L-Ornithine – Amino Acid That Could Increase HGH

L-Ornithine is a HGH Boosting Supplement

L-Ornithine has been brought into the bodybuilding industry with HGH optimisation as its goal.

Studies indicate it is an effective HGH booster and has a place in a HGH maximising supplement sack.

About L-Ornithine

L-Ornithine is amino acid that is used to dispose excess nitrogen in the urea cycle.

It is synthesised from essential amino acids and therefore sourced from standard sources of protein such as poultry and finish.

L-Ornithine is primarily marketed to support athletic performance, but it has a range of other benefits too.

These include easing anxiety, speeding up skin repair and liver support.

It has entered the bodybuilding world as a supplement primarily to assist increasing HGH levels naturally, along with other amino acids such as discussed on this website like L-arginine and L-glutamate.

Standard doses range from 2-6g, with the latter being upper safe limit of intake. However, this dose rarely causes any side effect.

A higher dose of 10g or higher can cause diarrhea and intestinal side effects but this is not fully scientifically confirmed. Side effects seem to mild but include:

  • Intestinal upset
  • Restlessness
  • Insomnia

It should not be taken with MAOIs, erectile dysfunction medications or drugs reducing blood pressure.


The HGH Connection

Ornithine injections have been clearly proven able to increase HGH levels (1).

A combination combining 2.2g Onithine, 3g Arginine and 12mg Vitamin B12 for 3 weeks increased HGH by 35.7% an hour after exercise, as well as IGF-1 (2).

A study using 12 subjects who lifted weights, tested a range of Ornithine doses whilst measuring HGH concentrations (3).

The highest dose, which was 170mg/kg (12g for a 70kg man), was able to spike HGH levels 318% 90 minutes after. On the lower doses there was no spike.


There is mixed evidence, but overall seems to suggest that L-Ornithine supplements could produce a meaningful boost in HGH and therefore it’s not a surprise that it is bought by many bodybuilders.

Like all the supplements that can potentially boost HGH naturally, L-Ornithine is more of an icing on the cake compared to the core components of HGH boosting such as sleep, diet and training.

I recommend this L-ornithine supplement:

Swanson L-Ornithine Amino Acid (500mg, 60 Vegetarian Capsule)




  1. Evain-Brion D, et al. Simultaneous study of somatotrophic and corticotrophic pituitary secretions during ornithine infusion test. Clin Endocrinol (Oxf). (1982)
  2. Zajac A, et al. Arginine and ornithine supplementation increases growth hormone and insulin-like growth factor-1 serum levels after heavy-resistance exercise in strength-trained athletes. J Strength Cond Res. (2010)
  3. https://www.sciencedirect.com/science/article/pii/S0271531705802659

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