Is becoming a vegetarian/vegan worth it?

[Mnementh]

scrapking said:

Mnementh said:
[...]Our (the humans) digestive system is badly equipped for a purely herbivore diet, our intestines are too short. Still we are able to digest fruits, nuts and mushrooms (although the last one poorly). Unlike most herbivores we cannot digest grass, leaves or bark, we just aren't equipped for it. these foods make us sick. Some plant products like seeds we can only digest if we help our digestive system: by breaking it down into flour and baking it into bread. 

No actual study I'm aware of is connecting meat and diseases, only excessive consumption of it.

So no, not eating meat isn't natural. That said, a vegan diet poses also no big problem for human adults if done right (look out for Vitamin B12 and maybe iron). It is strongly recommended not to feed children a vegan diet, the risks of malnutrition are way too high. But for adults it is fine.

Why does our inability to eat grass mean we're poorly suited to be herbivores?  That statement isn't scientific.  (1) Our intestines average about 10x our trunk length, which puts us in the herbivore range.  A pure carnivore is like a feline, it dies if it doesn't eat meat.  A pure omnivore is like a canine, it can live on meat alone or it can live on plants alone.  If humans don't get the nutrients from plants, we'll die of scurvy.  Humans must eat plants to survive.  And we can eat many raw seeds simply by chewing them, or soaking them in water.  B12 and iron?  See my source above, omnivores tend to have more nutrient deficiencies than vegans.  A typical whole food, plant-based diet will contain more total nutrients than a typical omnivorous diet.  Meat, dairy, eggs have very high caloric densities.  So if you're trying to manage your weight (as we all should be), then you'll eat less total food and get fewer total nutrients as an omnivore.  A tiny bit of tuna has as many calories as a gigantic garden salad, but the tuna has fewer nutrients and has a smaller variety of nutrients.

(2) Traditionally we ate mostly fruit and flowers (though the fruit we used to eat was less sweet than the fruits we have today, it was kind of halfway between a modern fruit and vegetable in its fibrousness and nutrition profile).  Omnivores and carnivores can produce vitamin C, that's why dogs and cats don't need to eat fruit and leafy greens to get vitamin C like we do, their bodies produce it.  We're a whole heck of a lot closer to herbivores than we are omnivores.  And you see that in the diseases we get.  14 of the top 15 things that kill North Americans are related to omnivorous diets (in whole or in part).

(3) There are lots of studies that connect animal products and disease.  Here's a study that shows that the less meat and dairy you eat, the lower your risk of diabetes drops:  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3638849/pdf/nihms330464.pdf  That's one of hundreds I could cite.  Eating even small amounts of meat increase your risk of many diseases.

(4) There is zero risk of malnutrition to children on an appropriate vegan diet.  Quite the opposite, see my point above about the high caloric density animal foods reducing the total nutrient density of the diet.  Got a source for your claim?

(5) B12 comes from bacteria, it's not synthesized by animals.  They're giving B12 supplements to farm animals these days, as they've made the soil too sterile for them to get it the old fashioned way.  If you eat factory farmed animals, you're effectively eating B12 supplements filtered through animal flesh, rather than taking a B12 supplement directly.  Source:  http://baltimorepostexaminer.com/carnivores-need-vitamin-b12-supplements/2013/10/30#sthash.cy38jSbk.dpbs

(1) Our intestines are a lot shorter than is expected from herbivores, but longer than expected for carnivores. But the results differ a lot. For humans I find lengths of 5-10 meters for the whole intestine:

http://hypertextbook.com/facts/2001/AnneMarieThomasino.shtml

That puts us roughly around 1:10, with exceptions in each direction.

I find in different places that carnivores have between 3-6 times the length of the body. For instance here, it falls into the range:

http://www.second-opinions.co.uk/carn_herb_comparison2.html

I find given the length-relation for herbivores like cows and sheep given with more than 20:1. For instance here (sorry german, it puts the sheep at 24:1): https://de.wikipedia.org/wiki/Darm#L.C3.A4nge

Humans seem to fit in the range well between pure herbivores and pure carnivores. Matching the description of Omnivores.

Overall it seems that the length-relation is a weak description, as there are herbivores with extremely short relation as the panda with around 3-5:1 and carnivores like the dolphin with a relation of around 30:1. But there is a tendency towards longer intenstines in herbivores and and a tendency towards shorter in carnivores and humans are pretty much in the midst: http://www.vivahealth.org.uk/wheat-eaters-or-meat-eaters/length-digestive-tract

(2) It has been shown that prehistoric men used the resources they found. While the northern tribes usually put together as eskimos have suaully eaten mostly fish and meat of seals and caribous, other regions used more fruit or meat of big animals. This really differs a lot depending on there it was located. Seemingly being able to digest a broad range of foods allowed the humans to settle all over the world.

(3) There are also a lot of study that show connection between some plant foods and diseases. For instance tomato and testicular cancer. That is all difficult, because humans are no lab, results are difficult to reproduce and are dependent on a lot of cofactors.

(4) German link again: http://www.dgkj.de/uploads/media/1406_EK_Empfehlungen_Ernährunggesunder_Säuglinge.pdf

This recommends:

"Eine vegane Ernährung (rein pflanzliche Ernährung ohne Gabe von Milch und Ei) ohne Nährstoffsupplementierung ist abzulehnen, da sie zu schwerwiegenden Nährstoffdefiziten führt."

roughly translated: A vegan nutrition (purely plant-based nutrition without milk or eggs) without nutritional supplements has to be disapproved. as it leads to serious nutritious deficits.

As I research it, the stand in english literature is a bit different, but still recommends the suplements. This is also clearly right, as a deficience of B12 especially while grwoing up leads to permanent brain and nerve damage. But the supplements can be produced andare also vegan as the Vitamin is synthesized in a chemical lab. With these supplement it is all right.

(5) I know it comes from bacteria, like a lot of chemical substances. Plants don't need B12, as they have no bervous system. Vertebrate do need it though. They usually have these bacteria inside their intestines. But these bacteria need time to break down foods and create B12. And here is the kicker: most herbivores have very long intestines (see above) and therefore the food stays long enough for the bacteria to produce enough B12. Other herbivores with shorter intestines like the elephant need to eat all day (more than 20 hours a day). Not only because of B12, but because their intestines aren't breaking down the plant food well enough to extract a lot of nutrients. Another group of herbivores like hare eat their own feces, to get the B12 bacteria produced and have a chance of another full round. Omnivores and carnivores get the missing B12 they don't produce themself from animals they eat.