Optical lenses are named after lentils. The Latin word for the seed is lens, and glass lenses borrowed the name because of their shape. The plant, Lens culinaris, was one of the first crops people farmed.
A cup of cooked lentils (198 g) has 230 calories, 17.9 g of protein and 15.6 g of fiber, and about 35% of the calories come from protein. The same cup covers 90% of the daily value for folate (358 µg) and 37% for iron (6.59 mg).
Iron is the catch. In one isotope study, women absorbed only about 2.2% of the iron in a lentil dal, against 23.6% from a ferrous sulfate dose. Absorption was higher in women with low iron stores, so the body adjusts to some degree.
Health benefits of lentils
The top findings from 22 studies, strongest evidence first
What the stars mean
- Strong. Several randomized trials, pooled in a meta-analysis, point the same way, or regulators (FDA or EFSA) have approved the claim.
- Moderate. Good randomized trials support it, but there are fewer of them, or their results vary.
- Limited. Small, short or single trials, or mixed results. Promising, but it needs confirmation.
Population and lab studies get no stars: they show a link or a mechanism, not proof.
How we rate evidence →- ★★★Lower “bad” LDL cholesterolWhole pulses, lentils among them, lowered LDL by 0.14 mmol/L across 38 trials, at a median of 130 g a day for 6 weeks. Eating lentils daily for 12 weeks also lowered fasting LDL and total cholesterol in adults with a larger waist.
- ★Smaller blood sugar rise after mealsReplacing half the carbohydrate in rice or potato with lentils cut the blood sugar rise by about 20% and 35% in healthy adults. Lentils in chili and soup cut it to 48 to 61% of the control.
- ★Kept insulin resistance from rising in 8 weeksIn 30 adults with a larger waist, 8 weeks of lentil lunches kept insulin resistance from rising, while it rose on lentil-free lunches. The larger lentil portion did better than the smaller one.
- ★Less hunger, though not always less eatenA lentil meal led to less food eaten at a pizza meal 260 minutes later than a macaroni and cheese meal. Green lentil chili cut the desire to eat by 20.1% compared with rice chili, but people did not eat less.
- ★Little iron absorbed from lentil dalWomen absorbed only about 2.2% of the iron in a lentil dal, against 23.6% from ferrous sulfate. Women low in iron absorbed more.
All 22 studies, strongest evidence first
Whole dietary pulses, with lentils among them, lowered LDL cholesterol by 0.14 mmol/L across 38 trials
Meta-analysis of 38 randomized trials (2,095 people) of whole pulses as a group: beans, chickpeas, peas and lentils. People ate a median 130 g a day (0.5 to 0.67 cup) for 6 weeks. Non-HDL cholesterol fell 0.22 mmol/L and apoB 0.08 g/L, and HDL fell slightly (0.03 mmol/L). Results looked similar by pulse type, but the authors say more trials on lentils, chickpeas and dried peas are needed.
Replacing half the carbohydrate in rice or potato with lentils cut the blood sugar rise by about 20% and 35%
Randomized crossover trial in two groups of healthy adults (24 in each). They ate 50 g of available carbohydrate from white rice or instant potato, or a half-and-half mix with cooked large green, small green or split red lentils. Blood sugar peaks and totals were lower with the lentil mixes (large green lentils with rice only just missed significance), and insulin fell with potato but not with rice. These were single meals, not long-term effects.
Eating lentils daily for 12 weeks lowered fasting LDL and total cholesterol in adults with a larger waist
Randomized trial in 38 adults with an increased waist circumference. They ate seven prepared midday meals a week containing 980 g of cooked green lentils in total, or meat-based meals with none. After-meal glucose, IL-17 and IL-1β responses were also lower. Stomach symptoms were rated none or mild throughout.
Eight weeks of lentil lunches kept insulin resistance from rising, more so at the higher dose, in adults with a larger waist
Randomized trial in 30 adults who finished 8 weeks of five midday meals a week with 0 g, 300 g or 600 g of cooked green lentils. HOMA-IR, a measure of liver insulin resistance, rose 1.2 units on the lentil-free meals and fell by 0.9 units (300 g) and 1.5 units (600 g) relative to that group. A share of 87.4% reported no or mild stomach symptoms.
Swapping lentils into chili and soup cut the relative blood sugar response to 48 to 61% of the control, while muffins changed less
Three randomized crossover trials in healthy adults (24 for muffins, 24 for rice chili, 20 for potato soup). Each food gave 25 g of available carbohydrate from green or red lentils or from the wheat, rice or potato control. Muffins scored 88% (green) and 84% (red), and the green lentil muffin did not lower the glucose rise significantly. Insulin responses were lower with green lentils in all three foods.
