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A lot of hearsay on bodybuilding forums (as well as "research" published by some supplement companies) suggests that creatine and L-glutamine compete for "receptors" and that taking them together can limit the effectiveness of both.

Further, there is an argument that L-glutamine may compete in a similar way with protein if taken with meals (and so, the logic goes, not effective for bulking since bulking requires constant eating).

Can anyone substantiate or disprove this with a solid explanation of how creatine and L-glutamine are absorbed?

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2 Answers 2

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The following is taken from an archived article on musculardevelopment.com (the author is a professional bodybuilder and nutrition PhD).

There's not an ounce of truth to this. Creatine and glutamine have completely different receptors. Creatine transport into skeletal muscle is regulated by the Creatine Transporter while glutamine transport into skeletal muscle is regulated by a system known as "System Nm." The only thing these transporters have in common is that they are both sodium-dependent transporters, meaning that they use differences in sodium concentrations across the cell membrane to drive Creatine into cells. Apparently somewhere along the line, somebody believed that since glutamine and Creatine transporters both shared that characteristic, they must be the same transporter and the myth spread from there. Let the confusion end here: they do not share the same transporter, and taking protein/glutamine with Creatine won't decrease Creatine uptake into muscle.

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No, they do not complete with each other for absorbtion and serve different functions. Glutamine will help shift your body from it's post workout catabolic state and will help with muscle repair and growth.

Glutamine is a non-essential ammino acid which helps prevent the breakdown of muscle fiber. Creatine helps the muscle fiber store more H2O and ATP energy. Supplementing with creatine also helps muscle recover faster from working out.

Protien: Glutamine is directly involved in the regulation of protein synthesis and breakdown. So how is it going to compete with protien? Also the protien you're taking contains ammino acids including glutamine so again, why would it compete? Glutamine is absorbed into the bloodstream, kidneys, liver and gut. Protien is processed in the stomache and then the intestine and finally absorbed by the gastrointestinal tract

Creatine: Creatine is derived from 3 non essential amino acids: glycine, methionine and arginine. After ingestion, creatine binds with phosphates in your body to form creatine phosphates. This phosphate bound creatine molecule donates its own phosphate molecule with ADP to reform ATP. Creatine absorbtion can be increased by using carbohydrates. Most people use some type of juice.

Also, are you going to be taking glutimine orally or through injections?

http://www.getbig.com/articles/glut-1.htm 
http://www.bodybuilding.com/fun/beast37.htm 
http://en.wikipedia.org/wiki/Protein_(nutrient) 
http://en.wikipedia.org/wiki/Creatine 
http://www.building-muscle-guide.com/what-is-creatine.html
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Any references for this information? –  Janis Peisenieks Mar 18 '11 at 16:54
    
Can you elaborate on what the absorption mechanisms are and demonstrate why they don't compete? Only the first sentence addresses my question - I wasn't asking what benefits of these supplements were, and I don't think the biochemical reactions are subject to opinion... –  Greg Mar 18 '11 at 19:38
    
updated my answer –  DustinDavis Mar 18 '11 at 20:58
    
Orally, mixed with a beverage just like my creatine. So I get that both glutamine and creatine are (or are derived from) amino acids, which make up proteins. But wouldn't it make intuitive sense that amino acids are all absorbed by a similar mechanism and that having an abundance of one in your gut (say, glutamine) would compete with your ability to digest the glycine, methionine and arginine at the same time? I think the missing piece of this answer is an explanation of how the digestion process differs for these different amino acids. –  Greg Mar 19 '11 at 19:47

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