--- topic: "Beans and Legumes" title: "Beans and Legumes: Health and Digestibility" order: 1 description: "What trials and large cohorts show about beans, lentils and chickpeas, and how to soak, cook and introduce them so they are easy on your gut." question: "Are beans good for you, and how do you make them easy to digest?" answer: "Yes: beans probably lower LDL cholesterol and blood sugar, and soaking, thorough cooking and a gradual start keep the gas manageable." actions: - "Build up to about three-quarters of a cup (130 g) of cooked beans, lentils or chickpeas a day, the typical amount in cholesterol trials, starting with half a cup [1][4]." - "Soak dried beans overnight (16 hours was tested), pour off the water, then boil in fresh water until soft; this trims gas-causing sugars and, with thorough cooking, disarms lectin [5][6][7]." - "Canned beans are a fine shortcut. Drain and rinse them, and prefer cans labeled BPA-free or beans in glass jars or cartons [8]." cautions: - "Raw or undercooked red kidney beans can cause severe vomiting and diarrhea within hours. Always soak and cook them thoroughly [5]." - "If you have irritable bowel syndrome, beans can set off symptoms. Start with a spoonful and see our [low-FODMAP guide](/fodmap-diet/ibs-and-gut-relief)." - "With advanced kidney disease, ask your care team before making beans a daily food, because they are rich in potassium and phosphorus." confidence: 4 confidenceNote: "Several meta-analyses of randomized trials agree on cholesterol and blood-sugar effects and large cohorts link beans to lower mortality, but the effects are modest and trials are short." evidenceSummary: rctCount: 2 observationalCount: 1 metaAnalysisCount: 5 totalParticipants: "1,100,000+ (pooled cohorts)" replicated: true newestStudyYear: 2023 references: - id: "1" pmid: "24710915" title: "Effect of dietary pulse intake on established therapeutic lipid targets for cardiovascular risk reduction: a systematic review and meta-analysis of randomized controlled trials" authors: "Ha V, Sievenpiper JL, de Souza RJ, et al." year: 2014 journal: "CMAJ" - id: "2" pmid: "19526214" title: "Effect of non-oil-seed pulses on glycaemic control: a systematic review and meta-analysis of randomised controlled experimental trials in people with and without diabetes" authors: "Sievenpiper JL, Kendall CW, Esfahani A, et al." year: 2009 journal: "Diabetologia" - id: "3" pmid: "36811595" title: "Legume Consumption and Risk of All-Cause and Cause-Specific Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies" authors: "Zargarzadeh N, Mousavi SM, Santos HO, et al." year: 2023 journal: "Adv Nutr" - id: "4" pmid: "22104320" title: "Perceptions of flatulence from bean consumption among adults in 3 feeding studies" authors: "Winham DM, Hutchins AM" year: 2011 journal: "Nutr J" - id: "5" pmid: "2249712" title: "Red kidney bean poisoning in the UK: an analysis of 50 suspected incidents between 1976 and 1989" authors: "Rodhouse JC, Haugh CA, Roberts D, et al." year: 1990 journal: "Epidemiol Infect" - id: "6" pmid: "11795242" title: "The domestic processing of the common bean resulted in a reduction in the phytates and tannins antinutritional factors, in the starch content and in the raffinose, stachiose and verbascose flatulence factors" authors: "de Oliveira AC, Queiroz KS, Helbig E, et al." year: 2001 journal: "Arch Latinoam Nutr" - id: "7" pmid: "29580532" title: "Changes in levels of phytic acid, lectins and oxalates during soaking and cooking of Canadian pulses" authors: "Shi L, Arntfield SD, Nickerson M" year: 2018 journal: "Food Res Int" - id: "8" pmid: "22110104" title: "Canned soup consumption and urinary bisphenol A: a randomized crossover trial" authors: "Carwile JL, Ye X, Zhou X, et al." year: 2011 journal: "JAMA" - id: "9" pmid: "27030531" title: "Effects of dietary pulse consumption on body weight: a systematic review and meta-analysis of randomized controlled trials" authors: "Kim