Fava beans: a folate bean with a real danger for G6PD deficiency

A systematic review of 26 randomized trials on extracted plant proteins found only 2 that used fava bean protein, and judged the evidence on plant proteins not yet sufficient for dietary recommendations. That is the strongest evidence on fava beans as a food, and it is a gap. The best documented fact about this bean is a danger for one group. Among 1000 G6PD-deficient patients at one Egyptian pediatric hematology unit, diet set off 83.4 percent of hemolytic crises, fava beans 32.6 percent and falafel 19.4 percent. Ninety-two percent of the crises came at ages 1 to 3. It is a single clinic's series and does not tell you how common favism is. For people without the deficiency, the numbers are mostly about folate. The USDA record gives raw beans in the pod 148 mcg folate per 3.5 oz (100 g), from a single record. Boiling legumes for 45 to 75 minutes keeps about 45 percent of folate by the USDA group factor dated 1975, which was not measured on fava beans. A cup of cooked fava beans weighs 6.5 oz (185 g) in the US survey food list.

The numbers, per 3.5 oz (100 g)

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

How much is actually in it

• Per 100 g, raw fava beans in the pod list 148 mcg folate, 0.402 mg copper and 40.9 mcg vitamin K in the USDA reference record. — Single SR Legacy record, raw in pod Evidence E source
  Folate 148 mcg (37% DV), copper 0.402 mg (45% DV), vitamin K 40.9 mcg (34% DV)

What a real portion looks like

• In the US dietary survey food list, one cup of cooked fava beans weighs 6.5 oz (185 g). — FNDDS food 41102210 Fava beans, cooked Evidence E source
  1 cup 185 g; unspecified quantity 92 g

What your body absorbs

• In a randomized crossover trial in 9 adults, two fava bean hull bread rolls a day gave over 85% of daily fiber needs, but the hull plant metabolites were poorly absorbed into blood. — 9 healthy adults aged about 54, two 3-day sessions (n = 9) Evidence B source
  Fiber >85% of daily recommendation; plasma indole-3-propionic acid up (P = 0.009); poor systemic bioavailability of hull metabolites

What cooking and storage change

• For legumes boiled 45 to 75 minutes and drained, the USDA retention table keeps 45% of folate, 60% of thiamin and 80% of iron. — Food group Legumes and Legume Products (factor set on the group) Evidence E source
  Folate 45%, thiamin 60%, copper 65%, iron 80%, zinc 85% retained

What it does to your health

• In a randomized trial of 16 young adults, 0.33 g/kg of fava bean protein after resistance exercise did not raise muscle protein synthesis more than an amino-acid-free control, 78% vs 58%. — 16 healthy recreationally active adults aged about 25, single session (n = 16) Evidence B source
  Post-exercise myoFSR +78% [33, 123] vs +58% [9, 107], p = 0.732
• In a randomized crossover meal test in 33 men, a fava bean and split pea meal led to the same later energy intake as fiber-matched meat or egg meals, about 2608 vs 2636 kJ. — Healthy men aged 18 to 50, four test days (n = 33) Evidence B source
  Ad libitum intake bean/pea 2608 ± 194 kJ vs meat/fiber 2636 ± 200 kJ, p > 0.05

Safety, limits and interactions

• A case report describes a 47-year-old with G6PD deficiency who developed both hemolysis and methaemoglobinemia after fava beans, and warns that methylene blue worsens hemolysis. — One 47-year-old patient (n = 1) Evidence D source
  Jaundice from day 2; discharged after 2 days on oxygen
• Canned fava beans sampled in northern Iran had cadmium below the EU limit and a non-carcinogenic risk judged negligible for 95% of consumers. — Canned pinto and fava beans from chain stores in Rasht, 2023, 4 fava brands (n = 90 samples) Evidence C source
  Fava iron 7.079 mg/kg, arsenic 0.01 mg/kg; carcinogenic risk 1.30 x 10^-5 for fava

What people believe that the data does not support

• In a Sardinian survey of 536 adults, 62.5% wrongly believed that inhaling fava bean pollen is a favism hazard, while 99% knew eating the beans is a trigger. — 536 adults, online survey in Sardinia, 2025 (n = 536) Evidence C source
  62.50% attributed hazard to pollen; 25.93% to peas; 99.07% named ingestion

