Green Glow contains 500 mg of L-arginine.
L-arginine is an amino acid your body uses to build proteins. It is also the precursor your cells use to make nitric oxide, a small signalling molecule that relaxes the inner lining of blood vessels and lets more blood through.[1] Healthy adults make some L-arginine from glutamine and proline. Diet covers the rest. Nuts, seeds, legumes, fish and poultry are the main food sources.[1]
If you have read about L-arginine for fertility, for endometrial blood flow around ovulation or for circulation during exercise, this page covers the forms, the dose and what the research actually shows in women.
Forms of L-arginine
L-arginine is the free amino acid form used in most supplements. It is absorbed in the small intestine then converted to nitric oxide by an enzyme called nitric oxide synthase. Plasma levels peak about an hour after an oral dose then fall back over a few hours.[1]
L-arginine HCl is the same molecule paired with hydrochloride for stability. It behaves identically once absorbed.
L-citrulline is a related amino acid that the kidneys convert into L-arginine. Some studies suggest it raises plasma arginine more efficiently than oral arginine itself. The two are sometimes used interchangeably for circulation outcomes.[1]
nōuxx Green Glow uses free L-arginine. Absorption is best on an empty stomach or between meals. Large protein-heavy meals compete for the same intestinal transporters.[1]
How much you need
L-arginine is not classed as essential in healthy adults because the body can make it. There is no recommended daily intake from EU food agencies. Typical Western diets supply 4 to 6 grams per day from food.[1]
Fertility trials have used 1 to 6 grams of L-arginine per day, sometimes alongside other nutrients.[3] The 500 mg in nouxx Green Glow sits below those research doses. It is a nutritional input, not a treatment for a fertility problem.
The science on women's health
Fertility
L-arginine has been studied in women trying to conceive on the theory that better uterine blood flow supports endometrial thickness and implantation. A 2022 umbrella review of immunonutrients in reproduction grouped arginine with the amino acids most studied for gamete quality. The authors concluded that mechanistic data are interesting but clinical trials are small and inconsistent. They did not recommend routine use.[2] A 2020 Cochrane review of female subfertility included 63 trials of various antioxidants, including L-arginine and antioxidant combinations. The 63 trials were not all studies of L-arginine. Overall evidence quality was low to very low. The authors could not draw firm conclusions on live birth rates for any single antioxidant including arginine.[3]
The mechanism is plausible. Nitric oxide made from arginine relaxes uterine arteries and supports endometrial vascular development.[1] The clinical signal in healthy women trying to conceive is not yet strong enough to make a claim.
EU authorised health claims
Under EU law, no specific health claim is currently authorised for L-arginine. The European Food Safety Authority has not approved a claim because the available evidence has not yet met the EU bar for cause-and-effect in healthy adults.
Most fertility trials are small and cannot establish a benefit for healthy women at the 500 mg dose in nouxx Green Glow.[2][3] We do not make formal health claims for L-arginine.
References
[1] Wu G, Meininger CJ, McNeal CJ, Bazer FW, Rhoads JM. Role of L-arginine in nitric oxide synthesis and health in humans. Advances in Experimental Medicine and Biology 2021;1332:167-187. doi.org/10.1007/978-3-030-74180-8_10
[2] Di Renzo L, Gualtieri P, Alfano V, et al. Immunonutrients involved in the regulation of the inflammatory and oxidative processes: implication for gamete competence. Journal of Assisted Reproduction and Genetics 2022;39(4):817-846. doi.org/10.1007/s10815-022-02472-6
[3] Showell MG, Mackenzie-Proctor R, Jordan V, Hart RJ. Antioxidants for female subfertility. Cochrane Database of Systematic Reviews 2020;8:CD007807. doi.org/10.1002/14651858.CD007807.pub4