Lentils eaten 2 hours before a standard meal lowered the blood sugar rise after it, compared with white bread
Randomized trial of a lentil, chickpea, yellow pea or navy bean meal against white bread, followed by a fixed-size meal 2 h later. Blood glucose was lower after lentils and chickpeas at 150 and 165 minutes, and the total rise was lower after lentils. Lentils also reduced appetite over the first 2 h.
A lentil meal led to less food eaten at a pizza meal 260 minutes later than a macaroni and cheese meal
Randomized crossover trial in 25 young men who ate four 250 kcal meals: canned chickpeas, lentils or yellow split peas with macaroni and tomato sauce, or macaroni and cheese. Lentils and yellow peas, but not chickpeas, lowered appetite over the 260 minutes. After the pizza, blood sugar was lower following lentils and chickpeas than following yellow peas.
A lentil premeal slowed the stomach emptying of a second meal about 4 hours later, but blood sugar did not differ
Experiment in 10 people and 7 dogs that compared a lentil premeal with a bread premeal of equal carbohydrate, then a solid second meal 4.0 to 4.5 hours later. Emptying of that meal was delayed after lentils, yet the glucose response to it was the same under both conditions. It is a small, early study.
Green lentil chili raised fullness by 17.5% compared with rice chili, but people did not eat less
Two randomized crossover trials in 24 healthy adults each, replacing rice in chili and wheat in muffins with green or red lentils. Desire to eat fell 20.1% with green lentil chili, while red lentil chili and both muffins did not change satiety. Food eaten at a test meal and over 24 h did not differ.
Lentil pasta lowered calorie intake at the next meal compared with durum wheat pasta in healthy adults
Randomized repeated-measures study of lentil, chickpea, durum wheat and gluten-free pasta with tomato sauce, in 20 people (ad libitum lunch) and 40 people (2-hour appetite test). Lentil pasta also lowered the desire to eat and raised fullness, with stronger effects in women. One author reports supplies from the pasta maker Barilla.
Blended lentils raised appetite by about 6% compared with whole lentils but did not change the blood sugar response
Double-blind crossover trial in 12 adults who ate breakfasts with whole lentils, blended lentils or none, with or without capsules of an enzyme (alpha-galactosidase) meant to ease stomach discomfort. After the blended meal, glucose was 4.5 mg/dL lower than with no lentils and did not differ from the whole-lentil meal. The enzyme had no main effects.
Whole pea and lentil meals lowered the blood sugar rise in adults with type 2 diabetes or metabolic syndrome, more than the same pulses as flour
Crossover study in 11 adults with type 2 diabetes and 8 with metabolic syndrome. Meals gave 50 g of available carbohydrate from half a cup of whole pulse or the dry weight of pulse flour, and a glucose drink was the control. Pea and lentil were tested together, so the abstract does not show lentils alone.
All 8 lentil varieties tested in people had a low glycemic index, from 10 to 23
Lab tests on 20 cooked lentil varieties, then 8 of them in 10 volunteers. The glycemic index and the glucose rise were not predicted by rapidly digestible, slowly digestible or resistant starch taken one at a time. It was a small study.
Women absorbed only about 2.2% of the iron in a lentil dal, against 23.6% from ferrous sulfate
Crossover study in 19 women, 6 of them anemic, who ate 330 g of dal made from lentils labeled with an iron isotope, and on another day a ferrous sulfate dose. Absorption from dal rose as iron stores (serum ferritin) and the hormone hepcidin fell, so women low in iron absorbed more.
Older adults who ate the most lentils had about a third lower risk of type 2 diabetes
Cohort of 3,349 older Spanish adults at high heart risk in the PREDIMED study, with 266 new diabetes cases over a median 4.3 years. The top against the bottom quarter for lentils gave a hazard ratio of 0.67 (range 0.46 to 0.98), and total legumes 0.65. Chickpeas were borderline. Everyone followed a Mediterranean-style diet, and a link is not proof of cause.
Older adults who ate the most lentils had a 37% lower risk of dying from cancer
Cohort of 7,216 PREDIMED participants followed a median 6.0 years, with 425 deaths. The top against the bottom third for lentils gave a hazard ratio of 0.63 (range 0.40 to 0.98). For total legumes and dry beans, though, the top third had a higher risk of dying from cardiovascular disease, and the authors say the two effects may offset each other. The abstract gives no heart-death figure for lentils.
Uruguayans who ate the most legumes, beans and lentils alike, had less than half the odds of colorectal cancer
Case-control study of 11 cancer sites (3,539 cases and 2,032 hospital controls). The highest against the lowest third of legume intake gave an odds ratio of 0.43 (range 0.32 to 0.59) for colorectal cancer and 0.68 for all sites combined, with no link for lung, breast, prostate or bladder cancer. Case-control studies rely on people recalling past diet.
