Kidney beans with meat: what the pork does for the iron

Nobody has studied kidney beans with meat as a dish, so this page is built from its two halves. The strongest evidence nearby is a myth test. A meta-analysis of 6 trials of kidney bean extract sold as a slimming aid found a weight loss of 3.9 lb (1.77 kg) against placebo that did not reach significance (95% CI -3.33 to 0.33), and every one of those trials had serious flaws. The EU has refused the weight loss claim for white kidney bean extract. The useful finding is about iron. In a randomized trial in 45 healthy women, adding 1.8 oz (50 g) of pork to a phytate-rich meal raised non-heme iron absorption by 44%, and 75 g raised it by 57%, while 25 g made no significant difference. That meal was rice and peas, and the absolute gain was only 2.6 to 3.4 percentage points.

As people eat it, per 3.5 oz (100 g)

What a real portion looks like

• In US survey data a cup of kidney beans with meat weighs 9.2 oz (260 g) and an unspecified serving is counted as 130 g. — US survey food code, Kidney beans with meat Evidence E source
  1 cup 260 g, quantity not specified 130 g

What your body absorbs

• In 45 women, adding 50 g or 2.6 oz (75 g) of pork to a phytate-rich meal raised non-heme iron absorption by 44% and 57%, while 25 g made no significant difference. — 45 healthy women, mean age 24, single labeled meals (n = 45) Evidence B source
  +44% (P < 0.001) with 50 g, +57% (P < 0.001) with 75 g, 25 g not significant (P = 0.13)
• In 20 young women, experimental beans bred low in phytic acid gave 60% to 130% more iron absorption than their parent bean lines, showing how much phytic acid holds back iron from beans. — 20 young women, crossover double test meals of four bean lines (n = 20) Evidence B source
  Fractional absorption 6.1% (95% CI 2.6 to 14.7) from low-phytate bean vs parent lines, +60% and +130%

What cooking and storage change

• In 21 women, cooking the 2.6 oz (75 g) of pork at 120 C rather than 70 C did not weaken the boost that meat gives to non-heme iron absorption from a phytate-rich meal. — 21 women aged about 25, labeled meals with 75 g pork cooked at 70, 95 or 120 C (n = 21) Evidence B source
  Extra absorption 0.9% (70 C), 0.7% (95 C), 2.0% (120 C, P < 0.001)
• FDA says raw or undercooked kidney beans carry a lectin that causes nausea, severe vomiting and diarrhea, and that soaking 5 hours then boiling at least 30 minutes destroys it. — consumers preparing dry kidney beans Evidence E source
  Canned and properly cooked beans have low levels

What it does to your health

• In a pilot crossover trial in 8 adults, three quarters of a cup of red kidney beans lowered blood pressure and pulse wave velocity 2 hours after eating compared with rice. — 8 healthy adults, single servings of 3/4 cup beans or rice, at least 6 days apart (n = 8) Evidence B source
  Lower BP and PWV at 2 h vs rice (p < 0.05), size not given in abstract
• Observational data link US adult eating patterns with about two servings of beans a day to higher diet quality scores than patterns without beans. — US adults, NHANES 2001-2018 Evidence C source
  HEI-2015 61.2 vs 48.8 for the top bean pattern vs no beans

Safety, limits and interactions

• Laboratory data suggest that common bean lectins act as anti-nutritional factors that can upset the gut, and heating is one of the steps that changes their activity. — review of characterization and processing studies Evidence D source
  Qualitative

What people believe that the data does not support

• A meta-analysis of 6 poor-quality trials found bean extract sold as a slimming aid did not significantly reduce weight, 3.9 lb (1.77 kg) versus placebo. — 6 RCTs of Phaseolus vulgaris extract supplements (n = 6 trials) Evidence A source
  Weight MD -3.9 lb (95% CI -7.3 to 0.73; metric: -1.77 kg, -3.33 to 0.33), body fat MD -4.1 lb (-7.5 to -0.71; metric: -1.86 kg, -3.39 to -0.32)
• The EU rejected the claim that a white kidney bean extract helps to reduce body weight. — EU food labeling Evidence E source
  Non-authorized claim

