water lentils
Sarah Biren
Sarah Biren
January 1, 2024 ·  5 min read

Water Lentils: These Tiny Specks Are The New Superfood

You may have heard about water lentils, also known as rootless duckweed, water lenses, watermeal, Mankai, and lemnoidea. If not, here’s everything you need to know about this up-and-coming superfood. Water lentils are quick-growing aquatic plants that float on water’s surface. They are one of the smallest plants in the world, and one of the fastest to spawn. They appear worldwide in canals, ponds, and lakes, and they also appear in historical cuisines and medicines. Today, they’re become known as a nutritious food for people and animals.

What are Water Lentils?

Water lentils are already being grown and harvested in farms in the U.S., but they’ve been eaten in Thailand and other Asian countries for a long time now. Compared to crops like soy, spinach, or kale, water lentils require considerably less water to grow. Therefore, they’re highly environmentally sustainable and has another important factor when it comes to sustainable farming: They can be grown all year round with hydroponic cultivation. Remember, they are easy to cultivate and grow rapidly, making them a viable and economical source of feed for livestock. It’s also a food that can greatly benefit those on plant-based diets. [1]

Nutrition-wise, it’s easy to see why. Initial research found that water lentils contain complete protein, bioavailable iron, and vitamin B12, which rarely appears in plants. In fact, it contains 5 grams of protein, 4 grams of fiber, 15% of the recommended daily intake of vitamin B12, plus other nutrients like choline and omega-3 fatty acids. But more notably, it contains an impressive 45% of the recommended daily intake for iron.

Complete protein is hard to find in plants. To be considered a complete protein, the food must contain nine essential amino acids the body doesn’t make alone. Animal-based proteins like eggs, dairy, and meat are complete proteins, but plants often lack all nine essential amino acids. This is why it’s important to consume a variety of plant-based protein sources. Soy is one of the few plant-based complete proteins, so tofu and its other byproducts are commonly consumed by vegetarians and vegans. But even soy, while a complete protein, is low in the essential amino acid methionine. Now, water lentils can join its rank since it contains as much complete protein as an egg. 

More Health Benefits

Additionally, vitamin B12 and iron are two other nutrients that are hard to come by in plant-based diets, making water lentils even more inviting. The iron found in plants is often poorly absorbed by the body unlike the iron from animal-based foods. But the iron in water lentils are highly bioavailable, making it an even more valuable resource for vegans, vegetarians, and those with low iron who can’t take iron supplements. 

Similarly, vitamin B12 is also found primarily in animal products, so those who abstain from those foods are at risk of a deficiency. Currently, vegan sources of vitamin B12 come in the form of supplements, fortified foods, and certain fermented foods and mushrooms. Fortunately, it seems that the B12 in water lentils is also bioavailable. [2] However, further evidence is needed to show that water lentils can indeed improve B12 status in humans. [3]

Aside from being a potentially good resource for those with plant-based diets, water lentils may provide unique benefits for everyone. Currently, researchers are investigating its effects on common issues, like obesity and metabolic disorders, with potentially promising results. A 2019 study from the Ben-Gurion University of the Negev tested the effects of water lentils compared to a yogurt shake with the same amount of calories, protein, carbohydrates, and fats. After two weeks, the participants who took the water lentils had better glucose levels and reported feeling more full than those who took yogurt shakes.

Another study found in the Journal of Nutrition found that incorporating water lentils into a Mediterranean diet can increase the consumption of iron and folic acid, even though the diet involves little red meat. Furthermore, the study showed that this iron content treated iron deficiency in anemic rats and the regular treatment. [4]

Recipe Ideas and a Word of Caution

Traditionally, water lentils are eaten in salads, omelets, or curries. They are also available as Mankai powders and frozen cubes to add to smoothies, soups, and the like. The taste is neutral, vaguely like spinach, so it’s an easy addition to many foods you don’t mind turning green, from pancakes to casseroles. 

Remember, the research behind water lentils is still in its early stages. Although some people claim to use it to treat medical conditions like rheumatoid arthritis, gout, lung infections, and more, there is little to no scientific evidence to back these claims. Aside from the benefits of any nutritious food, research has yet to determine if water lentils have medicinal uses. So as of now, monitor the effects after consuming Mankai in case of an adverse reaction, especially if on medications, since studies have yet to determine if the food interacts with anything. 

Additionally, there is not enough information concerning consuming water lentils while pregnant or breastfeeding, so experts advise staying on the safe side and avoiding it under those circumstances. It’s always best to consult a doctor before trying new products and follow the directions on the product label. [5]


  1. “Water lentils (duckweed) in Jordan irrigation ponds as a natural water bioremediation agent and protein source for broilers.Ecological Engineering. Maisa’a W. Shammout, Hana Zakaria. October 2015
  2. “What Is Mankai? Your Guide To The New Supergreen.” Forbes Health. Taylor Wallace, Sarah Davis. June 16, 2022
  3. “Is Duckweed a reliable source of vitamin B12?” Vrg.org. January 28, 2020.
  4. “Mankai duckweed plant found to offer health benefits.Science Daily. ] American Associates, Ben-Gurion University of the Negev. August 5, 2019
  5. “Duckweed – Uses, Side Effects, and More.WebMD

    Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.