response 46 of 52:

Jul 10 02:39 UTC 2007

On My Way To Somewhere Else:    Things I never knew before

Undercooking beans can be as bad as undercooking meat. Beans have a
toxin in them (lectin) that is destroyed by cooking.  

Lectins are found in most types of beans, including soybeans. Reduced
growth, diarrhea, and interference with nutrient absorption are caused
by this class of toxicants. Different lectins have different levels of
toxicity

Kidney beans are the most toxic, and there is a specific illness called
Red Kidney Bean Poisoning

(From the USDA Natural Toxins Handbook)

Nature of Disease:      The onset time from consumption of raw or
undercooked kidney beans to 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.
         
Diagnosis of Human Illness:     Diagnosis is made on the basis of
symptoms, food history, and the exclusion of other rapid onset food
poisoning agents (e.g., Bacillus cereus, Staphylococcus aureus, arsenic,
mercury, lead, and cyanide).

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. [That's
about 176 F]


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I don't know about the rest of you, but I've sampled soaking/soaked
kidney beans frequently without ill effect.  I'd never even heard of
this, even among my vegetarian/vegan friends.  Has anyone else been
warned about red kidney beans, or any other beans, for that matter?

response 48 of 52:

Jul 10 03:17 UTC 2007

I have never heard that raw or undercooked beans could be harmful. 

I did learn recently that a huge number of the beans sold in Mexico are
grown right here in Michigan. That means that if you go to the Mexican
grocery and buy a can of beans imported from Mexico, there is a good
chance that they were originally canned here. 

response 50 of 52:

Jul 10 15:35 UTC 2007

SaveALot had about 20 different canned bean products, so let's look at
this picture:

Mexican workers migrate north to work in Michigan's bean fields during
the summer.  The beans are dried and canned.  They are shipped to Mexico
to be sold and then the familiar Mexican brands are shipped north to
feed Mexican migrants.

I find it intriguing that poor families buy more canned beans than dried
beans.  At least, SaveALot dedicates much more precious shelf space to
canned bean products than they do to dried beans, which means that there
is higher demand for them.  

In fact, I was amazed that an extreme-value grocery had that many
options.  Their profit model includes limiting choices (for example,
only 1 kind of flour, from one supplier, in one size).  

 I can see that time=money is an equation that factors in to the
decision process.  If you earn more per hour working than you save per
hour cooking, it is a *very* rational decision.  The money saved by
cooking beans is far less than minimum wage, or overtime during the
growing season.  (Notice that I'm assuming these folks are making at
least minimum wage).  

And, given the quest for People Chow, I suspect these buyers come home
at least as exhausted from a day of work as folks in air-conditioned
offices.

response 52 of 52:

Jul 22 11:16 UTC 2007

I've read about the kidney bean thing; i think i had a mild case of it
once (after soaking/cooking red ones at too low a temp).  My impression
is that a fair number of plants have chemical defenses against being
eaten, so best to know what you're doing before consuming them in large
quantities or prepared in unusual ways.