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Phaseolus vulgaris
Caution🐾Gartenbohne · (Phaseolus vulgaris var. nanus)
Bean family (Fabaceae)
Description
Growing compact and low without need for support, the bush form of the common bean produces its green pods from July through October. Raw pods and raw or undercooked mature seeds are always toxic due to the lectin phytohaemagglutinin (phasin) and must be boiled vigorously for at least ten minutes. Thoroughly cooked, the pods supply dietary fibre, folate and iron, while the dried seeds, rich in the storage protein phaseolin, have long served as a staple plant protein in rural cooking. Tea made from dried, seed-free pods is recognised by the German Commission E as a mild diuretic for minor urinary complaints; folk medicine also used it for gout, though without scientific confirmation. Savory is the traditional cooking companion, its essential oil said to ease the beans' typical flatulence.
Green beans (young pod vegetable) are a versatile culinary ingredient: blanched, steamed, in stews or as salad. Per 100 g fresh green bean they deliver approx. 36 kcal, 2.7 g dietary fibre, vitamin K (43 µg), vitamin C, manganese and iron. As dry beans (mature seeds), protein content rises to approx. 10 g/100 g (cooked). WARNING: Raw, undercooked or mature beans are ALWAYS toxic (phasin/phytohaemagglutinin) — consume only when thoroughly cooked (min. 10 minutes boiling).
Preparation & dosage
Dried, seed-free bean pods (Phaseoli fructus sine semine) are recognised as a herbal medicinal product under the German Kommission E and EMA-HMPC: approved traditional remedy for minor urinary complaints, flushing the urinary tract and increasing urine production (mildly diuretic). Kommission E (BGA, 1986) recommends it as supportive treatment for dysuria. Total daily dose 5–15 g dried pods as tea infusion, divided into several doses. Use for a maximum of 2 weeks without medical consultation. Not suitable for children under 18 or in cases of cardiac/renal oedema.
Preparation & dosage
Pour 150 ml boiling water over 2.5 g dried bean pods, steep 10 minutes, strain. Drink 2–6 cups daily; concurrently drink plenty of fluids (min. 2 litres/day) for urinary flushing.
- Dry amount
- 2.5–2.5 g
- Doses per day
- 4×
- Max duration
- 2 weeks
Mature dry beans (seeds) are an important plant protein source: approx. 21–25 g protein per 100 g dry bean; biological value increases when combined with cereals (complementary amino acids). Contains iron (approx. 6 mg/100 g), folate (approx. 394 µg/100 g), magnesium and zinc. The phaseolin protein accounts for approx. 40–50 % of seed nitrogen. Traditionally important as a filling staple food and meat substitute in legume-centred diets (Mediterranean cuisine, folk cooking). Always consume thoroughly cooked.
In Central European folk medicine, bean pod teas were traditionally also used for gout and rheumatic complaints — folk tradition without clinical confirmation. The assumed effect is based on the mild diuretic action (flushing uric acid) and the flavonoid content of the pods. Kommission E finds no proven efficacy for these indications.
Preparation & dosage
Beans are rich in dietary fibre (approx. 6–9 g/100 g dry bean, cooked), acting prebiotically and promoting gut microbiome health. Contained oligosaccharides (raffinose, stachyose) can cause flatulence in sensitive individuals — thorough cooking and combining with savory (Satureja) traditionally reduce this effect. Antioxidant polyphenols (quercetin, kaempferol, anthocyanins in dark varieties) contribute to protection against oxidative stress.
Savory (Satureja hortensis) is the classic culinary companion for cooking beans — not only as a spice but also because the essential oils of savory are traditionally held to reduce the typical bean flatulence (oligosaccharides). This use is passed down in folk medicine and is not clinically proven, but is deeply rooted in Central European kitchen practice. Here the bean is the food combined with the herb.
Beans supply notable amounts of B vitamins, especially folate: approx. 394 µg/100 g (dry bean, raw) — one of the highest values among vegetables. Folate is essential for cell division, DNA synthesis and neural tube development in pregnancy. Vitamins B2, B6 and vitamin E are also present. The vitamin K content of young green beans (approx. 43 µg/100 g) supports blood coagulation and bone health.