Who this works differently for

• Among 1000 Egyptian patients with G6PD deficiency, 92% had their hemolytic crisis at ages 1 to 3, and fava beans were the most common trigger, in 32.6%, with falafel in 19.4%. — 1000 G6PD-deficient patients, pediatric hematology unit, Tanta, 2011-2016 (n = 1000) Evidence C source
  Fava beans 32.6%, falafel 19.4%, broad bean 7.6% of triggers; 932 males vs 68 females
• Two boys aged 12 and 14 with undiagnosed G6PD deficiency needed transfusions and pediatric ICU care after eating fava beans. — Two pediatric patients, unknown G6PD status (n = 2) Evidence D source
  Methaemoglobin 6.1% and 7%; ICU stays of 3 and 4 days; full recovery
• The FDA-approved warfarin label says the amount of vitamin K in food may affect therapy and advises patients to eat a normal, balanced diet with a consistent amount of vitamin K. — patients taking warfarin sodium Evidence E source
  No effect size given; the label asks for a consistent amount of dietary vitamin K rather than avoidance

What is still unknown

• A systematic review of 26 randomized trials on extracted plant proteins found only 2 on fava bean protein and judged the evidence not sufficient for dietary recommendations. — Adults in RCTs of concentrated, isolated or hydrolyzed plant proteins (n = 26 studies) Evidence A source
  Plant protein effects comparable, not superior, to animal protein
• In 38 people with past favism, 92.1% later resumed eating fava beans without symptoms and 2 had a single recurrence. — 38 patients with a history of favism, 2005-2012 (n = 38) Evidence C source
  35/38 resumed without symptoms; 2 (5.2%) single recurrence

The bottom line

The few trials on fava foods are small and short. In 16 young adults, isolated fava bean protein after resistance exercise did not raise muscle protein synthesis significantly more than a control without amino acids, 78 percent against 58 percent (p = 0.732). In 33 men, a fava bean and split pea meal led to the same later energy intake as fiber-matched meat or egg meals, 2608 against 2636 kJ, after a single meal. In 9 adults over two 3-day sessions, two rolls made with fava bean hulls supplied over 85 percent of the daily fiber recommendation, while the plant compounds in the hulls were poorly absorbed into the blood. If you have G6PD deficiency, or a child who has never been tested, fava beans are a known trigger of hemolysis. Two boys of 12 and 14 with undiagnosed deficiency needed transfusions and pediatric intensive care after eating them, and both recovered fully. Those boys and a 47-year-old in another case report developed methaemoglobinemia alongside the hemolysis. Both reports warn that methylene blue, the usual treatment for methaemoglobinemia, worsens hemolysis in these patients. Favism is also hard to predict. Of 38 people with past favism, 35 later ate fava beans again without symptoms and 2 had a single recurrence. That is a small retrospective series and not a reason to try. In a Sardinian online survey of 536 adults, 62.5 percent believed that breathing fava bean pollen is a favism hazard, a belief the authors call incorrect. Almost all of them, 99 percent, knew that eating the beans is a trigger. Canned fava beans from 4 brands in Rasht, northern Iran, had cadmium below the EU limit of 0.1 mg/kg, and a risk model judged the non-carcinogenic risk negligible for 95 percent of consumers. The same model put the carcinogenic risk from toxic elements for canned fava bean consumers at 1.30 in 100,000. That covers one region and one season. We have no card yet on fava beans and medicines, and that gap is not a sign of safety.

