The global population is expected to reach 9 billion by 2050, and demand for increased food production carries with it the likelihood of increased greenhouse gas emissions (World Bank, 2023). Food systems contribute a quarter of global greenhouse gas emissions each year, more than 14 gigatons CO₂e in 2025 (World Resources Institute, 2026)_. Diversifying food sources is one strategy for reducing food system emissions (World Resources Institute, 2026). Seaweed-based products are one such alternative; as a “blue food” they have the potential to generate lower emissions and environmental stressors than many terrestrially-farmed products (e.g., Gephart et al., 2021), and some species contain quantities of protein, carbohydrates, and essential amino acids that compare favorably to animal- and plant-based sources in specific respects (Garcia-Vaquero & Hayes, 2016; Cherry et al., 2019). While seaweed has been used as a dietary staple for centuries in different parts of the world (e.g., wakame, dulse, nori/gim), its use as an alternative source of protein, dietary fiber, and nutrition to conventional animal- and plant-based sources is growing (Hentati et al., 2020; Thompson, 2008).

This chapter covers the state of the science, technology, markets, and policies involved in producing seaweed-based food for human consumption. For steps in seaweed cultivation and dewatering/drying, refer to the “Cultivation and Dewatering/Drying” chapter. Seaweed typically moves from harvested biomass to a finished food product in two stages: processing and post-processing. Processing stabilizes the biomass and prepares it for safe consumption by removing impurities and improving digestibility, followed by transformation into value-added foods or ingredients. Post-processing packages the output either as a standalone seaweed food (such as nori, kombu, or seaweed “bacon”) or as an ingredient for incorporation into more processed products (such as seaweed flour, snacks, beverages).

Processing of seaweed-based foods

Processing the seaweed biomass stabilizes it, removes impurities, salts, heavy metals, and iodine; and improves digestibility (i.e., reduce polysaccharide concentration). Methods range from simple physical treatments (e.g., blanching, boiling, grinding) to more intensive chemical extractions, depending on the intended product and applicable food safety regulations.(Stévant & Rebours, 2021; Wan et al., 2019).

As appropriate, seaweed biomass is processed further to transform it into value-added products (e.g., noodles, flour) and/or mask any negative¹ sensory traits associated with flavor and texture (Gaiero et al., 2025). The extent ranges from minimal (such as nori, kombu) to rigorous transformation (e.g., seaweed “bacon”, producing a “sea-veggie burger” from Laminaria; see Figure 1).

This section presents an overview of the workstreams involved in producing a food product from fresh seaweed biomass. Food-specific species selection, cultivation, and harvesting activities are detailed here; for more general steps in seaweed cultivation and dewatering/drying, refer to the “Cultivation and Dewatering/Drying” chapter.

Species Selection

Of the over 10,000 species of seaweed, approximately 700 have been documented as edible (Pereira, 2016). Of these species, five species/genera dominate the seaweed food market, making up roughly 32 million tons of fresh weight produced in 2023 (FAO, 2024; Ozogul et al., 2024). Active R&D is underway to identify and mass-produce seaweed strains with improved nutritional composition, taste, and texture compared to conventional products (Ozogul et al., 2024). Table 1 summarizes seaweed groups in the global food market, and how they are used.

Table 1. Top cultivated seaweeds in the world, as of 2020. Adapted from Chopin and Tacon (2021) and Saraswat et al. (2026).

Cultivation and harvesting

Seaweed’s nutritional and biochemical composition varies by species, location and season. Farms  producing seaweed for food production use selective cultivation and harvesting practices to maximize quality, including rotational cultivation of different seaweed species throughout the year to maintain  consistent supply and choosing sites that limit seaweed uptake of heavy metals, iodine, and other compounds that can be toxic to humans (Ozogul et al., 2024).

Harvest timing for food is based on peak nutritional value rather than maximum biomass. For example, although Saccharina latissima and Palmaria palmata reach peak growth in summer, they are often harvested in early spring, when protein and essential amino acid concentrations are highest (Bak et al., 2018; Stedt et al., 2022). Producers may also use post-harvest treatments to increase key nutrients before sale; for instance, soaking harvested seaweed in seafood-processing wastewater (e.g., herring tub water) can increase protein and amino acid content (Stedt et al., 2022).

