L-arginine is a conditionally essential amino acid that plays a role in building the proteins in our body. Although arginine is synthesized in the body, it is not made in sufficient quantities to meet the metabolic requirements during certain health conditions. In such cases, l-arginine supplements may help.
This nutritionally essential amino acid has many health benefits and has been used to treat several ailments. It may treat heart disease, reduce high blood pressure, ease inflammation in the digestive tract, aid diabetes treatment, heal wounds, and boost immune health. This article discusses the potential health benefits, dosage, risks, and side effects of l-arginine. Read on to know more.
What Is L-arginine?
L-Arginine (2-amino-5-guanidino-pentanoic acid) is a conditionally essential and proteinogenic amino acid. It has been studied extensively as a precursor of nitric oxide (a compound that relaxes blood vessels in humans). An individual’s body naturally produces l-arginine though there are cases where it is supplemented. People who are under certain medications are prescribed this amino acid in the form of oral medication.
In the following section, we will explore the benefits of l-arginine.
What Are The Benefits Of L Arginine?
1. May Help Treat Heart Disease
In a study, long-term oral administration of l-arginine for 6 months improved the symptoms of non-obstructive coronary artery disease (1). L-arginine helps in the treatment of coronary abnormalities caused by high blood cholesterol levels (2). L-arginine enhances blood flow in coronary arteries. This may help in treating various cardiovascular conditions.
L-arginine is the precursor of nitric oxide. Nitric oxide plays a role in various physiological effects in the cardiovascular system. The oral administration of l-arginine could improve symptoms of cardiovascular disease (3). Dietary supplementation of l-arginine, along with regular physical exercise, was also found to benefit patients with chronic heart failure (4). L-arginine has anti-inflammatory and metabolic properties that help treat non-diabetic patients with cardiovascular disease (5).
2. May Reduce High Blood Pressure
Oral administration of l-arginine could significantly lower both systolic and diastolic blood pressure levels (6). External l-arginine had also rapidly reduced systolic and diastolic blood pressure levels in both healthy humans and patients with hypertension (7). In one study, l-arginine supplemented at 4 grams per day could significantly lower blood pressure in women with gestational hypertension. The supplement also reduced the need for an antihypertensive therapy (8), (9). L-arginine supplementation in pregnant women with chronic hypertension could reduce their blood pressure levels. The supplement could also offer protection in high-risk pregnancy (10).
3. May Ease Inflammation Of The Digestive Tract In Premature Infants
L-arginine may ease the inflammation of the digestive tract in premature infants. In a study, dietary supplementation of l-arginine enhanced the intestinal growth and eased inflammation in weanling piglets (11). Similar outcomes could be expected in human babies too, though more research is warranted.
In another study, plasma l-arginine concentrations were lower in premature infants diagnosed with necrotizing enterocolitis (NEC). NEC is a disease that destroys intestinal walls in premature infants (12). L-arginine supplementation was found to reduce the incidence of all stages of NEC (13), (14).
4. May Treat Gastrointestinal Tract Problems
Mice studies reveal that l-arginine can improve colonic motility. It also has the potential to alleviate GI discomfort (15). However, more long-term research is needed to understand this effect of l-arginine in humans.
5. May Help Prevent Diabetes And Related Complications
L-arginine may help prevent diabetes and related complications. Diabetes is associated with reduced plasma levels of arginine. Evidence suggests that l-arginine supplementation may be an effective way to improve endothelial function in individuals with diabetes mellitus. L-arginine may also counteract cell damage and reduce the long-term complications of type 2 diabetes. It also improves insulin sensitivity (16).
L-arginine supplementation was also found to reduce the risk of diabetes mellitus (17).
L-arginine-enriched biscuits with low sugar and protein content were found to enhance endothelial function and improve glucose metabolism, insulin sensitivity, and insulin secretion (18).
6. May Boost Immune Health
L-arginine may boost immune health by stimulating lymphocytes (white blood cells) (19). Intracellular l-arginine levels directly impact the metabolic fitness and survival capacity of T cells (a type of white blood cell) that are crucial for anti-tumor responses (20).
