Ornithine α-ketoglutarate – a remarkable anabolic amino acid

Ornithine alpha-ketoglutarate (OKG) is a salt formed of 2 molecules of the amino acid ornithine and 1 alpha-ketoglutarate (intermediate in the kreb cycle). There is evidence that the benefit of OKG is not the simple addition of the effects of ornithine (Orn) and alpha-ketoglutarate (AKG), because the presence of both moieties is required to induce the generation of key metabolites such as glutamine, proline, and arginine (Arg), whereas this does not occur when one or the other is given separately.

OKG activity has been associated with its ability to induce the secretion of anabolic hormones, such as insulin and growth hormone, and to increase glutamine and polyamine synthesis (polyamines are essential for muscle regeneration and growth). (R) This is quite markworthy as the majority of glutamine and arginine gets oxidized in the intestine and only a small percentage reach the bloodstream.


Ornithine alpha-ketoglutarate is Anabolic to muscle

This anabolic effect of OKG is very effective against sarcopenia, burn patients, surgery and other stressful catabolic conditions, by increasing anabolic hormones and increasing muscle protein synthesis (decreasing protein breakdown and increase protein synthesis) as well as aid in achieving/maintaining/retaining a positive nitrogen balance. (RRR, R) During such stressful times, high doses are used, 20g or 0.35g/kg of body weight/day.

OKG is successfully used in short stature children to increase their growth. During the OKG phase (15g daily for 5 months), doubled their growth rate by increasing IGF-1. (R)

OKG further aids in building the muscle as it increases insulin, and insulin is the primary driver of amino acids into muscles so that hypertrophy can occur.


As OKG consists of Orn and AKG, taking OKG will increase both these compounds in the body as well.


What does the Alpha-ketoglutarate part do?

Alpha-ketoglutarate potently stimulates the Kreb cycle that aids/speed up energy production as well as increases muscle protein synthesis and hypertrophy to name a few. (7) AKG enhances iron absorption, which would be most beneficial for rapid growing humans/muscle builders.

AKG increases the conversion of proline to hydroxyproline for collagen synthesis. In a study performed in growing pigs, it was displayed that enteral AKG administration increased the level of proline in the portal and arterial blood by 45% and 20%, respectively, when compared to animals that were not given AKG, which makes it very effective at increasing proline.

AKG has also been shown to boost immunity, (8) reduce catabolic proteins, 4E-BP1 and MAFbx, and increased anabolic proteins, namely Akt, mTOR, and S6. AKG has a direct effect on protein synthesis, which is independent of its metabolite, glutamate/glutamine.

A G-couple receptor senses AKG levels, and low AKG levels will down-regulate all the above-mentioned factors. (R)


What does Ornithine do?

Ornithine increases growth hormone, assists in the breakdown of ammonia to urea in the urea cycle, lower cortisol, improve sleep, lower serotonin, reduce fatigue, etc… More on ornithine here



So basically OKG would provide all the benefits of glutamine, arginine, proline, ornithine and alpha-ketoglutarate, all compacted into one amino acid salt.

I advise to take 5g before bed to spike growth hormone, improve sleep quality and to aid in building muscle during sleep. You can always start at a smaller dose to first see how you react to it, before increasing the dose to 5g. However, even up to 20g daily has been shown to be very well tolerated, but might be unnecessary.

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