L-arginine (or arginine) is a type of amino acid, and as we know, amino acids are the “building blocks” of proteins. We obtain arginine from our diets, especially animal sources of protein foods, including beef and other types of red meat, poultry, fish, eggs, and dairy products.
In addition to occurring naturally in “complete proteins” that supply all the essential amino acids we need, it’s also created in laboratory settings so it can be used to make supplements that benefit heart health, exercise performance, mental capabilities and much more.
What Is L-Arginine?
While not exactly an essential amino acid — meaning one that the body cannot make on its own and, therefore, must get from outside sources — L-arginine is considered somewhat essential because it’s highly important for many functions yet usually present in low quantities, especially as someone gets older.
What is arginine used for? One of the reasons people take supplemental arginine is because of its ability to improve blood flow and circulation.
In the body, it is converted into nitric oxide, which causes blood vessels to open wider. This has multiple benefits, such as improving heart and brain health.
Another important aspect of L-arginine is that it stimulates the production of certain hormones, especially beneficial human growth hormones and insulin that help usher glucose into cells to be used for growth and energy output.
This is one of the reasons it’s believed to enhance physical performance, stamina and strength.
L-arginine is different than arginine vasopressin (AVP), which is an antidiuretic hormone in humans and most mammals that promotes the reabsorption of water and increases blood pressure.
Research suggests that L-arginine benefits include:
- fighting inflammation
- lowering risk for arteriosclerosis and heart attack
- repairing blood vessels
- fighting congestive heart failure and coronary artery disease
- helping lower high blood pressure
- improving athletic performance and high intensity exercise tolerance
- increasing immune function
- reducing muscle pains (especially in the legs caused by blocked arteries)
- improving kidney function
- improving mental capacity
- fighting dementia
- correcting impotence, erectile dysfunction and male infertility
- preventing the common cold
To dive a little further into the capabilities of L-arginine, it helps to understand how nitric oxide (NO) works in the body.
Nitric oxide is a type of natural reactive gas that both plants and animals produce. It’s created using the L-arginine and nitric oxide synthase (making L-arginine its precursor) and is actually a type of byproduct that forms from many different chemical reactions.
L-arginine is needed by the endothelial cells (the ones lining the inside of all blood vessels) in order to form enough nitric oxide to keep blood flowing freely.
- Nitric oxide improves circulation by dilating blood vessels, so when people don’t have enough in their arteries their risk for heart disease is higher.
- NO keeps your blood pressure level within a normal range by signaling blood vessel muscles to relax, expand and let blood through, while also preventing clots and plaque from forming.
- Research suggests that as someone ages, his or her ability to produce enough NO in the artery linings decreases. Fortunately, obtaining more L-arginine — either through supplemental arginine or dietary arginine — can help to enhance nitric oxide capabilities and correct impaired endothelial function.
The benefits of L-arginine go beyond producing NO to help with circulation, however. As you’ll see, it has important roles in nerve signaling, cell replication and fighting oxidative stress that results in disease and signs of aging.
1. Improves Heart Health
Research shows that L-arginine is beneficial for lowering inflammation and improving the health of the cardiovascular system, which is why oral L-arginine supplements are some of the most popular types recommended by cardiologists.
For people with high risk factors for coronary heart disease, these supplements can be an effective measure for preventing a heart attack or stroke.
Some of the ways that L-arginine improves cardiovascular health include:
- potentially helping to prevent high blood pressure (although findings have been mixed overall)
- improving blood flow in people with clogged arteries (coronary artery disease)
- lowering cholesterol and triglyceride levels
- helping relieve congestive heart failure
- improving stamina
- reducing symptoms associated with cut-off blood flow from the heart to the limbs (called claudication)
- reducing fasting blood sugar
It’s also also commonly used for treating chest pains (angina pectoris) because of the effects of nitric oxide preventing blood clots (thrombosis) that cut off blood supply. Two to three grams a day of L-arginine supplementation has been shown to resolve nitrate intolerance in most people with angina, according to some studies.
And finally, arginine is capable of safely improving exercise performance in people with low stamina, circulation problems and a history of heart disease.
2. Lowers Inflammation and Fights the Effects of Aging
Beyond heart health, one of the primary benefits of L-arginine is fighting disease-causing inflammation and raising immune function.
It’s been found to have substantial free radical-scavenging abilities due to its effects on the enzyme called superoxide dismutase (SOD) as well as other antioxidant mechanisms. It’s commonly used in combination with antioxidants like vitamin C and omega-3 fish oil supplements, helping slow the aging process and preventing many chronic diseases.
L-arginine also positively affects both central nervous system and immune system functions since in the brain NO acts as a neurotransmitter and protective agent against outside threats.
