L-arginine: Benefits, Side Effects and Dosage

what does l-arginine do

L-arginine is one of many amino acids that the body needs to function efficiently. Similarly to other amino acids, L-arginine (or arginine) possesses a role in building protein that the body can use to help rebuild tissue and build muscle.

With growing popularity as a fitness supplement, two key areas of interest are the question of ‘what are the benefits of L-arginine for bodybuilding?’, and whether taking an L-arginine supplement can improve athletic performance. 

You will find the answers to both questions explored within this article, as well as some of the most research-validated health benefits of L-arginine for men and women. 


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What is L-arginine?

does l-arginine work

Arginine is a 'semi-essential' amino acid which, as we mentioned, is obtained from the diet and is necessary for the body to make proteins. L-arginine releases the enzyme nitric oxide in the blood, and the role of nitric oxide is to widen blood vessels in the bloodstream. This may help certain circulatory conditions.

One advantage to L-arginine unlike other acids and nutrients in the body is that deficiencies of it are rare due to its abundance in many different types of foods. In addition to its presence in food, the human body can also create it.

Occasionally, though rare, a person’s need for the amino acid L-arginine may exceed the body’s ability to produce or consume it naturally. This is more common for older adults or those suffering/diagnosed with certain medical conditions. 

If this is the case, a person may be prescribed L-arginine in the form of oral medication, injections, or creams. The term L-arginine is used when referring to arginine supplements.

L-arginine Benefits

#1 Enhances Athletic Performance

l-arginine blood pressure

One of the most commonly searched questions surrounding this amino acid is L-arginine benefits for bodybuilding. 

L-arginine has gained a reputation amongst the bodybuilding community as a supplement that can aid in circumstances where people are wanting to build muscle mass, as well as aiming to lean out. 

Due to L-arginine’s reputation as a supplement that stimulates vasodilation (the widening of blood vessels), it has been linked directly to enhanced performance, as in order to reach maximum performance during a workout an efficient flow of blood to working muscles is needed.

In a study published in 2010, researchers analysed nine healthy men who consumed 6g of L-arginine powder or a placebo and were then asked to perform a series of exercise bouts varying from moderate intensity to severe intensity

The results found that compared to the placebo, the L-arginine group had significantly enhanced tolerance or took significantly longer to get tired when performing high-intensity exercise. In turn, this provided evidence that L-arginine does improve exercise efficiency and exercise tolerance by showing that through the addition of the supplement prior to working out, a person can carry out a more effective and thorough workout.

Similarly, results from other trials conducted further support the theory that a diet rich in L-arginine can reduce systolic blood pressure and therefore can improve exercise efficiency and exercise tolerance in healthy humans.

#2 Improves Muscle Building

L-arginine benefits muscle

Another one of the commonly acknowledged L-arginine benefits is its contribution to muscle growth, as it is needed for the synthesis of most proteins. While the muscle mass increases, L-arginine also signals muscle cells, encourages the release of growth hormone and promotes a fast metabolism. 

By reducing the fat stores underneath the skin and promoting muscle growth, it has been proven that L-arginine can increase fitness performance and improve strength - leading to increased muscle mass.

There is substantial research that explores the claim that L-arginine taken as a supplement can promote muscle growth, decrease the muscle to fat ratio, improve muscle strength and decrease fat stores. 

The existing research exploring L-arginine benefits for muscle mass presents an array of results. For instance, in one study L-arginine powder was given as a supplement to 24 pigs over a 60-day period. On average, the pigs experienced an increase in skeletal-muscle by 5.5% and a fat decrease by 11%. The results show that L-arginine supplementation promoted muscle gain and reduced body fat significantly. 

Further studies conducted offer the same or similar findings in that implementing a supplementation into your lifestyle can lead to overall body growth, with increased lean deposition and mineral bone density, all while avoiding increasing fat accretion all together. Of course, the reslts are optimised when paired with an effective training programme; why not combine L-arginine with our guide on how to get bigger arms fast for quicker results.

#3 Reduces High Blood Pressure and Treats Heart Disease

What are the benefits of l-arginine

Some research suggests that artificial L-arginine consumed orally can lower blood pressure in healthy people, and those with a type of high blood pressure that affects the arteries in the lungs and the right side of the heart (pulmonary hypertension). There is also evidence to suggest that infusions of L-arginine can reduce blood pressure in people with hypertension (high blood pressure).

