Toxicity in Beans? You Bet!
Organic Lifestyle
Comments Off on Toxicity in Beans? You Bet!
Most people think of beans as a benign part of the diet—and that they are, but not when they’re raw. Even when they’re organic.A word of warning right up front: don’t nibble raw shell beans (Phaseolus vulgaris) while you’re shelling them out of their pods or otherwise preparing them for cooking. They contain glycosides that can produce hydrocyanic acid in the human digestive system, and there are cases of children dying from eating raw beans. . Just 10 minutes of cooking detoxifies them. Raw soybeans and favas don’t contain the glycosides, but have their share of other toxins. One more word of warning: it’s rare, but some people, mostly of Mediterranean descent, lack an enzyme to break down fava beans, and can have a serious reaction to them. If that’s your heritage, nibble a little fava before you launch into a plateful or have your doctor give you the test for favism.
To be on the safe side, boil shell beans for 10 minutes, then pour out the water and add fresh water. Return to a boil to finish cooking. And while sprouting makes beans’ starch and protein more digestible, raw sprouted beans—except mung beans–contain a substance that inhibits trypsin, a digestive enzyme. So sprouted seeds of green beans should be cooked, such as in a stir fry. A good general rule is to cook beans and avoid them raw.
The toxic compound, phytohaemagglutinin, is present in many varieties of common shell beans but is especially concentrated in red kidney beans. As its name suggests, it encourages the clumping of red blood cells together—otherwise known as blood clots. Clots can cause heart attacks and strokes, among other vessel-blocking problems. Phytohaemagglutinin can be deactivated by boiling beans for 10 minutes. However, for dry beans, the FDA recommends an initial soak of at least five hours in water; the soaking water should be discarded. The 10 minutes required to degrade the toxin is much shorter than the hours required to fully cook the beans themselves. However, lower cooking temperatures may have the paradoxical effect of potentiating the toxic effect of haemagglutinin. Beans cooked at 80 °C (176 °F) are reported to be up five times as toxic as raw beans. Outbreaks of poisoning have been associated with the use of slow cookers, whose low cooking temperatures may be unable to degrade the toxin. The primary symptoms of phytohaemagglutinin poisoning are nausea, vomiting, and diarrhea. Onset is from 1 to 3 hours after consumption of improperly prepared beans, and symptoms typically resolve within a few hours. Consumption of as few as four or five raw kidney beans may be sufficient to trigger symptoms. Beans are also high in purines, which are metabolized to uric acid. Uric acid is not itself considered a toxin, but it may promote the development of gout. For this reason, persons with gout are often advised to limit their consumption of beans.
The bottom line: don’t eat raw beans, period.
