Pinto beans: a cup a day moves LDL, and the gas fades by week two

The cholesterol claim for beans holds up, and the size is modest. Across 38 randomised trials in 2095 adults, a median 130 g a day of whole pulses for a median 6 weeks lowered LDL cholesterol by 0.14 mmol/L (95 percent CI 0.08 to 0.19), with GRADE certainty moderate to high. For beans specifically the effect grew with the dose up to 1 cup a day, about 0.25 mmol/L per extra half cup, though the interval on that slope runs from 0.02 to 0.48. An earlier pooling of 26 trials in 1037 adults put the LDL drop at 0.17 mmol/L. Twenty-one trials in 940 adults found 0.34 kg of weight loss over a median 6 weeks without calorie restriction, an effect the authors call modest. Systolic blood pressure fell 2.25 mm Hg in 8 feeding trials with 554 adults, and diastolic did not change significantly. Those are pulses pooled, and no trial isolates pinto from the other beans for cholesterol. The closest is 180 adults with mildly raised cholesterol who ate 120 g a day of a four-bean mix that included pinto for 6 weeks. Their LDL fell 0.21 mmol/L against rice-based control foods, and the same weight of peas did not reach significance. The gas is real and short. Across three feeding studies of half a cup of beans a day, fewer than half of adults reported more flatulence from pinto beans in the first week, and in the crossover trials that fell to 6 percent by the second week.

The numbers, per 100 g

What a real portion looks like

• In 38 randomised trials with 2095 adults, a median 130 g a day of whole pulses for a median 6 weeks lowered LDL cholesterol by 0.14 mmol/L. For beans the effect grew linearly up to 1 cup a day, about 0.25 mmol/L per extra half cup. — 38 RCTs, 52 comparisons, 2095 adults, trials of at least 3 weeks, searched to March 2025 (n = 2095) Evidence A source
  LDL-C -0.14 mmol/L (95% CI -0.19 to -0.08); non-HDL-C -0.22 (-0.30 to -0.14); apoB -0.08 g/L; HDL-C -0.03 mmol/L; beans dose-response -0.25 mmol/L per 0.5 cup (95% CI -0.48 to -0.02) up to 1 cup/d
• Modelling on NHANES 2001-2018 data for 44 574 US adults, adding one daily serving of kidney, black, pinto beans or chickpeas raised Healthy Eating Index scores by 15 to 16%, and two servings by 19 to 20%, in both younger and older adults. Intakes of shortfall nutrients rose with them. — 44 574 US adults aged 19 and over (23 554 aged 19-50, 21 020 aged 51 and over), NHANES 2001-2018, dietary modelling (n = 44 574) Evidence C source
  HEI-2015 +15-16% with 1 serving, +19-20% with 2 servings (p < 0.0001); shortfall nutrient intakes up (p < 0.0001)

What your body absorbs

• In young women, only 2.5% of the iron in whole common bean porridge was absorbed, and removing both the beans' polyphenols and phytic acid raised absorption 2.6-fold, and removing polyphenols from already dephytinised porridge doubled it. — women, 16 or 17 per study, 6 stable iron isotope absorption studies with red common beans (n = 16-17 per study) Evidence B source
  Mean absorption 2.5% from whole bean porridge; polyphenol plus phytate removal 2.6-fold higher (P < 0.001); 200 mg bean polyphenols lowered absorption from bread by 45%
• In 29 non-anaemic young adults, a meal of 100 g of cooked common beans delivered about 0.41% of its iron into red blood cells, and a variety bred for higher iron did no better. — 29 young adult volunteers in Brazil, two groups (13 and 16), 100 g cooked labelled common beans, erythrocyte incorporation measured at 14 days (n = 29) Evidence B source
  Iron absorption 0.409% (SD 0.040%) from common beans vs 0.407% (SD 0.038%) from the biofortification-target variety, no difference