The bottom line

Beans hold their own iron back. In a crossover trial in 20 young women, experimental bean lines bred low in phytic acid gave 60% to 130% more iron absorption than their parent lines, and those lines are not the beans sold in shops. Cooking the meat hotter does not cancel its effect on iron. In 21 women given 2.6 oz (75 g) of pork cooked at 70, 95 or 120 C, the higher temperatures did not impair absorption from a meal that was again not beans. For the heart there is one tiny trial. In 8 healthy adults, blood pressure and arterial stiffness were lower 2 hours after three quarters of a cup of red kidney beans than after rice, from a single serving with no meat and no effect size in the abstract. US survey data link eating patterns that include beans with higher diet quality scores, 61.2 against 48.8, an association that pools several kinds of bean. A cup of the dish weighs about 9.2 oz (260 g) in US survey records. The caution that matters is cooking the beans. The FDA says raw or undercooked kidney beans carry a lectin, PHA, that can cause nausea, severe vomiting and diarrhea. Soaking for at least 5 hours and then boiling in fresh water for at least 30 minutes destroys it, and canned or properly cooked beans have low levels. Laboratory reviews describe bean lectins as anti-nutritional factors that can upset the gut, with no human dose data behind that. We have no card on pregnancy, children or drug interactions for this dish.

Sources

1. kbwm-r6-09 · dataset
   FNDDS 41106170 Kidney beans with meat (fdc 2707386): 1 cup 260 g · Quantity not specified 130 g
   USDA FNDDS 2021-2023, food code 41106170, fdc 2707386 · checked 2026-10-03
2. kbwm-r6-01 · RCT
   Forty-five healthy women with a mean (+/-SD) age of 24 +/- 3 y were randomly assigned to 1 of 3 groups ... Twenty-five grams meat did not increase nonheme-iron absorption significantly (P = 0.13), whereas absorption increased 44% (P < 0.001) and 57% (P < 0.001), respectively, when 50 and 75 g meat were added to the basic meal.
   Am J Clin Nutr, 2003 · checked 2026-10-03
3. kbwm-r6-03 · RCT (crossover)
   Iron bioavailability from common beans is negatively influenced by phytic acid (PA) and polyphenols (PPs). ... Fractional iron absorption from the lpa bean high in PPs was 6.1% (95% CI: 2.6, 14.7), which was 60 and 130% higher compared with the parent high in PPs (P < 0.001) and low in PPs (P < 0.001), respectively.
   J Nutr, 2013 · checked 2026-10-03
4. kbwm-r6-02 · RCT
   Twenty-one women (25 +/- 3 y) were served a basic meal without meat and two other meals consisting of the basic meal plus 75 g of pork meat cooked at 70, 95 or 120 degrees C. ... Increasing the cooking temperature of meat did not impair nonheme iron absorption compared with cooking at 70 degrees C.
   J Nutr, 2003 · checked 2026-10-03
5. kbwm-r6-05 · agency guidance
   In canned and properly cooked kidney beans, the low levels of PHA won't affect you. But at high levels in raw beans, PHA can lead to nausea, severe vomiting, and diarrhea. Soaking the beans for a minimum of 5 hours and then boiling them in fresh water for at least 30 minutes will remove and destroy this toxin.
   US FDA, Natural Toxins in Food · checked 2026-10-03
6. kbwm-r6-04 · RCT (crossover, pilot)
   Vascular tone (primary endpoint), haemodynamics and serum biochemistry (secondary endpoints) were measured in 8 healthy adults before and at 1, 2, and 6 h after eating ¾ cup of beans or rice. 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).
   Nutr Metab Cardiovasc Dis, 2021 · checked 2026-10-03
7. kbwm-r6-10 · cross-sectional
   Adults consuming Bean Dietary Patterns 1, 2, 3 and 4 had significantly higher diet quality scores (as assessed by USDA's Healthy Eating Index-2015) compared to the no-bean pattern (61.2 ± 0.5, 58.9 ± 0.5, 55.2 ± 0.4 and 56.5 ± 0.8 vs 48.8 ± 0.2 p's < 0.0001).
   Nutr J, 2024 · checked 2026-10-03
8. kbwm-r6-06 · systematic review (mechanistic)
   Studies have shown that lectins are anti-nutritional factors that can cause intestinal disorders. ... These purification strategies entail considerations such as effects of proteolysis, heating, gamma radiation, and high-hydrostatic-pressure that can have crucial outcomes in either eliminating or improving bioactivities of the lectins.
   Crit Rev Food Sci Nutr, 2018 · checked 2026-10-03
9. kbwm-r6-07 · meta-analysis of RCTs
   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 2026-10-03
10. kbwm-r6-08 · regulatory decision
    POL-HC-8466 Standardised aqueous extract from white kidney bean (Phaseolus vulgaris L.) Helps to reduce body weight -/- Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-8466, snapshot 2026-09-21 · checked 2026-10-03