Can Humans DIGEST Cellulose.. ??

Discussion in 'Biology & Genetics' started by srimukh, May 18, 2009.

  1. srimukh Registered Senior Member

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    All herbivorus animals have enzyme called 'Cellulase', which digests the cellulose present in plants they eat.

    But we lack that enzyme, but even then we can digest the RAW FRUITS & VEGETABLES we eat. How is that possible?
    Does the remaining nutrients get digested and the left over cellulose is thrown out intact?
    :confused:
     
  2. TFL ʞǝǝƃ ɐ ʇsnɾ Registered Senior Member

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    More or less, to my understanding. It's also known as fiber in this regard. ;)
     
  3. scifes heckle the snobs Valued Senior Member

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    as far as my knowledge goes cellulose isn't present in fruits..it's as TFL said a harder fiber used to support and enforce plants ..

    but i think people USED to digest it..(cavemen)..that's one of the explenations for us having a cecum..
     
  4. Enmos Moderator

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    Cellulose is present in fruit. It's the primary component of cell walls in green plants.
     
  5. scifes heckle the snobs Valued Senior Member

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    strangly enough..you're right..but i'm sure humans can't digest it..i guess it's just used as fiber instead of totally breaking it down..
     
  6. Enmos Moderator

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    Remarks like this is what makes you annoying.

    Humans cannot digest cellulose (or very poorly) because they don't produce cellulases.
    Edit: To be more precise, humans lack the symbiotic bacteria that produce cellulases to help break down cellulose.
     
    Last edited: May 18, 2009
  7. CharonZ Registered Senior Member

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    Precisely. No mammals produce cellulases, however certain other animals (as e.g. certain insects and mollusks) possess one. However, certain gut bacteria also found in humans are actually able to degrade cellulose but generally the amount appears to be too low to be significant.
     
  8. ElectricFetus I'm just going for a walk... Valued Senior Member

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    Not only would we need cellulase but we would need multiple stomachs for the preprocessing of cellulose just so that the cellulases can do their works with high enough throughput to power our bodies, and even then we may need to live like sloths to reduce energy consumption.
     
  9. scifes heckle the snobs Valued Senior Member

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    lol, i didn't mean to offend you..only i was sure it was otherwise and research to find it's true, that's all

    then what about #4?? is it really left and used as fiber?
     
  10. scifes heckle the snobs Valued Senior Member

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    you totally reminded me of cows..with their 5 stomachs...and digesting mechanism..

    and cows are mammals(?) does that mean they digest it?
     
  11. Enmos Moderator

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    Ok fair enough.

    Yep. It aids the smooth working of our intestines. It prevents constipation for example.
    To evolve the ability to digest cellulose now would probably not be very beneficial ;)
     
  12. Pete It's not rocket surgery Moderator

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    Yes, although indirectly. The way I understand it is that in cows and other animals like them (including hippos, camels, sheep, deer, giraffe, and maybe even whales) cellulose is digested by bacteria in one of the stomachs, then the bacteria themselves are digested a little further on. Horses, elephants, rhinos, and pigs also digest cellulose through bacteria, but in a different way and not as efficiently.

    I think termites digest wood (which is mostly cellulose) also via gut bacteria.
     
  13. ElectricFetus I'm just going for a walk... Valued Senior Member

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    they use bacteria to do it, and yes there body is pretty much dedicated to mulching cellulose so the bacteria can do their job, and they eat copious amounts to break even.
     
  14. srimukh Registered Senior Member

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    satisfaction

    no problem scifes. i think im satisfied with the point that cellulose is used as fiber.. for many puposes..:cool:
     
  15. srimukh Registered Senior Member

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    no problem scifes. i think im satisfied with the point that cellulose is used as fiber.. for many puposes..:cool:
     
  16. scifes heckle the snobs Valued Senior Member

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    yippee!
    so i'm not the only one having posting problems..:)
     
  17. Giambattista sssssssssssssssssssssssss sssss Valued Senior Member

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    What I am wondering is how much of an impedance is cellulose to assimilation of nutrients. I know it probably depends on the food.
     
  18. Giambattista sssssssssssssssssssssssss sssss Valued Senior Member

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    Vegetables, cellulose, and nutrient absorption!

    http://fernsfronds.blogspot.com/2009/04/nutrition-note-cooking-carrots.html


    From http://www.carrotmuseum.co.uk/nutrition.html
     
    Last edited: May 20, 2009
  19. Fraggle Rocker Moderator

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    Cetaceans are indeed artiodactyls. Based upon DNA analysis they were recently discovered to be descended from primitive hippopotamuses. Cetacea was demoted from an order to a suborder of Artiodactyla. However, all whales and dolphins are carnivores. The artiodactyl digestive system, supremely adapted for the digestion of cellulose, has evolved completely into a carnivorous digestive system. The baleen whales filter krill (tiny crustaceans) while the toothed whales (sperm whales and dolphins) are predators who hunt fish, or, in the case of the orca, other mammals and perhaps aquatic birds.

    This is an example of how easily two closely related animals can have entirely different diets: the hippopotamus grazes, the porpoise fishes. I brought this up on the thread about eating meat: gorillas are herbivores who can get their calories from cellulose; humans aren't and can't.
     
  20. Pete It's not rocket surgery Moderator

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    Interestingly and unlike other carnivores, cetaceans do have a forestomach with a fermentation role in digestion like ruminants.
     

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