removes the CO2 that has been building up in our oceans. The CO2 acidifies the water, harming fish and coral reefs. Supporting seaweed by creating consumer demand is an effective way to help reverse this acidification.
  • Acidification of the oceans is interlinked with the problem of CO2 in our atmosphere and climate change. Seaweed’s high growth rate makes it a promising option for dealing with climate change.
  • Many types of seaweed are good at removing nitrogen from water, reversing the impact of agricultural run-off (which is killing many marine zones like the Gulf of Mexico).
  • Researchers in the Netherlands have calculated that it would only take 1% of the ocean (an area equivalent to Washington State) to grow enough seaweed to supply enough protein for the entire human population.

I could go on, but I think the list above would be sufficient to convince most people of the virtues of seaweed. And that’s half the point of Green Stars reviews: sharing suggestions for sustainable living so that we can all make better choices. How about writing an ethical review about your favorite seaweed product and spreading the word on how seaweed can help the planet?  You could adapt it by adding something about the company that you buy the seaweed from. For example, This is Seaweed, uses compostable bags to package native seaweeds harvested off the Irish coast, while Ocean’s Halo donates 1% of revenue to ocean conservation work. On a related note, seaweed has become a contender to replace plastic for product packaging. So perhaps soon we’ll have sustainable seaweed that’s packaged in biodegradable bags made from seaweed!

Health benefits of seaweed

Seaweeds are generally recognized to have a host of health benefits – here’s a good review paper for reference. Green and red seaweeds can have really high protein content, for example dulse (Palmaria palmata) and nori (Porphyra tenera) have protein contents of up to 35 and 47% of dry weight, respectively – similar to that of lentils. They are low in fat, but the fat that they do contain is typically rich in omega-3 fatty acids, which are widely known to be beneficial. They are very good sources of carotenoids and other antioxidants – hence their vibrant green and red colors – and also minerals like calcium and iron. They are also very rich in polysaccharide fibers that we generally don’t digest but that can greatly improve our gut health by feeding the right kind of microbes.

Seaweed sustainability and nutritional benefits. Left Image: Nori (a type of kelp seaweed) growing on rocks on the shore. Right image: vegan sushi rolls made from nori containing bright red faux roe
Nori (laver) growing on the shoreline (left) and used to make sushi (right). The sushi contains vegan “faux-roe,” made from amaranth and beets!

Is seaweed good for your brain?

Many lines of scientific study have yielded evidence of the neuroprotective effects of seaweed, including antioxidant, anti-neuroinflammatory, cholinesterase inhibitory activity and the inhibition of neuronal death. So, besides the general health benefits, seaweed may play an important role in preventing dementia, which is on the rise worldwide.

50 million people worldwide have Alzheimer’s disease (AD) or a related dementia. The prevalence is highest in Western Europe and the US (where 10% of people over 65 have AD). The East Asian countries (Japan, Korea, and China), where seaweed is a staple food, have a significantly lower incidence of dementia (including AD) than Europe. (Yes, I know that the implied causality in that statement will infuriate most scientists! Maybe listening to KPOP prevents dementia!) But more evidence linking seaweed and prevention of AD has been brewing for a while and made scientific headlines last week.

Seaweed and Alzheimer’s disease

On November 2, Chinese regulators approved a drug to treat Alzheimer’s disease—the first new treatment to enter the global market in 17 years. The drug is a mix of polysaccharide fibers (oligomannate) derived from seaweed. The researchers (who published their results in Cell Research) presented a hypothesis that AD can be caused by a lack of harmony in our digestive tract (dysbiosis) and that these oligomannate fibers improve the quality of the microbial population in our gut.

Together, our findings highlight the role of gut dysbiosis-promoted neuroinflammation in AD progression and suggest a novel strategy for AD therapy by remodeling the gut microbiota.

The drug (GV-971) consists of fairly short chains of mannose, the sugar that some seaweed polysaccharides are made from, so it’s similar to some of the fibers that will turn up in your gut as you digest seaweed. An earlier study showed that mannobiose and mannotriose (chains of 2 and 3 mannose sugars, respectively) are about as effective as GV-971 at protecting human neuronal cells. You can get these by eating brown seaweeds – kelps, such as kombu and wakame.

Seaweed sustainability and health benefits. The left image shows kombu (a type of kelp) growing in the ocean. The right image shows a bowl of broth next to some dried kombu and shiitake mushrooms.
Kombu (a type of kelp) growing on a synthetic reef in Korea (left) and used to make a broth (right). The Kitchn suggests using shiitake mushrooms instead of bonito flakes to make an umami-rich vegetarian kombu broth.

You are a symbiotic organism

The relationship between human health and our microbial communities (mainly in our gut) is one of the most fascinating fields in science at the moment, in my nerdy opinion. Links between the microbes that inhabit our bodies and various diseases have been popping up all over the scientific/medical world these days. And, although not everybody accepts the gut dysbiosis theory for AD (the mechanism for this GV-971 drug really isn’t clear yet) there’s certainly there’s a strong connection between the gut and the brain. In fact most of your serotonin (the “happiness” neurotransmitter that’s involved in memory and learning)  resides in your gut, aka your “second brain” – the enteric nervous system.

We depend on the microbes that live inside us and these microbes depend on what we eat. And the majority of evidence points towards plant-based fibers (whether from broccoli, oats, or seaweed, etc.) being the preferred food source of our “good” microbes. An excess of sugar or meat and dairy will feed those “bad” microbes that put us out of balance, sometimes causing inflammation and stress that can lead to cancer, heart disease, obesity, and digestive disorders.

Conclusion: Seaweed is good for you and the planet

Seaweed is one of the most nutritious and sustainable foods that you can eat. The nutritional benefits of seaweed include antioxidants, omega-3 fatty acids, and fibers that can help restore your gut and your brain. I feel that it will soon emerge as a leading food for protection against Alzheimer’s disease and other forms of dementia. As far as sustainability goes, seaweed is a star crop that can heal the oceans while taking pressure off the land. Stay tuned for more posts on the link between ethical consumerism and health. If you write an ethical (green stars) review of a seaweed, please let me know!

18 thoughts on “Why you should eat seaweed: sustainability and health benefits

  1. Used to enjoy the benefits years ago (many). My daughter uses it a lot, so this is really good news. I’ll have to get back to it. Thanks again for your hard work on our behalf (and the planet’s).


    1. Thank you again, Frances! Yes, especially as we get older, we should remember to incorporate more seaweed into our diets. The stats on the prevalence of Alzheimer’s are quite shocking. Take care!


  2. Thank you for a very informative post. Seaweed has always been gathered here in Donegal, especially duse, nori and carrageen. My late father used it a lot in his garden, and I sometimes collect it after a storm. The plants love it.


    1. Hey Brigid! I just finished some seaweed that I bought on a trip to the Aran islands a couple of years ago. Delicious dulse! Its true – it’s good on gardens and was important durign the famine years. Congrats on your book bestseller tag success!


  3. I discovered that I quite like snacking on baked seaweed crisps after my dad accidentally bought a box full of them. But I don’t like that they’re individually packaged in snack portions (in both a plastic wrapper and with a plastic tub thing holding them). I’ve been looking for other brands with a compostable bag since This is Seedweed seems to be European and I was hoping to find something a bit more local. :/ Hopefully I’ll find something!


    1. Hey Shauna. Totally agree – those little seaweed snacks are delicious but one of the most over-packaged things on the planet! I think it’s a marketing thing. I’ll keep an eye out for good solutions – in the meantime, one option is to buy large packs of big nori sheets, which has a lot less packaging per unit of seaweed. You can season and divide up into your own containers.


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