Bean toxin report from Food Reference.com
Posted by: plain_sister_ <plain_sister_@...>
Red Kidney Bean Poisoning is an illness caused by a toxic agent,
/Phytohaemagglutnin/ (Kidney Bean Lectin). This toxic agent is found in
many species of beans, but it is in highest concentration in red kidney
beans (/Phaseolus vulgaris/). The unit of toxin measure is the
hemagglutinating unit (hau). Raw kidney beans contain from 20,000 to
70,000 hau, while fully cooked beans contain from 200 to 400 hau. White
kidney beans, another variety of /Phaseolus vulgaris/, contain about
one-third the amount of toxin as the red variety; broad beans (/Vicia
faba/) contain 5 to 10% the amount that red kidney beans contain.
As few as 4 or 5 beans can bring on symptoms. Onset of symptoms varies
from between 1 to 3 hours. Onset is usually marked by extreme nausea,
followed by vomiting, which may be very severe. Diarrhea develops
somewhat later (from one to a few hours), and some persons report
abdominal pain. Some persons have been hospitalized, but recovery is
usually rapid (3 - 4 h after onset of symptoms) and spontaneous.
The syndrome is usually caused by the ingestion of raw, soaked kidney
beans, either alone or in salads or casseroles. As few as four or five
raw beans can trigger symptoms. Several outbreaks have been associated
with "slow cookers" or crock pots, or in casseroles which had not
reached a high enough internal temperature to destroy the glycoprotein
lectin. It has been shown that heating to 80 degrees C. may potentiate
the toxicity five-fold, so that these beans are more toxic than if eaten
raw. In studies of casseroles cooked in slow cookers, internal
temperatures often did not exceed 75 degrees C..
All persons, regardless of age or gender, appear to be equally
susceptible; the severity is related only to the dose ingested.