Which Nutreval is better, FMV or Plasma?

[sweetlily]

1. There are two Nutreval tests listed on the GDX website: FMV and Plasma. It looks like the only difference is that the FMV measures amino acids in urine, while the Plasma test measures amino acids in plasma. Is this correct? Unfortunately the GDX website lists the analytes in the Nutreval test but it doesn’t say which are measured in urine and which are measured in plasma.

2. If you could get amino acids measured only one way—urine or plasma—which is preferable? (I already had urinary “OAT” but this doesn’t include all amino acids). From what I can tell it seems the plasma is more accurate at getting at the picture of methylation, transsulfuration, b12/6 metabolism, etc, because urinary levels of some substances are influenced by so many factors that are extraneous; while blood levels are more tightly regulated.

As a thought experiment suppose I took a large dose of X, much more than my body needed, and suppose that X is excreted in urine. Then the blood level of X *might* more accurately reflect whether I had the “right” level of X and the urine would have a whole lot of X that my kidneys excreted because I didn’t need it. Does this argument make sense to answering the question “Urine or plasma for amino acid measurement?”

 

[Valentijn]

Blood should be more accurate. But urine amino acids is typically cheaper and might include far more amino acids.

 

[sweetlily]

Thanks, I appreciate this valuable insight. Yet I am still curious about which will shed the most accurate light on the dynamics of the underlying biochemistry?

 

[BFG]

I am also getting the NutrEval testing done soon. Here is a link to a Metametrix article detailing in which circumstances plasma amino acid might be more beneficial over urine and vice versa.

http://www.metametrix.com/files/learning-center/articles/amino-acid-profiling.pdf

I'm still cannot decide which one, but I think I'm leaning toward the plasma.

 

[invisiblejungle]

I did the Nutreval with urine amino acids last year, but if I ever do it again I'll probably do the blood amino acids. The urine results aren't easy to interpret.