L-arginine is a non-essential amino acid that helps to build strong bones and muscles, as well as help to decrease overall systemic inflammation (1).
L-arginine is also important for growth in infants and young children. In adults, it becomes a semi-essential amino acid. That means it’s necessary for healing from certain kinds of trauma like burn injuries and it’s useful for other bodily functions (2).
As an adult, your body makes arginine and it can also be found in many foods, making it easy to get even with a normal diet. That said, supplementing has a host of benefits.
The antioxidant action is also what gives L-arginine many of its other benefits, from better cardiovascular health to increased exercise performance to controlling blood sugar levels in people who have diabetes.
1L-arginine helps fight aging and maintain muscle mass in the elderly, decreasing the risk of serious injuries like fractures, falls and even death. Building protein is incredibly important not just if you’re an athlete or someone who exercises regularly, but also if you’re a normal person, and especially as you start to age, no matter what your workout schedule. As people age, muscles get smaller and bones lose some of their previous strength, becoming more prone to injury (4).
This is partly responsible for why older people feel weaker, lose mobility, and tend to fall down more easily. After the fourth decade of life, skeletal muscle mass steadily decreases, leading to an increased risk of osteoporosis, fractures and even death in extreme circumstances (5).
Supplementing with L-arginine could help fight such negative outcomes. A 2008 study showed that supplementing a normal diet with amino acids (in this case, L-arginine and a group of essential amino acids) improved lean body mass, strength, and physical ability in elderly patients (6).
Furthermore, while L-arginine is commonly used as an exercise supplement for younger individuals and athletes, it’s been shown to positively affect exercise performance in the elderly as well (7).
In one randomized controlled trial, arginine supplementation increased the anaerobic threshold in elderly (between the ages of 50 and 73) male cyclists. Such increased performance may be due to L-arginine’s antioxidant/anti-inflammatory effects.
2L-arginine is an antioxidant that can help fight systemic inflammation. As an anti-inflammatory agent, L-arginine can be used as a supplement to combat myriad chronic diseases. This is especially true for gastrointestinal diseases and other gut conditions.
In one 2008 study, L-arginine decreased inflammation and increased muscle regeneration for patients suffering from Duchenne Muscular Dystrophy, a lethal disorder characterized by muscle inflammation and the degeneration of skeletal muscle (8).
Furthermore, L-arginine’s most salient anti-inflammatory effects can be seen in the way it helps the digestive system. Oral supplementation of L-arginine has been shown to decrease intestinal inflammation from diseases like malaria (9).
While it can be dangerous in high doses, arginine supplements at low or normal doses can improve gut function and fight sepsis (10).
Animal trials also show that L-arginine may be a promising avenue for future inflammation treatments. In rats who were at risk for chronic renal failure, L-arginine supplements increased kidney function and decreased levels of inflammatory cytokines, which are a type of molecule that causes inflammation (11).
When combined with a supplement of several antioxidants, L-arginine was very effective in normalizing kidney function, blood pressure and levels of inflammation.
3L-arginine has been shown to positively affect cardiovascular health. Another area in which L-arginine can significantly affect outcomes is cardiovascular disease. In one 2014 study, which took place in Iran, consistent L-arginine supplementation reduced risk factors such as fasting blood sugar and lipid blood profile significantly when compared to the placebo group (12).
Dietary intake of plant-based L-arginine has also been negatively correlated with the incidence of coronary heart disease (13).
While it’s still slightly controversial and merits further research, there are clear benefits associated with L-arginine supplementation in terms of cardiovascular health. L-arginine can help make blood vessels more pliable and less prone to blockage or constriction (14).
4L-arginine can lower high blood pressure. In an umbrella review of seven separate meta-analyses of L-arginine’s effect on the human body, evidence from every study pointed towards significant benefits in reducing both systolic and diastolic blood pressure (15).
This is due to the vasodilation effects of L-arginine.
Other studies have even theorized that the anti-hypertension benefits of certain diets are due in large part to the presence of arginine more than any other factor (16).
However, the results are not 100% conclusive. Some studies show huge benefits as a result of L-arginine supplementation and others show almost no effect at all. That said, numerous reviews show high blood pressure can be managed with proper arginine supplementation (17).
Overall, L-arginine is one of the most promising supplements for combating high blood pressure.
5L-arginine can boost your workout performance if you’re an athlete. As an amino acid, L-arginine helps you build the proteins that make up your muscles. Perhaps it’s no surprise, then, that supplementation increases workout performance. A 2007 study showed that L-arginine supplementation changes your metabolism, making you more sensitive to insulin and increasing capillary growth in muscles (18).