Processing

Seaweed-based food products require processing to stabilize biomass during transport, reduce levels of biotoxins, and improve digestibility by breaking down cell walls. Dependent on the final product, subsequent processing steps may occur to isolate and refine target compounds into ingredients (e.g., selective compound extraction; Naseem et al., 2024) or more transformed final products (e.g., seaweed flour; Afonso et al., 2019). The steps are summarized in Figure 2; innovative technologies are described in Table 2.

Stabilization

Mechanical size reduction (e.g., chopping, milling, grinding) prepares biomass for subsequent steps. Ensiling (lactic acid fermentation) and freezing research are being conducted to extend shelf life, with the added benefit of improving flavor and digestibility (Stévant & Rebours, 2021).

Biotoxin reduction

Heat treatments using water or steam (e.g., blanching, soaking) are used to reduce levels of iodine and heavy metals to within regulatory limits, and also stabilize the seaweed for further processing (Stévant & Rebours, 2021). These steps can degrade heat-sensitive nutrients like water-soluble vitamins and minerals. Novel non-thermal alternatives (e.g. pulsed electric field and high-pressure processing) and alternative solvents (ionic liquids, subcritical water) are being  studied to see if they can achieve similar safety outcomes while better preserving these compounds (Stedt et al., 2022).

Digestibility and polysaccharide extraction

Seaweed cell walls are rich in polysaccharides that reduce digestibility and limit access to proteins and other desirable compounds. Acid, alkaline, and osmotic treatments break down these walls but risk degrading product quality at high temperatures or chemical concentrations. Gentler alternatives — enzyme-assisted (EAE), ultrasound-assisted (UAE), microwave-assisted (MAE), pulsed electric field, high-pressure (HPP/PLE), and subcritical water extraction (SWE) — improve compound release more selectively while reducing heat damage and solvent use (Stedt et al., 2022; Suarez Garcia et al., 2023, Jönsson et al., 2020; Suarez Garcia et al., 2023). While these innovative methods are desirable for industry-scale use due to their specificity in targeting desirable compounds, higher yields compared to traditional methods, and lower environmental impact, each is in varying levels of technological readiness. For example, excessive temperature and microwave power for MAE can degrade heat-sensitive compounds and reduce total yield, requiring fine-scale controls (Dobrinčić et al., 2020). UAE requires specialized equipment to control ultrasound waves as well as the surface tension and viscosity of the solvent for optimal performance (Bordoloi et al., 2020). EAE will provide maximum efficiency at scale if cost-effective seaweed-specific enzymes are developed (Matos et al., 2021).

Selective compound extraction and transformation

Creating substitutes for high-carbon products like animal- and plant-based meat requires processing techniques that can isolate and purify target bioactive compounds from whole seaweed. In addition to mechanical disruption, osmotic shock, ultra-sonication, or enzymatic hydrolysis will break open cell walls/membranes to expose desirable compounds for extraction (Gaiero et al., 2025). Subsequent rounds of centrifugation will then isolate the compound from cellular debris and undissolved particles (Naseem et al., 2024). Additional processing steps, like “salting out” (ammonium sulfate precipitation) or hot/cold aqueous extraction, can be used to precipitate compounds from crude seaweed slurry (e.g., protein or agar; O’Connor et al., 2020; Naseem et al., 2024; Ozogul et al., 2024). A growing toolkit of non-thermal and “green” processing technologies is being developed to selectively access seaweed compounds desirable for food production (see Table 2) (Zollman et al., 2019; Sharma and Zalpourri, 2022; Lewandowska et al., 2023; Choulot et al., 2025).

Table 2. Emerging seaweed-based food pre-/processing techniques, claimed benefits, and technological readiness/status. Sources : Wan et al. (2019), Jönsson et al. (2020), Stévant and Rebours (2021), Suarez Garcia et al. (2023), Naseem et al. (2024), Ozogul et al. (2024)

Humans have consumed seaweeds for more than 15,000 years as a food/medicinal product (Corrigan et al., 2025). The following Technology Readiness Levels (TRLs) are used to assess the technological readiness of seaweed as a low-carbon food at commercial scale in the food industry, whether consumed whole or used to substitute for animal- and plant-based food sources.

