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People with Crohn's Disease and IBD should avoid undercooked Red Beans & more

Ever get nauseated from your food? It may not always be the Crohn's.

Some things to avoid eating and why.

D Bergy

Scientists find why red beans
and rice can be nauseating

People cry foul when fowl is undercooked, but what about red beans and rice? Scientists have discovered how lectins, a family of proteins believed to be a natural insecticide that is abundant in undercooked legumes and grains, can make you feel temporarily miserable.
“It’s known that it can be a toxin,” Dr. Paul L. McNeil, cell biologist at the Medical College of Georgia, says of the lectin protein that’s commonly found in vegetables. Lectins, which bind strongly to carbohydrates that decorate cell surfaces, have a particular affinity for the heavy-carbohydrate coats of epithelial cells that line the gastrointestinal tract.

Researchers have long known that ingesting too much undercooked lectin can cause nausea, diarrhea and vomiting. What they didn’t know was how lectin caused food poisoning.

Work published Aug. 1 in PloS One shows lectins disable GI tract cells, which are constantly bombarded while digesting food, from repairing tears in cells walls from all the activity. Repair normally occurs in seconds: internal membranes move up to patch the tear, the cell recovers and the one-cell layer lining of the GI tract remains intact.

“If those individual cells cannot repair tears, they die,” says Dr. McNeil. “That means you have gaps in the integrity of the surface area of the epithelium and you are exposing the nasty internal world of your GI tract to your blood supply.”

The epithelial lining is a continuous, natural barrier between digesting food in the GI tract and the blood supply. When intact, it allows only good stuff like nutrients to pass through.

“Your body senses that lack of barrier function and tells you to eliminate the entire contents of the GI tract,” says Dr. McNeil, noting that lectin’s apparent role as a natural insecticide and as a source of food poisoning are related. “If you get vomiting and diarrhea you are going to eliminate the entire contents of your gastrointestinal tract, right? And, you are not going to eat red beans again the next day, right? That is probably the point if they are natural insecticides. Alcohol will do the same thing. When you drink too much alcohol, you can destroy the lining of your stomach.”

But the scientist who first identified how injured cells patch themselves says lectin blocks this repair mechanism better than anything else he’s seen. Interestingly, he and his colleagues showed in PloS Biology in 2006 how roughage – which includes beans – help people stay “regular” by causing more cell tears, which enables more mucus to escape from cells, essentially greasing the GI tract.

That same research team, which includes Dr. Katsuya Miyake, MCG cell biologist, and Dr. Toru Tanaka, pharmacologist at Josai University in Japan, has now shown lectin is also very good at blocking mucus expulsion from cells.

In fact, they discovered lectin’s role in stopping cell-patching and mucus release while researching roughage. The multipurpose lectin is a powerful stain the team used to look at mucus released by cells after tearing. They found if they used too much lectin there was no patching or mucus, just cell death.

“Biologically it’s interesting because it might tell us more about the mechanism of repair,” says Dr. McNeil, who wants to learn more about how lectin interferes with repair. “We know the mechanism involves surface binding because you can add lectin and the cells can’t repair. You take the same culture of cells, wash the lectin away, injure other cells in the culture and they repair fine. We also know it’s a very rapid, surface-initiated inhibition.”

In addition to the immediate discomfort undercooked beans and rice can cause, long term concerns ingestion of lectin has also been linked to colorectal cancer and celiac disease, a common problem in which individuals are sensitive to gluten, a mixture of proteins derived from wheat flour that includes lectins. The small intestine of the celiac sufferer is unable to properly absorb nutrients after gluten ingestion.

Oddly, in a laboratory dish, safe from mechanical stresses that cause surface tears, lectin can make cells divide, “which is quite the opposite of making cells sick,” Dr. McNeil says. A recent Science paper implicated lectin in diabetes as well.

“It’s possible that this bioactive property of lectin that binds to our cells could have long-term consequences taken even in small amounts,” he says, noting that thorough cooking destroys most but not all lectin. “Maybe the bloating and gas is telling us something about lectin when it’s just a minor irritation.”

