General Discussion Triathlon Talk » A few more nutrition questions... Rss Feed  
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2013-10-23 7:04 PM

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Subject: A few more nutrition questions...
I posted this in the supplement thread, but thought I would start a new thread in hopes of a response. The article I'm referencing is posted in the supplement thread--can't paste it with my phone :/

I had never considered viscosity as a determinant of absorption. 

It has been my understanding that protein consumption should be spread out because the body can only absorb "so much" per meal, but that amount was ~35g.  Am I way off here? Is the 8-10g/hour from the whey solely because it's a liquid?  That seems like too big a discrepancy between liquids and solids.

If it doesn't get absorbed, does that mean that those calories aren't being absorbed by the body either? 

Finally, that same article mentioned a pretty big window (.36-2.0g/lb) for the recommended amount of grams of protein/lb of body weight.  What do you all recommend for endurance athletes?

 



Edited by switch 2013-10-23 7:07 PM


2013-10-23 7:55 PM
in reply to: switch

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Subject: RE: A few more nutrition questions...

i read a pretty in depth article on this the other day... but can't find it now. i believe the issue really comes down to that your body only has ~1.5 hours from when you consume protein to absorb it before it passes too far along in your gut where absorbtion isn't possible anymore.  thus if your body can only absorb 10-15 grams per hour... well you can see how the math adds up

i think the article stated 20g was optimal per meal, and that there was no evidence of additional protein synthesis for any amount consumed above that per meal.

i'll post the article if i can find it again.

2013-10-24 10:31 AM
in reply to: Clempson

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Subject: RE: A few more nutrition questions...
Originally posted by Clempson

i read a pretty in depth article on this the other day... but can't find it now. i believe the issue really comes down to that your body only has ~1.5 hours from when you consume protein to absorb it before it passes too far along in your gut where absorbtion isn't possible anymore.  thus if your body can only absorb 10-15 grams per hour... well you can see how the math adds up

i think the article stated 20g was optimal per meal, and that there was no evidence of additional protein synthesis for any amount consumed above that per meal.

i'll post the article if i can find it again.




That is true. Where it makes a difference is in the type of food and how long it takes to empty the stomach. Something like a shake which is essentially liquid with mostly predigested protein added will empty the stomach very quickly, where a solid meal will take longer. The time in the intestine for absorption remains the same, however. So a 50g protein shake will leave the stomach very quickly, and the entire batch will move through, where 50g of protein from a solid source will leave the stomach in smaller chunks, allowing for more absorption in the same area.

Fiber also speeds up the process of movement through the intestine, not the reverse.

John
2013-10-24 10:58 AM
in reply to: tkd.teacher

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Subject: RE: A few more nutrition questions...

My registered dietitian says there are no documented studies that prove exactly how much protein a person can or cannot absorb in a specific amount of time.  She says everything out there is just theory and there are just as many studies that lean toward humans' ability to absorb 40+ grams in one sitting versus much less than that.

If any of you can point me to something that scientifically proves we cannot absorb more than X grams of protein in one sitting, I would love to take a look.  I certainly don't want to waste time ingesting something that I won't even absorb, but I have yet to find anything that would dissuade me from taking in a post workout shake with more protein than what I find in a serving of milk.  

2013-10-24 11:13 AM
in reply to: noelle1230

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Subject: RE: A few more nutrition questions...
I'll dig around and see what I can find.

Did see this one the other day, suggesting that fast acting protein (whey) may be better for older athletes versus casein being better for younger athletes.

http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2002.036897/ful...

John
2013-10-24 11:23 AM
in reply to: tkd.teacher

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Subject: RE: A few more nutrition questions...

Originally posted by tkd.teacher I'll dig around and see what I can find. Did see this one the other day, suggesting that fast acting protein (whey) may be better for older athletes versus casein being better for younger athletes. http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2002.036897/ful... John

Older, yep, that's me   Thanks, keep em coming!



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