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Phaseolus vulgaris
Caution🐾Gartenbohne · (Phaseolus vulgaris var. vulgaris)
Bean family (Fabaceae)
Description
Trained on poles or trellises, this climbing form of the common bean is a familiar sight in kitchen gardens. Freshly harvested, immature pods provide vitamin K, vitamin C, folate and dietary fibre, but must always be cooked — raw or insufficiently heated beans contain the lectin phytohaemagglutinin and can cause severe poisoning even in small amounts. Dried seeds are a clinically studied source of plant protein with a low glycaemic index and resistant starch that acts prebiotically and helps buffer blood sugar. Because of their vitamin K content, intake should stay consistent for people on vitamin K antagonists such as phenprocoumon. A traditional infusion made from the pods serves in folk medicine as a mild diuretic for flushing the urinary tract.
Fresh green beans (harvested immature pod) are a nutrient-rich vegetable providing vitamin K, vitamin C, folate and dietary fibre — to be consumed cooked only.
Preparation & dosage
FRESH GREEN BEANS (vegetable): Harvest young, immature pods (approx. 10–15 cm, seeds still small and soft) and ALWAYS cook for a minimum of 10 minutes in plenty of rapidly boiling water — never eat raw. Discard the cooking water, which contains leached lectins and oligosaccharides. Use as a side dish, in salads (after cooling), soups, stews or bean puree. Blanched and frozen, the produce keeps 10–12 months.
Dried bean seeds are a plant protein source (approx. 7–9 g/100 g cooked) with low glycaemic index, high dietary fibre, folate, iron and potassium — to be consumed only after proper cooking.
Preparation & dosage
DRIED BEANS (pulse): Soak dried beans for at least 8–12 hours in plenty of cold water; discard soaking water. Then boil vigorously in fresh water for at least 45–60 minutes (strong boiling is essential to fully denature phytohaemagglutinin — do NOT use a slow cooker for dried kidney beans). Discard the cooking water (leached lectins and oligosaccharides). Use cooked beans in soups, stews, salads (after cooling), hummus-style dips or bean paste. Tinned/canned beans are already cooked — drain and rinse before use.
Traditional bean hull tea (Phaseoli pericarpium) — folk medicinal mild aquaretic for urinary flushing therapy; evidence at folk medicine level only.
Preparation & dosage
BEAN HULL TEA (Phaseoli pericarpium): Pour 250 ml boiling water over 3–5 g dried, chopped bean hulls (outer pods without seeds — use only from ripe dried beans; green pods are less suitable), cover, steep 15 minutes, strain. 2 cups daily for a maximum of 4 weeks. Folk medicinal use as a mild aquaretic (diuretic) for mild urinary tract infections and flushing of the urinary tract — adjunctive only, no substitute for medical treatment. Important: drink plenty of fluid (at least 2 litres of water daily) during use. Fever, severe pain or blood in urine: see doctor immediately.
- Dry amount
- 3–5 g
- Doses per day
- 2×
- Max duration
- 4 weeks
Cooked dried beans are a clinically supported plant protein source with low glycaemic index — beneficial for blood glucose management and LDL cholesterol reduction.
Preparation & dosage
PLANT PROTEIN SOURCE / DIABETIC DIET: Cooked beans (tinned or home-cooked) have a low glycaemic index (GI approx. 20–40 depending on variety) and high satiety effect. A protein source in vegetarian and vegan diets (beans + cereal = complete amino acid profile). Studies show: regular legume consumption (at least 3–4 × weekly 80 g cooked beans) lowers LDL cholesterol and improves glycaemic control. Not for self-treatment of diabetes — dietary therapy under medical/dietetic supervision.
Traditional kitchen bean in stews, salads and gratins — a classic of European and Latin American cuisine; traditionally combined with savory to reduce flatulence.