WARNING — RAW TOXICITY: Raw beans (pods AND seeds) contain phytohaemagglutinin (PHA, 'phasin'), a heat-labile lectin. As few as 4–5 raw soaked red kidney bean seeds can trigger acute poisoning (nausea, severe vomiting, diarrhoea, abdominal cramps; symptoms appear 1–3 hours after ingestion). Green garden beans contain PHA at lower concentrations than red kidney bean varieties, but are also toxic when raw. ALWAYS cook thoroughly: green beans min. 10 minutes in vigorously boiling water; dry beans soak 12 hours, discard soak water, then boil at least 30 minutes. Do not use cooking/soaking water — PHA is water-soluble. Slow cookers operating below 100 °C CANNOT adequately inactivate the toxin — never cook uncooked dry beans in a slow cooker without pre-boiling. 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.
Well-cooked beans are safe in pregnancy and lactation — a valuable source of folate, iron and protein. Bean pod tea (medicinal use) is not recommended for pregnant or breastfeeding women according to the EMA-HMPC monograph — safety data are lacking. Strictly avoid raw beans.
Cooked beans as food are safe. Medicinal bean pod teas should be avoided during lactation (no safety data per EMA-HMPC).
Well-cooked green beans as complementary food are suitable from approx. 8–10 months (as purée). Medicinal bean pod teas are not recommended for children and adolescents under 18 per EMA-HMPC — safety data lacking. Raw beans are particularly dangerous for children — strictly avoid.
Drug interactions
Antikoagulanzien (Vitamin-K-Antagonisten, z. B. Phenprocoumon, Warfarin)
Green beans contain vitamin K (approx. 43 µg/100 g). With large consumption quantities, elevated vitamin K levels can weaken the anticoagulant effect of vitamin K antagonists. Relevant only with very high bean consumption — clinically barely significant at normal dietary intake.
Contraindications
- Raw beans (pods and seeds) of any kind — raw consumption strictly prohibited.
- Bean pod tea in oedema caused by cardiac or renal insufficiency — flushing therapy is contraindicated.
- Known hypersensitivity to Phaseolus vulgaris constituents.
Harvested part: pods and beans
- Time of day:
- Green beans: harvest in the morning or early evening — pods are cooler and firmer. Regular harvesting every 2–3 days significantly extends the plant's bearing period; unharvested pods become fibrous and inhibit further flowering.
- Drying:
- Fresh green beans: use without drying (refrigerator max. 3–5 days). For bean pod tea preparation: pick mature but still green to yellowing pods, remove seeds, dry pod shells in thin layers at 40–50 °C or in an airy, shaded spot until brittle. Store dried material airtight in a dark, cool tin (usable up to 1 year).
- Storage:
- 1 months — Fresh green beans: unwashed in the refrigerator crisper, max. 3–5 days. Do not store near ethylene-releasing fruits (apples, tomatoes). Can be blanched and frozen (up to 12 months).
- Time of day:
- Dry beans (mature seeds): harvest when pods are fully dried and brown, seeds rattle when shaken. Harvest on a dry day; pull up plants and hang in an airy spot for post-drying. Thresh only when pods are completely dry.
- Drying:
- After harvest: hang plants upside down for 2–3 weeks in a dry, ventilated space. Thresh seeds from pods, clean and allow to dry completely at room temperature. Moisture above 14 % promotes mould. Store in airtight jars or bags in a dark, cool place.
- Storage:
- 24 months — Dry beans (seeds): airtight, dark and cool (below 15 °C), dry. Shelf life 2–3 years with optimal storage. Check for pest infestation (bean weevil).
- Phytohämagglutinin (PHA / Phasin)OtherContent: 0,2-3 % (sortentypisch variabel)Seed
Heat-labile lectin (glycoprotein) — the bean's primary defence compound against herbivores. Agglutinates erythrocytes and damages intestinal mucosa (inhibits nutrient absorption). Red kidney beans contain the highest concentrations; green garden beans considerably less. Complete inactivation by boiling (min. 10 min in vigorously boiling water) — not by slow-cooker temperatures.
- PhaseolinOtherContent: 40-50 % des SamenstickstoffsSeed
Main storage protein of garden bean (vicilin type); makes up the majority of protein content. Contains all essential amino acids but is low in sulphur-containing amino acids (methionine, cysteine) — biological value increases when combined with cereals (complementary proteins). Shows antioxidant and genoprotective properties in laboratory studies.
- Quercetin & Kaempferol (Flavonol-Glycoside)FlavonoidContent: variabel, je nach SorteSeed
Main flavonoids of garden bean — antioxidant, anti-inflammatory and cytoprotective (laboratory studies). Quercetin-3-O-glucoside and kaempferol glycosides demonstrated in pods and seeds. Anthocyanins (delphinidin, petunidin, malvidin in dark/red varieties) contribute to antioxidant potential. Cooking and storage reduce content.