One double-blind, randomized trial found that L-arginine supplements increased performance among 56 male soccer players, in comparison with a placebo control group. BMI, body fat mass and lean body mass weren’t affected (19).
In other words, arginine helped athletes play better without seriously affecting or changing their body composition.
In another 2014 study, published in Biology of Sport, L-arginine supplements helped male wrestlers perform better. However, researchers didn’t record any noticeable difference in the athletes’ heart rates or plasma lactate levels (20).
Scientists are still trying to figure out exactly why L-arginine is an effective workout supplement, but for the meantime, it’s known to increase performance significantly compared to a placebo.
6L-arginine may be able to help prevent infections and speed up recovery. L-arginine has been linked not just to anti-inflammatory effects, but also to T-cell activation. T-cells are essentially the immune system’s worker bees; they help you fight off infections and stay healthy (21).
It’s theorized that arginine can act as an immune system booster, lowering the chances of infection or complication from chronic diseases. A meta-analysis of 11 trials and 321 patients, from 1966 to 2013, showed that L-arginine supplementation increased T-cell proliferation and decreased the rate of infection (22).
L-arginine’s immune-boosting capabilities may even extend to cancer treatment. Cancer immunotherapy is centered around getting your own immune system to recognize cancerous tumors as something to be destroyed rather than a natural part of your body. A 2018 study showed that arginine is critical to activating the T-cells that either recognize cancer as hostile or don’t (23).
In another study, supplementation stopped tumor growth in mice with breast cancer and prolonged their survival (24).
7L-arginine has even been touted as a possible treatment for erectile dysfunction. When administered in combination with pycnogenol, L-arginine helped men who suffered from regular erectile dysfunction achieve normal erections (25).
On its own, it also helped 5% of participants achieve a normal erection. On the other hand, a different study didn’t show any increase in achieving erection compared to placebo (26).
One meta-analysis argued that while positive evidence is available, L-arginine has yet to be studied with a large sample size and higher levels of standardization (27).
8L-arginine may help treat fertility issues in women. Women who have issues with fertility may also benefit from L-arginine supplementation. After five months of supplementation with L-arginine, 33% of women (compared to 0% in a placebo group) became pregnant (28).
9L-arginine can help modulate blood sugar levels in people with diabetes. In both human and animal trials, arginine supplements have helped improve kidney function and increase insulin sensitivity. When administered to type II diabetic rats, L-arginine improved glucose tolerance and preserved renal function (29).
While it didn’t totally cure diabetes, it did relieve the symptoms and even tackle the root cause (insulin resistance).
Another 3-month long, double-blind human study found that long-term L-arginine supplementation significantly improved peripheral and hepatic insulin sensitivity in patients with type II diabetes, though it wasn’t able to completely overcome their deficit (30).
10L-arginine supplementation may help treat mental health conditions. Many scientists have reported increased levels of arginine and other amino acids in the blood samples of patients with schizophrenia (31).
Other studies have reported a direct link between bipolar disorder and arginine’s role in the body (32).
In another focused study, the frontal cortexes of individuals with schizophrenia were analyzed in comparison to a control group and abnormal arginine metabolism was found (33).
It’s not entirely clear what role arginine has in causing or in fighting the onset of schizophrenia and other mental health issues, but it certainly plays a part. According to this study, future schizophrenia treatments could potentially be based on altering arginine levels in the brain.
1L-arginine may cause blood pressure changes As stated above, L-arginine lowers blood pressure. For patients who suffer from hypertension, this is a good thing, but any change in blood pressure should be carefully monitored. If you don’t already suffer from high blood pressure, supplementing with L-arginine could unexpectedly lower your blood pressure.
That might also lead to other blood-associated abnormalities, like bleeding. This is especially true if you’re already taking any other blood-pressure drugs or blood thinners. If you’re not sure whether L-arginine would be dangerous for you, ask your physician before you start supplementing.
2L-arginine could change your blood glucose levels. The same mechanism that makes L-arginine a possible diabetes treatment, increased insulin sensitivity, could lead to unforeseen side effects if it rapidly changes the amount of sugar in your blood (34).
3L-arginine can raise potassium levels. When administered to patients who suffered from kidney disease, L-arginine dramatically raised potassium levels in the kidney and liver. Potential users who suffer from kidney disease should consult a doctor before starting L-arginine supplementation.
4L-arginine can cause IBS like symptoms in certain individuals such as abdominal pain, bloating and diarrhea.
5L-arginine may be safe for pregnant women. L-arginine appears to be safe for pregnant women and even children, although there’s not much research on the effects within these populations so it’s best to stick to a low dose or act your doctor.