What cooking and storage change

• FDA's Bad Bug Book says the lectin phytohaemagglutinin occurs in many species of beans and is highest in red kidney beans, and advises boiling beans for at least 30 minutes and never cooking them, or dishes containing them, in a slow cooker. — FDA guidance for consumers and professionals on natural toxins in food Evidence E source
  Raw kidney beans 20,000-70,000 haemagglutinating units vs 200-400 fully cooked; boiling 10 min destroys the toxin, 30 min advised; slow-cooker casseroles reach only about 75 C
• In a Brazilian potassium analysis of cooked plant foods for cardiac patients, beans stayed below 200 mg potassium per 100 g with every cooking method, and soaking time or cooking technique made no statistically significant difference for legumes. — cooked vegetables and legumes analysed for potassium; sensory acceptance rated by 68 heart disease patients in Porto Alegre (n = 68 raters) Evidence D source
  Beans under 200 mg K/100 g across methods; lentils benefited most from soaking; pressure cooking gave the lowest losses; no significant differences for legumes by soaking duration or method

What it does to your health

• Across 26 randomised trials with 1037 adults, about one serving (130 g) of pulses a day for at least 3 weeks lowered LDL cholesterol by 0.17 mmol/L compared with isocaloric control diets. — 26 RCTs, 1037 adults, at least 3 weeks, pulse-emphasising diet vs isocaloric diet without pulses, searched to 5 February 2014 (n = 1037) Evidence A source
  LDL-C mean difference -0.17 mmol/L (95% CI -0.25 to -0.09); no effect on apolipoprotein B or non-HDL cholesterol
• In 21 randomised trials with 940 adults, diets containing about one serving (132 g) of pulses a day for a median 6 weeks produced a modest 0.34 kg weight loss versus diets without pulses, even when calories were not restricted. — 21 RCTs, 940 adults, at least 3 weeks, whole dietary pulses vs comparator diets, searched to 11 May 2015 (n = 940) Evidence A source
  Body weight -0.34 kg (95% CI -0.63 to -0.04, P = 0.03); significant in both weight-loss and weight-maintaining designs; body fat percentage may fall (6 trials)
• In 8 isocaloric feeding trials with 554 adults with and without hypertension, swapping pulses for other foods lowered systolic blood pressure by 2.25 mm Hg, with no significant change in diastolic pressure. — 8 isocaloric controlled feeding trials of at least 3 weeks, 554 adults with and without hypertension, searched to 5 May 2013 (n = 554) Evidence A source
  Systolic BP -2.25 mm Hg (95% CI -4.22 to -0.28, P = 0.03); mean arterial BP -0.75 (-1.44 to -0.06); diastolic -0.71 (-1.74 to 0.31), not significant
• In 180 adults with mild hypercholesterolaemia, 6 weeks of 120 g a day of a bean mix that included pinto beans lowered LDL cholesterol by 0.21 mmol/L versus rice-based control foods, while the same amount of peas did not. — adults with mild hypercholesterolaemia in Edmonton and Winnipeg, 60 per group, 3-arm parallel single-blind RCT, 6 weeks (n = 180) Evidence B source
  LDL-C -0.21 mmol/L (95% CI -0.39 to -0.03) beans vs rice; peas -0.11 (-0.29 to 0.07), not significant; total cholesterol -0.28 (-0.49 to -0.06); no change in glucose, insulin or blood pressure
• In 26 healthy young adults, an extruded corn snack made with 40% pinto bean flour gave a lower blood glucose and insulin response over 2 hours than the plain corn snack or snacks made with whole or split yellow pea flour. — 26 healthy young adults, double-blind randomised repeated-measures crossover, snacks with 40% pulse flour vs 100% corn control, ad libitum meal at 120 min (n = 26) Evidence B source
  Pinto bean snack: lower pre-meal glucose iAUC (p < 0.05) and insulin iAUC (p < 0.05) vs control, whole yellow pea and split yellow pea; no difference in food intake or appetite
• In a pilot crossover of 8 healthy adults, blood pressure and pulse wave velocity were lower 2 hours after three quarters of a cup of pinto beans than after navy beans. By 6 hours the darker black and red kidney beans relaxed vessels more than pinto beans. — 8 healthy adults, single-blind randomised crossover, 3/4 cup of black, navy, pinto or red kidney beans or white rice, measurements at 1, 2 and 6 h (n = 8) Evidence B source
  2 h: BP and PWV lower after pinto vs navy bean (p < 0.05); 6 h: PWV lower after black bean vs pinto, wave reflection lower after red kidney and black bean vs rice, navy and pinto (p < 0.05)

