Will seaweed become a staple in our menus? Although its nutritional attributes are well recognised, its potential health benefits require further study, and consumer acceptance remains uncertain. Experts addressed these questions at the French Nutrition Days, 2025 in Lyon, France, examining the production, regulation, nutritional value, and acceptance among consumers.

Florence Dufreneix, MSc, project manager at the CEVA, a technology and innovation centre dedicated to algae, marine plants, and marine biotechnology in Pleubian; Annaïg Lan, PhD, associate professor at Paris Institute of Technology for Life, Food and Environmental Sciences in Palaiseau; and Maxime Michaud, PhD, socio-anthropologist at the Institut Lyfe Research and Innovation Center in Écully, France, outlined the current evidence and limitations of seaweed for clinicians and nutrition specialists.

Limited Production

“There is great diversity among seaweeds, including microalgae and macroalgae, and green, red, or brown species,” said Dufreneix. She is the coordinator of the multidisciplinary ALGOMENU project, funded by the French National Research Agency, which aims to study French microalgae and assess their potential health effects.

In parallel, the ANR France 2030 PROMALG-Health project focuses on algae digestibility in the context of healthy and sustainable hospital nutrition.

Globally, approximately 220 seaweed species are cultivated, with six genera accounting for 95% of the consumption. Approximately 37 million tons of macroalgae, mainly red and brown species, are produced annually. “Compared with staple crops such as maize or wheat, volumes remain modest but have increased by about 10% per year in recent years,” Dufreneix said.

Production is largely concentrated in Asia. European output totals roughly 300,000 tons, or about 1% of global production, representing €350 million in 2018.

“France accounts for 19% of European production, ranking second after Norway. Almost all production involves harvesting wild seaweed, mainly in Brittany, with limited cultivation of seaweed. It is a developing sector, roughly comparable at present to shallot production in France,” Dufreneix said.

Microalgae cultivation consists mainly of spirulina, accounting for approximately 75% of the volume, followed by Chlorella and Haematococcus pluvialis, which are used in infant formulas for their docosahexaenoic acid content. In France, harvested macroalgae are mainly kelps used for alginate extraction in the food industry, alongside edible species such as royal kombu, alaria, wakame, sea spaghetti, nori, dulse, and sea lettuce.

Regulatory Framework

“Seaweeds are primarily used as texturising agents, with approximately 30% for human consumption and 10% for other purposes. Regulatory requirements vary by market,” she stated.

The European Union Novel Food Regulation applies to foods with negligible consumption before 15 May 1997. Other regulations have set maximum levels for contaminants, such as nickel, pesticides, and cadmium, in seaweed-based supplements.

“At present, no harmonized European limits exist for heavy metals in seaweed, although discussions are ongoing, with conclusions expected in 2026” she added. In 2024, 62 seaweed species and six seaweed extracts were authorised as Novel Foods.

Specific regulations have been implemented in France. These recommendations were based on the recommendations of the French High Council for Public Health and the French Agency for Food, Environmental and Occupational Health and Safety (ANSES).

The regulations set maximum limits, expressed in mg per kg of dry weight, for selected contaminants. These include heavy metals such as inorganic arsenic, lead, cadmium, mercury, and tin, as well as other elements such as iodine. A regulatory summary is available on the CEVA website.

Overall, except for cadmium, heavy metal levels in seaweed are generally below the regulatory thresholds.

In a 2020 opinion, ANSES recommended ensuring cadmium concentrations as low as possible, proposing a maximum of 0.35 mg/kg of dry matter to ensure that most consumers remain below the tolerable daily intake.

CEVA responded to the proposed lower limit by cautioning that “such a threshold would effectively prohibit the consumption of certain seaweeds that have been traditionally consumed in Asia for centuries and whose nutritional benefits are widely recognized.”

CEVA also noted that seaweed is only one of the many contributors to dietary exposure to heavy metals.

Nutritional Density

Lan detailed the nutritional profile of seaweed. “Seaweeds are used in salads, snacks, flavour enhancers, and as alternatives to meat products, including in high-end restaurants. Despite nearly 10,000 known species, only a small fraction is authorised for consumption in France.

Seaweeds contribute to flavour, texture, and gelling properties and may function as salt substitutes because they contain more potassium than sodium. They are rich in nutrition, provide fibre and protein, and represent a non-fish-based source of long-chain omega-3 fatty acids, such as eicosapentaenoic acid and docosahexaenoic acid. The composition varies widely depending on the species, growing conditions, and season.