SJ, de Souza RJ, Choo VL, et al." year: 2016 journal: "Am J Clin Nutr" - id: "10" pmid: "24898241" title: "Consumption of nuts and legumes and risk of incident ischemic heart disease, stroke, and diabetes: a systematic review and meta-analysis" authors: "Afshin A, Micha R, Khatibzadeh S, et al." year: 2014 journal: "Am J Clin Nutr" - id: "11" pmid: "15228991" title: "Legumes: the most important dietary predictor of survival in older people of different ethnicities" authors: "Darmadi-Blackberry I, Wahlqvist ML, Kouris-Blazos A, et al." year: 2004 journal: "Asia Pac J Clin Nutr" - id: "12" pmid: "26355953" title: "Toxicity Assessment of Common Beans (Phaseolus vulgaris L.) Widely Consumed by Tunisian Population" authors: "Nciri N, Cho N, El Mhamdi F, et al." year: 2015 journal: "J Med Food" --- Yes. Beans, lentils and chickpeas are among the best-studied everyday foods. In trials, about three-quarters of a cup a day lowered LDL ("bad") cholesterol [1] and improved markers of blood sugar control [2], and large cohort analyses link them to a lower risk of early death [3]. Gas is the main complaint, and most people who get it say it fades within two to three weeks [4]. Thorough cooking takes care of the lectin worry [5]. ## How it works Beans, lentils, chickpeas and dried peas are called pulses. They deliver protein, slowly digested starch and fiber together, which is why they lower the glycemic index of a whole diet [2]. **What the trials found.** In 26 trials, a median of 130 g a day (about three-quarters of a cup cooked) lowered LDL cholesterol by 0.17 mmol/L, roughly 7 mg/dL [1]. A pulse-rich diet also led to a small weight loss of about 0.34 kg over a median of six weeks, even when calories were not restricted [9]. In observational data, each extra 50 g a day went with 6% lower all-cause mortality [3], and eating four 100 g servings a week went with 14% lower coronary heart disease [10]. Elderly people in Japan, Sweden, Greece and Australia had lower death rates the more legumes they ate [11]; our [Blue Zones](/blue-zones/longevity-secrets) article covers the wider pattern. **Why beans cause gas.** They contain raffinose-family sugars that your small intestine cannot digest, so gut bacteria ferment them. Soaking for 16 hours, discarding the leftover soaking water and then cooking cut raffinose by 25%, stachyose by 25% and verbascose by 42% in common beans [6]. Starting small also helps. In three feeding studies of half a cup a day, fewer than half of people noticed more gas in week one, and 70% or more of those who did said it eased by the second or third week [4]. **Lectins and phytic acid.** Raw red kidney beans contain a lectin that causes acute poisoning, but it is inactivated by thorough cooking of well-soaked beans [5]. Soaking alone barely changed lectin levels in Canadian pulses, while cooking was far more effective [7]. Sprouting does not solve it either: in white beans, soaking and four days of sprouting slightly raised measured lectin, and only cooking presoaked beans made it disappear [12]. Soaking also lowered phytic acid, which binds minerals, by 85% in one bean study [6]. Our [lectins](/lectins/the-plant-paradox-debate) and [phytic acid](/phytic-acid/mineral-absorption-and-antinutrients) articles explain the debate. **Canned or dried.** Canned beans arrive fully cooked, so raw-bean poisoning is not a concern. The question is the can lining. In a randomized crossover trial, volunteers who ate a daily serving of canned soup for five days had urinary bisphenol A (BPA, a plastic chemical that acts like a hormone) more than ten times higher than after fresh soup. That trial used one soup brand in 2010, so check for BPA-free cans [8]. ## The evidence in detail **Cholesterol.** Ha and colleagues pooled 26 randomized trials (1,037 people, each at least three weeks) comparing pulse-rich diets with similar-calorie diets. At a median of 130 g a day, LDL fell by 0.17 mmol/L (95% CI 0.09 to 0.25), but apolipoprotein B and non-HDL cholesterol did not change, and the authors asked for longer, better trials [1]. **Blood sugar and weight.