Helpful for detoxifying the body, it can even lower the presence of ammonia within the blood, which is why it’s sometimes used to treat people with metabolic problems and damage to the urethra where ammonia is excreted from the body. Ammonia (ammonium hydroxide) is a product of the body breaking down proteins, and one cause of necrosis of tissues that can lead to cellular destruction and inflammation.
3. Boosts Exercise Performance, Intensity and Recovery
L-arginine is known to effectively improve blood flow, which means it helps bring nutrients and oxygen to muscle and joint tissues. This means with L-arginine’s help, you can enjoy more of the many benefits of exercise, possibly at a higher intensity and with less pain.
- It can increase heat and circulation to damaged joints or cold hands and feet, especially in people with complications from other health conditions like poor blood flow, arthritis or diabetes.
- It’s been shown in some studies to improve walking distance and lower muscle aches and pains, including in people suffering from painful intermittent claudication (narrowing of blood vessels in the legs and feet caused by fatty deposits).
- It’s used by the body to increase production of human growth hormone, prolactin and several amino acids — including creatine, L-proline and L-glutamate.
- Studies suggest it arginine improves glucose tolerance and sensitivity to insulin, similarly to how exercise does, by allowing more glucose to enter cells.
- L-arginine’s roles in metabolic health are important for building strong muscle tissue, fighting inflammation causing bone and joint pain, repairing injuries, and for general nervous system functions.
- It’s also been shown to help increase time to exhaustion among athletes and to increase tolerance to high intensity exercise.
- There’s also evidence that it may help with bodybuilding, exercise performance and putting on muscle mass. Supplementation has been shown in some studies to increase plasma insulin and help builds stronger muscles even when you’re resting due to its effects on the body’s capillaries. These hormonal changes affect your metabolism in a positive way by helping repair, build and maintain the youthful foundation of the skeletal-muscle system.
In most cases, arginine increases resting growth hormone levels at least 100 percent (in comparison, regular exercise can increase growth hormone levels by 300 percent to 500 percent). Even more powerful is the combination of L-arginine plus exercise.
4. Improves Immunity, Helps Prevent Infections and Speeds Up Healing
Low-circulating L-arginine has been found in some patients suffering from illnesses, trauma and cancer. It’s believed that certain immune system suppressor cells (called MSCs) might cause arginine deficiency or low levels circulating within the blood.
This is problematic because the immune system’s protective lymphocytes and T-cells depend on arginine for defending the body.
L-arginine is used with omega-3 fish oils and other supplements for reducing risk for infections (especially respiratory infections or problems with the lungs), improving wound healing, and shortening recovery time following cancer, illness or surgery.
It’s sometimes added to topical ointments used to treat wounds for several reasons: It helps keep blood flowing more freely, can fight pain and swelling, forms L-proline, which is important for collagen synthesis within the skin, and increases antioxidant activity.
It’s also used to improve protein function in helping to heal burns and might even help fight cavities and tooth decay. Although more research is still needed, because L-arginine has immune-enhancing effects, it’s commonly given to people undergoing chemotherapy or healing from surgeries, viruses and infections (including HIV).
5. Helps Treat Erectile Dysfunction and Infertility
What does L-arginine do sexually? A number of studies have shown that L-arginine is involved in the process of proper cell replication in addition to enhancing blood circulation.
This means that arginine benefits for men include improving both sperm production and motility.
Men who deal with cardiovascular problems tied to low levels of NO in the blood are more likely to suffer from erectile dysfunction and fertility issues, since an erection requires the relaxation of smooth muscles triggered by nitric oxide. While not effective for every man, research suggests that a significant percentage of male infertility cases (up to 92 percent, according to some studies) can be treated with L-arginine supplements combined with other dilators, antioxidants or anti-inflammatories.
Some research suggests that high stress levels can lower the presence of L-arginine in the sperm production pathway, so overly stressed men can especially benefit from supplementing.
A combination of L-arginine, L-glutamate and yohimbine hydrochloride is commonly used to treat ED and seems to work better than L-arginine alone. In fact, many of the most commonly prescribed medications for ED work similarly to L-arginine by increasing nitric oxide production.
A standard dosage of arginine for ED is about three to six grams daily (divided into two doses).
Even women can experience better reproductive help from L-arginine — doctors sometimes prescribe topical creams that contain this amino acid for helping heal sexual problems and naturally treat infertility in both sexes since it improves circulation to genital tissue.
Additionally, there’s some research that suggests treatment with N-acetyl cysteine (NAC) and L-arginine together can help balance hormones naturally and restore normal sexual function in women with polycystic ovary syndrome and estrogen imbalances.
Risks, Side Effects and Interactions
Although it’s generally safe, considering it’s a natural amino acid, there are some potential L- arginine side effects to be aware of. If you have a history of heart disease, low blood pressure, diabetes, kidney problems or an active virus (like herpes or shingles), it’s not recommended to supplement with it until you speak with a doctor first.
