Articles · Nutrients
Beans: the cheapest protein on your plate?
Why lentils, chickpeas and beans pack protein, fibre, iron and folate for very little money, what the evidence says about them and heart health, and how to keep the wind down.
· 4 min read
What costs little, keeps for a year in the cupboard, carries protein, fibre, iron and folate, and turns up in some of the world's favourite dishes, from dal to chilli to hummus? If you guessed beans, you've guessed the most underrated food in the shop.
What's in a cup of cooked beans?
Roughly, a cup of cooked pulses gives you:
- Lentils: about 18 g of protein and 16 g of fibre.
- Black or kidney beans: about 15 g of protein and 13–15 g of fibre.
- Chickpeas: about 15 g of protein and 12 g of fibre.
They also bring iron, folate, potassium and magnesium, with almost no fat. A cup of cooked lentils carries most of an adult's daily folate and a good share of the day's iron (plant iron is absorbed less well, so add some vitamin C to the meal).
Think about it: How often do beans, lentils or chickpeas turn up in your week: never, once, or most days?
Is bean protein "complete"?
Beans are a little low in one building block of protein (methionine), and grains are a little low in another (lysine). Eaten across the day, they make up for each other, so there's no need to combine them at every meal. Rice and beans, dal and chapati, or hummus and pitta just happen to do it on one plate.
What does the evidence say?
A 2019 review of long-term studies found that people who ate the most pulses had somewhat lower rates of heart disease (about 10% lower for coronary heart disease), high blood pressure and obesity than those who ate the least. The authors rated the certainty of this evidence low to very low, and they found no clear link with diabetes or with death rates. So beans aren't a miracle; they're a cheap, filling, nutritious food that fits well into a healthy diet.
They're also kind to the planet: a large study of food production found that even the lowest-impact animal proteins typically have bigger environmental footprints than plant proteins such as beans and peas.
The Beaneater, Annibale Carracci, c. 1580–1590, Galleria Colonna, Rome. A man caught mid-spoonful over a bowl of beans, with bread, spring onions and a glass of wine. In the 1580s, a painting of an ordinary person simply eating lunch was a bold idea. The beans, as ever, were the cheap and filling part. Public domain · Wikimedia CommonsWhat about the wind?
Beans contain sugars called oligosaccharides that we can't digest, so bacteria in the gut ferment them, and that makes gas. Some ways to keep it down:
- Start small and eat beans regularly: the gut gets used to them.
- Soak dry beans overnight and throw away the soaking water before cooking.
- Rinse canned beans in a sieve before using them.
- Choose lentils and split peas, which many people find easier on the gut.
Try this: Keep three cans in the cupboard: chickpeas, black beans and lentils. Each one turns a vegetable soup, a salad or a pasta sauce into a filling meal in five minutes.
Think about it: Which meal you already make could take half a can of beans? A bolognese, a curry, a soup?
Quick quiz
About how much protein is in a cup of cooked lentils?
About 18 g, with about 16 g of fibre too.
Do you have to eat beans and grains at the same meal to get complete protein?
No. Eaten across the day, they make up for each other.
What's one easy way to make beans cause less gas?
Start with small amounts and eat them often, rinse canned beans, or soak dry beans and throw away the water.
Sources
General information, not medical advice. If you have a health condition, are pregnant or take medication, ask a doctor or dietitian what is right for you.