** A meta-analysis of 41 trials found pulses alone lowered fasting glucose (standardized mean difference -0.82) and insulin, and pulses in low-glycemic diets lowered glycated proteins such as HbA1c, but heterogeneity was high and mostly unexplained [2]. For body weight, 21 trials (940 people) showed a loss of 0.34 kg (95% CI 0.04 to 0.63) at about 132 g a day. That is modest, and long-term effects are unknown [9]. **Heart disease and death.** A meta-analysis of 25 observational studies and 2 trial reports (501,791 people) found legumes went with lower coronary heart disease (risk ratio 0.86 per four weekly 100 g servings), but not significantly lower stroke or diabetes [10]. A later dose-response analysis of 32 cohorts (1,141,793 people, 93,373 deaths) found all-cause mortality 6% lower at higher intakes (hazard ratio 0.94) and stroke mortality 9% lower, but no clear association with cardiovascular, coronary or cancer mortality, with low to moderate certainty [3]. The earlier Food Habits in Later Life study followed 785 people aged 70 and over for up to seven years and reported a 7% to 8% lower mortality hazard per 20 g a day of legumes; it is the smallest of these studies and adjusted only for age, sex, smoking and, in one model, ethnicity [11]. People who eat more beans also tend to eat better overall, so confounding is likely. **Gas.** Winham and Hutchins analyzed three feeding studies (17, 29 and 80 adults) of half a cup of pinto beans, baked beans or black-eyed peas daily for 8 to 12 weeks. In week one, fewer than half reported more gas with pinto or baked beans and 19% with black-eyed peas. By week two of the crossover trials this had fallen to 6% for pinto beans, 24% for baked beans and 12% for black-eyed peas. In the 12-week parallel trial, 45% reported more gas in week one, 30% in week three and 15% to 23% in weeks 6 to 12. Between 3% and 11% reported more gas even on control foods [4]. **Lectins and antinutrients.** Between 1976 and 1989, the UK recorded 50 suspected red kidney bean poisonings. Nine were confirmed by finding the lectin in the beans, and others were diagnosed from symptoms appearing 1 to 7 hours after eating; in many cases the beans had been eaten raw or heated inadequately [5]. In peas, lentils, chickpeas, faba and common beans, soaking cut lectins by only 0.11% to 5.18% and had no effect on phytic acid, whereas cooking worked better on most antinutrients [7]. In three Tunisian white bean varieties, soaking or germination did not remove the lectin (measured by immunoassay), while cooking or autoclaving presoaked beans eliminated it and abolished its blood-clumping activity [12]. The "no effect of soaking on phytic acid" result conflicts with the 85% phytate drop after soaking common beans [6], which may reflect different beans and soaking conditions. **Cans.** In 75 volunteers (a randomized, single-blinded crossover with five-day phases), urinary BPA averaged 20.8 micrograms per liter after daily canned soup versus 1.1 after fresh soup, a 1,221% increase [8]. It tested one brand of vegetarian soup, not beans, in healthy adults with a median age of 27. **Null and mixed results.** Pulse diets did not change apolipoprotein B or non-HDL cholesterol [1], and blood-sugar benefits varied widely between trials [2]. In cohorts, legumes were not clearly tied to stroke or diabetes in one analysis [10], or to cardiovascular, coronary or cancer mortality in another [3]. Soaking results for phytic acid conflict between studies [6][7]. **Bottom line (confidence 4 of 5).** Beans likely lower LDL cholesterol and improve blood-sugar markers a little, and they are associated with modestly lower mortality. Effects are modest, most trials are short, and cohort data may be confounded. Digestive effects are real but usually temporary.