Common Names: Green bean, Common bean, French bean, String bean, Snap bean, Wax bean, Haricot bean

The genus Phaseolus includes many varieties of edible beans. The Green bean, also known as the French bean or Common bean, has a long, slender green pod with small seeds inside. The entire pod is edible. The Wax bean is a pale yellow variety of Green bean.

The pods are usually harvested when immature, before the seeds inside have grown too large. When the pods are left on the plant to mature fully, the ripe seeds can then be dried and used as Haricot beans.

The green pods are commonly used as a vegetable. The young leaves can be eaten raw or cooked as a potherb.

The green or dried mature pods, or the seeds alone, are diuretic, hypoglycaemic and hypotensive. Ground into flour, the seeds are used as a homeopathic remedy.

Allergens/Function:

Allergens:
A 32 kd IgE-binding protein, recognised by antichitinase antibodies was recognised and designated PvChI, and is a class I chitinase closely resembling the major avocado allergen Prs a 1. This reactive component was strongly induced by ethylene treatment. Immunoblot inhibition assays demonstrated cross-reactivity between both allergens. Purified PvChI induced positive skin prick test responses in 7 of 8 patients with latex-fruit allergy. This allergen was completely inactivated by heating. (Sanchez-Monge 2000 ref.3706 7)

A 35 kDa protein, probably a novel allergen and not a chitinase, was detected in a 20-year-old girl who experienced anaphylaxis to string bean. She reacted to boiled string bean, inducing a stronger reaction than raw string bean. (Asero 2001 ref.4132 9)

In 3 women who developed asthma and rhinitis after exposure to raw green beans, but who tolerated ingestion of green beans, immunoblots of raw and cooked green beans extract showed two IgE-binding bands with apparent molecular weights of 41.1 and 70.6 kD. A 47-kD IgE-binding protein was detected only in raw green bean extracts. (Daroca 2000 ref.3853 1)

Allergens were partly sensitive to heat, but boiling completely abolished skin prick reactions. (Igea 1994 ref.1188 2)

Adverse Reactions:

IGE AND IMMUNE:
Allergic reactions - food allergy, etc. See other legumes, e.g., pea, soya.

This study describes the development of asthma and rhinitis in 3 women after exposure to raw green beans, and one of them also when exposed to raw chards. All women tolerated ingestion of green beans. Multiple episodes while handling these vegetables for cooking was reported. Skin- and serum-specific IgE were positive. Bronchial challenge test with these allergens showed positive responses to raw, but not cooked, green beans and chards. Oral food challenges with green beans (raw and cooked) and chards were negative in all patients. (Daroca 2000 ref.3853 1)

This article desribes occupational asthma in a homemaker; She experienced rhinoconjunctivitis, asthma attacks, and contact urticaria while trimming raw green beans or inhaling vapor from boiling green beans. She was able to eat and touch cooked green beans without any ill effect and showed no reactivity to any other foods. The result of the skin prick test with raw green beans was positive, but negative with boiled green beans. Rub test with the green beans on the patient's forearm elicited wheals and pruritus within 10 minutes. Bronchial provocation test, with both green bean extracts was positive and immediate. Basophil histamine release test was positive. (Igea 1994 ref.1188 2)

Green bean is frequently associated with food allergy, but allergic reactions caused by skin contact or by inhalation of vapors from boiling legumes are rare. (Igea 1994 ref.1188 2)

Anaphylaxis in a 20-year-old girl occuring 1 hour after ingestion. Symptoms were gastroenteritis, generalised urticaria and collapse. She reacted to boiled string bean, inducing a stronger reaction than raw string bean. (Asero 2001 ref.4132 9)

Recurrent otitis media with effusion was associated with a variety of foods, including beans (not specifically string bean but closely related members of the same family) (Arroyave 2001 ref.7020 1)

A study reports on an atopic housewife, in whom rhinoconjunctivitis and acute asthma were associated with two vegetables of taxonomically unrelated botanical families (Swiss chard/Chenopodiaceae family and green beans/legume family). Skin tests, histamine release test, and specific IgE determination by RAST, bronchial responses after specific bronchial challenges were positive for both. (Parra 1993 ref.480 41)

Infantile food protein-induced enterocolitis syndrome (FPIES) is a severe, cell-mediated gastrointestinal food hypersensitivity typically provoked by cow's milk or soy. This study reports on other foods causing this syndrome: 14 infants with FPIES caused by grains (rice, oat, and barley), vegetables (sweet potato, squash, string beans, peas), or poultry (chicken and turkey) were identified. Symptoms of typical FPIES are delayed (median: 2 hours) and include the onset of vomiting, diarrhea, and lethargy/dehydration. Eleven infants (78%) reacted to >1 food protein, including 7 (50%) that reacted to >1 grain. Nine (64%) of all patients with solid food-FPIES also had cow's milk and/or soy-FPIES. Initial presentation was severe in 79% of the patients, prompting sepsis evaluations (57%) and hospitalization (64%) for dehydration or shock. None of the patients developed FPIES to maternally ingested foods while breastfeeding unless the causal food was fed directly to the infant. (Nowak-Wegrzyn 2003 ref.7791 5)

OCCUPATIONAL EXPOSURE:
Farmer

Occupational asthma. (Igea 1994 ref.1188 1)

Occupational contact dermatitis caused by leaves of Phaseolus plant is reported in a farmer. (Spiewak 2000 ref.7303 9)

NON IMMUNE:
Anti-hyperglycemic effect (Roman-Ramos 1995 ref.6804 2)