Safety, limits and interactions

• In 90 cans of pinto and fava beans sampled from Iranian chain stores in 2023, cadmium stayed below the EU limit of 0.1 mg/kg, mercury was undetectable, and the non-carcinogenic risk from toxic elements was negligible for 95% of consumers. — 90 canned pinto and fava bean samples, cluster sampling from chain stores in Rasht, Gilan Province, Iran, 2023 (n = 90 samples) Evidence C source
  Element order mercury < cadmium < arsenic < lead < tin < copper < zinc < iron; cadmium 0.004 mg/kg in pinto; iron 3.57 mg/kg in pinto; modelled lifetime cancer risk 2.68 x 10^-5 for pinto consumers

What people believe that the data does not support

• Across three feeding studies of half a cup of beans daily for 8 to 12 weeks, fewer than half of adults reported more flatulence from pinto beans in the first week, and 19% from black-eyed peas. — adults in three feeding studies: 3 x 3 crossover with pinto beans and black-eyed peas (n = 17), crossover with baked beans (n = 29), parallel trial with pinto beans vs control soup (40 + 40), 8 or 12 weeks (n = 126) Evidence B source
  First week: under 50% reported increased flatulence with pinto or baked beans, 19% with black-eyed peas; 3-11% reported it on control diets
• In the crossover feeding trials, reports of increased flatulence from half a cup of pinto beans a day fell from 50% of participants in the first week to 6% by the second week. — adults in two randomised crossover feeding trials, half a cup of beans daily, weekly symptom questionnaire (n = 46) Evidence B source
  Pinto beans: increased flatulence reported by 50% in week 1 and 6% in week 2; black-eyed peas 19% then 12%; vegetarian baked beans 47% then 24%
• A meta-analysis of six randomised trials of Phaseolus vulgaris bean extract sold as a weight-loss supplement found no significant difference in weight loss versus placebo, 1.77 kg with a confidence interval crossing zero, and every included trial had serious methodological flaws. — 6 RCTs of P. vulgaris extract vs placebo in adults, all with serious methodological flaws Evidence A source
  Weight: MD -1.77 kg (95% CI -3.33 to 0.33), not significant; body fat: MD -1.86 kg (95% CI -3.39 to -0.32); heterogeneity in both

Who this works differently for

• In 17 adults with type 2 diabetes, a breakfast of pinto beans with rice, matched for 50 g of available carbohydrate, gave a significantly lower 3-hour glucose area under the curve than white rice alone. The effect held for pinto and black beans but not kidney beans. — 17 adults with type 2 diabetes (14 on metformin, 3 diet/exercise) aged 35-70, 4 x 4 randomised crossover, test breakfasts after a 12 h fast (n = 17) Evidence B source
  Net glucose lower than rice control at 90, 120 and 150 min for all three bean meals; iAUC significantly lower for pinto/rice and black bean/rice, not for kidney bean/rice

The bottom line

One cup of cooked beans is the top of the dose curve in the meta-analysis, and the 2024 trial used 120 g, about three quarters of a cup. In 17 adults with type 2 diabetes, 14 of them on metformin, a breakfast of pinto beans with rice matched for 50 g of available carbohydrate gave a lower 3-hour glucose area under the curve than white rice alone. The same held for black beans and did not for kidney beans, in single meals with 17 completers of 28 enrolled. In 26 healthy young adults, an extruded corn snack with 40 percent pinto bean flour gave lower 2-hour glucose and insulin than the plain corn snack, and that was flour in a snack rather than whole beans. Do not count the iron. In young women, 2.5 percent of the iron in whole common bean porridge was absorbed, and in 29 non-anaemic young adults a 100 g meal of cooked common beans delivered 0.41 percent of its iron into red blood cells. Both used red or Brazilian bean types, and no isotope study has used pinto. Canned pinto beans with added sodium, drained and rinsed, carry about 202 mg of sodium per 100 g in USDA's Foundation samples. The bean extract sold for weight loss is a different product from the bean. A meta-analysis of six randomised trials of Phaseolus vulgaris extract against placebo found a weight difference of 1.77 kg with a confidence interval from 3.33 kg of loss to 0.33 kg of gain, and every included trial had serious methodological flaws. Dietary modelling on NHANES data for 44 574 US adults put Healthy Eating Index scores 15 to 16 percent higher with one added daily serving of kidney, black, pinto beans or chickpeas, in a simulation of added servings rather than in observed eaters. In a pilot crossover of 8 healthy adults, blood pressure and pulse wave velocity were lower 2 hours after three quarters of a cup of pinto beans than after navy beans, and by 6 hours black beans beat pinto on vascular tone. That is eight people and many comparisons, and nobody has repeated it. The caution that is documented is about raw and undercooked beans. FDA's Bad Bug Book says the lectin phytohaemagglutinin is found in many species of beans and is highest in red kidney beans. Its advice is to boil beans for at least 30 minutes and never to use a slow cooker for them or for dishes that contain them. FDA gives no pinto-specific figure. In 90 cans of pinto and fava beans from chain stores in one Iranian province in 2023, cadmium stayed below the EU limit of 0.1 mg/kg and mercury was undetectable, which speaks for that market and that year. A Brazilian laboratory analysis of cooked legumes found beans below 200 mg of potassium per 100 g with every cooking method and no significant effect of soaking time. That is one laboratory's cooked samples against a Brazilian food table, not a clinical result, and anyone whose potassium is restricted should go by the composition table on this page and their own clinician, not by that figure. We have no trial of pinto beans in pregnancy or in children, and no card on allergy or on interactions with medicines.