- Phaseolin-PhytoalexinePhenolic acidContent: Spuren (stressinduziert)Fruit
Secondary defence compounds (pterocarpane type) formed in pods and leaves under pathogen attack or mechanical stress. Demonstrated in bean pod tea (Phaseoli fructus sine semine); discussed as one of the active principles of the mild diuretic effect. Not to be confused with the storage protein phaseolin.
- Ballaststoffe (Zellulose, Hemizellulose, Pektin)PolysaccharideContent: 2,7 % (grüne Bohne) / 6-9 % (Trockenbohne, gekocht)Seed
Mixture of soluble fibre (pectin — prebiotic, cholesterol-modifying) and insoluble fibre (cellulose — intestinal motility). Oligosaccharides (raffinose, stachyose) are indigestible and fermented in the large intestine — cause flatulence in sensitive individuals. Thorough cooking and discarding soak water reduces oligosaccharide content.
- Folsäure (Vitamin B9)VitaminContent: 394 µg/100 g (Trockenbohne, roh)Seed
Exceptionally high folate content — beans are among the best plant-based folate sources. Essential for DNA synthesis, cell division and neural tube closure (pregnancy). Heat-sensitive: cooking loss 30–60 %. Green beans contain approx. 33 µg/100 g (fresh); dry beans considerably more.
- Eisen & Mineralstoffe (Fe, Mg, Zn, K)MineralContent: Fe: 1 mg/100 g (grün) / 6 mg/100 g (trocken)Seed
Dry beans are an important non-haem iron source; bioavailability is reduced by co-occurring phytic acid and tannins, but improved by vitamin-C-rich accompaniments. Magnesium (approx. 60 mg/100 g, dry cooked), zinc and potassium contribute to cardiac function, muscle contraction and immune defence.
- Kieselsäure (Silicium)MineralContent: Spuren (in Hülsen)Fruit
Bean pods (Phaseoli fructus sine semine) contain silicic acid in addition to flavonoids and amino acids — regarded as a contributing principle of the mild diuretic effect of bean pod tea (functionally similar to horsetail). Not clinically proven.
- [3]MonographBGA Kommission E Monographie — Phaseoli fructus sine semine (Samenfreie Gartenbohnenhülsen), BAnz Nr. 50, 13.03.1986(accessed: 2026-05-22)
- [4]MonographEMA HMPC — Community herbal monograph on Phaseolus vulgaris L., fructus sine semine (traditional use, 2014)(accessed: 2026-05-22)
- [5]MonographUSDA FoodData Central — Beans, snap, green, raw (FDC search: Phaseolus vulgaris)(accessed: 2026-05-22)
- [6]MonographPlants For A Future (PFAF) — Phaseolus vulgaris database entry(accessed: 2026-05-22)
- [7]MonographPolyphenol-Rich Dry Common Beans (Phaseolus vulgaris L.) and Their Health Benefits — PMC5713300(accessed: 2026-05-22)
- [8]MonographArzneipflanzen-Lexikon — Gartenbohne (Phaseolus vulgaris)(accessed: 2026-05-22)
- [9]MonographCliniTox Giftpflanzen — Phaseolus vulgaris L.: stark giftig ++ (Institut für Veterinärpharmakologie und -toxikologie, Universität Zürich)(accessed: 2026-08-10)
- [1]WikipediaGartenbohne (Wikipedia DE)(accessed: 2026-05-22)
- [2]WikipediaPhaseolus vulgaris (Wikipedia EN)(accessed: 2026-05-22)
🤝 Permaculture Partners
In your garden, this plant acts as:
✨ Best symbiotic partners
- 🌿 Apium graveolens Classic companions: bean fertilises, celery uses the nitrogen.
- 🌿 Celeriac Classic companion-planting partner.
- 🌿 Chard Classic companion-planting partner.
- 🌿 Cucumber Classic companion-planting partner.
- 🌿 Cucurbita pepo Bush bean fertilises with nitrogen, squash shades bean bed.
- 🌿 Summer savory Savory strengthens beans and deters black bean aphid.
- 🌿 Eggplant Bush bean deters Colorado-beetle relatives from eggplant.
- 🌿 Potato Bush bean deters Colorado potato beetle (classic rule).
- 🌿 Maize Bush bean fixes nitrogen for hungry maize.
⚠️ 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)