Direct human consumption (TRL 5–9)

• Part of daily diets around the world, with varying TRL levels according to the type of food product and its production at commercial-scale

As substitute for animal- and plant-based food sources (TRL 7–9)

• Already in market as a feed additive and feed ingredient, technology for production and integration with other feedstocks are already in place

Context

Food systems contribute approximately 14 Gt CO₂e annually (roughly a quarter of global greenhouse gas emissions) with animal protein, particularly beef, accounting for a disproportionate share. Seaweed-based foods offer a substitution pathway for high-carbon protein sources, but the climate case depends precisely on what is being displaced, with it climate advantage specific to displacement of beef and other red meat.

There are few life cycle analyses (LCAs) that directly compare seaweed-based foods to animal and plant-based substitutes; we used LCAs with the same functional unit of nutrition (e.g., protein content) to compare climate impact between different animal meat substitutes. LCAs to date are incomplete in several respects (reviewed in Waqas et al., 2024). First, they do not cover the full end-to-end product lifecycle, excluding emissions generated by transporting products to consumers and re-emissions upon product end-use through consumption and biodegradation (Eikenbusch et al., 2026). Second, there are few direct assessments of seaweed as a substitute for high-carbon food sources like animal- and plant-based protein, limiting abilities to calculate mitigation potential at scale (Eikenbusch et al., 2026). Thirdly, taxonomic and geographic data gaps exist for major farmed species of seaweed (Gephart et al., 2021; Eikenbusch et al., 2026). Finally, LCAs used below are reflective of current processes and do not take into account improvements in processing conditions.

The estimates below are based on currently available LCAs.

Emissions Reduction Potential

Note: The mitigation potential estimates presented here are screening-level calculations to establish order-of-magnitude plausibility under specific adoption scenarios. Each estimate is derived by combining published or estimated values for current or forecasted seaweed-based product emissions performance in currently available LCAs (e.g., methane reduction per animal, GHG intensity relative to a displaced product) with assumptions about adoption rates and addressable market size.

Evidence Base

The key published study providing a direct protein-equivalent comparison between a seaweed product and conventional meat patties is Pandey et al. (2026), which evaluated global warming potential (GWP) per 15 g of protein across nine patty formulations. A seaweed burger patty generates approximately 0.14 kg CO₂e per 15 g protein (cradle-to-retail), against 2.14 kg CO₂e for a beef patty — a displacement factor of approximately 2.0 kg CO₂e per 15 g protein, or roughly a 93% reduction relative to beef (Figure 3). However, the same study finds that the seaweed patty’s GWP exceeds beetroot, mussels, chickpea, and chicken patties. Another study (Eikenbusch et al., 2026) showed similarly that the GWP of seaweed-based protein sources was higher than that for plant-based sources, though the magnitude varied according to species and cultivation practice (for example, Devaleraea mollis (e.g., Pacific dulse) onshore vs. Saccharina latissimi nearshore summarized in Figure 4).The climate case is therefore compelling only where beef or other high-carbon meat is the displaced product.

A broader theoretical framing from (DeAngelo et al.,2023) modeled substitution of global average food crops with seaweed, finding 1–6 tons CO₂e avoided per ton of seaweed dry weight. Applied to 2023 total production (~3.6 Mt dry weight) this yields a theoretical range of 3.6–21.6 Mt CO₂e/yr — a useful scale illustration but not a projected scenario, as it assumes substitution across all food markets.

McDonald’s, a global powerhouse in burger production, sells roughly 2.4 billion burgers a year; if beef patties were substituted with seaweed at similar scale, almost 6 million tons CO₂e could be mitigated each year and require nearly 9.5 million tons of fresh seaweed. Again, this is an indication of potential scale and not a near-term projection.

Figure 4. Global warming potential (kg CO₂ eq) per kg of seaweed and non-seaweed protein ingredients, ordered lowest to highest. Seaweed species Saccharina latissimi and Devaleraea mollis (Garibaldi and Bandon farms) are labeled green. D. mollis values are the average of a range of GWP. Source: Eikenbusch et al. (2026)

Calculation

Seaweed species used in food production are selected for nutritional composition as well as flavor, texture, and appearance, and can meet or exceed levels found in conventional products (e.g., Palmaria palmata and its essential amino acid profile compared to chicken eggs; Table 7) (World Bank, 2023). A critical performance threshold that the products must clear is digestibility, which not only differs by species used and processing methodology, but by the consumer (e.g., some individuals can digest seaweed more easily due to pre-existing intestinal bacteria; Sultana et al., 2023). Table 6 and Figure 5 summarize the nutritional benefits of incorporating seaweed into different food products, as well as their nutritional profiles compared to conventional food sources.

