L-arginine

What is L-arginine? Why do we need it?

L-arginine is an amino acid that helps the body build protein. Under certain circumstances, such as illness or stress, the body may require additional amounts [i]. L-arginine is also used supplementally because it may help your body produce proteins after exercise[ii]. Additionally, recent research suggests that L-arginine may lower blood pressure, improve cholesterol and improve overall blood vessel health[iii][iv].

Where does dietary L-arginine come from?

L-arginine is also found in most protein-rich foods, including fish, red meat, poultry, soy, grains, beans and dairy products[v].

What does deficiency of L-arginine look like?

L-arginine deficiency is pretty rare as the body can usually produce adequate amounts of it on its own, and it is found in plenty of foods. However, in certain circumstances, such as severe illness or medical conditions, the body's ability to produce or use L-arginine may be compromised[vi].

People who are deficient in L-arginine may exhibit symptoms such as:

Impaired wound healing, Poor immune function, Cardiovascular issues, Sexual dysfunction

What does L-arginine do? What are the benefits of taking L-arginine supplementally?

Nitric oxide production

L-arginine is a precursor to nitric oxide (NO), a molecule that helps dilate and relax blood vessels, thereby improving blood flow[vii]. Nitric oxide is important for cardiovascular health and plays a role in regulating blood pressure[viii].

Athletic performance

L-arginine is used by athletes and bodybuilders due to its potential to enhance performance[ix]. As such, it is believed to increase blood flow to muscles and promote muscle growth and maintenance of strength[x][xi][xii].

Blood pressure

L-arginine is a precursor to nitric oxide (NO), a molecule that helps dilate and relax blood vessels, leading to improved blood flow. By promoting the production of nitric oxide, L-arginine may have a blood pressure-lowering effect[xiii].

Blood sugar regulation

Research shows that L-arginine may benefit those with diabetes by improving glucose metabolism[xiv]. Nitric oxide also plays important roles in cellular function and how your body responds to insulin[xv]

Cholesterol and healthy blood vessels

Some studies suggest that L-arginine supplementation may have a positive impact on certain markers of cholesterol metabolism[xvi]. Although L-arginine does not directly affect cholesterol levels in the body, nitric oxide, synthesised from L-arginine, plays a role in maintaining the health and function of blood vessels[xvii].

Precautions:

Allergies

It is very rare, but some people might be allergic or sensitive to L-arginine. Symptoms may include rash, itching, swelling, dizziness, or difficulty breathing. If you experience any signs of an allergic reaction, discontinue use and seek immediate medical attention[xviii].

Guanidinoacetate methyltransferase deficiency

Those with an inherited disorder that affects arginine metabolism, should avoid L-arginine due to the potential for adverse effects[xix].

Herpes virus outbreaks

L-arginine may promote the replication of the herpes simplex virus (HSV), potentially leading to outbreaks[xx].

Surgery and bleeding disorders

L-arginine can affect blood clotting. It may increase the risk of bleeding during and after surgery[xxi].

Dosage

Please follow the advice of a nutritional therapist or the recommendations as per the product packaging when taking L-arginine supplements.

Specific medical conditions

In some cases, higher doses of L-arginine may be recommended for specific medical conditions, such as certain cardiovascular diseases or wound healing. In such cases, supervision by a healthcare professional is required.

Side Effects

Gut issues

In rare cases, L-arginine may cause digestive discomfort such as bloating, diarrhoea, or abdominal pain. These side effects are usually mild and go away quickly[xxii].

Low blood pressure

L-arginine has the potential to lower blood pressure. While this can be beneficial for those with high blood pressure, it may cause symptoms such as dizziness, light-headedness, or fainting in some. If you’re aware that you have low blood pressure or are taking medications that lower blood pressure, it is important to monitor your blood pressure closely while using L-arginine[xxiii].

Interactions

Blood pressure medications

L-arginine has the potential to lower blood pressure. If you are taking medications for high blood pressure or other cardiovascular conditions, it is important to discuss the use of L-arginine with your healthcare provider, as it may interact with these medications[xxiv].

