Water Lentils (Duckweed) as EU Novel food? Failed!

On November 30, a scientific opinion titled "Safety of Lemna minor and Lemna gibba whole plant material as a Novel Food pursuant to Regulation (EU) 2015/2283" was published in the EFSA Journal, which has been widely discussed. According to recent studies, common water lentils contain a wide range of nutrients. Some species can contain up to 45% protein and they provide all the essential amino acids that meet the FAO reference standards to support human growth and development. They also contain a variety of carbohydrates, including starch, cellulose, trace hemicellulose and pectin, which provide functional properties and nutrition. In addition, they are rich in minerals, vitamins and phytochemicals, especially lutein and beta-carotene, which are positively associated with a reduced risk of many chronic diseases. They can be used in traditional cereals by partially replacing wheat flour or to extract proteins and phytochemicals as functional ingredients. In a 2017 report in Daily Mail of UK, it was noted that certain species of water lentils contain more protein than soybeans. This means that water lentils powder could even replace the whey powder made from milk and soy, offering new hope for vegetarians.

What is less well known is that there are many historical records of generations of people consuming water lentils in Myanmar, Laos and northern Thailand. It is commonly used in these countries and regions to make soup or to fry eggs. It is noteworthy that under systematic plant taxonomy, there are disparities between different species of water lentils. So what's so special about the two water lentils players, who are listed in the EFSA Journal this time?

The Latin name of the first player is Lemna minor, a member of the Lemna genus, Lemnoideae subfamily, and the Araceae family. This plant is found in paddy fields, marshes or other still waters, often mixed with Spirodela polyrrhiza and forms a dense floating community on the water surface. Due to the rapid reproduction of this species, it is usually overwhelmingly dominant in the community. Like the Chinese Ming Dynasty medical scientist Li Shizhen said, "A single leaf re-product into several ones overnight." It is widespread in warm regions of the world: it is found in Africa,, southwestern Asia, Europe, and North America. It is not only a good pig feed and duck feed, but also a bait for grass carps. People take water lentils to treat swelling (inflammation) of the upper airways, yellowed skin due to liver problems (jaundice), and arthritis.

The Latin name of the second player is Lemna gibba, which belongs to the same genus as Lemna. It is often found in a wide range of still- or slow-moving water bodies and can also grow on mud or wet rocks. This species is found not only in temperate regions of Europe but also in the UK, the Himalayas, Africa, South America, and North America. It is only absent in polar and tropical regions.

At the request of the European Commission, the EFSA Panel of Experts on Nutrition, Novel Foods, and Food Allergens has issued a professional assessment opinion on the two species as Novel Foods in accordance with Regulation (EU) 2015/2283. According to its publication, "Safety of Lemna minor and Lemna gibba whole plant material as a Novel Food pursuant to Regulation (EU) 2015/2283", both failed to pass the relevant safety review. The reasons are given as follows. The expert team concluded that there could be potential safety issues considering the manganese content of the declared variety compared to other leafy vegetables. SCF/NDA 2006 states that there may be a risk of adverse effects if manganese is taken orally in excess of normal dietary levels and that there is no evidence of any health benefit from high dose intake of manganese. Referring to the data given by the China National Center For Food Safety Risk Assessment (CFSA), the manganese content in cereals varies from 0.4-40 mg/kg and in vegetables and fruits from 0.2-10.4 mg/kg.

For manganese, the EU has not established a Tolerable Upper Intake Level (UL). The relevant EU regulatory documents explain that manganese inhalation can be neurotoxic. Oral administration of manganese has also been shown to cause neurotoxic effects, despite its low absorption rate in the gastrointestinal tract. This, coupled with the limitations of human data and the lack of NOAELs for key endpoints in animal studies, has created a considerable degree of uncertainty in the assessment results. Therefore, it is not possible to set a clear upper limit for the average daily intake of manganese. The Dietary Intake for Chinese Residents recommends a daily intake of 3.5 mg of manganese for adults, with a maximum tolerable intake of 10 mg per day, which means that a lifetime intake of 10 mg per day will not pose a health risk. According to the results of the Fourth National Nutrition Survey in 2002, the average dietary intake of manganese in China is 6.8 mg per day, which is lower than the maximum tolerable daily value.