Preparation & dosage
KITCHEN — TRADITIONAL PREPARATIONS: Cooked beans (white, red, black, borlotti) in classic dishes: stews (minestrone, chilli con/sin carne), bean salad with vinegar and oil (only from cooled, fully cooked beans), bean puree (hummus-style), bean bread (cooked beans as flour substitute up to 30 %), fermented soy-sauce analogues (traditional in Latin America). Savory (Satureja hortensis/montana) is the traditional kitchen companion — reputed to reduce flatulence and aid digestion, effect empirical. Always: never raw or merely lukewarm. Slow cookers (< 100 °C) may fail to inactivate lectins sufficiently — insist on vigorous boiling.
Cooked dried beans are a significant source of folate, non-haem iron and potassium — especially relevant in vegetarian/vegan diets and during pregnancy.
Preparation & dosage
FOLATE / IRON / POTASSIUM — MICRONUTRIENT USE: 100 g cooked white beans provide approx. 130 µg folate (≈ 65 % of EU daily requirement), 3.7 mg iron (≈ 26 % DV) and 561 mg potassium (≈ 28 % DV). Particularly relevant in pregnancy (increased folate demand) and vegetarian/vegan diets (iron supply). Combining with vitamin-C-rich vegetables (peppers, tomatoes) enhances non-haem iron absorption. Not a substitute for supplementation in clinically confirmed deficiency.
Beans are rich in dietary fibre and resistant starch — prebiotic effect, blood glucose buffering and promotion of gut health, clinically documented.
Preparation & dosage
DIETARY FIBRE / RESISTANT STARCH: Cooked beans contain 6–8 g dietary fibre per 100 g (soluble + insoluble) and resistant starch (especially high after cooling). Both fractions act as prebiotics, promote gut microbiome diversity and increase stool frequency. Slowly digestible carbohydrates buffer blood glucose rise. Note: dietary fibre and non-absorbable oligosaccharides (raffinose, stachyose) can cause bloating and flatulence — gradual increase in consumption amount is recommended.
CRITICAL — RAW BEANS ARE TOXIC: Raw or insufficiently heated beans (green pods AND dried beans) contain phytohaemagglutinin (PHA, phasin), a lectin that causes nausea, severe vomiting, diarrhoea and abdominal cramps — as few as 4–5 raw kidney beans can trigger severe poisoning in an adult. Lethal dose for adults is approximately 100 raw kidney beans. The toxin is FULLY denatured by vigorous boiling (at least 10 minutes at a rolling boil for green beans; at least 45–60 minutes for dried beans after soaking). WARNING slow cookers: temperatures below 80 °C can activate PHA rather than denature it — do NOT use a slow cooker for dried beans without first boiling vigorously for 10 minutes. Tinned/canned beans: industrially sterilised, safe. Additionally, indigestible oligosaccharides (raffinose, stachyose) cause bloating and flatulence — normal phenomenon, not dangerous. Toxic to dogs and cats: Raw beans contain phasin (a lectin) that causes vomiting and diarrhoea in dogs and cats too. CliniTox: strongly toxic ++. Cooked beans are harmless.
Fully cooked beans are safe in pregnancy and nutritionally valuable (folate, iron, fibre). Raw — never, as always. Bean hull tea (aquaretic) should be avoided in pregnancy due to insufficient safety data.
Fully cooked beans are safe and recommended during lactation. Bean hull tea should be avoided during lactation due to lack of safety data.
Fully cooked beans are suitable from the start of complementary feeding (from approx. 6 months, pureed). Flatulence may be more pronounced in infants — test small amounts. Bean hull tea not for children under 12 years. If a toddler ingests raw beans (even a few), seek medical advice immediately.
Drug interactions
Eisenpräparate / Nicht-Häm-Eisenresorption
Phytic acid in beans can inhibit absorption of non-haem iron (and oral iron supplements). When oral iron preparations and large quantities of beans are consumed simultaneously, levels may be lower than expected. Vitamin C in the same meal partially counteracts this effect.
Orale Antikoagulanzien (Vitamin-K-Antagonisten: Warfarin, Phenprocoumon)
Green beans contain relatively high amounts of vitamin K1 (phytomenadione), which can reduce the anticoagulant effect of vitamin K antagonists. With consistent, steady consumption in usual amounts, not an acute problem — but fluctuations in consumption amounts should be avoided; INR monitoring recommended.
