Lima beans and butter beans are the same species, Phaseolus lunatus. Raw, they contain linamarin, the same cyanide-releasing compound found in cassava. It stays locked in the bean until the tissue is damaged by chewing or crushing, when an enzyme turns it into hydrogen cyanide, a trait that protects the wild plant from insects. Cooking destroys that enzyme and lowers the cyanide, so raw lima beans should not be eaten.
The amount varies a lot by variety. Commercial US lima beans are low, usually 100 to 170 mg of cyanide per kg according to Oregon State University Extension, but a survey report from Food Standards Australia New Zealand quotes averages from 100 mg/kg for a white American variety to 3,000 mg/kg for a black Puerto Rican one. Wild and colored types can be far higher, so beans of unknown variety need the most careful cooking.
Cooked, a cup (188 g) has 216 calories, 14.7 g of protein, 13.2 g of fiber, 49% of the daily value for copper and 39% of folate. The research is thin: no trial tested lima beans on their own for cholesterol or blood pressure, and the few human tests of lima beans are small and old. Much of the evidence below comes from pulses as a group, animals and the lab.
Health benefits of lima beans
The top findings from 11 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 cholesterolEating about 130 g a day of whole pulses (beans, lentils, chickpeas and peas together) lowered LDL a little (by 0.14 mmol/L across 38 trials). The study does not name lima beans.
- ★Low rise in blood sugar after eatingIn eight healthy volunteers, lima beans were one of six traditional foods with a low glycemic index, or blood sugar rise (16 to 40). The range covers all six foods, not lima beans alone.
- ★Salt did not change the blood sugar responseAdding 4.25 g of table salt did not change the blood sugar or insulin response to lima beans, mashed potatoes or white rice.
- ★Folate absorbed as well as from waterIn 7 healthy men, folate blended into lima beans was absorbed about as well as folate in plain water. Added folate was tested, not the natural folate in lima beans.
- Population studyLinked to a lower risk of early deathIn 32 studies following people, each extra 50 g a day of legumes went with a 6% lower risk of death from any cause. This covers legumes as a group, not lima beans.
All 11 studies, strongest evidence first
Eating about 130 g a day of whole pulses (beans, lentils, chickpeas and peas pooled) lowered LDL cholesterol by 0.14 mmol/L
Meta-analysis of 38 randomized trials (2,095 people) of whole pulses as a group, lasting a median of 6 weeks. The abstract does not name lima beans. Non-HDL cholesterol also fell, HDL fell slightly (0.03 mmol/L), and results were similar across pulse types. Certainty of evidence was moderate to high for most outcomes.
Lima beans were one of six traditional foods that all gave a low blood sugar rise, with glycemic indices of 16 to 40
Eight healthy volunteers ate portions with 25 g of carbohydrate of corn, lima beans, white or yellow tepary beans, mesquite or acorns. The abstract gives the range for all six foods, not for lima beans alone. Insulin responses and lab starch digestion followed the same pattern as blood sugar.
Adding 4.25 g of table salt did not change the blood sugar or insulin response to lima beans, mashed potatoes or white rice
A human test of three carbohydrate foods with different glycemic indices, each eaten with and without salt. Peak levels and total blood sugar and insulin did not differ for any food, so the authors conclude that salt does not affect starch absorption. The abstract gives no number of people and no separate result for lima beans.
Folate blended into lima beans was absorbed about as well as folate in plain water
In six trials, 7 healthy men took one dose of labeled folate forms blended into lima beans, tomatoes, orange juice, a citrate buffer or water, and urine was collected for 48 hours. Lima beans, tomatoes and the buffer matched the water control, while orange juice lowered the absorption of the polyglutamyl form by about a third compared with folic acid. Added labeled folate was tested, not the natural folate in lima beans.
Higher legume intake went with a 6% lower risk of dying from any cause, but not with fewer heart disease or cancer deaths
Meta-analysis of 32 cohorts (1,141,793 people) of legumes as a group. The abstract does not say which legumes, and lima beans are not named. Each extra 50 g a day went with the 6% lower risk, and higher intake went with 9% lower stroke mortality. Certainty was low to moderate, and cohorts show links, not cause.
In pigs fed extra cholesterol, cooked butter beans significantly inhibited the rise in blood cholesterol
36 growing boars ate a purified diet with added cholesterol for 42 days, with or without 30% cooked legumes: baked beans, peas, lentils or butter beans (Phaseolus lunatus, the lima bean). Cholesterol rose in every group but less with baked beans, peas and butter beans, and HDL held. Fecal steroid excretion did not differ, so how it works is unclear.
In rats on a high-cholesterol diet, butter beans lowered raised blood cholesterol more than lentils or peas did
60 rats ate for 8 weeks diets in which 330 g per kg was replaced by baked beans, marrowfat peas, lentils, butter beans (Phaseolus lunatus) or Bambara groundnut. Baked beans and butter beans worked best, and Bambara groundnut made high cholesterol worse. Fecal bile acids and sterols did not explain the differences.
