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Medical Mechanism of diarrhea

  1. Apr 4, 2010 #1


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    I have a disagreement to resolve about diarrhea as a result of a food irritation or allergy (as opposed to flu or other) a short time (less than a couple of hours) after ingestion.

    1] The food is basically liquified and passes out as diarrhrea. The food eaten is expelled as liquid within those few hours.
    2] The food irritates the intestinal lining, causing it to flush with water. The water that exits is simply water that has not been reabsorbed yet (the main purpose of the large intenstine). The food that was eaten does not exit the body in so short a time.

    Which is closer to correct?

    Follow-up question: how fast can eaten food plausibly reach the rectum?
  2. jcsd
  3. Apr 4, 2010 #2
    If I had to choose definitively I'd say #2, #1 has the understanding but is wrong in stating that it's the food that you just ingested that is passed very quickly. (I assume that's why you are asking this question anyways)
    Your food is liquified by water secreted by various organs during normal digestion. The distal small intestine and colon (large intestine) are during normal digestion supposed to absorb the water.

    However for various reasons the organs (stomach, upper small intestine, pancreas... and i think gall bladder) may secrete too much liquid which can not be absorbed fast enough OR the bowl movement may move too quickly for complete absorbtion. Causing a looser stool than normal, which is diarrhea. (Diarrhea is also increase in frequency but that doesn't apply in this case :tongue: just a side note)

    Now about the speed issue. The food that you eat is not the food that is in your stool, if it occurs directly after eating. The food will take a pretty long time to be passed, I'd say over 24 hours for the entire food item to be passed. However the food may definitely cause irritation which causes the water secreting organs to secrete more than normal amounts of water, which as explained before leads to looser stool. It all depends on the situation though, for instance if it's food poisoning there are some cases where the toxins are already on the food when ingested and some cases were the toxins form in the intestine. Both effect the delay of symptoms... or it could be due to other causes, there are plenty of them.

    As for the follow-up question, I honestly have no idea what to say, it all depends on what is in the food... possibly as fast as 8 hours. I'm not entirely sure though.

    EDIT: I changed some of the numbers to avoid confusion.
    Last edited: Apr 4, 2010
  4. Apr 5, 2010 #3


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    Tis is as I knew, just looking for confirmation.

    My opponent is quite well-versed in health matters. It would be astonishing (and quite a coup for me) if my opponent were wrong.

    Which is why is I almost doubted myself.

  5. Apr 5, 2010 #4
    I'm pretty sure proteins take the longest amount of time to be digested. One thing with #2 though is that it assumes that the food irritates the intestinal wall. This may be true but more than likely the food you ingested hasn't gone to the small intestine just yet. Food will stay in your stomach for up to 6 hours before being completely emptied. (if you don't eat anything else) By this time you could already be feeling the food poisoning or other factors.
  6. Apr 5, 2010 #5
    Actually I heard starchy veggies are as they have a cell wall and have lots of fiber. Meat seems so because we eat so much more by weight. We rarely eat a pound of broccoli. But steak, no problem.
    Last edited: Apr 5, 2010
  7. Apr 5, 2010 #6
    Hmm, I checked my notes to make sure. I was wrong it's not proteins, it's fat.

    It goes fat-protein-carbs. However since they are all mixed together normally it effects the rates.
    Digestion of carbs begins right in your mouth, proteins do not get digested until they hit your stomach and fats have to wait for the small intestine.

    My notes might be wrong however never know :tongue:
  8. Apr 5, 2010 #7


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    I prolly could have told you this. Even with no GI trouble, fats sometimes manage to be expelled still-undigested.

    Also any diabetic will tell you that fats take the longest (and are therefore good), carbs take the shortest (and are therefore bad).
  9. May 9, 2010 #8
    there are some resistant starches that we do not have enzymes for, but which bacteria may break down lower in the gut.

  10. May 9, 2010 #9


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    Eat a can of spinach and watch your stool the next day.
  11. May 9, 2010 #10


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    Last edited by a moderator: Apr 25, 2017
  12. May 12, 2010 #11
    DaveC426913, this is not all diarrhea, but it happens: http://en.wikipedia.org/wiki/Gastric_dumping_syndrome

    Early and Late dumping occur. Early is your #2 (I think this is a joke, the number?), and late would be #1. In fact, both occur in the course of evacuation of this type, really the issue is cause: infection? Irritation of bowel? Bacterial activity? This is more informative than the method of diarrhea.
  13. May 12, 2010 #12


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    Last edited by a moderator: Apr 25, 2017
  14. May 12, 2010 #13


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    The question being asked was: can the food itself physically pass through your GI tract in the space of less than a couple of hours.

    If the additonal information you supplied does not change that, I'm not concerned about it.
  15. May 12, 2010 #14
    Early dumping aside, yes it can pass through within 2-3 hours. Insoluble fiber such as leafy veg can be detected in stool within 2 hours in the case of diarrhea, ignoring GDS. The pyloric valve can allow excess acid which inflames the GI tract causing the muscles to act rapidly in concert to flush the irritant. The large bowel releases water, and you get a mixture of hardened stool in a rush of new contents. More common in children.
  16. May 12, 2010 #15
    drinking enough water is one way to make this happen. but don't try it, you might just die of hyponatremia if your gut is unsuccessful at expelling the poison.
  17. May 13, 2010 #16
    Most likely you will vomit copiously and feel miserable, death is a risk, but most vomit. I should add that some vit c and strong coffee can achieve the same results, but any diarrhea carries a risk of electrolyte imbalance and dehydration.
  18. May 13, 2010 #17
    i think it takes several grams of vitamin c to reach bowel tolerance. and coffee tends to make people poop, but not necessarily diarrhea. the safe and easy way would be magnesium.
  19. May 13, 2010 #18
    That would work of course, but it can be dangerous. No one should induce what they cannot with coffee and OJ without a doctor.
  20. May 13, 2010 #19
  21. May 13, 2010 #20
  22. May 14, 2010 #21


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    I'm tempted to answer the original question as "yes."

    Diarrhea can be produced in a few different ways.

    One of them is that a somewhat undigested and/or undigestable food makes a hasty exit through the digestive system, possibly aided by some additional water secreted within the intestines to try to compensate for the osmolarity shifts of this undigested food trying to get out.

    Another way is via an inflammatory process (food sensitivity, allergy, virus, bacterial infection, etc.) that alters the permeability of the intestinal walls to water. In that case, it's not from the food itself rushing through, but from the water rushing into the intestines through these "leaky" spaces between cells lining the walls of the intestines.

    So, the cause of the diarrhea makes all the difference in the explanation and you're both right.
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