L-Arginine
Overview:
Arginine is a conditionally essential amino acid (essential in times when the body has undergone a state of trauma or illness and experiences prolonged dietary deprivation (reference 2)) that is most often used in athletic supplements as a result of its direct influence in the production of nitric oxide. Increased production of nitric oxide in the body translates into increased blood flow and the muscular sensation know as the “pump”. Arginine is a very popular supplement, as 5% of females and 8% of male NCAA athletes currently make use of it (reference13). This amino's uses range from forming vital nutrients (like creatine) to regulating cellular function, effectively perpetuating health of both hair and muscle growth (reference 3). Limited studies on weight training benefits have led to no conclusive evidence of improvement, however a study notes improved power output during ergometer sprints and increased fatigue resistance on a knee extension test (references 10-11).
Benefits:
The most relevant benefits of ingesting arginine as a nutritional supplement for our scope include the items listed in the overview such as improved immune system functionality and muscle growth in individuals who may be arginine-deprived. Additionally, Arginine has been studied to protect the pancreas and directly stimulate insulin release (reference 8), which can prove useful in individuals with glucose intolerance (reference 9). Arginine is converted to another amino acid, citrulline (included in our mix), during the nitric oxide cycle (reference 1.3 – metabolism diagram). Studies have demonstrated that the presence of either amino acid lowers blood pressure without affecting heart rate (reference 7), improving blood flow to extremities.
It is worth noting that excess levels or arginine do not necessarily yield higher levels of nitric oxide and therefore benefits may be capped in already healthy, arginine-sufficient individuals (references 4-5).
Synergies:
L-Lysine (an essential amino acid) has been acutely demonstrated to improve arginine’s effect on increasing growth hormone. 1.2 grams of lysine and 1.2 grams of arginine promote growth hormone secretion greater than the sum of the two on separate occasions (reference 6).
Side Effects:
The observed symptoms from taking 10+ grams of arginine daily includes upset stomach and diarrhea as result of the release of water and electrolytes into the gut.
Dosage:
Standard doses range from 3-6 grams taken before or during a physical activity.
Further Reference:
1. Malinauskas BM, et al Supplements of interest for sport-related injury and sources of supplement information among college athletes . Adv Med Sci. (2007)
2. Tharakan JF, et al Adaptation to a long term (4 weeks) arginine- and precursor (glutamate, proline and aspartate)-free diet . Clin Nutr. (2008)
3. de Jonge WJ, et al Overexpression of arginase I in enterocytes of transgenic mice elicits a selective arginine deficiency and affects skin, muscle, and lymphoid development . Am J Clin Nutr. (2002)
4. Bode-Böger SM, Scalera F, Ignarro LJ The L-arginine paradox: Importance of the L-arginine/asymmetrical dimethylarginine ratio . Pharmacol Ther. (2007)
5. Shin S, Mohan S, Fung HL Intracellular L-arginine concentration does not determine NO production in endothelial cells: implications on the "L-arginine paradox" .Biochem Biophys Res Commun. (2011)
6. Lin KY, et al Impaired nitric oxide synthase pathway in diabetes mellitus: role of asymmetric dimethylarginine and dimethylarginine dimethylaminohydrolase .Circulation. (2002)
7. Figueroa A, et al Watermelon extract supplementation reduces ankle blood pressure and carotid augmentation index in obese adults with prehypertension or hypertension . Am J Hypertens. (2012)
8. DiMagno MJ, et al Secretagogue-stimulated pancreatic secretion is differentially regulated by constitutive NOS isoforms in mice . Am J Physiol Gastrointest Liver Physiol. (2004)
9. Monti LD, et al Effect of a long-term oral l-arginine supplementation on glucose metabolism: a randomized, double-blind, placebo-controlled trial . Diabetes Obes Metab. (2012)
10. Buford BN, Koch AJ Glycine-arginine-alpha-ketoisocaproic acid improves performance of repeated cycling sprints . Med Sci Sports Exerc. (2004)
11. Stevens BR, et al High-intensity dynamic human muscle performance enhanced by a metabolic intervention . Med Sci Sports Exerc. (2000)