Whether brown, green or red, lentil beans are a nutritious source of plant-based protein. While they don't provide as much protein as meat, fish, poultry and dairy, they offer fiber and phytonutrients you can't get from animal foods. Try them in soups, stews, curries and even cold atop a salad.
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One-half cup of boiled lentils provides 9 grams of protein.
Plant Protein in Lentils
A part of the legume vegetable family, including lentils, beans and peas, lentils are a low-calorie source of plant-based protein. One serving is typically one-half cup cooked, which contains 9 grams of protein, according to the USDA. According to a review published in the journal Nutrients in November 2015, lentils have a protein concentration of 20 to 29 percent.
Lentils' protein is considered "incomplete," and the protein they provide is often said to have a low biological value. In comparison, animal proteins are "complete," and have a high biological value.
Most plant proteins are considered incomplete and of low biological value simply because they are low in or missing one of the essential amino acids. Amino acids are the building blocks of protein that your body needs to maintain and build tissues, such as muscle and bone. Proteins play many other roles, too, as antibodies, enzymes and messengers, according to the National Institutes of Health. The body can't make the essential amino acids, so you must get them from food.
According to USDA data, the limiting amino acid in lentils is methionine. Aside from that, lentils are a good source of the other eight amino acids. The labels "incomplete" and "low biological value" are misleading; plant proteins are just as useful as animal proteins when you eat a variety of them in a balanced diet. All you need to do is eat other sources of methionine in your daily diet. Your body will take from each food what it needs to make proteins.
Foods that provide high levels of methionine include Brazil nuts, eggs, cheese, meat, soybeans and other beans, fish and shellfish and poultry.
Read more: The 14 Best Foods for Your Heart
Getting the Protein You Need
According to the National Academies of Medicine, women need 46 grams of protein a day and men need 56 grams a day. One serving of lentils provides 16 percent of a man's protein needs and 20 percent of a woman's daily needs. Or you can estimate your average protein needs using the formula .8 grams of protein per kilogram of body weight. For example, if you weigh 180 pounds, you need 65 grams of protein.
Even if your protein needs are higher, lentils can still make a valuable contribution to your daily intake. For example, eating more protein may aid weight loss, because it has a higher satiety value than carbs or fats, according to a review in Nutrition & Metabolism in November 2014. In a study published in Obesity Facts in June 2017, participants who ate a high-protein diet providing 1.34 grams of protein per kilogram of body weight lost significantly more weight than those who ate the standard protein diet providing .8 grams of protein per kilogram.
If you consume this higher protein quota, you'll need about 91 grams of protein a day if you weigh 150 pounds. In that case, a serving of lentils will provide about 10 percent of your protein needs.
Additional Lentils Benefits
The benefits of lentils nutrition don't stop at their protein content. In fact, if you're trying to manage your weight, you'll definitely want to eat more lentils as a protein source. Not only are lentils' calories low, with just 115 per serving, but they are also a rich source of dietary fiber. One serving provides almost 8 grams of fiber, which is 21 percent of the recommended daily intake (RDI) for men and 32 percent of the RDI for women.
Like protein, fiber has been shown to have similar effects on satiety, according to an article in the Journal of Nutrition and Metabolism in January 2019. Fiber swells in the stomach and slows gastric emptying, both of which help delay the release of the hormone ghrelin. Ghrelin is responsible for sending hunger signals to the brain, which tells you it's time to eat again. Suppressing the release of these hormones can make it easier to control your calorie intake.
Even if weight loss isn't your goal, you'll still be rewarded by including more lentils nutrition in your diet. With 3.3 milligrams of iron, according to the USDA, one serving of lentils provides 41 percent of the RDI for men and 18 percent of the RDI for women. Iron is responsible for the creation of healthy red blood cells that carry oxygen to the body's tissues.
Lentils are also rich in the mineral zinc, providing 16 percent of the RDI for women and 11 percent for men. Zinc plays important roles in immune function, protein and DNA synthesis, and wound healing. One serving of lentils contains 25 percent of the RDI for men and women for the mineral phosphorus, which is involved in bone mineralization, energy production and cell signaling.
Lentils are a better source of minerals than they are of vitamins, but you'll get a whopping 45 percent of your daily needs for folate from just one half cup serving, the USDA reports. Folate is critical for cell division and the creation of DNA and other genetic material. Because of this, pregnant women have increased folate needs — 600 micrograms — but one serving will still provide more than a quarter of the RDI.
Load Up on Lentils Nutrition
Although you may have eaten lentils only in lentil soup or Indian food, there are many more ways to include these little protein packets in your daily diet. You can sometimes find pre-cooked, packaged lentils at the supermarket, but dried lentils are simple to prepare.
After sorting to pick out any small, hard debris, rinse well and place the lentils in a pot. Cover with about one-half inch of water, then bring to a boil. Reduce the heat and simmer uncovered. How long you simmer them will depend on the type of lentil. According to the Mayo Clinic, green lentils need 40 minutes, brown lentils need 30 minutes and red lentils need 20 minutes.
You can serve the lentils hot with herbs and spices alongside a serving of fish or chicken and some veggies, or you can pop them in the refrigerator for later. Cold lentils make a great addition to a salad, but choose green lentils for this purpose as they stay firm during cooking.
But don't stop there. Get creative, adding lentils to burritos, making a lentil spread similar to hummus, using lentils to make veggie burgers and croquettes. Lentils can even make an appearance at breakfast in savory staples like huevos rancheros, omelettes and scrambles, and they can also be used to make muffins, pancakes and granola bars.
- USDA: "Basic Report: 16070, Lentils, Mature Seeds, Cooked, Boiled, Without Salt"
- Nutrients: "Lentil and Kale: Complementary Nutrient-Rich Whole Food Sources to Combat Micronutrient and Calorie Malnutrition"
- EUFIC: "High and Low Biological Value Protein Foods"
- National Institutes of Health: "What Are Proteins and What Do They Do?"
- USDA: "Total Amino Acids in Lentils (Cooked)"
- USDA: "Top 10 Foods Highest in Methionine"
- Purdue: "Vegetarians"
- National Academies of Medicine: "Summary Tables, Dietary Reference Intakes"
- Nutrition & Metabolism: "A High-Protein Diet for Reducing Body Fat: Mechanisms and Possible Caveats"
- Obesity Facts: "Effect of a High-Protein Diet Versus Standard-Protein Diet on Weight Loss and Biomarkers of Metabolic Syndrome: A Randomized Clinical Trial."
- Journal of Nutrition and Metabolism: "The Role of Fiber in Energy Balance"
- National Institutes of Health: "Iron"
- National Institutes of Health: "Zinc"
- Oregon State University: "Phosphorus"
- National Institutes of Health: "Folate"
- Mayo Clinic: "I Know Lentils Are Supposed to Be Good for Me, but How Do I Prepare Them?"
- Lentils: "Lentils for Breakfast? Science Says YES!"