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Health help from kelp

TResearch Autumn

Leathrach is a very common kelp found in low-level waters around the Irish, North European and eastern North American coast

A common native Irish kelp species could offer a promising preventative remedy for high blood pressure.

Health issues that can lead to heart disease, such as diabetes, inflammation and high blood pressure (hypertension) are a growing global concern. Data collected over the past 20 years found the number of adults with hypertension had doubled to approximately 26% of the global adult population in 2019. This number is set to rise to 29% of the global population by 2025, which will affect 1.56 billion people.

Seaweed is considered a potential resource of bioactive compounds that may be used to treat such ailments. It has a long history of use as both food and medicine, especially in Asian cultures. In recent times, there has been a growing interest across the world in the use of seaweed ingredients and bioactive compounds in pharmaceutical and nutraceutical products.

Through their ALGIPRO project, researchers from Teagasc and the Cawthron Institute, New Zealand, have been exploring the bioactive compounds of kelp – the common name for one order of brown seaweeds known as Laminariales – and their ability to treat health conditions.

Using a native Irish resource to improve health

One particular ailment that seaweed bioactive compounds may impact is hypertension caused by the enzyme Angiotensin Converting Enzyme 1 (ACE-1), which causes the narrowing of blood vessels.

Hypertension is usually treated using drugs, but there are side effects associated with them. This has prompted the pursuit of natural remedies that may prevent the development of high blood pressure – and kelp is a known source of several bioactives with potential suitability.

Diane Purcell-Meyerink, Marie Skłodowska-Curie Fellow at Teagasc and ALGIPRO project member, says: “We have explored the generation of bioactive peptides containing hydrolysates (a protein product consisting of small proteins and peptides made using enzymes), which may exert a positive effect in humans due to their health-promoting properties.

“We chose to focus our investigation on the potential of the native Irish kelp species Laminaria digitata, called ‘oarweed’ in English, or in Irish ‘Leathrach’ or ‘Coirrleach’.”

Leathrach is a common kelp found in low-level waters around the Irish, North European and eastern North American coast and can grow up to 2.5 metres long and 60 centimetres wide. Surveys of the Irish coast have found Leathrach around the entire Irish coastline, with 56% of the coast from Donegal to Cork having some level of kelp coverage.

“Despite its accessibility,” Diane adds, “it is a relatively untapped kelp species.”

TResearch Autumn

Leathrach in different forms, from raw seaweed to final protein powder

The creation of a promising product

To isolate the proteins from Leathrach, the researchers broke down the cell wall using enzymes. Hydrolysis and filtration treatments resulted in a protein powder, and the protein content of this powder was found to be 24%. In comparison, the whole raw seaweed was found to have 15% protein.

Protein hydrolysates within the kelp where then tested for bioactivities, specifically their ability to inhibit ACE-1.

“When compared to a popular commercial ACE-1 inhibitory drug, ACE-1 was inhibited by 75% by the protein hydrolysate,” says Diane. “In addition, the total amino acid content of the hydrolysate was 32% essential amino acids – an excellent profile. This is significant as essential amino acids can act as important dietary supplements.”

Thanks to the researchers’ study, a seaweed protein powder with ACE‐1 inhibitory bioactivities has been extracted from Leathrach. This powder has potential applications as a protein source for functional food use, and further work will be done to assess its antihypertensive activity. If suitable, it could be a key product in helping to control blood pressure. 



4-5 meters

The maximum length for Irish kelp species is 4-5 meters.


1.28 billion

people are estimated to have had hypertension in 2019.



We acknowledge Karen Hussey (Teagasc) for her assistance in the sample analysis for this project.


Diane Purcell-Meyerink has received funding from the Research Leaders 2025 programme (co-funded by Teagasc and the European Union’s Horizon 2020 research and innovation programme), under the Marie Skłodowska-Curie grant agreement number 754380.



Diane Purcell-Meyerink

Research Leaders 2025 and Marie
Skłodowska-Curie Fellow

Teagasc Food Research Centre,
Ashtown, Co. Dublin.



Maria Hayes

Senior Research Officer

Teagasc Food Research Centre,
Ashtown, Co. Dublin.


Mike Packer

Senior Research Scientist

Algal Biotechnology Group

Cawthron Institute, New Zealand.