Contraindications
- Raw or insufficiently heated consumption (green pods or dried beans) — phytohaemagglutinin poisoning risk.
- Hypersensitivity to legumes (Fabaceae allergy); cross-reactions with other leguminosae possible.
- Bean hull tea: not for existing kidney disease or impaired renal function without medical consultation.
Harvested part: pods and beans
- Time of day:
- Morning, after dew has dried (approx. 9–11 am) — pods are then turgid and snap off cleanly. Harvest tip: pick climbing/pole beans daily or every 2 days — missed pods that ripen to seed maturity inhibit new flower and pod formation.
- Drying:
- GREEN BEANS (fresh consumption): Harvest young pods at approx. 10–15 cm length (before seed maturity) by snapping off — no tool needed. Pods should be firm, deep green and stringless (climbing/pole beans: variety-dependent — prefer stringless varieties). For short-term storage (3–5 days): refrigerate unwashed. For freezing: blanch 2–3 minutes, shock in ice water, dry, freeze in portions (keeps 10–12 months). Do NOT store raw and eat raw later — always cook.
- Storage:
- 12 months — Fresh: 3–5 days in refrigerator (vegetable drawer, approx. 7–10 °C), do not wash before storage. Blanched and frozen: up to 12 months. Do not store at room temperature — wilts rapidly.
- Time of day:
- On a dry, sunny day in late summer to early autumn (Sept–Oct) — pods should be dry, light beige to yellowish-brown and rustling; seeds rattle when shaken. Harvesting in damp conditions greatly increases mould risk.
- Drying:
- DRIED BEANS (pulse): Pull/cut whole plants or individual ripe pods from the bed when most pods are paper-dry. Hang pods to ripen further in a well-ventilated, dry place (bundled, upside down — 2–4 weeks). Then open pods by hand and remove seeds. Post-dry seeds 1–2 weeks on clean paper at room temperature (< 25 °C, < 50 % relative humidity). Store in airtight jars, dry, cool and dark. Always soak (8–12 h) and boil vigorously before cooking.
- Storage:
- 24 months — Dried beans (fully dried, < 12 % moisture) in airtight jars or containers, cool (< 20 °C), dry and dark: keeps 1–3 years. Older beans require longer cooking time. Discard entirely if mould or weevil infestation (bean bruchid beetle) is present.
- Phytohaemagglutinin (PHA, Phasin — Klasse der Lektine)OtherContent: 1–3 % (Rohbohnen)Seed
Seed glycoprotein (lectin) of the Phaseolus genus that agglutinates erythrocytes and damages the intestinal mucosa. Highest concentration in red kidney beans. Thermolabile: full denaturation ensured by 10-minute vigorous boiling (100 °C); slow cookers (70–80 °C) inactivate PHA insufficiently. Raw bean poisoning presents within 1–3 hours with vomiting and diarrhoea.
- PhaseolinOtherContent: ca. 40–50 % des SamenproteinsSeed
Legumin-type globulin; the principal storage protein of the bean seed and main constituent of plant protein content. Contains all essential amino acids, but sulphur-containing amino acids (methionine, cysteine) are limiting — complementary cereal (methionine-rich) provides a complete amino acid profile.
- Pflanzliches Protein (Gesamtrohprotein)OtherContent: 6–9 % (gegart) / 20–25 % (trocken)Seed
Cooked beans provide 7–9 g protein per 100 g at low caloric density. Biological value approx. 75 (reference egg = 100); combinable with cereal to exceed 90. Important plant protein source in vegetarian, vegan and carbohydrate-reduced diets.
- Dietary Fibre / Ballaststoffe (löslich + unlöslich, inkl. resistente Stärke)PolysaccharideContent: 6–8 g/100 g gegartSeed
Mixture of insoluble cellulose/hemicellulose fractions and soluble pectins + galactomannans. After cooling, retrograde starch forms (resistant starch type RS3), acting as a prebiotic and slowing blood glucose rise. Bean hulls (Phaseoli pericarpium) also contain dietary fibre and are used in folk medicine as an aquaretic.
