Cultivating seaweed provides nutritious food and feed; a sustainable alternative to plastic packaging; and a solution to reduce alarming levels of phosphate run-off all while capturing carbon. It’s time to kickstart the seaweed revolution and start growing it globally at scale, says Vincent Doumeizel, United Nations senior advisor.
The cultivated seaweed industry produces around 36 million tonnes of seaweed every year, generating eight million jobs and around $12 billion in revenue – all while producing healthy ingredients in a manner that does not require water, land, or pesticides.
This “seaweed revolution”, however, has taken place almost exclusively in just one part of the world: Asia accounts for 99% of all seaweed cultivation. In the rest of the world, we are still hunters and gatherers when it comes to the ocean, Vincent Doumeizel, senior advisor at the United Nations Global Compact, told delegates at the Fi Europe 2023 Future of Nutrition Summit.
Given the benefits that seaweed production and consumption can have on human and planetary health, however, Doumeizel is leading the charge for this revolution to spread around the world.
In addition to the hundreds of thousands of varieties of microalgae that exist, there are around 12,000 varieties of macroalgae, or seaweed. These can be classified into three types – red, brown, and green – and, unlike terrestrial plants, they are all edible.
Seaweed has huge potential as a healthy food source. Some varieties contain up to 40% protein, compared with 25% for soymeal; it has zinc and omega-3 fatty acids; and it is also the only vegetable that contains vitamin B12, important for cognitive health and brain development. According to Doumeizel, it is “the best prebiotic you can find on Earth”.
The nutritional benefits that seaweed can offer people also apply to animals. Doumeizel, author of The Seaweed Revolution, questioned the logic behind deforesting the Amazon and Cerrado in Brazil to grow soy for salmon feed when it is more sustainable, nutritious, and closer to their natural diet to feed them seaweed.
Seaweed is also a traditional food source for land animals that graze in coastal areas. Nordic seaweed brand Lofoten notes that the Norwegian names for certain seaweeds refer to the livestock that eat it: grisetang and sauetang literally mean “pig seaweed” and “sheep seaweed”.
There is a staggering amount of genetic diversity among seaweed varieties. Green algae is genetically closer to an oak tree or strawberry than it is to a red algae, while the genetic difference between a red and green algae is bigger than the genetic difference between a fungi and an elephant. This genetic diversity means there is a huge diversity in the potential functional applications that can be harnessed.
While food manufacturers will be familiar with the functionalities of carrageenan, agar agar, alginate, and other phycocolloids for food and drink applications, seaweed can also be used as a material for packaging; textiles for clothes and shoes; sanitary towels and tampons; and more, Doumeizel said.
The 2022 Earthshot prize went to Notpla, a UK startup that makes seaweed-based alternatives to plastic. Notpla is already commercialising its food-grade plastic alternative – a natural polymer that is made without chemical modifications – and examples include culinary oil pipettes, dry food sachets, seaweed-coated cardboard food containers, and edible energy gel pods.
Seaweed can also be a powerful tool to tackle climate change by reducing greenhouse gas emissions. Seaweed can sequester up to 20 times more carbon than forests, Doumeizel said, while adding 0.5% of Asparagopsis taxiformis – a species of red algae – to cow feed can reduce methane emissions by over 80% without significantly impacting meat quality or the sensory characteristics of the beef.
Growing seaweed in water absorbs excessive nutrients in water, such as phosphates and nitrogen, that are caused by fertiliser run-off. These nutrients are directly responsible for harmful algal blooms – a phenomenon known as eutrophication – that remove light and deplete oxygen levels in the water, killing off plant and animal life.
Cultivated seaweed absorb the excess nutrients from the water, thus reducing the risk of algal blooms and restoring marine life. The nutrient-rich seaweed can then be harvested and used as a soil fertiliser in a virtuous, circular cycle. Just as Asia is a global leader in seaweed production for food, some Asian countries are leaders in this respect too.
What’s more, the phosphates lost in run-off are in fact a precious, non-renewable resource that is being rapidly depleted worldwide, largely due to the global agri-food industry’s heavy dependence on phosphate-based fertilisers. This has sparked fears of a so-called “phosphogeddon”.
“The Chinese have already started their seaweed revolution,” Doumeizel said. “They have found a very good solution. They cultivate seaweed in this area full of nutrients – specific seaweed that remains on the ropes. They harvest them once a year and they put them back on land. They create a circular economy for their agriculture. They upcycle all their – we should not say waste, we should say bioresources – from the ocean to the land.
“In five years’ time, China will be neutral in phosphates when we are struggling with prices going up in North Africa – [without] talking about the ethical aspect of phosphate extraction.”
Beyond the practical benefits, there is also a symbolic importance to these solutions, Doumeizel said.
“We are talking about something that is really powerful here – reconnecting the land and the ocean,” he said. “Remember that 80% of biodiversity of life on the planet is in our ocean. Life comes from and is in our oceans, so it is important to reconnect them both.”
Image credits: © iStock/Plateresca; © Informa Markets