Because arginine can be used to treat a wide range of conditions, from erectile dysfunction to cardiovascular disease, there is also a wide range of recommended dosages. Doses between 5-20g per day are probably the best combination of both effective and safe, as that’s also the most commonly-studied range (35).
As with any supplement, it’s best to start a new regimen slowly, taking only a couple of grams per day at the most. A good rule is to monitor your body for at least one or two weeks, looking for any abnormal changes, before starting to slowly increase your dose. If you’re worried about how much L-arginine to take, ask your physician.
Where does L-arginine come from? L-arginine can be found in dietary staples that contain protein. Think dairy, red meat, poultry products like chicken, etc. In most normal diets, excluding malnutrition or other dietary conditions, L-arginine is commonly found and easy to get.
Does your body make L-arginine on its own? As an adult, your body manufactures its own store of L-arginine (as well as receiving it from your diet). In children, however, arginine is especially important for growth, so a correct diet/amount of arginine intake is more important.
Can you get L-arginine from your diet alone? Yes. As long as you’re eating a diet that contains some kind of protein (like red meat, chicken or dairy), you’re more than likely getting enough arginine, as your body also produces it on its own. Arginine deficiencies are quite uncommon. Supplementation isn’t so much for the purpose of treating an arginine deficiency as for getting the benefits that come with an increased amount of arginine in the body.
What’s the best time of day to take an L-arginine supplement? There isn’t necessarily a recommended time to take L-arginine. Like most other supplements, however, taking it daily at mealtimes is a good plan of action.
Is L-arginine safe to take? Yes. L-arginine is safe to take in healthy patients. Children, patients with liver/kidney disease, or users who are already taking some kind of blood-regulating drug should contact their doctor before starting to supplement with L-arginine.
Can pregnant women supplement with L-arginine? In general, the evidence points towards L-arginine being a safe choice for pregnant women. In one study, L-arginine supplementation actually proved beneficial by decreasing the risk of pre-eclampsia. In animal studies, it has increased productivity and increased the rate of embryonic survival. Pregnant women who are already taking other medications should consult their doctor first.
Can I take L-arginine if I have a kidney/liver disease? If you have a chronic liver or kidney disease, you may be able to still take L-arginine, but it’s best to consult a doctor beforehand, as supplementation could either affect any drugs you’re currently taking or dramatically increase your body’s potassium levels, increasing the risk of further complications.
What drugs does L-arginine interact with? Blood thinners, hypertension-lowering drugs, and drugs that deal with the kidney or the liver are all possible interactions with L-arginine. Elderly patients, in particular, may want to be careful, as L-arginine could cause unexpected vasodilation in combination with other blood thinners.
Does L-arginine help treat erectile dysfunction? Yes, L-arginine can help treat ED. It does this by becoming the gas nitric oxide (NO) in the body. NO is important for erectile function because it helps blood vessels relax, so more oxygen-rich blood can circulate through your arteries.
Is L-arginine safe to take daily? The safety of long-term arginine supplement use is not clear.
Can arginine cause weight gain? L-arginine can cause weight gain by adding muscle or stimulating increased levels of HGH (Human Growth Hormone). However, it increases HGH levels when taken in very large amounts.
Can you take l arginine with Viagra? Taking sildenafil (Viagra) and L-arginine together might cause blood pressure to go too low.
Is arginine or citrulline better? Neither is better or worse as they are part of the same family. L-citrulline is an amino acid normally made by the body. The body converts L-citrulline to L-arginine, another type of amino acid.
Can you take too much L-arginine? Yes, you can take too much L-arginine. L-arginine is considered safe in moderate doses, too much L-arginine can have severe side effects, including death.
Can you take L-arginine on an empty stomach? Yes, L-arginine can be taken on an empty stomach. However, taking L-arginine, or l-arginine hydrochloride, taken on an empty stomach, can cause a significant release of growth hormone in many people depending on the dose.
Is L-arginine a blood thinner? No L-arginine is not a blood thinner, but it may have similar effects. Because it dilates blood vessels, L-arginine may also increase excessive bleeding risks. Hemophiliacs, people on blood thinners and people taking gingko balboa should refrain from taking L-arginine.
L-arginine is a promising supplement for a wide range of conditions, from diabetes to cardiovascular disease to even erectile dysfunction and possibly cancer. Its potential as a blood thinner and an anti-inflammatory is also already well-researched and established.
In terms of more futuristic treatments, like cancer immunotherapy and diabetes cures, it also presents a promising avenue of research.