The European Food Safety Authority (EFSA) has officially approved water lentils, also known as duckweed, for production and consumption as fresh vegetables in the EU. The approval is the result of nearly ten years of research by Wageningen University & Research (WUR). To demonstrate the safety, health aspects, and sustainability of water lentils for consumers, a so-called Novel Food dossier was built and submitted.
To reduce pressure on land use and the impact on climate change, we need to move to a more plant-based diet. According to research associate Ingrid van der Meer - initiator and driving force behind the study - water lentils can play an important role in this protein transition. “Water lentils are high in vitamins and minerals and have a high protein content at dry weight. In addition, their exponential growth means they produce very high yields per hectare, so cultivation requires relatively little space. Especially if you grow them in stacked layers. And because they grow in a closed environment on a layer of water, no agricultural land is needed.”

Strict EU Regulations
The only problem: until now, water lentils had not been authorised for human consumption in the EU. Van der Meer: “EU legislation defines food products and crops that were not being consumed to a significant degree in Europe before 1997 as Novel Food. To grow and sell such a crop, you need to meet strict requirements. In other parts of the world, like Asia, water lentils are already eaten on a much wider scale. But that is not a criterion for the EFSA. Despite being mentioned in a Dutch herb book from 1644, water lentils have never found their way to the general public here."

Creating Novel Food dossier
With the protein transition in mind, Van der Meer hoped to promote them by applying for EFSA approval. For this purpose, she and her research team at Wageningen Plant Research, together with colleagues from Wageningen Food & Biobased Research, compiled a Novel Food dossier. “Some of the things we needed to demonstrate was that water lentils can be grown in a clean and sustainable way and that they are healthy and safe for consumption. We did this by cultivating them in a grower's greenhouse. This material was then subjected to numerous analyses, such as protein and starch content, the amount of minerals and metals and the presence of possible pathogens, pesticides and toxic substances. And lots more.”

Effects on human body
To visualise the effect on humans and digestion, the researchers conducted intervention studies with volunteers. Van der Meer: “In an initial study, subjects were asked to eat a large amount of water lentils. We then studied whether the proteins were properly digested and absorbed and what the health effects were. In a second study, subjects were asked to eat a dish containing water lentils, such as soup and quiche for a fortnight. They were served the same dish with spinach. We monitored the effects using questionnaires, blood tests and other health tests. Both studies showed that the proteins were well digested and absorbed by the body and that there were no adverse health effects, such as allergic reactions, constipation or increased blood pressure.”

Tasty and healthy
In the experiment, volunteers were also asked how they perceived dishes with water lentils, says Van der Meer. “We noticed that they found it slightly strange at first, possibly because of the association with duckweed. However, once they got used to the idea, they almost unanimously said they enjoyed the dishes, at least as much as those with spinach. Incidentally, we did not include this assessment in the dossier because taste is not a criterion for EFSA. But health is. What makes water lentils extra special compared to other vegetables is that they score high on all the essential amino acids. This also meets the recommended levels set by the WHO for a six-month-old baby."

EFSA approval finally obtained
Despite all the efforts and evidence, EFSA was not convinced of everything, says Van der Meer. “Two years after submission and additional questions from EFSA, the scientific committee said that the manganese content was still too high. After modifications to the cultivation systems, we succeeded in reducing the level of this mineral to below 6 milligrams per kilogram, which was the (arbitrary) level set by the EFSA. Two years later, they were convinced by this. Last July, we received confirmation that water lentils are considered safe, provided everything meets all the levels and specifications that we demonstrated. After nearly a decade of work, that was a huge relief. With Ursula von der Leyen, as President of the European Commission, having given her signature, water lentils have finally been included in EU legislation, paving the way for large-scale production and consumption. I’m really happy about that.”

Who will try them?
Whilst compiling the Novel Food dossier, Van der Meer also worked on projects to inform companies and consumers and make them enthusiastic about water lentils. “Because that’s our ultimate aim.” If the industry and consumers don't try them, everything will have been for nothing. Fortunately, there’s a lot of enthusiasm, but also caution. Growers, producers and supermarkets are waiting to see who will take the first step. It needs to be a chain effort. One way to introduce consumers to water lentils is through restaurants. We have now found a number of chefs experimenting with dishes in restaurants and through workshops.”

In the supermarket in three years’ time
Meanwhile, WR's researchers are also working with partners to further develop the product itself. Van der Meer: “Among other things, we are looking at how to package and preserve water lentils. One option is to process them as frozen cubes, but you can also bag them as fresh produce. They keep a lot longer in a bag than freshly chopped lettuce, for example. You can also incorporate water lentils in other products, such as pesto, ravioli and pakora. So there are plenty of possibilities. Now, it’s mainly a matter of getting them accepted by the food industry, but I am hopeful that things will work out. It would be amazing if water lentils were on supermarket shelves in about three years’ time.”