Analysis: This tiny green plant found on ponds packs a protein punch, is nutritious, sustainable and climate-friendly
By Marcel AK Jansen and Alexandra Jansen, UCC
The consumption of sufficient amounts of protein is critical for human health. Consumption of, amongst others, meat, milk and eggs can often satisfy the human dietary protein requirement. However, consuming enough protein can be a challenge for flexitarians, vegetarians and especially vegans. Plant proteins are a good alternative to animal-derived proteins, but there is a need to identify further plant protein sources, especially ones that appeal to modern consumers by being grown locally in a sustainable manner, and that help increase choice.
For a plant to be suitable as a protein source it needs to contain a sufficiently high concentration of protein. It also needs to contain sufficiently high concentrations of essential amino acids, i.e. those amino acids that the human body can't make itself, and for which humans are dependent on their diet. Finally, a good plant protein source needs to be safe, i.e. doesn’t contain toxins, allergens or other substances that may negatively affect human consumers, and it has excellent organoleptic properties, i.e. flavour, colour, texture and smell are acceptable to human consumers.
Remarkably, the answer to the quest for a new plant protein crop for human consumption has already been around for hundreds of years in south-east Asia, and especially in Thailand. Duckweed, a small group of aquatic plants with almost worldwide distribution, has been shown to have a very high content of proteins and essential amino acids and to be suitable for human consumption.
From Futureville Ireland, Why Duckweed is a good alternative to animal protein
A native duckweed species, Wolffia globosa, is referred to in the Thai language as "Kai Pam" and is a meat-replacing ingredient in traditional recipes. Wolffia globosa looks like small (less than 1 mm diameter) green beads. Its taste has been described as a mild matcha-like flavour. In recipes it is used either fresh, like a salad, or as dried powder that is mixed into a wide variety of different products such as bread, stews, soups or burgers. Thai and Japanese entrepreneurs have selected the best duckweed lines from wild populations, and this traditional crop is now being cultivated on a massive scale to be sold as an "innovative" superfood.
The term superfood relates not just to the high protein content, but also to the high content of vitamins, minerals, polyunsaturated fatty acids and dietary fibre. Similarly to Southeast Asia, in countries such as the USA and Israel commercial, large scale, duckweed farms are now active to supply the market with plant protein for human consumption.
In Europe the situation is somewhat different. Duckweed has been used for hundreds of years in an ointment developed in the Middle Ages by St Hildegard von Bingen. She was a nun who developed the ointment as a treatment against colic, heart pain and to support the immune system. However, despite being widespread in rivers and lakes, duckweed was not a recognised product for human consumption in the European Union.
This necessitated registration of duckweed as a novel food by the European Food Safety Authority (EFSA). EFSA considered both safety and nutritional benefits of consumption of duckweed and in 2025 EFSA approved several duckweed species for human consumption in the European Union. Included in the approval are two duckweed species that are widespread in Ireland, these are Lemna minor and Lemna gibba. Thus, new exciting opportunities to develop this protein-crop in Europe have now arisen.
Developing Lemna minor or Lemna gibba as novel protein crops for Europe involves development of novel cultivation and harvesting techniques. In this regard, Ireland is at the forefront of pioneering duckweed cultivation in Europe. The Department of Agriculture, Food and Marine (DAFM)-funded "Duck-Feed" project is developing suitable aquatic growth media for duckweed cultivation, while the Circular_IMTA_DEMO project, also funded by DAFM, is trialling upscaling by cultivating duckweed on one hectare of canals in Offaly as part of the Just Transition of the region.
The cultivation of duckweed in Co. Offaly has turned out to be sustainable and climate friendly. High yields of 30 tonne dry duckweed per year have been achieved, which compares very favourably with other crops. Moreover, duckweed at the site in Offaly was fertilised using water from the cultivation of rainbow trout, using a scheme pioneered by Bord Iascaigh Mhara. The result is a very low carbon crop that is nutritious and sustainable.
Further exciting developments are taking place at University College Cork (UCC). Indoor, multilayered, stacked duckweed systems allow cultivation of many square meters of duckweed per square meter of floor space. Duckweed grows particularly fast, and the amount of duckweed can double in two days allowing for frequent supply of fresh plants for consumption. In UCC, yields of several kilograms of duckweed per square meter of floor space are achieved, even in winter, thanks to LED lighting and temperature control. Thus, one could have a vision of locally produced protein-rich fresh duckweed.
But this is not just a vision: A commercial duckweed growth system has already been successfully trialled in the International Space Station, giving astronauts access to fresh, nutritious and protein-rich food in space. Clearly, if growing fresh, nutritious duckweed in space is a possibility, then the step towards cultivation in a basement, loft, cafeteria or supermarket near you doesn’t sound too far-fetched.
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Marcel AK Jansen is a professor in Environmental Plant Physiology at University College Cork. Alexandra Jansen is outreach manager for the Duck-Feed project at University College Cork.
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The views expressed here are those of the author and do not represent or reflect the views of RTÉ
