5. Associated Foods:
Phytohaemagglutinin, the presumed 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.
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°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°C.
NOTE: The following procedure has been recommended by the PHLS to render kidney, and other, beans safe for consumption:
Soak in water for at least 5 hours.
Pour away the water.
Boil briskly in fresh water, with occasional stirring, for at least 10 minutes.
Undercooked beans may be more toxic than raw beans.
3.When using dried beans, don't simmer them in water until done and discard the liquid - up to 70 percent of the antioxidants that beans provide end up in the simmering liquid. Instead, simmer the beans until they are done and then let them soak the nutrients back in by leaving them in the liquid for an hour.
To clarify, Dr. Weil's instructions on the linked page DO NOT suggest cooking your beans in the soaking water. Rather, the tips suggest that you not discard the liquid remaining once the beans are cooked.
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