Cooked lima beans of three varieties digested slowly, with predicted glycemic indices of 34 to 39% in a lab test
Laboratory analysis of three Phaseolus lunatus varieties. The cooked seeds held 38 to 45 g of resistant starch per kg, and enzyme tests gave low starch hydrolysis indices of 30.2 to 35%. The glycemic index was predicted from the test tube, not measured in people.
In a lab test of Philippine legumes, lima beans had the highest iron availability, 9.5 against 1.3 for groundnuts
Iron, zinc and calcium availability were measured in vitro, not in people, and lima beans led for iron only. In the same paper’s human tests, cholesterol fell with kidney beans (6% total, 9% LDL) and groundnuts, and lima beans were not reported. The abstract gives no units for the availability values.
Peptides made from lima bean protein lowered systolic blood pressure by 64% in rats
Lab study in which lima bean protein was broken down with enzymes and the pieces sorted by size. One fraction blocked the blood pressure enzyme ACE by 60.15% in a test tube, and the fraction with the strongest renin-blocking effect lowered systolic pressure by 64% and diastolic by 51% in rats. These are lab-made peptides, not cooked beans.
A lectin purified from a Brazilian lima bean variety reduced melanoma cells by up to 83% in a lab test
Lab study of a 128 kDa lectin from Phaseolus lunatus var. cascavel. It also showed antioxidant activity and reduced ethanol-induced stomach damage by up to 63% in an injury test. This is a single purified protein, not a cooked bean.
Who should be careful with lima beans
Most people can eat lima beans freely once they are cooked. Take a little care if one of these applies:
- Raw or undercooked beans. Raw lima beans release cyanide when chewed and should not be eaten. In a lab test of lima bean flour, soaking for 9 hours cut the cyanide by 30%, while 20 minutes of autoclaving or toasting left none detectable. Wild, home-grown or colored beans of unknown variety can hold much more, so give them thorough cooking. Canned beans are already cooked.
- Irritable bowel syndrome or a gassy gut. Beans are naturally high in galacto-oligosaccharides, which can trouble people on a low FODMAP diet. Monash University says canned beans, or beans that are boiled and drained, tend to be lower in FODMAPs, and a 2015 Monash post rated boiled lima beans low at a half serve of 1/4 cup (39 g) and high at a full serve.
How to choose, store and eat lima beans
- Dried: sort out stones and damaged beans, then soak them (boil for 2 minutes and rest for 2 hours, or leave them in the fridge overnight). Drain, rinse, and simmer in fresh water for 40 to 60 minutes.
- Canned: already cooked. In an Australia and New Zealand survey, 5 of 6 canned butter, lima or mixed bean samples had no detectable cyanide and the highest had 6.8 mg/kg, against 32 mg/kg in one of 3 raw lima bean samples. Draining and rinsing also lowers FODMAPs.
- Fresh or frozen: fresh pods should be dark green, plump and firm. Frozen beans can go straight into the pot without thawing.
Keep fresh lima beans whole in their pods in the fridge for about 2 days, and store dried beans in an airtight container in a cool, dry place for up to 6 months. The two main types are baby lima and Fordhook, and Fordhooks are slightly larger and starchier.
Sources
- EFSA Panel on Contaminants in the Food Chain. Evaluation of the health risks related to the presence of cyanogenic glycosides in foods other than raw apricot kernels. EFSA Journal. 2019.
- Survey of cyanogenic glycosides in plant-based foods in Australia and New Zealand 2010-13. Food Standards Australia New Zealand. 2014.
- Cressey P, Saunders D, Goodman J. Cyanogenic glycosides in plant-based foods available in New Zealand. Food Addit Contam Part A. 2013.
- Adeparusi EO. Effect of processing on the nutrients and anti-nutrients of lima bean (Phaseolus lunatus L.) flour. Nahrung. 2001.
- Is there cyanide in lima beans? Oregon State University Extension Service. 2019, reviewed 2024.
- Including legumes on a low FODMAP diet. Monash FODMAP blog. 2016.
- 10 foods you didn’t know you could eat on a low FODMAP diet. Monash FODMAP blog. 2015.
- Lima bean. Purdue Extension FoodLink.
- Smith J. Lima beans or butter beans? Illinois Extension. 2017.
History of lima beans
The lima bean is a New World crop, found wild and grown from Mexico to Argentina. It was domesticated more than once, with large-seeded types in the Andes and small-seeded types in Mesoamerica, and genetic work finds at least three wild gene pools behind them. Estimates put the Andean domestication at around 2000 BC and the Mesoamerican one at around AD 800.