Other drug interactions

L-arginine may interact with certain medications such as nitrates and erectile dysfunction medications like sildenafil (known as Viagra)[xxv]. It is advisable to consult with a healthcare provider or pharmacist to check for any potential interactions before taking L-arginine with other medications.

Pregnancy and breastfeeding

Although dietary L-arginine in food is required for development of the baby, limited research is available on the safety of L-arginine supplementation. It is recommended to consult with a healthcare professional before using L-arginine if you are currently pregnant or breastfeeding[xxvi].

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[ii] Pahlavani N, Entezari MH, Nasiri M, Miri A, Rezaie M, Bagheri-Bidakhavidi M, Sadeghi O. The effect of l-arginine supplementation on body composition and performance in male athletes: a double-blinded randomized clinical trial. Eur J Clin Nutr. 2017 Apr;71(4):544-548.

[iii] Furuno T, Mullen MJ Thorne SA Thomson H Donald AE Powe A et al. Intravenous L-arginine restores endothelial function in healthy young smokers (abstract). Circulation 1996;94:3052.

[iv] Norouzi M, Nadjarzadeh A, Maleki M, et al. Evaluation of the recovery after heart surgery following preoperative supplementation with a combination of beta-hydroxy-beta-methylbutyrate, L-arginine, and L-glutamine: a double-blind randomized placebo-controlled clinical trial. Trials 2022;23:649.

[v] Pahlavani N, Jafari M, Sadeghi O, Rezaei M, Rasad H, Rahdar HA, Entezari MH. L-arginine supplementation and risk factors of cardiovascular diseases in healthy men: a double-blind randomized clinical trial. F1000Res. 2014 Dec 12;3:306.

[vi] Morris CR, Hamilton-Reeves J, Martindale RG, Sarav M, Ochoa Gautier JB. Acquired Amino Acid Deficiencies: A Focus on Arginine and Glutamine. Nutr Clin Pract. 2017 Apr;32(1_suppl):30S-47S.

[vii] Bailey SJ, Winyard PG, Vanhatalo A, Blackwell JR, DiMenna FJ, Wilkerson DP, Jones AM. Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise tolerance. J Appl Physiol (1985). 2010 Nov;109(5):1394-403.

[viii] Maxwell AJ, Anderson B. A nutritional product designed to enhance nitric oxide activity restores endothelium-dependent function in hypercholesterolemia (abstract). J Am Coll Cardiol 1999;33:282A.

[ix] Meirelles CM, Matsuura C, Silva RS Jr, Guimarães FF, Gomes PSC. Acute Effects of L-Arginine Supplementation on Oxygen Consumption Kinetics and Muscle Oxyhemoglobin and Deoxyhemoglobin during Treadmill Running in Male Adults. Int J Exerc Sci. 2019 Mar 1;12(2):444-455. PMID: 30899346; PMCID: PMC6413837.

[x] Knechtle, B. and Bosch, A. The influence of arginine supplementation on performance and metabolism in athletes. INTERNATIONAL SPORTMED JOURNAL 2008;9:22-31

[xi] Hiratsu A, Tataka Y, Namura S, Nagayama C, Hamada Y, Miyashita M. The effects of acute and chronic oral l-arginine supplementation on exercise-induced ammonia accumulation and exercise performance in healthy young men: A randomised, double-blind, cross-over, placebo-controlled trial. J Exerc Sci Fit 2022;20:140-147.

[xii] Viribay A, Burgos J, Fernández-Landa J, Seco-Calvo J, Mielgo-Ayuso J. Effects of arginine supplementation on athletic performance based on energy metabolism: A systematic review and meta-analysis. Nutrients. 2020;12:1300.

[xiii] Abukhodair AW, Abukhudair W, Alqarni MS. The Effects of L-Arginine in Hypertensive Patients: A Literature Review. Cureus. 2021 Dec 17;13(12):e20485.