L-arginine blood pressure effects and benefits have been widely explored over the years, with studies containing strong evidence to suggest that L-arginine’s role in lowering blood pressure in those who suffer with hypertension is likely as a result of the nitric oxide and its effects in widening blood vessels. 

However, L-arginine's vasodilation effects may not only have implications for high blood pressure. In a year-long trial, consisting of a group of 65 patients who were given a tablet containing L-arginine, the results showed those consuming L-arginine experienced less oxidative stress or cellular damage, better cardiovascular function, and the reduced progression of atherosclerosis.

The health benefits of L-arginine for improved vascular function are highly researched. L-arginine's ability to lower blood pressure has potential implications for high blood pressure during pregnancy, the progressive dysfunction of the cardiovascular system in ageing and walking distance for anyone with intermittent leg cramping, leg weakness or 'intermittent claudication' or atherosclerosis. 

L-arginine supplementation also has the potential to lower the need to take blood pressure-lowering drugs eliminating the chance of serious side effects.


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#4 Treating Erectile Dysfunction (ED)

Benefits of l arginine for men

One of the most studied L-arginine benefits is its work as a possible treatment for erectile dysfunction (ED). 

L-arginine, as we have discussed, creates nitric oxide (NO) in the body which helps to relax blood vessels, allowing oxygen-rich blood to circulate more freely to the tissues where they are needed. Healthy blood flow is essential in anyone suffering from ED. Taken alone, L-arginine has little effect.

However, L-arginine when taken in combination with other bioactives, the results are very different. This can be supported by the findings of a 2003 study which explored the treatment of erectile dysfunction with pycnogenol and L-arginine. Researchers concluded that oral consumption of L-arginine, in combination with Pycnogenol causes a significant improvement in sexual function in men with ED without any side effects. 

L-arginine has also been used and proven effective in science to improve erectile dysfunction of a mild to moderate severity - at least in the short term.

Another combination is L-arginine and Pycnogenol, the trademark name for a mixed supplement, which has been shown to allow men ages 25 to 45 to achieve normal erections without side effects.

#5 Treating Growth Hormone Deficiencies

The benefits of l-arginine

L-arginine has long been used as a medication for treating those with a deficiency in the Human Growth Hormone (HGH). 

The Growth Hormone Reserve Test is used to identify whether the HGH being released from the pituitary gland is deficient or not. The test is carried out by injecting arginine into the body to raise HGH levels, measuring the pituitary glands ability to secrete growth hormone in response. If a deficiency in HGH is detected, the medicine given is L-arginine.

A famous example of HGH deficiency is PSG's Lionel Messi. Messi's contract, signed on a napkin, was conditional upon the football club paying for 13-year-old Messi's HGH treatment.  

Athletes may inject HGH after training. For example, use of HGH has come to public attention popular with its ban in the Tour de France. Its use is based on anecdotal stories of gains in strength, improved sex, better energy and increased muscle mass influencing younger athletes who want the best results possible. 

Interestingly, there's very little evidence to support the proposed benefits of HGH at safe levels. It's possible that HGH does have benefits at unsafe levels which can cause serious side effects. 

However, the medicine given for low HGH is L-arginine and as discussed previously L-arginine shows consistent results in reducing fat whilst increasing lean body mass in animal studies, though yet to be confirmed in human trials.

Certainly if considering only the research, if an athlete is interested in increasing muscle mass and strength, they're far more likely to see results with L-arginine supplementation at a side effect free dose than the dangerous doping levels of HGH. 

#6 Anti-Aging Benefits

what does l-arginine do

L-arginine is one of the most metabolically versatile amino acids that plays an important role in the synthesis of nitric oxide, polyamines, proline, glutamate, creatine, agmatine and urea, which are involved in the regulation of aging and lifespan. 

In fact, the anti-aging benefits of L-arginine powder show greater potential than any pharmaceutical or nutraceutical agent ever previously discovered. Through a combination of its metabolic and physiological pathways, L-arginine shows sufficient evidence in improving the likes of delay in mental exhaustion, deepness of sleep, anxiety and stress, as well as general mood; all of which have a significant link to ageing signs. By improving these bodily functions, L-arginine, in turn provides indirect benefits to anti-ageing.

Potential Risks of L-arginine

What is l-arginine

Research has shown that L-arginine is generally well tolerated and safe when consumed in supplement form, even when taken daily over long periods of time of a year plus. However, L-arginine can cause unpleasant side effects when taken in excessively large quantities, including: abdominal pain, nausea, bloating and diarrhea - particularly when taken in doses of 9g or more per day.