In a Spanish clinic series, lentils were the most common legume allergy in children, found in 43 of 54
Case series of 54 children with legume allergy. Lentil allergy was diagnosed in 43 (80%) and chickpea allergy in 32 (59%). Reactions began at a median age of 22 months, and 38 children (70%) had positive skin tests to at least 3 legumes. These children were already known to be allergic, so it does not show how common lentil allergy is overall.
Rats fed a diet of 70.8% red lentils for 6 weeks weighed less than rats on a standard diet, 443 g against 511 g
Study in 36 rats, not people. Body fat percentage and triglycerides were lower on the lentil diet than on a corn starch diet, and Firmicutes gut bacteria fell. A diet that is mostly lentils is far from a human meal.
Mice fed lentils, chickpeas, beans or peas on a high-fat diet had more varied gut bacteria and more Bacteroidetes
Study in mice, not people. In each pulse group, 35% of the diet’s protein came from the pulse. Bacteroidetes rose while Proteobacteria and Firmicutes fell. Lentils were tested alongside three other pulses, and the study does not show a health effect in people.
A black lentil water extract cut colon tumors in mice from an average of 12.8 to 7.8
Study in mice, not people. Mice given a colon-cancer-causing chemical and a gut irritant received the extract at 600 mg/kg of body weight for 11 weeks. The disease activity index was 2.4 against 6.3 in untreated mice, and the inflammatory signal IL-6 in plasma fell 72.6%. It was an extract of black lentils, not whole cooked lentils.
Dry lentils held 216 to 290 µg of folate per 100 g, more than chickpeas or field peas
Lab analysis of 10 lentil varieties grown in North Dakota in 2010 and 2011, with a mean of 255 µg per 100 g. Chickpeas held 42 to 125 µg, yellow field peas 41 to 55 µg and green field peas 50 to 202 µg. These are dry lentils; cooked lentils hold less per 100 g because they absorb water.
Who should be careful with lentils
Most people can eat lentils freely. Take a little care if one of these applies:
- Legume allergy. Lentil was the most common legume allergy in a Spanish series of 54 allergic children, and 37 of them (69%) reacted to more than one legume on challenge. If you are allergic to one legume, ask your allergist about the others.
- Irritable bowel syndrome or a gassy gut. Monash University says legumes are high in GOS, a fermentable carbohydrate, and that canned legumes, or ones boiled and drained, tend to be lower. In an 8-week trial, 87.4% of people reported no or mild stomach symptoms, but IBS may be different.
- Low iron stores. Lentils have 6.59 mg of iron per cup but little of it is absorbed. Vitamin C in a meal raised non-heme iron absorption in a study of 299 people eating meals in general, not lentils.
How to choose, store and eat lentils
- Red and yellow split lentils: they cook in about 10 to 15 minutes and break down into a purée. In the chili trial, red lentils brought the relative blood sugar response to 48%, against 58% for green.
- Green, brown and black lentils: they hold their shape and take about 20 to 30 minutes. Green lentil chili raised fullness by 17.5% against rice chili, and red did not.
- Canned lentils: they are already cooked, and rinsing them well lowers the sodium. Monash lists boiled green lentils as low FODMAP at ¼ cup (23 g).
Lentils need no soaking. Dried lentils keep for about a year in a tightly sealed container in a cool, dry, dark place, and cooked lentils keep for a week in the fridge or up to three months in the freezer.
Sources
- Lentils. The Nutrition Source, Harvard T.H. Chan School of Public Health.
- Including legumes on a low FODMAP diet. Monash FODMAP blog. 2016.
- Getting enough fibre: low FODMAP foods and IBS. Monash FODMAP blog. 2021.
- Martínez San Ireneo M, Ibáñez MD, Sánchez JJ, Carnés J, Fernández-Caldas E. Clinical features of legume allergy in children from a Mediterranean area. Ann Allergy Asthma Immunol. 2008.
- Wilson SMG, Peterson EJ, Gaston ME, Kuo WY, Miles MP. Eight weeks of lentil consumption attenuates insulin resistance progression without increased gastrointestinal symptom severity: a randomized clinical trial. Nutr Res. 2022.
- Hallberg L, Brune M, Rossander L. Effect of ascorbic acid on iron absorption from different types of meals. Hum Nutr Appl Nutr. 1986.
- DellaValle DM, Glahn RP, Shaff JE, O’Brien KO. Iron absorption from an intrinsically labeled lentil meal is low but upregulated in women with poor iron status. J Nutr. 2015.
- Chamoun D, Duncan AM, Lukus PK, et al. Postprandial blood glucose and insulin response in healthy adults when lentils replace high-glycemic index food ingredients in muffins, chilies and soups. Nutrients. 2024.