Peru’s Moche culture, which flourished from about AD 1 to 800, grew lima beans heavily and showed them in its art. The name comes from the capital, Lima. When Peru was a Spanish viceroyalty, beans shipped to the rest of the Americas and to Europe came in boxes labeled “Lima, Peru.”
By about 1300, cultivation had spread north of the Rio Grande, and in the 1500s lima beans were planted in the Old World. They kept many names. In the US South and the UK they are butter beans, in India they are double beans, and in Valencia the garrofó is a main ingredient of paella.
In the US, the Fordhook 242 won an All-America Selections award in 1945, and Delaware and the mid-Atlantic grow lima beans for processing. In southern Italy, a Sieva-type ecotype called ‘fagiolo a Formella’ grows in Campania and, to its authors’ knowledge, is the only Italian lima bean ecotype. Scientists also use the plant as a model for how crops defend themselves, from cyanide in wild seeds to scent and nectar signals.
Sources
- Lima bean. Wikipedia.
- Garcia T, Duitama J, Zullo SS, et al. Comprehensive genomic resources related to domestication and crop improvement traits in Lima bean. Nat Commun. 2021.
- Chacón-Sánchez MI, Martínez-Castillo J. Testing domestication scenarios of Lima bean (Phaseolus lunatus L.) in Mesoamerica: insights from genome-wide genetic markers. Front Plant Sci. 2017.
- Ballhorn DJ, Kautz S, Heil M, Hegeman AD. Cyanogenesis of wild lima bean (Phaseolus lunatus L.) is an efficient direct defence in nature. PLoS One. 2009.
- Cuny MAC, La Forgia D, Desurmont GA, et al. Role of cyanogenic glycosides in the seeds of wild lima bean, Phaseolus lunatus: defense, plant nutrition or both? Planta. 2019.
- Piergiovanni AR, Sparvoli F, Zaccardelli M. ‘Fagiolo a Formella’, an Italian lima bean ecotype: biochemical and nutritional characterisation of dry and processed seeds. J Sci Food Agric. 2012.
- Smith J. Lima beans or butter beans? Illinois Extension. 2017.
Frequently asked questions about lima beans
Are lima beans good for you?
For most people, yes, once they are cooked. A cooked cup (188 g) has 14.7 g of protein, 13.2 g of fiber, 49% of the daily value for copper and 39% for folate, for 216 calories. Few studies tested lima beans themselves, so the best-supported result is for pulses as a group: LDL cholesterol 0.14 mmol/L lower across 38 trials that did not name lima beans.
Are raw lima beans poisonous?
Yes, raw lima beans can release cyanide and should not be eaten. They contain linamarin, and chewing or crushing the bean lets an enzyme turn it into hydrogen cyanide. Cooking destroys that enzyme and lowers the cyanide, and canned beans are already cooked. Commercial US beans are low, usually 100 to 170 mg of cyanide per kg according to Oregon State University Extension, but wild and some colored varieties can be far higher.
Are lima beans and butter beans the same thing?
Yes, both names mean Phaseolus lunatus. Butter bean is the usual name in the UK and the US South, and in the US it can also mean particular types, such as the small-seeded Sieva. Illinois Extension says the only difference is the name, and it lists baby lima and Fordhook as the two main types.
How long do you cook lima beans?
Dried lima beans need an overnight soak and then 40 to 60 minutes of simmering, according to Illinois Extension. For cyanide, Oregon State says boiling for more than 30 minutes in a large amount of water removes about 80%, but that research was mostly on cassava and its page has no data on common lima bean methods. Canned beans only need heating through, and frozen beans can go straight into the pot.
Are canned lima beans safe to eat?
Yes, canned lima beans are already cooked. In a survey of retail foods in Australia and New Zealand, 5 of 6 canned butter, lima or mixed bean samples had no detectable cyanide and the highest had 6.8 mg/kg, against 32 mg/kg in one of 3 raw lima bean samples. Draining and rinsing canned beans also lowers their FODMAPs, according to Monash University.
Do lima beans cause gas?
They can, and no trial here measured gas. Beans are naturally high in galacto-oligosaccharides, and Monash University says canned beans, or beans boiled and drained, tend to be lower in FODMAPs. A 2015 Monash post rated boiled lima beans low FODMAP at a half serve of 1/4 cup (39 g) and high at a full serve, so check the current app.
Are lima beans high in protein?
A good amount for a plant food. Cooked lima beans have 7.8 g of protein per 100 g, or 14.7 g in a cup (188 g), which is about 30% of their calories. The protein scores 95 out of 100 for completeness, limited by methionine and cysteine.
Are lima beans good for people with diabetes?
They look like a slow-carb food, but human evidence is thin. Eight volunteers had low glycemic indices, from 16 to 40, for lima beans and five other traditional foods, and a lab test predicted 34 to 39% for cooked lima beans. A cooked cup has 26.1 g of net carbs and 13.2 g of fiber, so portions still count. Check choices with your care team.