Depending on your needs, a better option possessing less risks is to obtain L-arginine through the form of a diet. As with any supplement or medication, consult with a doctor or dietician before taking L-arginine. This is important too because it's necessary to understand how the supplement may interact with any additional medications.

For certain groups of people, L-arginine can pose a serious risk. A few include: death in children and infants, as mentioned, L-arginine can be potentially fatal for anyone who has suffered a heart attack, anyone about to go into surgery, and L-arginine can worsen herpes.

As with many supplements, L-arginine powder and other forms can have negative interactions with medications, including those prescribed for high blood pressure and Viagra so be sure to consult a doctor prior to implementing a supplementation of L-arginine into your diet.

L-arginine Dosage

There is no specific RDA (recommended dietary allowances) for arginine as it is produced efficiently in the body of healthy adults. 

Looking at L-arginine dosage, clinical trials have shown L-arginine can be used safely up to 1200mg per day. If you're considering how to take L-arginine, when sold as a supplement L-arginine powder will regularly contain around 3000mg per serving, so looking for a capsule of around 1200mg may be a better alternative.


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What Does L-arginine Do?

L arginine benefits bodybuilding

The human body needs arginine to function, with arginine benefits including: building protein for muscle repair, wound healing, immune function, cell division and in the regulation and release of hormones. 

However, a person’s need for arginine, such as athletes, the elderly and some with certain medical conditions, may exceed how much the body can produce or how much can be consumed in diet. 

Researchers have been exploring the health benefits of L-arginine supplements for over sixty years, with well-researched L-arginine benefits including: improved circulation, lowered blood pressure, regulating Human Growth Hormone in children, anti-ageing, improved male fertility, correcting digestive disorders and easing symptoms of type two diabetes.

How Does L-arginine Work?

Firstly, L-arginine turns into nitric oxide inside the body, a potent vasodilator, meaning it dilates blood vessels, which may aid in circulatory conditions and muscle oxygenation in exercise. Secondly, identical to arginine amino acid benefits, L-arginine helps the body build protein. 

For example, L-arginine is a precursor for the synthesis of proline, important for metabolism, glutamate, essential for immune function, and for anyone interested in L-arginine for bodybuilding, creatine for improved strength and building lean muscle.

Where to Buy L-arginine?

l-arginine health benefits

Like when purchasing any supplements and vitamins, it is highly advised to purchase from retailers and health stores that carry a trusted reputation. L-arginine supplements are widely available from names such as Amazon, Holland and Barrett and Nature’s Best, both in the form of tablets and powder - however the tablets are much easier to get your hands on.

Depending on the tablet depends on the additional features they may provide; for instance, Nature’s Best Arginine 1000mg High Strength tablets advertise that they are free-form for both fast release and easy absorption, whereas the Vitamaze L-arginine capsules, which provide 4500mg per serving, boasts its absence of the ‘controversial additive’ Magnesium Stearate which many other forms of the tablet include.

It is important to note that there is a broad range of offerings on the market and the dosage of the tablets varies, so ensure you know what dosage you are specifically looking for to best compliment your diet and lifestyle.

Similarly, you’ll find that many sports retailers, such as MyProtein stock AAKG (Arginine Alpha-Ketoglutarate), which is a combination of L-arginine and alpha-ketoglutarate (one of two ketone derivatives of glutaric acid). The combination of these two are often sold in the form of pre-workouts.

Whether you’re after L-arginine for weight loss purposes, or it's muscle or blood pressure advantages, it is always important to research the products further, then from here, retailers such as Amazon, Holland and Barrett, and Nature’s Best are great places to begin your search.

When to Take L-arginine?

When considering when to take L-arginine, it is important to note, like other single amino acids, it's recommended to take it between meals for maximum absorption. 

While different brands have slightly differing recommendations, the general consensus is that L-arginine tablets and supplements are best taken half an hour prior to any meal and you plan to go to sleep - this is also the general instruction for all amino acids. 

All brands recommend a daily consumption of between one and four tablets, evenly distributed as two tablets in the morning and then two in the evening. The guidance from Amazon’s Vitamaze L-arginine supplements add that in intensive training periods or in special stress, you can take an additional two capsules in the day.

