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Screening seaweeds for positive health benefits

Screening seaweeds for positive health benefits

The SeaHealth Project aims to provide new insight and technical know-how for the seaweed processing sector to develop high-value functional prebiotic ingredients from raw biomass.

Teagasc’s SeaHealth project is screening seaweed extracts that have the potential to positively impact the human gut microbiome if ingested.

The gut microbiome is the community of bacteria, fungi and viruses that inhabit our gut. An imbalance in the beneficial versus harmful bacteria ratio (dysbiosis) of the gut microbiome may affect our health.

Gut bacteria influence metabolism, absorption of nutrients, our immune status and our nervous and neuroendocrine systems. The positive impacts of a healthy gut microbiome are the result of antibacterial activity of good gut bacteria such as Bifidobacteria and Lactobacilli against pathogens in the gut and the production of health-beneficial short chain fatty acids (SCFA) that signal the immune and neuroendocrine systems. This interaction has been called “the gut microbiome-immune system-brain axis”.

Bacteria require specific nutrients to grow. They consume components such as dietary fibres and polyphenols, which humans cannot digest in the stomach. Fibre is composed of complex polysaccharides that occur naturally in plants, while polyphenols are produced to protect plants from environmental stresses and herbivores. These components are considered ‘prebiotics’ due to their growth-enhancing benefits towards good health-promoting bacteria in the gut.

In the SeaHealth project, polysaccharides and polyphenols from Irish and Australian seaweeds were extracted and fed to an in vitro gut created using human intestinal bacteria. The abundance of bacteria and the amount of beneficial SCFA that the bacteria produced was assessed after 24 hours, following the addition of whole, dried seaweed, polysaccharide or polyphenol extracts.

Evaluating the potential of seaweeds

New knowledge concerning the use of seaweeds including Ecklonia radiata, Phyllospora comosa and Ulva ohnoi has been generated and disseminated to industry and the scientific community. The prebiotic potential of seaweeds and seaweed extracts was evaluated using 16s RNA gene sequencing of human stool-derived bacterial populations following in vitro fermentation and analysis of the health-beneficial SCFA produced by bacteria.

The study found that the abundance of beneficial bacteria was significantly increased by the inclusion of whole dried seaweed, polysaccharide and polyphenol extracts compared with the known prebiotics inulin and epigallocatechin gallate (EGCG – a polyphenol).

The beneficial bacteria that were enhanced included Lactobacilli, Bifidobacteria and Streptococcus, which produce lactic acid; and Eubacteriaceae, Akkermansia, Butyricicoccus, Blautia, Roseburia, Barnesiella and Faecalibacteria, which produce SCFA. Compared with the inulin and EGCG-fermented samples, the production of SCFA (particularly butyric, acetic and propionic acids) by bacteria was up to three times greater in samples fermented with whole dried seaweed, polysaccharide or polyphenol extracts.

Broad benefits to industry

Potential functional food ingredients were identified in farmed biomass and other currently underused sustainable seaweed resources to minimise any environmental impacts. This could help generate growth, access new markets and increase value-added output for the seaweed processing and ingredients sectors.

Raw, unprocessed seaweed biomass is a low-value commodity. New knowledge generated by the research project – such as optimised procedures for isolation, and the extraction and stabilisation of high-value algal polyphenolic and polysaccharide functional ingredients – will be shared. The development of new health-beneficial products could provide novel prebiotic ingredients that are nutritionally balanced and may benefit the gut.

Project outputs will provide technical know-how and understanding of consumer attitudes, supporting further use and development of functional food ingredients from raw seaweed biomass. This could potentially lead to further research in this area.

Seaweeds have unique polysaccharides and polyphenols that differ from those in terrestrial plants and are a sustainable source of potentially prebiotic compounds to ameliorate dysbiosis of the gut. Prebiotic effects found in vitro have the potential to exert similar effects in vivo if consumed as a food ingredient. Clinical trials would be required, however, to evaluate bioaccessibility, bioavailability and safety. 

Prebiotic ingredients: market drivers

There are four main factors driving accelerated growth in the global prebiotic ingredients market:

  • Increased incorporation of prebiotics into foods and beverages.
  • Consumer awareness of the importance of gut and immune health.
  •  Demand for reduction in calories, sugar and fat in foods using fibre-replacement.
  •  Growing demand for prebiotic ingredients for the dairy product industry.

$20.78 billion

Estimated value of the global prebiotic ingredients market by 2030 – based on a predicted annual growth rate of 13.25% from a 2021 value of $6.78 million. Source: Prebiotic Ingredients Market – Global Industry Analysis, Size, Share, Growth, Trends, Regional Outlook, and Forecast 2022–2030


The SeaHealth Project is funded by the Research Leaders 2025 postdoctoral programme, co-funded by Teagasc and the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 754380.


Emer Shannon, Research Leaders 2025, Marie Skłodowska-Curie Fellow, Food BioSciences Department, Teagasc Food Research Centre,
Ashtown, Dublin 15.
Michael Conlon, Principal Research Scientist, CSIRO Health and Biosecurity, Australia
Sarah Hotchkiss, Projects Manager, CyberColloids Ltd, Carrigaline, Co. Cork
Maria Hayes, Senior Research Officer, Food BioSciences Department, Teagasc Food Research Centre, Ashtown, Dublin 15.

This article was first published in TResearch Spring 2023