Loading…
Food · Grains & Legumes · Legumes
food source · 3
→Iron
The iron in lentils is non-heme iron, so how much is absorbed depends on the meal: phytate and calcium hold it back, and vitamin C in the same meal clearly helps it get absorbed.
Mechanism · Vitamin C helps on the spot
Non-heme iron has to be reduced to ferrous iron before DMT1, the transporter on gut cells, will take it in. Vitamin C reduces ferric iron to ferrous iron and holds it in a soluble complex, so it does not turn into a compound that cannot be absorbed (Hallberg 1989). This has to happen in the gut during the same meal: a vitamin C tablet a few hours later does nothing for the iron in this bowl of soup.
Numbers · Single-meal swings even out
Cooked lentils have about 3.3 mg of iron per 100 g, near the top among plant foods, but it is non-heme iron, so how much is absorbed depends on the meal: vitamin C pulls it up, and tea, phytate and calcium push it down. Swings like these within one meal become much smaller across several days of a varied diet (Hurrell and Egli 2010). Soaking the lentils and pouring off the water removes part of the phytate.
iron-bioavailability-hurrell-egli-2010Lentils are a good plant source of folate: cooked lentils have about 90–180 µg of dietary folate equivalents per 100 g, about 20–45% of an adult's daily need.
Mechanism · Same production line as iron
When the bone marrow makes red blood cells, folate runs cell division (it supplies material for copying DNA) and iron loads hemoglobin into the red cell. Short of folate, the cells come out large and few; short of iron, they come out small and pale. Lentils pack the materials for both steps into one seed, and these are exactly the two that people who eat no meat tend to run short of together.
Numbers · The folate in a serving of lentils
Cooked lentils have about 90–180 µg of dietary folate equivalents per 100 g, about 20–45% of the adult daily need of 400 µg DFE, which matters especially in early pregnancy. Folate dissolves in water and is damaged by heat, so long cooking loses some; with lentil soup, it is best to drink the broth too.
Lentils are a high-protein bean that can serve as a staple: cooked lentils have about 9 g of protein and 8 g of fiber per 100 g, and protein supplies about 30% of their calories, which is rare for a staple food.
Mechanism · Its gap is not the grain's gap
Lentil protein is incomplete: it is rich in lysine and low in methionine. Grains are the other way round, which is why lentils with rice turn up in many cuisines: the two gaps offset each other. There is no need to pair them precisely in one meal; eating both over the day is enough.
Numbers · Cooked and dry lentils
Cooked lentils have about 9 g of protein, 20 g of carbohydrate (about 8 g of it fiber) and about 0.4 g of fat per 100 g, at about 116 kcal; dry lentils are about 2.5 times as concentrated, with about 25 g of protein per 100 g. Protein supplies about 30% of their calories, against about 7–8% for rice. Lentils have a glycemic index (GI) of about 25–30, which makes them a low-GI food.