There’s some research suggesting that taking arginine supplements after a heart attack may be dangerous. Because there’s a possibility of this supplement leading to complications n people with a history of heart attacks, avoid taking arginine supplements if this applies to you.
Is L-arginine safe to take daily? Consuming it from natural food sources isn’t harmful, but daily high doses might complicate your condition, especially if you take other medications or a series of supplements.
Talk to your doctor about what dose might be most beneficial for you and whether or not you should worry about adverse reactions based on your current situation.
If you’re generally healthy and taking a dose around one gram daily, it’s still possible to experience short-term side effects like abdominal pain, bloating, diarrhea, gout, worsened allergies or asthma, and low blood pressure.
It’s also possible that this supplement can cause allergic reactions or increased swelling in the lungs and airways, so people with existing allergies or asthma should use L-arginine with caution.
Finally, 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.
Everyone produces some L-arginine on his or her own, but how much depends on factors like your age, inflammation level, condition of your heart and arteries, gender, diet quality, and genetics.
Some of the reasons someone might not produce optimal levels of L-arginine include:
- eating a vegetarian/vegan diet low in complete protein sources
- having poor digestive health that makes metabolizing protein difficult
- high levels of oxidative stress caused by free radicals (due to diet, stress or pollution)
- genetic factors
What foods are high in arginine? Essentially, any food that is high in protein supplies some L-arginine, but the denser protein sources are the best.
To naturally help your body make and use more L-arginine and nitric oxide, focus on eating a diet based on whole, real foods — especially “clean” sources of protein, which provide a full range of amino acids.
Complete proteins are most beneficial because not only do they supply L-arginine, but they also provide all of the other acids needed to help with muscle tissue growth and proper neurotransmitter function.
Wild-caught fish like nutritious salmon is an especially great choice because in addition to L-arginine, it supplies anti-inflammatory omega-3 fatty acids that further help maintain cardiovascular health.
If you’re a plant-based eater or suffer from the symptoms of lactose intolerance, other ways to obtain more L-arginine aside from animal proteins include eating nuts, seeds, coconut products, sea vegetables, or whole grains and beans in moderation.
Some of the top foods high in arginine include:
- Cage-free eggs
- Dairy products like cultured yogurt, kefir and raw cheeses (choose organic and raw dairy whenever possible)
- Grass-fed beef or meat and pasture-raised poultry (including turkey and chicken)
- Liver and organ meats (such as chicken liver pate)
- Wild-caught fish
- Sesame seeds
- Pumpkin seeds
- Sunflower seeds
- Seaweed and sea vegetables
- Brazil nuts
- Coconut meat
While it’s always best to get nutrients from natural food sources whenever possible, L-arginine is also sold as an over-the-counter and prescription medication, including in capsule/pill form and as L-arginine power.
This amino acid is considered “semi-essential” because many people get enough of it from their diets alone.
Doctors sometimes prescribe high L-arginine doses along with other supplements for various conditions, including heart disease, migraines and infections — or even for treating side effects of diabetes, HIV or cancer.
Other supplements that are often used with arginine include citrulline, ornithine and arginase. Arginase converts L-arginine into L-ornithine and urea, while agmatine is a chemical substance naturally created by arginine.
The suggested dosages of L-arginine supplements depends a lot on the condition it’s being used to treat.
For example, with help treating heart conditions or erectile dysfunction, three to six grams daily (divided into two doses) might be taken, while for enhancing exercise performance, doses up to nine grams a day are not uncommon.
For generally healthy adults who are looking to prevent inflammation and benefit from better circulation, about one gram daily (1,000 milligrams) is usually the recommended dose.
Higher doses obviously come with more risk for side effects — plus some research shows that more is not always better when it comes to L-arginine’s functions within blood vessel walls.
- L-arginine is an amino acid that we obtain from our diets, especially animal sources of protein foods, including beef and other types of red meat, poultry, fish, eggs, and dairy products.
- Research has shown arginine benefits heart health, lowers inflammation, fights the effects of aging, boosts exercise performance, improves immunity, helps prevent infections, speeds up healing, and helps treat erectile dysfunction and infertility.
- Everyone produces some L-arginine on his or her own, but how much depends on factors like your age, inflammation level, condition of your heart and arteries, gender, diet quality, and genetics. Some of the reasons someone might not produce optimal levels of L-arginine include eating a vegetarian/vegan diet low in complete protein sources, having poor digestive health that makes metabolizing protein difficult, high levels of oxidative stress caused by free radicals (due to diet, stress or pollution), smoking and genetic factors.
- To naturally help your body make and use more L-arginine and nitric oxide, focus on eating a diet based on whole, real foods — especially “clean” sources of protein, which provide a full range of amino acids.