Sources

1. pnto-v1-01 · meta-analysis of RCTs
   Thirty-eight trials (52 trial comparisons, n=2095) with a median of 6 weeks and dose of 130 g/d (0.5-0.67 cup/d) showed that whole dietary pulses decreased low-density lipoprotein-cholesterol (mean difference, -0.14 mmol/L [95% CI, -0.19 to -0.08])...A linear inverse relationship was shown for beans up to 1 cup/d for low-density lipoprotein-cholesterol (coefficient, -0.25 mmol/L/0.5 cup [95% CI, -0.48 to -0.02])
   J Am Heart Assoc, 2026 · checked 2026-09-23
2. pnto-v1-15 · cross-sectional
   The beans considered were kidney beans, black beans, chickpeas, and pinto beans...Total diet quality, as measured by Healthy Eating Index-2015 scores, was 15-16 % greater with an additional serving of beans and 19-20 % higher with 2 servings of beans relative to the US typical dietary pattern (p values<0.0001).
   Maturitas, 2024 · checked 2026-09-23
3. pnto-v1-11 · RCT
   The mean iron absorption from whole bean porridge was 2.5%. PP and PA removal increased absorption 2.6-fold (P < 0.001) and removal of PP from dephytinized porridge doubled absorption (P < 0.001).
   J Nutr, 2010 · checked 2026-09-23
4. pnto-v1-12 · RCT
   The study included 29 young adult volunteers divided into 2 groups...Mean iron absorption from the meal with common beans was 0.409% (±0.040%) and mean iron incorporation from the meal with target beans for biofortification 0.407% (±0.038%) and did not differ between the groups.
   Clin Nutr ESPEN, 2018 · checked 2026-09-23
5. pnto-v1-13 · agency document
   Phytohaemagglutinin, the presumed toxic agent, is found in many species of beans, but is in highest concentration in red kidney beans (Phaseolus vulgaris)...Consumers should boil the beans for at least 30 minutes to ensure that the product reaches sufficient temperature, for a sufficient amount of time, to completely destroy the toxin. Slow cookers should not be used to cook these beans or dishes that contain them.
   FDA, Bad Bug Book: Foodborne Pathogenic Microorganisms and Natural Toxins, 2nd edition, 2012, chapter Phytohaemagglutinin · checked 2026-09-23
6. pnto-v1-16 · laboratory analysis
   Among legumes, beans showed potassium levels below this threshold across all methods...ANOVA tests revealed no statistically significant differences in potassium content for legumes across soaking durations or cooking methods.
   Clin Nutr ESPEN, 2025 · checked 2026-09-23
7. pnto-v1-02 · meta-analysis of RCTs
   Diets emphasizing dietary pulse intake at a median dose of 130 g/d (about 1 serving daily) significantly lowered LDL cholesterol levels compared with the control diets (mean difference -0.17 mmol/L, 95% confidence interval -0.25 to -0.09 mmol/L).
   CMAJ, 2014 · checked 2026-09-23
8. pnto-v1-03 · meta-analysis of RCTs
   Findings from 21 trials (n = 940 participants) were included in the meta-analysis. The pooled analysis showed an overall significant weight reduction of -0.34 kg (95% CI: -0.63, -0.04 kg; P = 0.03) in diets containing dietary pulses (median intake of 132 g/d or ∼1 serving/d) compared with diets without a dietary pulse intervention over a median duration of 6 wk.
   Am J Clin Nutr, 2016 · checked 2026-09-23
9. pnto-v1-04 · meta-analysis of RCTs
   Eight isocaloric trials (n = 554 participants with and without hypertension) were included in the analysis. Dietary pulses, exchanged isocalorically for other foods, significantly lowered systolic (MD = -2.25 mm Hg (95% CI, -4.22 to -0.28), P = 0.03)