He notes lectin is easily among the top-10 causes of food poisoning but is unlikely to be lethal because the body is so good at sensing the break in the GI barrier and eliminating the problem.

Source: Medical College of Georgia



Senior Member
:ycool: VERY INTERESTING!!! I've heard (anecdotally) that there is a type of bean that can kill if not properly prepared (usually requires pre-boiling, rinsing, soaking & repeat prior to cooking... can't recall whether it was red bean, lima beans, etc, etc..)
AND I know that Health Inspectors test the temperature of cooked rice in kitchens and IF it isn't kept at the right temperature, it must be thrown out... not served to the public. Now, I live on (practically) white rice... not allowed wild or brown rice, so it makes me think. And all of the GI patients I've chatted with stress avoiding beans in any form... and I do miss the homemade beans that I once ate frequently & with great gusto... Figured it was just a cautionary thing to avoid eating gassy foods, but after reading this, seems there is just a little more to the story than I had assumed.
I guess this confirms more and more the theory that legumes and grains are not suitable for people with GI disorders. Then has been written about in "The Maker's Diet" and " The Specific Carbohydrate Diet".

Although it makes much sense, I find it very difficult to go on a grain free diet. I've eliminated all legumes from my diet (they don't suit me at all), but I still need to eat white rice and some bread for energy and not to keep losing weight.

Anybody gone on a grain free, legume free diet and was able to keep his weight and energy?
Hey Kev,

Why can you eat white rice but not the unbleached or wild rice? What makes the white rice different?

I love all kinds of rice, especially wild rice. I would never have thought that rice would have any kind of negative effect on anyone.

It does make sense in relationship to the leaky gut thing. I think the outward signs of this leaking could be the arthritis, skin problems, anxiety, depression, and other inflammatory related symptoms. Trying to keep the integrity of the intestinal tract is appearing more important all of the time. Also the most difficult thing to do since this disease is all about gut problems at it's source. Lectins may add to the problem, but I doubt it is a main instigator.

At least we can make sure we cook any of this stuff very well.

D Bergy


Senior Member
Welll, the white Vs brown/wild rice thing is similar to my being allowed white bread but not whole wheat bread... the processing the white rice undergoes (normally I abhor over processed foods) removes part of the rice that my digestive system isn't up to processing... apparently that doesn't happen with the wild rice, or brown rice.

As for thorough cooking, I have to overcook veggies till they're practically mush, and I hate it.. always preferred veggies raw or al dente (sp?). Anyway, even overcooked, I can't tolerate green veggies.. green beans, peas, you name it... but I can tolerate some other veggies... potatoes, parsnips, carrots (if mashed), even yellow beans... but not corn. go figure.. It isn't simple to figure out, I expected the green veg's to be gassy, but it also has to do with both their internal elements and their 'construction'.. Like, some veggies apparently have long strand fibres... and these can be hard to digest. Some fruits & veggies have a peel or skin that's too hard to digest or leaves a lot of residue in the digestive tract. it's all way tooo complex... which is why the food diary is so essential to anyone learning to cope with their particular form of disease... Like, I can cope with a very tiny amount of iceberg lettuce, cooked, in a Western sandwich, but if I substitute romain, then I am in for agony... Now, pre illness, I loved romain lettuce, now I just can't go it..
you'd think lettuce is lettuce is lettuce... but apparently my 'gut' thinks otherwise!
Hi Kev and D. It's all related to the fiber matrix. Most people with IBD cannot tolearte insoluble fiber or tough fiber matrix. When we over cook the veggies, we btreak the fiber matrix and it becomes easier on our digestive system. We also peel the fruits to remove the insoluble fiber, and eat them as ripe as possible so we have a broken down fiber matrix.

A good discussion on this is found the books, "What to Eat with IBD" and "The New Eating right for abd gut".

Ofcourse overcooking and peeling, decreases the vitamines form the food, as well as avoiding many of them because they hurt us. So a good multivit/min is important to keep us from lacking essential nutrients.

Also whole grain rice and bread, have very tough insoluble components which hurt the GI tract.......