Another common complaint is of the T-Nation forums, which are reported to be heavily censored towards any criticism of BioTest products and the articles on the site. For a long period of time, T-Mag and BioTest have had a running feud with fellow supplement maker, Syntrax. They were one of the first to have serious criticisms of the compound glycocyamine. A substance first seen in Syntrax's first incarnation of Swole, and the subsequent tide of copy cat formulas that followed. Since Syntrax has turned into SI03 and it's online message board disappeared, it left them in a limbo, with people wondering who is now behind the scenes at Syntrax and does the renowned Derek Cornelius still reside as president? But, the debate over the safety of glycocyamine is a valid one, the concern being that it raises homocysteine levels, which is generally answered with the inclusion of Betaine (also known as TMG) in most supplements.
Now T-Mag has made another striking accusation against glycocyamine - that it is a neurotoxin. Unfortunately, the research they use to validate this is questionable. Used as their first source for this is the study Activation of GABA(A) receptors by guanidinoacetate: a novel pathophysiological mechanism. Quoted from this studies abstract for the method to determine that the compound is neurotoxic: "To examine a potential role of GAA accumulation, we analyzed the electrophysiological responses of neurons induced by GAA application in primary culture and acute murine brain slices." To be clear this study was conducted in vitro and is not sufficient to define glycocyamine as a toxic compound.
The next claim to be made by Dave Barr, author of the article, is that glycocyamine inhibits the "sodium pump". According to the Wikipedia, the sodium pump is correctly termed as:
Na+/K+-ATPase (also known as the Na+/K+ pump or sodium-potassium pump) is an enzyme .. located in the plasma membrane (specifically an electrogenic transmembrane ATPase). It is found in the plasma membrane of virtually every human cell and is common to all cellular life. It helps maintain cell potential and regulate cellular volume.In essence, the sodium pump is not simply a brain enzyme as defined in the article, but actually a critical transport that regulates potassium and sodium, two highly important electrolytes, on a cellular level. Again, we see the author quote a study not done on humans, or even more pertinent, male athletes. Rats are the subject of this March 2006 study, titled Intrastriatal administration of guanidinoacetate inhibits Na+, K+-ATPase and creatine kinase activities in rat striatum. In the next study we see for the purported evidence against glycocyamine, is - surprise, surprise, "...the pathogenesis of the brain dysfunction in this disorder is not yet established. In the present study we investigated the in vitro effect of GAA on Na+, K+-ATPase and Mg2+-ATPase activities in synaptic plasma membrane from hippocampus of young rats."
However, just because these studies are not in vivo, or even done in male weightlifters or the human species, does that mean there is not valid evidence against glycocyamine? No, the evidence should be weighed as it, since it is some of the only good studies that show the activity of glycocyamine. There is one other problem with the studies all mentioned by Barr. All studies involve symptoms of an "inherited neurometabolic disorder" called a "GAMT deficiency" or Guanidinoacetate methyltransferase deficiency. Guanidinoacetate being another term for glycocyamine. But, what exactly does this mean? What is a Guanidinoacetate methyltransferase deficiency? The answer can be found through a quick Google search with the first result, a PDF study from the UK in 2001.
Guanidinoacetate methyltransferase (GAMT, EC 22.214.171.124) deficiency is a newly recognized inborn error of creatine synthesis. The clinical phenotype is variable including a spectrum of neurological involvement from progressive extrapyramidal movement disorder and severe muscular hypotonia, to epilepsy and mental retardation. Biochemical findings include high urinary excretion of guanidinoacetate (immediate precursor of creatine and substrate to the deficient enzyme activity), low urinary excretion of creatinine, and depletion of creatine in brain and muscle. Enzymatic diagnosis is possible by the demonstration of deficient GAMT activity in liver, skin fibroblasts and virus transformed lympho blasts. Prenatal diagnosis has not been performed so far. Symptoms are partly reversible under oral supplementation of creatine-monohydrate. GAMT deficiency is an autosomal recessive inherited disorder. In the 9 patients known so far in the literature, 5 mutant alleles have been identified which are located in exon 2 and exon and intron 6 of the GAMT gene. The most efficient way for investigation of patients at risk seems to be determination of guanidinoacetate in body fluids. Several analytical methods including gas chromatography/mass spectrometry, tandem mass spectrometry and column chromatography are available for this purpose.So, not only is the author of the Muscle Milk article using studies that were not conducted in humans, but they were conducted on specimens that had a specific disorder that already had a deficiency of glycocyamine in the first place, making them totally irrelevant for weight lifters.
Still, despite all the banter back and forth about the mostly non-existent dangers of glycocyamine, Muscle Milk is still not a great MRP. The author is right about the fats, but he fails to mention the high GI carbs in the protein shake - made of maltodextrin, it will raise insulin levels which will in turn put the body in a prime state for fat storage. Still, MCTs aren't as bad as the author made it out to seem. The other negative for me for Muscle Milk is the worst sin of all - whey protein concentrate. For anyone who is the slightest bit sensitive to dairy products, it will send the user running straight for the bathroom.
But, for most, Muscle Milk should be a "cheat" protein shake. With all the flavors, which are all incredible, anyone could find Muscle Milk as enjoyable as a shake from McDonalds. It should be used sparingly, when you get sick of the Neapolitans - chocolate, vanilla and strawberry, try a root beer or pina colada. But, worry more about the high GI carbs, low quality protein, and questionable fat content in the MRP - not the glycocyamine.
Testosterone Nation - Consumer Report: Muscle Milk