What are legumes?

The legume family includes beans (including soybeans and chickpeas), peas, lentils and alfalfa. It also technically includes peanuts, which we file under nuts.

Here we’ll be using the words ‘legume‘ and ‘pulse‘ interchangeably. Generally legume means the plant, and pulse means the seed – the part usually bought in a dried form – not the green beans or peas that are usually eaten whole and fresh.

Legume plants

What are they good for?

The most useful thing legumes provide in a plant-based diet is protein. They’re considered ‘nutrient-dense’, meaning they have high vitamin and mineral content for the amount of calories they provide. Of especial note are minerals such as iron and potassium, as well as B vitamins.

They also provide soluble fibre, which can help to reduce cholesterol and regulate blood sugar. They’re thus potentially useful against diabetes and heart conditions (1). As they help you to feel fuller for longer, legumes can be useful for weight loss.

Pulses have long provided an affordable source of nutrition throughout the world – particularly crucial in developing countries – but they’ve received increasingly bad press in the West over recent years.


Why are legumes so controversial?

This is largely because they’re high in antinutrients. Those grown non-organically will be particularly high in phytates and toxins. It’s especially a problem in crops grown on a massive scale for oil and animal feed, such as soybeans and peanuts.

When grown organically, stored and prepared carefully, when eaten in moderation and variety, pulses are highly nutritious. (Careful preparation also reduces their gas-producing properties 🙂 )

Is there really enough protein in legumes?

When asking this question, people often compare plant-based sources to animal-based. The overall composition is naturally going to be different – legumes will be proportionally higher in carbohydrates, higher in fibre, and lower in fats than meat, fish or dairy products.

People on a strict paleo diet would thus avoid them, in the same way as they’d avoid grains. But as part of a balanced plant-based diet, pulses are amazingly nutritious. It would be difficult to get everything you need just from other vegan sources.

Those who eat meat and dairy need to get carbohydrates from other sources – traditionally rice, wheat or potatoes. On a plant-based diet, you’ll get a fair amount of carbohydrate from legumes, so there’s not so much need for additional starch. This is perhaps an argument in their favour.


Nutrients in legumes

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But is the protein of good enough quality?

Protein in food is made up of 19 amino acids. 9 of these are ‘essential’, meaning the body cannot create them, so we need to get them from our diet. The quality of different proteins is determined by the relative proportions of these amino acids. This is known as the amino acid score.

Measuring the relative protein quality of different foods is tricky. It depends on bioavailability – i.e. the amount we can actually absorb. This will depend on a lot of different factors, such as the freshness, the reduction in antinutrients, and other ways in which the food is prepared, as well as the health of the person eating it. But a comparison is still worthwhile.

The following charts show the total protein per 100g (protein levels), followed by the overall amino acid score of various foods. You’ll see that the amino acid score for beef, while admittedly higher than lentils, is actually lower than that of chickpeas or any of the beans we looked at.


Protein levels in legumes

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What about individual amino acids?

The first chart below shows how many mg of amino acids are in 100g of that food item.

The second shows how many grams of each essential amino acid are present in 100g of that food item’s protein (amino acid levels) – i.e. the percentage level. The black line shows the level considered acceptable.


Amino Acids in Legumes

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The verdict

What we see from these charts is that although, for example, beef has 3 times as much protein per 100g as beans, the ratio of essential amino acids is actually just as good in beans as in beef.

Some say you have to eat rice with beans in order to create a ‘complete protein’, but as the figures show, rice doesn’t contribute anything staggering. The lentil is the only one to dip below the required level for any essential amino acid – methionine plus cystine.

So the figures show that legumes do provide good quality protein in the diet, with a similar profile to that of meat. When eaten as part of a balanced plant-based diet, along with other protein sources such as nuts, seeds and pseudograins, their contribution is significant.


Chickpea Plant

Some common legumes

Chickpeas

Also known as garbanzo beans, Egyptian peas, channa or gram, chickpeas are one of the earliest cultivated legumes, especially popular in India and the Middle East.

Chickpeas are often eaten whole in salads, stews and curries. Blended they can be made into dips like houmous, baked as falafel, or used as a thickener in soups.

In India gram flour is used in a variety of dishes, such as bhajjis, pakoras, dhokla, popadoms and laddu. India produces more than half the world’s supply (crop pictured above).

“Not only do chickpeas produce a valuable crop but at the same time they also provide a natural organic method of breaking the disease cycle in wheat and barley crops. This means less fungicide and less insecticide, resulting in a cleaner, greener environment.”
The Happy Snack Company

Butter Beans

Also known as lima beans, sieva beans or Madagascar beans, butterbeans are originally from the Andes and Mesoamerica. Peru cultivated them as early as the first century BC, and from the 1500s they have been exported worldwide.

Butterbeans are useful hot or cold. They can be pureed into a dip or spread as an alternative to houmous. In the USA butter beans are mixed with corn to make succotash. In Spain they’re used in paella.

Butter beans are especially high in potassium.

Black beans

Also known as turtle beans, black beans are native to Latin America, and are often used in soups and stews. In Southern USA, they can be found in Cajun or Creole cooking. They’re also used as a sauce or condiment in Chinese cuisine.

Lentils

Lentils get their name from their lens-like shape. Originally grown in Western and Central Asia and they are the oldest known legume crop – the earliest findings are from 11,000 BC in Greece.

Lentils are a staple in India, where they’re used as the main ingredient in dahl, and as a thickener in other curries. In the Americas they’re more commonly used in soups. They’re also popular in Ethiopia.

In ancient Rome, lentils were given as tokens of good fortune, as they resemble little coins. They’re still traditionally eaten in Italy on New Year’s Eve, as a symbol of luck for the year ahead.

Canada is the biggest producer of lentils, followed by India.

Soybeans

Soybeans (or soya beans) are proportionally higher in protein and lower in carbohydrate than other legumes, so they’re more widely recognised as a ‘complete’ protein.

They’re also higher in phytic acid though, and are toxic to humans in their raw form, so careful preparation is essential. Many believe they are only safe to eat when fermented.

Soy is widely used in dairy or meat alternatives, such as soy milk and tofu – more commonly known as bean curd in Asian cuisine. In Asia it’s also used to produce many fermented foods, such as tempeh, miso and soy sauce.

America and Brazil are the biggest producers of soy.

“Soy protein is essentially identical to the protein of other legume seeds and pulses. Moreover, soybeans can produce at least twice as much protein per acre than any other major vegetable or grain crop besides hemp, five to 10 times more protein per acre than land set aside for grazing animals to make milk, and up to 15 times more protein per acre than land set aside for meat production.”
Encyclopedia of Life


Fun facts about legumes

  • In ancient Greece white and black beans were used for voting at elections. Some believe the saying “spill the beans” comes from that tradition – revealing results prematurely.
  • In the 6th Century BC, Pythagoras shied away from eating legumes, as he believed they contained the souls of the dead.
  • As legumes were so prized in ancient Rome, four of the most powerful families took their names from them: Piso (pea), Cicero (chickpea), Lentulus (lentil) and Fabius (fava).





Got any tips or questions of your own about legumes? Leave us a comment below, we’d love to hear from you.

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