Table 4. Examples of seaweed-based food products and their performance compared to conventional products.

Table 5. State of the Market of global seaweed food and alternative protein market, included projected growth to 2030. Sources: Global Seaweed New and Emerging Markets Report (2023), Future Market Insights (2025), Grand View Research (2026a, 2026b)

Benefits

• Growing seaweed requires no arable land, high-carbon chemical fertilizers or freshwater resources Furthermore, it can be produced by recycling wastewater from other food production and processing workstreams (World Bank, 2023).
• Seaweed yields between five and eleven times as much tonnage per hectare as corn and soy, respectively reducing pressure on resources (Bellona Europa, 2017).
• If cultivating endemic/indigenous species, seaweed farms could provide bioremediation benefits to local ecosystems (Kim et al., 2015)

Risks

• Traditional industrial extraction of seaweed-based food products (e.g., alginates) can generate significant waste streams if irresponsibly managed (Ozogul et al., 2024)

Co-Benefits

• Seaweed proteins are rich in bioactives and contain essential amino acids, proteins, and dietary fibers that equal or surpass those found in terrestrial plant- and animal-based food sources. This potentially improves health outcomes (Wu et al., 2025; Pandey et al., 2026).
• Seaweed-based food products can contribute to the United Nations Sustainable Development Goal of Zero Hunger; they do not compete for finite land and water resources needed for terrestrial farming, addresses micronutrient and protein deficiencies for people who cannot afford healthy food (Wu et al., 2025)
• Consuming seaweed-based foods avoids the excessive antibiotic and pesticide use in animal and terrestrial plant production, respectively, and thus possible risks to human health (Yıldız et al., 2021)
• Seaweeds are suitable for limited diets (e.g., vegan, halal, kosher, etc.; Shannon & Abu-Ghannam, 2019)

Risks

• Consuming food products fed with seaweed can risk bioaccumulation of heavy metals, minerals, pigments, and marine biotoxins, which can negatively impact human health. There isn’t enough knowledge on the level to which daily intake of seaweed-based products will lead to significant bioaccumulation (Hafting et al., 2015; FAO, 2024; Stedt et al., 2022)
• Scaling seaweed-based food production will be limited by low rates of consumer uptake in markets where seaweed products are not widely consumed (Losada-Lopez et al., 2021)
• In some cases, commercialization or industrial scale seaweed farming could limit livelihood opportunities and/or compete with other uses, leading to inequitable distribution of benefits (FAO, 2024; Gonzalez and Murayama, 2024)

Community perception of using seaweed-based foods is variable. Communities in Asia (e.g., China, Japan, Indonesia, South Korea, Philippines) as well as a few isolated geographies in Europe (e.g., Ireland, France, Iceland, Wales) and the Americas (Nova Scotia, Maine, Hawaii) (Fleurence, 2016; Frazzini & Rossi, 2025; Mouritsen, 2013; G.-J. Wu & Hsiao, 2024) have used seaweed as a dietary staple for millennia. The seaweed foods market is growing in response to demand for natural products that promote human and animal health and plant-based food sources, but is constrained by limited familiarity and low prior experience (Roohinejad et al., 2017; Pandey et al., 2026). This lack of familiarity often leads to neophobia and a general aversion to novel foods. However, the disclosure of environmental and nutritional information significantly increases the willingness to try seaweed-based options. For example, when informed about its high iron content and low carbon footprint, consumer interest grows, as seaweed is viewed as a sustainable nutrient-booster in hybrid products (Pandey et al., 2026).

Global seaweed regulation is currently hindered by a “standards gap” and lack of food-grade frameworks (Cottier-Cook et al., 2023). In some countries seaweed has been integrated for centuries while it is considered “novel” in others. This leads to lack of classification and standards for food quality in some regions while others mandate rigorous time-consuming safety assessments before commercialization (Good Food Institute, 2022). Countries and regions (e.g., the European Union, Canda, Singapore) are pushing seaweed-forward policies to incentivize sustainable agriculture practices and bolster food security and economic resilience (Good Food Institute, 2022; World Bank, 2023). For example, the Codex Alimentarius Commission 37th Session of the Codex Committee on Fish and Fishery Products proposed the development of two new instruments: a Code of Practice for the Production of Seaweeds and a Group Standard for Seaweed.

Table 5. Example policies and regulations on seaweed-based food production and use.