Can Humans DIGEST Cellulose.. ??

[srimukh]

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?

 

[TFL]

Does the remaining nutrients get digested and the left over cellulose is thrown out intact?

More or less, to my understanding. It's also known as fiber in this regard.

 

[scifes]

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..

 

[Enmos]

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 ..

Cellulose is present in fruit. It's the primary component of cell walls in green plants.

 

[scifes]

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..

 

[Enmos]

strangly enough..you're right..

Remarks like this is what makes you annoying.

but i'm sure humans can't digest it..i guess it's just used as fiber instead of totally breaking it down..

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.

 

[CharonZ]

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.

 

[ElectricFetus]

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.

 

[scifes]

Remarks like this is what makes you annoying.

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

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.

then what about #4?? is it really left and used as fiber?

 

[scifes]

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.

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

and cows are mammals(?) does that mean they digest it?

 

[Enmos]

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

Ok fair enough.

then what about #4?? is it really left and used as fiber?

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

 

[Pete]

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

and cows are mammals(?) does that mean they digest it?

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.

 

[ElectricFetus]

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

and cows are mammals(?) does that mean they digest it?

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.

 

[srimukh]

satisfaction

no problem scifes. i think im satisfied with the point that cellulose is used as fiber.. for many puposes..

 

[srimukh]

no problem scifes. i think im satisfied with the point that cellulose is used as fiber.. for many puposes..

 

[scifes]

no problem scifes. i think im satisfied with the point that cellulose is used as fiber.. for many puposes..

yippee!
so i'm not the only one having posting problems..

 

[Giambattista]

What I am wondering is how much of an impedance is cellulose to assimilation of nutrients. I know it probably depends on the food.

 

[Giambattista]

Vegetables, cellulose, and nutrient absorption!

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

Another study in 2002 showed that cooking carrots increases their level of beta-carotene. Beta-carotene belongs to a group of antioxidant substances called carotenoids, which give fruits and vegetables their red, yellow, and orange colorings. The body converts beta-carotene into vitamin A, which plays an important role in vision, reproduction, bone growth and regulating the immune system.

The downside of cooking vegetables is that it can destroy some of the vitamin C in them. The reason is that Vitamin C, which is highly unstable, is easily degraded through oxidation, exposure to heat (it can increase the rate at which vitamin C reacts with oxygen in the air) and through cooking in water (it dissolves in water).

So in reality, unlike most other vegetables (though not all), carrots are more nutritious when eaten cooked than eaten raw (except when juiced). Because raw carrots have tough cellular walls, the body is able to convert less than 25 per cent of their beta carotene into vitamin A. Cooking, however, partially dissolves cellulose-thickened cell walls, freeing up nutrients by breaking down the cell membranes.

From http://www.carrotmuseum.co.uk/nutrition.html

 

[Fraggle Rocker]

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. . . .

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.

 

[Pete]

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.

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