- Clark SL, Ramdath DD, King BV, et al. Food type and lentil variety affect satiety responses but not food intake in healthy adults when lentils are substituted for commonly consumed carbohydrates. J Nutr. 2019.
History of lentils
Lentils were first cultivated in southwest Asia 8,000 to 10,000 years ago. A genetic study of 190 wild and cultivated lines points to a slow, drawn-out domestication, with two cultivated gene pools forming in the region. Their wild ancestor is Lens culinaris subspecies orientalis, and archaeologists are still unsure how many times lentils were domesticated.
Carbonized lentil seeds turn up at early farming villages. Wikipedia lists finds at Tell Ramad in Syria, dated to 6250 to 5950 BC, and at Hacilar in Turkey, dated to 5800 to 5000 BC. It also says lentils were part of the ancient Israelite diet, as roasted seeds, soup or stew, and Harvard’s Nutrition Source notes them in the diets of ancient Rome and Egypt.
The name comes from Latin lens. Wikipedia suggests the Roman family name Lentulus may come from the same word, and says optical lenses were named for the seed because of their lentil-like shape.
Today three countries grow most of the crop. In 2023, according to FAOSTAT figures quoted by Wikipedia, the world harvested about 7.07 million tonnes. Australia grew 1.84 million tonnes, Canada 1.67 million and India 1.56 million, together 72% of the total.
Lentils anchor dishes on several continents. Italians traditionally serve cotechino with lentils on New Year’s Eve, Egyptians eat them in kushari, Ethiopians in the stew misir wot, and in India split lentils are called dal.
Sources
- Liber M, Duarte I, Maia AT, Oliveira HR. The history of lentil (Lens culinaris subsp. culinaris) domestication and spread as revealed by genotyping-by-sequencing of wild and landrace accessions. Front Plant Sci. 2021.
- Lentil. Wikipedia.
- Lentils. The Nutrition Source, Harvard T.H. Chan School of Public Health.
Frequently asked questions about lentils
Are lentils good for you?
For most people, yes. A cooked cup (198 g) has 230 calories, 17.9 g of protein, 15.6 g of fiber and 90% of the daily value for folate. In 38 trials of whole pulses, which include lentils, LDL cholesterol fell by 0.14 mmol/L. Most lentil-only trials are small and short, so the evidence for lentils themselves is still limited.
Are lentils high in protein?
Yes, for a plant food. Cooked lentils have 9.02 g of protein per 100 g, or 17.9 g in a cup (198 g), which is about 35% of their calories. The protein is limited by the amino acids methionine and cysteine, and its completeness score here is 86 out of 100.
Do lentils raise blood sugar?
Less than rice or potato did in the trials. Replacing half the carbohydrate of rice or potato with lentils cut the blood sugar rise by about 20% and 35% in healthy adults, and 8 lentil varieties had a glycemic index of 10 to 23. In adults with type 2 diabetes or metabolic syndrome, whole pea and lentil meals lowered the rise compared with a glucose drink. Check portions and choices with your care team if you have diabetes.
Do lentils cause gas?
They can, but stomach symptoms were mild in trials. In an 8-week trial, 87.4% of people reported no or mild symptoms, and in a 12-week trial all symptoms were rated none or mild. Monash University says legumes are high in GOS and that canned legumes, or ones boiled and drained, tend to be lower. It lists ¼ cup (23 g) of boiled green lentils as low FODMAP.
Do you have to soak lentils?
No. Lentils cook quickly, so soaking is not needed: split red and yellow lentils take about 10 to 15 minutes, and whole green, brown and black lentils about 20 to 30. Undercooked lentils are hard to digest. Rinse canned lentils well to lower the sodium.
Are lentils good for weight loss?
No trial here tested weight loss. Green lentil chili raised fullness by 17.5% compared with rice chili, but people did not eat less at the next meal or over 24 hours. Lentil pasta did lower calorie intake at the next meal compared with durum wheat pasta. A cup has 230 calories and 15.6 g of fiber, so it fills a plate, but that is a swap effect, not a proven effect of lentils.
Which lentils are healthiest: red, green or brown?
The trials do not name a winner. In the chili trial, red lentils brought the relative blood sugar response to 48% and green to 58%, but only green lentil chili raised fullness (17.5%). Brown lentils were not tested on their own in these studies.
Are lentils high in iron?
They have a good amount, but little of it is absorbed. A cooked cup has 6.59 mg of iron, 37% of the daily value. In 19 women, only about 2.2% of the iron in lentil dal was absorbed, against 23.6% from ferrous sulfate, though women with low iron stores absorbed more. Vitamin C raised non-heme iron absorption in a study of 299 people eating meals in general, and a cup of lentils has only about 3 mg of it.