“Seaweeds contain a wide variety of polysaccharides, both sulphated and non-sulphated, and rare sugars such as fucose and rhamnose, and show potential prebiotic activity, although human data remain limited. Its mineral content ranges from 11% to 45%, and it contains vitamins A, K1, B9, and possibly B12. The iodine content is particularly high, which may help address iodine deficiency linked to reduced dairy intake and increased plant-based alternatives in Europe. The recommended intake is 150 µg/d, and intake levels among many individuals often fall below this threshold,” she said.

She noted that the protein content is highest in red seaweeds, with amino acid profiles comparable with those of animal sources, including lysine and methionine. Digestibility can be reduced in certain brown seaweeds because their polyphenol content inhibits digestive enzymes such as trypsin and pepsin. Seaweeds are also rich in phytochemicals such as phlorotannins, bromophenols, and terpenoids.

“They have potential antioxidant, antimicrobial, and anti-inflammatory effects. However, the supporting evidence comes mainly from extracts that are not purified, largely from cell models with few animal studies, and at pharmacological doses that are not compatible with whole-plant supplementation,” emphasised Lan.

In humans, epidemiologic data suggest an inverse association between regular seaweed consumption and the risk for certain metabolic disorders. A Korean study reported a reduced risk of developing type 2 diabetes among normal-weight adults who consumed seaweed regularly. Similarly, higher seaweed and iodine intakes were associated with a significantly lower incidence of metabolic syndrome, as reflected by improvements in blood glucose, blood pressure, and lipid profiles in a cohort of postmenopausal Korean women (n = 2588).

However, evidence from interventional studies is limited. A small number of trials, conducted primarily in Asia and involving small cohorts, suggest modest but favourable effects of seaweed on glucose and lipid metabolism.

“Algae are nutritionally dense and could be of interest as new food sources, but further studies are needed to clearly demonstrate their nutritional and health effects,” summarised Lan.

Niche Consumption

Consumer acceptance remains a major barrier to the broader dietary uptake of insects. Michaud presented the findings of an ongoing study funded by the ALGOMENU project.

“A product is only appealing if its acceptability among the population can be demonstrated. Seaweed remains a niche product. In France, consumption is largely driven by perceived health benefits and interest in locally sourced foods. While seaweed has an original and sometimes exotic appeal, this characteristic alone does not appear sufficient to sustain long-term consumption,” Michaud said.

Consumption in France mainly relies on Asian and Japanese seaweed varieties. Products such as seaweed tartare and seaweed-based condiments are becoming increasingly available. “When the project began, there was almost nothing on store shelves. Now, entire aisles are dedicated to these products,” Michaud noted.

Discovery Walks

Several initiatives have aimed to promote seaweed consumption, including foreshore discovery walks and cooking workshops for seaweed. These activities are the focus of doctoral research by Calixte Engelberg, whose qualitative fieldwork examines seaweed harvesting practices along the Brittany coastline in France between 2023 and 2025, based on unpublished data from the research.

“To fully benefit from these experiences, participants must understand the legal framework, which is very restrictive,” Michaud explained. Private harvesting is limited to small quantities, whereas professional harvesting requires prior authorisation. Harvesting locations depend on species, and timing is constrained by tidal cycles. “As with mushrooms, knowing where and when to harvest is essential,” he said.

Cooking Barriers

According to Michaud, “These guided outings encourage culinary curiosity and are often perceived as a form of local tourism. Participants take notes, seek information, and express interest in unfamiliar flavours and products. However, this enthusiasm does not consistently translate into the home consumption of seaweed. Preserving fresh seaweed remains challenging despite demonstrations and strong initial motivation to do so.

Follow-up interviews were often unsuccessful. “Many participants did not respond because they had not eaten the seaweed they harvested and felt uncomfortable about it,” Michaud said. When responses were obtained, participants commonly cited a reluctance to cook fresh seaweed because of limited culinary knowledge and hesitation to introduce it to others because of its distinctive taste.

Role of Influencers

In contrast, regular consumers emphasised the health benefits and the local, diverse, and flavourful nature of seaweed. “Exposure to seaweed in its natural environment appears to generate interest and positive perceptions. Knowledge of its nutritional qualities, combined with an interest in healthy and varied diets, supports its integration into dietary habits. However, storage constraints and culinary complexity remain major barriers to repeated use at home, concluded Michaud.

Future research should include interviews with regular consumers, observations in retail settings, and discussions with restaurateurs, with particular attention paid to the role of influencers in promoting seaweed consumption.

This story was translated from Medscape’s French edition.