[xiv] Hu S, Han M, Rezaei A, Li D, Wu G, Ma X. L-Arginine Modulates Glucose and Lipid Metabolism in Obesity and Diabetes. Curr Protein Pept Sci. 2017;18(6):599-608. doi: 10.2174/1389203717666160627074017. PMID: 27356939.

[xv] Mousavi SM, Milajerdi A, Fatahi S, et al. The effect of L-arginine supplementation on obesity-related indices: A systematic review and meta-analysis of randomized clinical trials. Int J Vitam Nutr Res. 2021;91(1-2):164-174.

[xvi] Thorne, S., Mullen, M. J., Clarkson, P., Donald, A. E., and Deanfield, J. E. Early endothelial dysfunction in adults at risk from atherosclerosis: different responses to L-arginine. J Am.Coll.Cardiol. 1998;32:110-116

[xvii] Quyyumi, A. A. Does acute improvement of endothelial dysfunction in coronary artery disease improve myocardial ischemia? A double-blind comparison of parenteral D- and L-arginine. J Am Coll.Cardiol 1998;32:904-911.

[xviii] Takano H, Lim HB, Miyabara Y, Ichinose T, Yoshikawa T, Sagai M. Oral administration of L-arginine potentiates allergen-induced airway inflammation and expression of interleukin-5 in mice. J Pharmacol Exp Ther. 1998 Aug;286(2):767-71. PMID: 9694932.

[xix] O'Rourke, D. J., Ryan, S., Salomons, G., Jakobs, C., Monavari, A., and King, M. D. Guanidinoacetate methyltransferase (GAMT) deficiency: late onset of movement disorder and preserved expressive language. Dev.Med.Child Neurol. 2009;51:404-407.

[xx] Smulders, R. A., Aarsen, M., Teerlink, T., De Vries, P. M., Van Kamp, G. J., Donker, A. J., and Stehouwer, C. D. Haemodynamic and biochemical responses to L-arginine and L-lysine infusions in normal subjects: L-arginine-induced vasodilatation cannot be explained by non-specific effects of cationic amino acids. Clin.Sci.(Lond) 1997;92:367-374.

[xxi] Lin PH, Johnson CK, Pullium JK, Bush RL, Conklin BS, Chen C, Lumsden AB. L-arginine improves endothelial vasoreactivity and reduces thrombogenicity after thrombolysis in experimental deep venous thrombosis. J Vasc Surg. 2003 Dec;38(6):1396-403.

[xxii] Brooks JR, Oketch-Rabah H, Low Dog T, Gorecki DK, Barrett ML, Cantilena L, Chung M, Costello RB, Dwyer J, Hardy ML, Jordan SA, Maughan RJ, Marles RJ, Osterberg RE, Rodda BE, Wolfe RR, Zuniga JM, Valerio LG Jr, Jones D, Deuster P, Giancaspro GI, Sarma ND. Safety and performance benefits of arginine supplements for military personnel: a systematic review. Nutr Rev. 2016 Nov;74(11):708-721.

[xxiii] Abukhodair AW, Abukhudair W, Alqarni MS. The Effects of L-Arginine in Hypertensive Patients: A Literature Review. Cureus. 2021 Dec 17;13(12):e20485.

[xxiv] Abukhodair AW, Abukhudair W, Alqarni MS. The Effects of L-Arginine in Hypertensive Patients: A Literature Review. Cureus. 2021 Dec 17;13(12):e20485.

[xxv] El-Khateeb E, El-Haggar SM, El-Razaky O, El-Shanshory MR, Mostafa TM. Randomized Clinical and Biochemical Study Comparing the Effect of L-arginine and Sildenafil in Beta Thalassemia Major Children With High Tricuspid Regurgitant Jet Velocity. J Cardiovasc Pharmacol Ther 2022;27:10742484221132671.

[xxvi] Daniela Menichini, Lia Feliciello, Isabella Neri & Fabio Facchinetti (2023) L-Arginine supplementation in pregnancy: a systematic review of maternal and fetal outcomes, The Journal of Maternal-Fetal & Neonatal Medicine, 36:1