In assessing the safety of floating water lentils, EFSA focuses on the identification and assessment of various components and potential hazard factors based on the characteristics of water lentils species. For example:

1. Sample composition and nutrient content (protein (amino acids), carbohydrates (sugars), fat, inorganic salts, vitamins, dietary fiber, oxalate (as calcium oxalate), beta-carotene, copper, iron, manganese, molybdenum, zinc, chromium, boron, ash content)
2. Nitrite and nitrite content (including dynamic changes during storage)
3. Microbial indicators (Bacillus cereus, Clostridium perfringens, coagulase-positive staphylococci, Enterobacteriaceae, mycobacteria, yeasts, Listeria monocytogenes, Salmonella, etc.)
4. Possible risks from bioconcentration (dioxins, heavy metals, cyanobacterial toxins, etc.)
5. Animal and human data (e.g., presence of allergenicity and cross-sensitivity; changes in blood levels of amino acids, glucose, and insulin during consumption. Heart rate, blood pressure, ear temperature, and presence of intestinal discomfort. In addition, blood, kidney, liver, cardiovascular, inflammation, toxicology, metabolism, iron metabolism, urine, and many other matters will be addressed.)
6. Information on recommended uses, reasonable intake, etc., given after considering all details

In this case, the EU Food Safety Authority's safety review of novel food products is very comprehensive. In the hazard identification, high manganese content was identified as a hazard factor based on the bioconcentration effect of water lentils.

ZMUni suggests that, when preparing EU novel food application materials, it is necessary to grasp the nature of the substance themselves and fully identify the hazard factors to assess their safety. In fact, this point is applicable to the EU's novel food application, especially to plants. In addition, it also has some reference significance for similar applications of a novel food or new food ingredients in other countries or regions.

References

1. EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), Turck D, Bohn T, et al. Safety of Lemna minor and Lemna gibba whole plant material as a Novel Food pursuant to Regulation (EU) 2015/2283[J]. EFSA Journal, 2022, 20(11): e07598. DOI: https://doi.org/10.2903/j.efsa.2022.7598
2. European Food Safety Authority. (2022, 30. November). Safety of Lemna minor and Lemna gibba whole plant material as a Novel Food pursuant to Regulation (EU) 2015/2283. https://www.efsa.europa.eu/en/efsajournal/pub/7598
3. Xu J, Shen Y, Zheng Y, et al. Duckweed (Lemnaceae) for potentially nutritious human food: A review[J]. Food Reviews International, 2022: 1-15.
4. Mosley, M. (2022, 1. Juli). DR MICHAEL MOSLEY: Boost your brain by drinking duckweed!Mail Online. https://www.dailymail.co.uk/health/article-10974441/DR-MICHAEL-MOSLEY-Boost-brain-drinking-duckweed.html
5. Nosowitz, D. (2021, 16. Juni). Scientists And Startups Want You To Start Eating. . .Duckweed?Modern Farmer. https://modernfarmer.com/2017/01/scientists-startups-want-start-eating-duckweed/
6. Klaus-J. Appenroth, K. Sowjanya Sree & Volker Böhm. (2017, 15. Februar). Nutritional value of duckweeds (Lemnaceae) as human food. ScienceDirect. https://www.sciencedirect.com/science/article/abs/pii/S0308814616313565
7. Hong D Y. Flora reipublicae popularis sinicae[J]. Science Press, 1983, 73(2): 1-144.
8. Mabey, R. (1996) Flora Britannica. Sinclair-Stevenson, London.
9. Clapham, A.R., Tutin, T.G. and Moore, D.M. (1987) Flora of the British Isles. 3rd Edition. Cambridge University Press, Cambridge.
10. European Food Safety Authority. (2022a, Januar 24). Guidance for establishing and applying tolerable upper intake levels for vitamins and essential minerals. https://www.efsa.europa.eu/en/efsajournal/pub/e200102
11. China National Center For Food Safety Risk Assessment. (2012, 16. März). Knowledge about manganese and health. https://www.cfsa.net.cn/Article/News.aspx?id=C3A3D689687AE8AAE134C92618FF8640948B90AAA101319E2B392ADFC8A5D500ADE75046E604CB2F
12. GR Garteich Ratgeber. (2022, 13. April). Kleine wasserlinse - lemna minor: Entengrütze, die pflanze der zukunft. Gartenteich Ratgeber. https://www.gartenteich-ratgeber.com/pflanzen/wasserpflanzen/schwimmpflanzen/kleine-wasserlinse/
13. Duckweed: Health Benefits, Side Effects, Uses, Dose & Precautions. (2021, 11. Juni). RxList. https://www.rxlist.com/duckweed/supplements.htm