Hi everyone

I know there are some science boffs on this forum, so here's one for you.

I know that when we consume plant proteins, our bodies have to break down those proteins into their constituent amino acids, from which we make proteins for our body, as and when needed.

I also understand that our bodies find it easier to break down plant proteins than animal proteins (and of course in each case it is easier when the foods are raw than cooked).

NOW...

(and please note I do not eat meat, and am asking this to help rather than hinder the vegan cause!)

let's assume we have raw plant food, and raw animal food.

Can anyone explain to me, SCIENTIFICALLY, but in layman's language, exactly HOW it is easier for our bodies to break down the plant food proteins into their constituent aminos than animal food proteins? (As raw food sources either don't say, or are too vague, and biochemistry sources are a little beyond me, unfortunately).

Many plants have free amino acids, fruits especially, not entirely formed proteins, as much is broken down during the ripening process (enzymes cleaving proteins).....animal protein is often cooked, coagulated, and damaged-denatured to some extent. Also, there are the acids formed breaking it down in the body, and the mineral balancing act that must ensue.

Ebhak

Quote

Many plants have free amino acids, fruits especially, not entirely formed proteins, as much is broken down during the ripening process (enzymes cleaving proteins).

Would that mean some fruits are partially pre-digested making the digestion easier ?

debbietook Wrote:
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> I also understand that our bodies find it easier
> to break down plant proteins than animal proteins


Not sure this is true actually as nice as it would be to say for the vegetarian movement.

debbietook Wrote:

> Can anyone explain to me, SCIENTIFICALLY, but in
> layman's language, exactly HOW it is easier for
> our bodies to break down the plant food proteins
> into their constituent aminos than animal food
> proteins? (As raw food sources either don't say,
> or are too vague, and biochemistry sources are a
> little beyond me, unfortunately).

It is easier to break down plant protein than animal ones, cooked or raw, because proteins are amino acids chains linked together one after the other. Our body needs simple amino acids or prebuilt chains of amino acids. It is easier to get the simple ones or some short chains from plant protein because the chains from the plants are smaller to begin with. That means our body needs to do less cuts in the chains to get what it needs. Less cuts = less energy.
It also means that more of the protein chains can be broken down with less waste at the end. If the chains are too long, like from animal proteins, the body cannot cut everything, and there is still some untouched parts at the end = waste.
I hope this can help you

Raw Fruit Festival
[www.raw-fruit-festival.net]
Health, Fitness and Fasting Retreats in Spain
[www.fit-in-nature.net]

Thanks for replies so far, particularly sgc's. All very understandable.

Do you have a scientific source for that, sgc? Not saying it isn't so - all makes sense to me. But it's always helpful to have a good academic source ready for those who ask.



Edited 1 time(s). Last edit at 03/06/2009 03:45PM by debbietook.

Hi Deb

I'm afraid I haven't come across any journal articles on the subject of protein digestion efficiency, and I've tried. The article below mentions the history of worlds current view of protein requirements and sources, which I'm sure you'll find of interest. The McDougal newsletter is a academic source listed in one of our uni databases.

Cheers geo


[www.nealhendrickson.com]

I take it from a big biology book: "Life: the science of biology"
BTW, in the same book, written by biologists, there is the different sources for vitamins. And for B12, one of the main source is water! It's in the book, because water with cobalt is sufficient for intestinal bacterias to produce B12 (a cobalt based compound). So simple!

Raw Fruit Festival
[www.raw-fruit-festival.net]
Health, Fitness and Fasting Retreats in Spain
[www.fit-in-nature.net]

That's certainly an academic source sgc. Parts of it are available on line, but can you please tell me which chapter and page the info on protein metabolism is?

Thx in advance, geo

communitybuilder Wrote:
-------------------------------------------------------
> debbietook Wrote:
> --------------------------------------------------
> -----
>
> > I also understand that our bodies find it
> easier
> > to break down plant proteins than animal
> proteins
>
>
> Not sure this is true actually as nice as it would
> be to say for the vegetarian movement.


Then I suggest you somehow find something to counter it.

Plant protein article: [www.raw-food-health.net]

It depends on how you define "easier."

There are many things to consider.

The pancreas is responsible for making the enzymes that break peptide bonds. I have never come across any convincing evidence that protein length is important for human health.

Plant proteins have some advantages and disadvantages compared to animal proteins. This is not a complete list.

advantages:
usually come with more fiber
usually come with protective phytochemicals
usually less apt to raise insulin production
usually associated with lower body weight
usually associated with lower body fat
usually associated with lower IGF-1 which is usually associated with lower cancer risks
usually associated with lower energy production/environmental impact costs
usually associated with lower net acid production
usually associated with more of the nonessential amino acids, which might in themselves be protective, although they are not as usable as the essential ones
usually associated with less kidney damage in the long term

disadvantages
lower net nitrogen utilization compared to animal sources
higher amount needed per body weight compared to animal source for the same net use
use rate limited by limiting amino acid present in the body pool at the time
this can be a problem in the third world countries, where people are very limited in what is available to eat (i.e. almost exclusively grains with very sparing quantities of beans or sometimes no beans)
b12 not forthcoming in the protein source
antinutrients in the plant source combined with the tough fibrous matrix make what is there even less available to the body


I don't like these easier/harder arguments. If you ate only the highest utilization sources (pure aminos in ideal ratios, some of which are animal sourced) you would need a lot less than what you could get from natural plant sources. And you could make that work pretty well for your body. But there's a lot of processing involved. As far as natural foods go, the highest net utilization protein source for humans is not flesh but the cooked whole egg.