- Oligosaccharide: Raffinose, Stachyose, VerbascosePolysaccharideContent: 2–5 % (Trockenmasse)Seed
Non-absorbable but fermentable sugars of the raffinose family. Not cleaved by human digestive enzymes; fermented in the colon by gut bacteria (Bifidobacterium, Lactobacillus) → CO₂, H₂, methane → flatulence. Prebiotic effect on microbiota composition. Soaking and discarding cooking water reduces oligosaccharide content.
- Folat (Folsäure-Äquivalente, Vitamin B9)VitaminContent: ca. 130–140 µg/100 g gegartSeed
Beans are one of the most folate-rich plant sources. Folate is essential for DNA synthesis and cell division, particularly critical in early pregnancy for prevention of neural tube defects. Heat-stable when cooked in the pod, but sensitive to cooking water loss (minimise losses by cooking briefly with little water).
- Nicht-Häm-Eisen (Fe²⁺/Fe³⁺)MineralContent: ca. 3–4 mg/100 g (Trockenbohnen gegart)Seed
Relevant plant iron source; bioavailability reduced by simultaneously present phytic acid (approx. 5–12 % absorbable). Combination with vitamin-C-rich vegetables triples absorption rate. Particularly important in vegan/vegetarian diets as an iron source alongside millet, quinoa and leafy greens.
- Kalium (K⁺)MineralContent: ca. 400–560 mg/100 g gegartSeed
Significant potassium content — relevant for blood pressure regulation (sodium-potassium balance), nerve and muscle function. Higher potassium intake is associated with reduced cardiovascular and stroke risk (EFSA assessment). For persons with advanced renal failure (stage 4–5), elevated potassium intake may be problematic — medical consultation required.
- [1]MonographUSDA FoodData Central — Beans, snap, green, raw (FDC ID 169141)(accessed: 2026-05-21)
- [2]MonographUSDA FoodData Central — Beans, kidney, all types, mature seeds, cooked, boiled, without salt (FDC ID 173743)(accessed: 2026-05-21)
- [3]MonographEFSA NDA Panel — Scientific opinion on dietary reference values for protein. EFSA Journal 2012;10(2):2557. (Legume protein quality and DRV context)(accessed: 2026-05-21)
- [5]MonographPlants For A Future (PFAF) — Phaseolus vulgaris database entry(accessed: 2026-05-21)
- [9]MonographCliniTox Giftpflanzen — Phaseolus vulgaris L.: stark giftig ++ (Institut für Veterinärpharmakologie und -toxikologie, Universität Zürich)(accessed: 2026-08-10)
- [4]BookFDA Bad Bug Book, 2nd Edition — Chapter: Phytohaemagglutinin (Red Kidney Bean Poisoning). FDA, 2012.(accessed: 2026-05-21)
- [6]WikipediaGartenbohne (Wikipedia DE)(accessed: 2026-05-21)
- [7]WikipediaPhaseolus vulgaris (Wikipedia EN)(accessed: 2026-05-21)
- [8]WikidataPhaseolus vulgaris — Wikidata item Q379813(accessed: 2026-05-21)
🤝 Permaculture Partners
In your garden, this plant acts as:
✨ Best symbiotic partners
- 🌿 Cucumber Classic companion-planting partner.
- 🌿 Cucurbita pepo Bean is nitrogen-rich, squash is heavy feeder — perfect symbiosis.
- 🌿 Zucchini Classic companion-planting partner.
- 🌿 Summer savory Savory is the classic bean partner against aphids.
- 🌿 Maize Bean fixes atmospheric nitrogen that hungry maize needs.
⚠️ Better not planted together
📦 Part of these planting sets:
Source: Helga und Margarete Langerhorst, Mein gesunder Naturgarten (eigene Kuration) | Klassische Mischkultur-Tradition (Three Sisters, Bauernregel)