High G Review

High G

High G
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High G, made by the same folks as High T and High T Black, is marketed as a performance enhancer/recovery supplement and features a variety of ingredients that may actually be effective. Unfortunately, we see some serious issues when it comes to the dosing of certain ingredients…


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High G, made by the same folks as High T and High T Black, is marketed as a performance enhancer/recovery supplement and features a variety of ingredients that may actually be effective. Unfortunately, we see some serious issues when it comes to the dosing of certain ingredients…[Skip to the Bottom Line]


Alpha GPC is considered one of the most bioavailable Choline sources and is generally used to increase Acetylcholine levels in the brain, which can enhance cognitive ability. However, it also has some direct (though under-researched) physical performance enhancement implications as well.

A 2008 study, published in the “Journal of the International Society of Sports Nutrition”, found that oral supplementation of 600mg of Alpha GPC (as AlphaSize) increased power output by an average of 14% in resistance trained males, measured by bench throws.

High G contains 150mg of active Alpha GPC (from 300mg AlphaSize) which, despite being less than what was used in the above-mentioned study, is still more than most Alpha-GPC-containing supplements we come across.


Phsophatidylserine is a phospholipid often derived from soy which has a fair amount of research regarding its effects on Cortisol.

A 2001 study, published in “Nutritional Neuroscience” found that treatment with 300mg of Phosphatidylserine daily was able to reduce subjective feelings of stress as well as the heart rate response to an acute stressor, in healthy young-adult subjects.

A 2008 study, published in “Neuroendocrinology”, found that Phophatidylserine (50-75mg) was able to significantly blunt the spike in exercise-induced Cortisol.

These findings were replicated in a separate 2008 study, published in the “Journal of the International Society of Sports Nutrition”, using 600mg.

Overall, Phosphatidylserine definitely possesses some anti-Cortisol properties, and High G contains a technically effective 100mg dose. So, at the very least, users may experience slightly lower Cortisol levels.


Arginine is a non-essential amino acid that acts as a precursor to Nitric Oxide which generally enhances physical performance, specifically endurance.

Although high doses (6g at least) of Arginine have been shown to increase circulating Nitric Oxide levels and muscle blood volume post-workout, it has failed to increase intra-workout strength in more than one study.

The AKG form, which API has elected to use in High G, is alleged to be superior due to better absorption, but research indicates this may not be the case.

A 2012 study from the “Journal of the International Society of Sports Nutrition” found no performance enhancement benefits with 3700mg of Arginine Alpha-Ketoglutarate prior to resistance training. In fact, in this particular study, subjects who received the AAKG actually performed slightly worse than the placebo group.

Due to the relatively small size of this study, it cannot be considered conclusive, but it certainly does not lend credibility to the notion that Arginine AKG is as effective as L-Arginine, let alone superior.

Unfortunately, the amount of Arginine present in High G is nowhere near the doses that are commonly used in studies, and even some of those failed. In the context of High G, Arginine is pretty useless.


L-Alanyl L-Glutamine, as the name implies, is a dipeptide made up of Alanine and Glutamine. The idea behind L-Alanyl L-Glutamine is based on the notion that dipeptides are able to share the same transport into the cell, and can therefore be absorbed into the cell more effectively than two separate amino acids, which would require two separate transports.

A 2012 study showed better absorption of Glutamine (determined by plasma glutamine levels) when subjects ingested L-Alanyl L-Glutamine, than when they just ingested L-Glutamine alone.

Unfortunately, the amount of L-Alanyl L-Glutamine in High G is pretty negligible, even it is more readily absorbed.


Leucine is an amino acid belonging to the group known as Branched Chain Amino Acids (BCAAs), along with Isoleucine and Valine.

Leucine’s primary mechanism of action is via activation of Mammalian Target of Rapamycin (mTOR) which is a signaling molecule that signals the body to synthesize protein. To put it simply, Leucine activates mTOR which in turn stimulates protein synthesis.

The most common ratio found in BCAA supplements, the same ratio found in Iso Amino, is 2:1:1 with the higher weight being Leucine. While there is no reliable scientific evidence to indicate one true “optimal ratio”, Leucine tends to be the most abundant because it is the most potent with regards to stimulation of muscle protein synthesis.

This was first demonstrated in a 1999 study from the “Journal of Nutrition”, but has been replicated several times since then.

A 2009 study, published in “Applied Physiology, Nutrition, and Metabolism”, found that Leucine’s stimulation of muscle protein synthesis was augmented by physical exercise, indicating that pre/intra workout Leucine supplementation may have a greater impact than at other times.

These results were consistent with those of an earlier (2001) study from the “American Journal of Physiology-Endocrinology and Metabolism” in which essential amino acid (include Leucine) ingestion prior to exercise had a greater influence protein synthesis than post-exercise ingestion in healthy human subjects.

Leucine has also been shown, in multiple studies, to preserve muscle mass in individuals with certain diseases characterized by muscular wasting, further establishing Leucine as a potent anti-catabolic agent, and indicating that it is particularly useful for those with inadequate protein intake (during fasting).

Unfortunately, as with the ingredient above, there is not enough Leucine in High G to influence muscle protein synthesis very much.


While Leucine is the most important with regards to muscle protein synthesis, Isoleucine appears to have unique benefits regarding glucose uptake by muscle cells (while lowering blood glucose). In rat studies, Isoleucine has been shown to lower blood glucose and increase glucose uptake into muscle cells. While the effect of Isoleucine (in isolation) on muscle glucose uptake has not been studied in humans, BCAAs in general due appear to increase glucose uptake, and based on the rat studies this may be due to Isoleucine more so than the others.