L-arginine Foods

how to take l-arginine

As we have highlighted, L-arginine is a semi-essential amino acid, which means as well as being naturally produced by the human body, it can be found in a number of foods, also. Foods which contain arginine include: poultry, seafood, red meat, nuts and seeds, whole grains, and dairy amongst others. 

If you’re wanting to increase your L-arginine intake via nuts but don’t know what kind would be most effective, we would highly recommend pumpkin seeds. Pumpkin seeds have one of the highest concentrations of L-arginine, with a single cup of dried pumpkin or squash seeds providing a total of 6.9g of the amino acid.

Alternatively, sesame seeds also act as a great source as they provide 4.8g per cup, as well as dried walnuts, almonds and pine nuts.

When looking to increase your L-arginine dosage through the use of meat, white meats are particularly a great source, with specific mention to turkey breast which provides approx 16.2g. However, chicken, pork loin chops and beef also provide a substantial source of L-arginine.

A less common source comes from seaweed. A cup of dried seaweed contains approximately 4.6g of the arginine. 

Arginine can also be found in numerous protein supplements in varying quantities.

Before You Go!

That concludes our guide on L-arginine. We hope this has provided you with enough knowledge of the amino acid to confidently implement it into your lifestyle 

Increasing L-arginine intake offers benefits for most, if not all, and while some benefits do not have the backing of substantial scientific research, there is enough evidence to support the advantages listed within this article and we would encourage researching further for additional potential profits this semi-essential amino acid can offer.

L-arginine is generally a very safe supplement to take, even for those with underlying conditions, however if you are prescribed any blood pressure medication we would advise you to talk to your GP before using L-arginine.

If you have a passion for the nutrition element of fitness and would be interested in developing your knowledge, why not take a look at our Level 4 Advanced Sports Nutrition course, where you will learn how diet and nutrition contribute to health and weight management, as well as how to write specialist nutrition plans to help clients reach specific exercise and sporting goals.

Otherwise, download our latest course prospectus for more information.


  1. Alvares TS, Conte CA, Paschoalin VM, Silva JT, Meirelles Cde M, Bhambhani YN, Gomes PS. Acute L-arginine supplementation increases muscle blood volume but not strength performance. Appl Physiol Nutr Metab 2012;37(1):115-126.
  2. Aoki, H., Nagao, J., Ueda, T., Strong, J. M., Schonlau, F., Yu-Jing, S., Lu, Y., and Horie, S. Clinical assessment of a supplement of Pycnogenol(R) and L-arginine in Japanese patients with mild to moderate erectile dysfunction. Phytother.Res. 2012;26(2):204-207.
  3. Akhondzadeh S, et al. (2010). Efficacy and safety of oral combination of yohimbine and L-arginine (SX) for the treatment of erectile dysfunction: A multicenter, randomized, double blind, placebo-controlled clinical trial.
  4. Bai, Y., Sun, L., Yang, T., Sun, K., Chen, J., and Hui, R. Increase in fasting vascular endothelial function after short-term oral L-arginine is effective when baseline flow-mediated dilation is low: a meta-analysis of randomized controlled trials. Am J Clin.Nutr. 2009;89(1):77-84.
  5. Bailey, S. J., Winyard, P. G., Vanhatalo, A., Blackwell, J. R., DiMenna, F. J., Wilkerson, D. P., and Jones, A. M. Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise tolerance. J Appl.Physiol 2010;109(5):1394-1403. 
  6. Berggren A, et al. Short-term administration of supraphysiological recombinant human growth hormone (GH) does not increase maximum endurance exercise capacity in healthy, active young men and women with normal GH-insulin-like growth factor I axes. J Clin Endocrinol Metab 2005;90:3268-3273. View abstract.
  7. Vasdev S, Gill V. The antihypertensive effect of arginine. Int J Angiol. 2008;17(1):7-22. doi:10.1055/s-0031-1278274.

Written by Annie Williams

Fitness Content Executive, OriGym

Join Annie on Facebook at the OriGym Facebook Group

Graduating from Liverpool John Moores University with a BA (Hons) in Journalism, Annie specialises in mental and physical wellbeing, with a specific interest in nutrition and mindfulness. Her long standing interest in fitness is what brought her to OriGym, and led her to become a qualified Personal Trainer and obtain specialist qualifications in Advanced Sports Nutrition. Annie’s primary professional attraction lies in following and tracking the ever-changing trends in the fitness industry. Beyond OriGym, Annie divides her time between personal writing, her passion for the countryside and mountain walking, and charitable runs.

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