   Am J Hypertens, 2014 · checked 2026-09-23
10. pnto-v1-05 · RCT
    Participants (n = 60 per group) were randomly assigned to 6 wk of regular consumption of foods containing either 120 g (∼0.75 cups) of beans (mixture of black, great northern, navy, and pinto) or 120 g (∼0.75 cups) peas (mixture of yellow and green), or identical foods containing white, parboiled rice (control foods)...Mean LDL-cholesterol was lower in the bean group (-0.21; 95% CI: -0.39, -0.03) but not the pea group (-0.11; 95% CI: -0.29, 0.07) relative to rice after 6 wk.
    J Nutr, 2024 · checked 2026-09-23
11. pnto-v1-09 · RCT
    In a randomized, repeated-measures crossover study, adults (n = 26) consumed extruded corn snacks made with the addition of 40% pulse flour from either whole yellow pea, split yellow pea, green lentil, chickpea, or pinto bean...Pinto bean snack also led to lower (pre-meal BG (p < 0.05) and insulin (p < 0.05) iAUC compared with control, whole yellow pea, and split yellow pea snacks.
    Appl Physiol Nutr Metab, 2021 · checked 2026-09-23
12. pnto-v1-10 · RCT
    Blood pressure and pulse wave velocity (PWV) were lower at 2 h following red kidney bean and pinto bean consumption compared to rice and navy bean, respectively (p < 0.05). There was greater vasorelaxation 6 h following consumption of darker-coloured beans, as shown by decreased vascular tone: PWV was lower after consuming black bean compared to pinto bean
    Nutr Metab Cardiovasc Dis, 2021 · checked 2026-09-23
13. pnto-v1-14 · cross-sectional
    In this descriptive-analytical, non-interventional cross-sectional study conducted in 2023, 90 samples of canned pinto beans and fava beans were randomly collected using cluster sampling from chain stores in Rasht city...In this study, the maximum measured cadmium level was below the EU standard limit (0.1 mg/kg)...The non-carcinogenic risk was negligible for 95% of consumers
    Sci Rep, 2026 · checked 2026-09-23
14. pnto-v1-07 · RCT
    Study 3 was a parallel arm trial with 40 subjects receiving ½ cup pinto beans and 40 consuming a control soup for 12 weeks...Less than 50% reported increased flatulence from eating pinto or baked beans during the first week of each trial, but only 19% had a flatulence increase with black-eyed peas.
    Nutr J, 2011 · checked 2026-09-23
15. pnto-v1-08 · RCT
    By the second week of the cross-over trials, reports of increased flatulence dropped to 6% of participants for the pinto beans, 12% for the black-eyed peas and to 24% for the vegetarian baked beans.
    Nutr J, 2011 · checked 2026-09-23
16. pnto-v1-17 · meta-analysis of RCTs
    We identified eleven eligible trials, and six were included. All the included RCT had serious methodological flaws. A meta-analysis revealed a statistically non-significant difference in weight loss between P. vulgaris and placebo groups (mean difference (MD) − 1.77 kg, 95 % CI − 3.33, 0.33).
    Br J Nutr, 2011 · checked 2026-09-23
17. pnto-v1-06 · RCT
    Seventeen men and women with type 2 diabetes controlled by metformin (n = 14) or diet/exercise (n = 3) aged 35-70 years participated in the randomized 4 × 4 crossover trial...Incremental area under the curve values were significantly lower for the pinto and black bean/rice meals compared to rice alone, but not for kidney beans.
    Nutr J, 2012 · checked 2026-09-23