High G undoubtedly contains a negligible amount of Isoleucine, so in this particular instance it is pretty useless.


Citrulline is actually significantly more effective at raising plasma Arginine than supplemental Arginine itself, and while results with Arginine are mixed, Citrulline has demonstrated clear efficacy as a performance enhancer.

A 2002 study, published in the “British Journal of Sports Medicine” found that Citrulline Malate supplementation (6g/day for 15 days) significantly increased ATP production during exercise in healthy adult males.

A 2009 study, published in the “Journal of Free Radical Research”, found that 6 grams of Citrulline Malate given to male cyclists before a race increased “plasma Arginine availability for NO synthesis and PMNs priming for oxidative burst without oxidative damage”.

Citrulline has been shown to increase the amount of reps performed at a given weight in a 2010 study from “The Journal of Strength & Conditioning” and a 2014 study from the “Journal of Strength and Conditioning Research”.

This is due to Citrulline increasing muscular contraction efficiency, effectively requiring less ATP for muscle contraction.

Unfortunately, judging by the weight of the proprietary blend as a whole, we can be certain that High T Black does not contain anywhere near a clinically effective dose of Citrulline.


High G contains effective ingredients but some appear significantly under-dosed. Arginine, Leucine, Citrulline, and Glutamine are crammed into a 600mg proprietary blend, but even 600mg of any of these ingredients by themselves would be insufficient. At over $1.50 per serving, High G is extremely overpriced, given the subpar doses of Citrulline, Arginine, Glutamine, Leucine, and Isoleucine.

[expand title=”REFERENCES” tag=”h5″]

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  2. Monteleone, Palmiero, et al. “Effects of phosphatidylserine on the neuroendocrine response to physical stress in humans.” Neuroendocrinology52.3 (2008): 243-248.
  3. Benton, D., et al. “The influence of phosphatidylserine supplementation on mood and heart rate when faced with an acute stressor.” Nutritional neuroscience 4.3 (2001): 169.
  4. Starks, Michael A., et al. “The effects of phosphatidylserine on endocrine response to moderate intensity exercise.” Journal of the International Society of Sports Nutrition 5.1 (2008): 1-6.
  5. Coëffier, Moïse, et al. “Enteral glutamine stimulates protein synthesis and decreases ubiquitin mRNA level in human gut mucosa.” American Journal of Physiology-Gastrointestinal and Liver Physiology 285.2 (2003): G266-G273.
  6. Candow, Darren G., et al. “Effect of glutamine supplementation combined with resistance training in young adults.” European journal of applied physiology 86.2 (2001): 142-149.
  7. Wilkinson, Sarah B., et al. “Addition of glutamine to essential amino acids and carbohydrate does not enhance anabolism in young human males following exercise.” Applied Physiology, Nutrition, and Metabolism 31.5 (2006): 518-529.
  8. Cury-Boaventura, Maria Fernanda, et al. “Effects of exercise on leukocyte death: prevention by hydrolyzed whey protein enriched with glutamine dipeptide.” European journal of applied physiology 103.3 (2008): 289-294.
  9. Carvalho-Peixoto, Jacqueline, Robson Cardilo Alves, and Luiz-Claudio Cameron. “Glutamine and carbohydrate supplements reduce ammonemia increase during endurance field exercise.” Applied Physiology, Nutrition, and Metabolism 32.6 (2007): 1186-1190.
  10. Harris, Roger C., et al. “L-glutamine absorption is enhanced after ingestion of L-alanylglutamine compared with the free amino acid or wheat protein.” Nutrition Research 32.4 (2012): 272-277.
  11. Kraemer Zhang Wax, Benjamin, et al. “Acute L-arginine alpha ketoglutarate supplementation fails to improve muscular performance in resistance trained and untrained men.”Journal of the International Society of Sports Nutrition 9.1 (2012)
  12. Bailey, Stephen J., et al. “Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise tolerance.” Journal of Applied Physiology 109.5 (2010): 1394-1403
  13. Kraemer Zhang Alvares, Thiago S., et al. “L-Arginine as a Potential Ergogenic Aidin Healthy Subjects.” Sports Medicine 41.3 (2011): 233-248
  14. Anthony, Tracy G., et al. “Oral administration of leucine stimulates ribosomal protein mRNA translation but not global rates of protein synthesis in the liver of rats.” The Journal of nutrition 131.4 (2001): 1171-1176.
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  16. Tipton, Kevin D., et al. “Stimulation of net muscle protein synthesis by whey protein ingestion before and after exercise.” American Journal of Physiology-Endocrinology and Metabolism 292.1 (2007): E71-E76.
  17. Tipton, Kevin D., et al. “Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise.” American Journal of Physiology-Endocrinology And Metabolism 281.2 (2001): E197-E206.
  18. Anthony Anthony, Joshua C., Tracy Gautsch Anthony, and Donald K. Layman. “Leucine supplementation enhances skeletal muscle recovery in rats following exercise.”The Journal of nutrition 129.6 (1999): 1102-1106.
  19. Doi, Masako, et al. “Isoleucine, a blood glucose-lowering amino acid, increases glucose uptake in rat skeletal muscle in the absence of increases in AMP-activated protein kinase activity.” The Journal of nutrition 135.9 (2005): 2103-2108.
  20. Doi, Masako, et al. “Isoleucine, a potent plasma glucose-lowering amino acid, stimulates glucose uptake in C2C12 myotubes.” Biochemical and biophysical research communications 312.4 (2003): 1111-1117.
  21. Giannesini, Benoît, et al. “Citrulline malate supplementation increases muscle efficiency in rat skeletal muscle.” European journal of pharmacology 667.1 (2011): 100-104.
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