Butter bean

The butter bean is a climbing or bush legume with trifoliate leaves, which bears flat, curved pods holding two to four seeds. The beans are broad, flattened and kidney-shaped, usually pale cream or greenish white, with some types speckled or red, purple and black.

Large-seeded types are called butter or lima beans, and small-seeded types are called sieva or baby limas. Cooked, they have a soft, starchy and buttery texture with a mild, slightly sweet flavour.

They are sold fresh in the pod, frozen, dried and canned, and in Britain tinned butter beans are a pantry staple.

Phaseolus lunatus was domesticated independently in two regions: the Andes, where large-seeded types were grown, and Mesoamerica, which gave small-seeded types. The Andean forms have been found in archaeological sites in Peru dating back several thousand years.

Spanish and Portuguese traders then took the bean around the world, to Europe, Africa and Asia. Madagascar and Myanmar (Burma) became leading sources, which explains the names Madagascar bean and Burma bean.

The name lima bean refers to Lima, the capital of Peru, from where the beans were shipped to Europe. The species name lunatus means moon-shaped and refers to the curved form of the seed.

Andean peoples were growing lima beans in the Moche and Nazca periods, and they are depicted in ceramics, with some Moche pottery showing runners carrying marked beans, although the interpretation is debated. They accompanied maize and squash in many indigenous agricultural systems.

After European contact, the beans spread through the Spanish empire and by the slave trade to West Africa and the Caribbean. They became a southern United States garden crop in the 18th and 19th centuries. Succotash, a stew of lima beans and corn, comes from Narragansett and other Native American cooking.

In 20th-century Britain, canned butter beans became a staple of cheap, filling meals. California became a major producer of dry lima beans in the United States.

Wild and primitive forms of some varieties contain cyanogenic compounds, and food safety rules in several countries restrict the sale of high-cyanide types.

Butter beans are simmered in soups and stews, baked in tomato sauce, mashed into dips and spreads, or served in salads. Fresh baby limas are cooked in succotash with sweetcorn, while dried beans are soaked and boiled.

Canned butter beans are used in Greek gigantes plaki, a dish of baked beans in tomato, and in Southern American butter bean stews. In Peru, they are served as pallares.

They can be blended into creamy soups without dairy, and flour can be made from dried beans.

Butter beans are a source of plant protein, fibre, folate, iron and potassium, and they have a relatively low glycaemic response. Pulses in general are linked to better cholesterol and blood sugar levels in observational studies.

Evidence specific to lima beans is limited, but they share the nutritional features of other beans.