I think you should make a choice and then make that choice work well within the confines of those parameters. Being healthy is the best advertisement.



Edited 1 time(s). Last edit at 03/07/2009 04:08AM by arugula.

Read 80-10-10

Animal protein is inferior in so many ways, and b12 is from our guts, doesn't hafta be in food, even raw, when you cook that animal protein it's utilization drops down, we need less plant protein then we do animal, many raw foodists to back this up, though the SADists need less then they eat as well, true. grains alone haver more then enough protein, and too much phosphorous.

animal protein sources are acidifying and come with toxic compounds, and unhealthy fats, and much more, plant proteins, the opposite.

if you take a random selection of enough fruit and greens, in a day, you will meet your protein needs, it's possible to not, but it's really easy if you have the slightest knowledge.

the anti-nutrients in plants are are overplayed.

and yes ripening fruit is breaking down to pure AA form often.

Arigula, just to clarify, I'm not concerned with whether plant food proteins are better for the body than animal proteins - I'm fully sold on that one! Although, I'm sure your information will be very useful for others here (especially as I suspect some aren't convinced :-)), so many thanks for taking the time.

When I said 'easier', I was asking about the specific processes that the body undertakes when breaking down raw plant proteins into its constituent amino acids as compared with breaking down raw animal proteins into its constituent amino acids.

Sgc, could you just give me the author of that book? And then I'm done!

Utopian Life Wrote:
-------------------------------------------------------

> Then I suggest you somehow find something to
> counter it.

The responsibility is on the one making the positive claim.

Quote

When I said 'easier', I was asking about the specific processes that the body undertakes when breaking down raw plant proteins into its constituent amino acids as compared with breaking down raw animal proteins into its constituent amino acids.

Quote

disadvantages
lower net nitrogen utilization compared to animal sources
higher amount needed per body weight compared to animal source for the same net use

Sounds like it is less efficient but I'm curious to see arugula's source on this.

It's funny the same people who will tell you denatured (broken down) protein is hard/impossible to digest will tell you plant protein is easier to digest because it's more broken down than meat.


RusticBohemian Wrote:
-------------------------------------------------------
> Plant protein article:
> [www.raw-food-health.net]
> ml


That article is horrible.

Especially this part - "Protein does not start having a detrimental effect on health until it rises above 10 percent of calories, so you should view that as a safe maximum."

It makes hundreds of unsupported statements & expects it's readers to accept them as fact on no evidence, this is an insult to the reader's intelligence.


Don't eat meat because it contains more toxicity than plants and because of moral reasons & ecological ones. No need to convince yourself every single thing about plants is superior to every single thing about animals. Unless you're eat a severely limited diet (just fruit for example) you probably won't have protein issues. If you do a few tablespoons of hempseed a day ought to do the trick.

seriously ? little teeny hemp sprouts are an major americann threat?

...Jodi, the banana eating buddhist

[When I said 'easier', I was asking about the specific processes that the body undertakes when breaking down raw plant proteins into its constituent amino acids ]

I did address that.

Most of the proteases that break down the proteins are secreted by the pancreas. I know of zero evidence that the pancreas is worn down by breaking down longer proteins.

I wrote that above.

The most common plant protein on the planet is rubisco. Compare it to skeletal muscle proteins and collagen:

540,000 Da rubisco
43,000 Da actin
140,000 Da myosin
300,000 Da collagen

where each individual amino is from about 90-200 Da.

If you think that bigger protein = pancreas wearing out sooner, then you'd better not eat plants anymore.

If you think that plant protein = less wear and tear, well, considering that you need from 2-4x as much of it compared to the ideal animal protein source, that argument doesn't hold either.

For a given net amino yield, it's not so much the protein source that may or may not have an adverse effect as it is all the stuff that comes along with it. You could take 10 g of individual aminos in the perfect proportion (some from plants, some from horse hooves/hair) or take 40 g of plant protein from raw food sources and have the same net nitrogen utilization. Does this make you fear for wear and tear your pancreas? It shouldn't.





Edited 1 time(s). Last edit at 03/07/2009 11:10PM by arugula.

Hi everyone

Reviewing this thread, would just like to thank everyone for their replies (and - arigula - I can see now that you did address my question :-))

I think the more overt reasons to concentrate on plant proteins is that

1. they tend to be lower in the sulfur-containing amino acids. The ones with sulfur (cysteine, methionine) tend to oxidize more easily. They are also associated with higher IGF-1 levels.

2. When too much is present, they tend to tip the net acid balance towards the less healthy side of the scale, this is why they are said to "leech" the bones of calcium if the net acid load is too high and not balanced with enough of the alkaline plant foods.

And the way they tell the general public how to deal with this is not

"eat less animal protein"

but rather

"keep animal protein high but eat more fruits and veggies and less grains"

Here is a letter discussing the problem
[www.ajcn.org]