Sources

1. fvbn-daily-r6-01 · Food composition database
   Beans, fava, in pod, raw (FDC 168574, SR Legacy, Vegetables and Vegetable Products): copper 0.402 mg per 100 g = 45% DV; folate 148 ug = 37% DV; vitamin K 40.9 ug = 34% DV; Foundation samples 0, CoFID match none
   USDA FoodData Central, SR Legacy 2018, FDC 168574 (Beans, fava, in pod, raw) · checked 2026-10-01
2. fvbn-daily-r6-02 · Survey food database
   FNDDS 41102210 Fava beans, cooked, fdc_id 2707367: 1 cup 185 g | 1 oz dry, yield after cooking 72 g | Quantity not specified 92 g
   USDA FNDDS, FDC 2707367, code 41102210 (Fava beans, cooked) · checked 2026-10-01
3. fvbn-daily-r6-06 · RCT crossover
   Two bean hull rolls provided over 85 % of the daily recommendation for dietary fibre; but despite being a rich source of plant metabolites (P = 0·04 v. control bread), these had poor systemic bioavailability.
   Br J Nutr, 2023 · checked 2026-10-01
4. fvbn-daily-r6-03 · Nutrient retention table
   USDA-RETN-R6:521 LEGUMES,CKD 45/75MIN,BOILED,DRND, Legumes and Legume Products (16): folate 45%, thiamin 60%, copper 65%, vitamin B6 65%, potassium 70%, magnesium 75%, iron 80%, calcium 85%, zinc 85% retained
   USDA Table of Nutrient Retention Factors, Release 6 (2007), code 521 LEGUMES,CKD 45/75MIN,BOILED,DRND · checked 2026-10-01
5. fvbn-daily-r6-04 · RCT
   However, ingestion of FBP did not evoke an increase in resting (FBP 29 [-5, 63] vs. CON 12 [-25, 49]%, p = 0.409, mean % change [95% CI]) or post-exercise (FBP 78 [33, 123]% vs. CON 58 [9, 107]%, p = 0.732) myoFSR.
   Nutrients, 2022 · checked 2026-10-01
6. fvbn-daily-r6-05 · RCT crossover
   No differences were found in energy intake at the ad libitum meal across test meals: meat/fiber 2636 ± 200 kJ (630 ± 48 kcal), egg 2771 ± 201 kJ (662 ± 48 kcal), bean/pea 2608 ± 194 kJ (623 ± 37 kcal), egg/fiber 2513 ± 203 kJ (600 ± 48 kcal), p > 0.05 (Figure 2).
   Nutrients, 2018 · checked 2026-10-01
7. fvbn-daily-r6-09 · Case report
   Patients with G6PD deficiency can develop both acute hemolytic anemia and methemoglobinemia secondary to fava beans ingestion. These patients should not receive methylene blue to avoid worsening hemolysis.
   Medicine (Baltimore), 2021 · checked 2026-10-01
8. fvbn-daily-r6-13 · Cross-sectional analysis
   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; however, the carcinogenic risk from potentially toxic elements for 95% of consumers of canned pinto beans and fava beans was 2.68 × 10⁻⁵ and 1.30 × 10⁻⁵, respectively.
   Sci Rep, 2026 · checked 2026-10-01
9. fvbn-daily-r6-11 · Cross-sectional survey
   While 99.07% correctly identified fava bean ingestion as a trigger and 74.25% identified certain medications, 62.50% incorrectly attributed hazard to pollen inhalation and 25.93% to pea consumption.
   Nutrients, 2026 · checked 2026-10-01
10. fvbn-daily-r6-08 · Retrospective series
    The highest prevalence of hemolytic crisis in G6PD deficiency patients was found within the age group of 1-3 years (920 patients; 92%) with mean age of the first presentation of 22.8±15.54 months. ... Diets were the most common precipitating factor of hemolysis in patients with G6PD deficiency (834 patients; 83.4% of studied cases) especially fava beans (326 patients; 32.6%) and falafel (194 patients; 19.4%)
    Endocr Metab Immune Disord Drug Targets, 2018 · checked 2026-10-01
11. fvbn-daily-r6-10 · Case series
    A 14-year-old boy, with short stature on growth hormone therapy and no history of hematologic disease, presented with acute hemolysis and respiratory distress one day after consuming Fava beans. ... Methylene blue, the primary treatment of methemoglobinemia, is contraindicated.
    Cureus, 2026 · checked 2026-10-01
12. sf-vkw-r1-9 · drug label
    The amount of vitamin K in food may affect therapy with warfarin sodium. Advise patients taking warfarin sodium to eat a normal, balanced diet maintaining a consistent amount of vitamin K.
    Warfarin sodium, FDA-approved label, drug interactions section, effective 2026-06-25 · checked 2026-10-08
13. fvbn-daily-r6-07 · Systematic review
    Plant protein sources used in interventions were most often pea (n = 16), followed by lupin (n = 4), fava bean (n = 2), rice (n = 2), oat (n = 2), hemp (n = 2) and lentil (n = 1). ... However, the current evidence is still not sufficient to formulate explicit dietary recommendations. In general, the effects of plant protein were comparable (but not superior) to protein originating from animals.
    Nutrients, 2020 · checked 2026-10-01
14. fvbn-daily-r6-12 · Retrospective cohort
    Thirty-three patients (86.7%) regularly ate fava beans before the attack, and 35 (92.1%) resumed eating fava beans within 1-17 years after the attack without symptoms. Two patients (5.2%) experienced a single recurrence of symptoms.
    Hematol Oncol Stem Cell Ther, 2013 · checked 2026-10-01