Seaweed’s Place in our Sustainability & Nutritional Toolkit

Words by Raoul Rechnitz. ANutr.

We are naturally looking to the sea as we realise that land-based agriculture and the monoculture practices that go along with it are steadily impacting our planet, and with it our health. We are only now beginning to think about the effects that this monoculture is having on our bodies. Coupled with this is an understanding that global warming is making it harder for land agriculture to be a tenable solution for our future needs. 

Looking to the sea, several solutions present themselves. The ocean makes up around 70% of the surface of our planet, and up to the present day, so many of the agri- or aqua-cultural practices we associate with it are inherently unsustainable and damaging to the variety of ecosystems within. From deep sea trawling to overfishing whole species to near extinction, using fish as a food source is fraught with dire consequences, many of them to do with human greed, coupled with the burgeoning global population.

Perhaps the most comprehensive solution for our own health, and sustainable for the health of the planet seems to be seaweed. A group of aquatic plants called algae which can photosynthesise and are some of the most effective carbon-sequestering organisms on Earth. The beauty of algae is its rate of growth, with reports from 3cm - 60cm a day, depending on how reputable your source [1] [2] and the fact that it is already a food source for native fish, reduces the negative impact of its cultivation. 

A major motivator for people in eating fish, especially oily ones like salmon and mackerel, is their omega-3 content. This family of essential polyunsaturated fatty acids contributes to the lowering of inflammatory biomarkers and proper functioning of the cardiovascular system [3]. Products such as cod liver oil, often taken as supplements, have been included in people’s daily routines for decades, often purported to help with joint care and general wellbeing. However, it is important to note that the Omega-3 content of these fish oils is not synthesised by the fish, rather it is absorbed from the algae that they ingest. Studies are showing that when comparing effects on cardiovascular health in particular, algal-sourced Omega-3 is similar in efficacy to fish oils [4]. In a world pushing for plant-based solutions, this is a simple sell.

Seaweed is used as a food source in remarkably few countries and cultures. Japan is one of the biggest consumers of seaweed in the world (one fifth of meals in Japan contain seaweed), and while there is a huge appetite for it there, when it comes to some European countries, there is some work to be done to fully establish it as a foodstuff [5]. Some species of algae sit somewhere near egg in terms of their amino acid profile, and can exhibit up to 47% protein per unit mass [6]. The protein profile of any candidate for our global larder is essential information. However, while seaweed’s low fat content and low calorific status are seemingly important to the ‘health-conscious’ in the UK, USA and parts of Europe, the opposite is true when looking at feeding a burgeoning population at home and elsewhere.

The world is looking for new and sustainable protein sources - with ingredients like soy that rushed to fill the void that spiralling meat consumption left no longer proving as low impact as they once seemed [7]. Exciting prospects like insects and lab-grown meat are possible solutions to this protein defecit, but perhaps we are getting caught in the same behaviour that landed us where we are currently, and drastically different solutions are the way forward. Conceptually, cultivation of seaweed can be done while focusing regenerating broken ecosystems in our oceans, but does this actually match up to the reality of how intensively we may have to farm seaweed for it to be a viable alternative for the future?

Farming seaweed generally involves placing of lines in the ocean and the growing of algae vertically towards the seabed. The overall implications of this are that we are not using precious space on land and due to the way that seaweed grows, nothing more needs to be added, so harmful fertiliser-intensive farming practices are not necessary. Carbon-sequestration is a huge benefit to this crop, but we have to be careful that placing of lines, the density of farming, and the harvest methods cause minimal disturbance to oceanic habitats.

While also invaluable from a human nutrition perspective, which will be explored greatly in subsequent features here, an incredibly exciting application of algae is its use as an animal feed. One of the biggest impacts of cattle cultivation for meat and dairy purposes, is the methane that the animals produce, contributing greatly to greenhouse gas emissions. Several studies in the past decade have shown a direct effect of feeding certain algal species to cattle on their methane yield, with reductions of up to 80% not uncommon [8].

So is seaweed our new saviour? It’s important to steer clear of sensationalising any change in the status quo, but so far, it seems that the benefits outweigh the negatives with seaweed. From a nutritional standpoint, the micronutrient profile of certain seaweeds, from DHA and EPA - those beneficial Omega-3 PUFAs discussed earlier - to a wide range of minerals that we will discuss in features to come, algae are proving extremely interesting as a food source, but potentially more as an additive than the main event as it stands.

Sources:

[1] - Cribb AB (1954) Macrocystis pyrifera (L.) Ag. in Tasmanian Waters. Marine and Freshwater Research 5, 1-34

[2] - https://www.guinnessworldrecords.com/world-records/503984-largest-alga

[3] - Gammone MA, Riccioni G, Parrinello G, D'Orazio N. Omega-3 Polyunsaturated Fatty Acids: Benefits and Endpoints in Sport. Nutrients. 2018 Dec 27;11(1):46

[4] - Doughman SD, Krupanidhi S, Sanjeevi CB. Omega-3 fatty acids for nutrition and medicine: considering microalgae oil as a vegetarian source of EPA and DHA. Curr Diabetes Rev. 2007 Aug;3(3):198-203.

[5] - Cherry P, O'Hara C, Magee PJ, McSorley EM, Allsopp PJ. Risks and benefits of consuming edible seaweeds. Nutr Rev. 2019 May 1;77(5):307-329

[6] - Černá M. Seaweed proteins and amino acids as nutraceuticals. Adv Food Nutr Res. 2011;64:297-312.

[7] - da Silva RFB, Viña A, Moran EF, Dou Y, Batistella M, Liu J. Socioeconomic and environmental effects of soybean production in metacoupled systems. Sci Rep. 2021 Sep 20;11(1):18662.

[8] - Roque BM, Venegas M, Kinley RD, de Nys R, Duarte TL, Yang X, Kebreab E. Red seaweed (Asparagopsis taxiformis) supplementation reduces enteric methane by over 80 percent in beef steers. PLoS One. 2021 Mar 17;16(3):e0247820.