L-arginine is an essential amino acid that is fundamental for the function of T lymphocytes (T-cells). Patients with cancer usually have an impaired T‐cell response that can decrease the potential therapeutic benefit of cancer vaccines and other forms of immunotherapy. L-arginine may regulate T-cell function in the case of chronic inflammatory diseases and cancer (21).
L-arginine metabolism plays a major role in autoimmune and neoplastic (tumor-related) diseases (22).
L-arginine supplementation inhibits the growth of breast cancer by enhancing innate and adaptive immune responses (23).
In one randomized clinical trial involving 63 participants with pulmonary tuberculosis, L-arginine supplementation showed reduced symptoms (24).
7. May Help Treat Erectile Dysfunction
L-arginine may help treat sexual dysfunction. Arginine is required for normal spermatogenesis. Oral administration of 500 mg of arginine–HCl per day to infertile men for 6–8 weeks markedly increased their sperm counts (16).
Oral administration of l-arginine in high doses lead to significant improvement in sexual function (25).
Long-term oral administration of pharmacological doses of l-arginine was found to improve erectile responses in an aging rat (26).
8. May Improve Blood Flow
L-arginine infusion was found to promote regional cerebral blood flow in hypertensive rats (27). It also could improve vasodilation (dilation of blood vessels that reduces blood pressure) in hypercholesterolemic (high levels of cholesterol in blood) humans (28).
L-arginine infusion in healthy subjects could inhibit platelet aggregation and blood viscosity and also promoted leg blood flow (29). L-arginine administration in rats could also improve post-traumatic cerebral blood flow (30).
9. May Aid Weight Loss
L-arginine has been proven to stimulate fat metabolism. This may help in weight loss. The amino acid alters the balance of energy intake and expenditure in favor of fat loss (31). It also regulates brown adipose tissue and reduces the accumulation of white fat in the body (32).
However, more long-term research is needed to understand this benefit of l-arginine in humans.
10. May Heal Wounds
Dietary l-arginine has been shown to improve collagen deposition and wound healing in both humans and animals. L-arginine may improve wound immune cell function by decreasing the inflammatory response at the wound site (16).
11. May Treat Anxiety
L-arginine is said to possess anti-stress and adaptogenic properties that help treat anxiety (33).
Dietary supplementation of a combination of l-lysine and l-arginine (two essential amino acids) may reduce the hormonal stress responses in humans with anxiety. However, concrete research is lacking in this area.
12. May Treat Burns
L-arginine administration during burn injuries was found to boost cardiac performance. It also could prevent bacterial translocation (34).
L-arginine supplementation during the early stage of burns was found to help with the resuscitation of the burn shock (35).
Oral dietary l-arginine supplementation of 100–400 mg/kg/day could accelerate the synthesis of reparative collagen in burned rats (16).
13. May Improve Kidney Function In People With Congestive Heart Failure
Nitric oxide deficiency contributes to cardiovascular events and the progression of kidney damage. Low plasma levels of l-arginine is one of the major causes of nitric oxide deficiency. Supplementation of l-arginine was found to improve kidney function (36).
Oral administration of l-arginine also had beneficial effects in renal function in patients with congestive heart failure (37).
In another study, a moderate increase in l-arginine supplementation significantly lowered blood pressure. It also had improved renal function in healthy individuals (38).
Further studies are warranted to understand this benefit.
14. May Enhance Exercise Performance
In a study, eight weeks of oral l-arginine administration (3 g) to 20 male subjects on an exercise program caused a significant increase in muscle strength and muscle mass (16).
In rat studies, treadmill exercise, along with l-arginine supplementation, was found to delay aging by suppressing oxidative stress and inflammation (39).
15. May Improve Hair Growth
Anecdotal evidence suggests that l-arginine may help improve hair growth. This amino acid may relax blood vessels and improve blood flow to the scalp and the base of hair follicles. However, research is limited in this regard.
These are the benefits of l-arginine. In the following section, we will look at its ideal dosage.
Recommended Dosage Of L-Arginine
Just like several other supplements and nutrients, the dose of l-arginine is highly dependent on the age, gender, and the condition of the user. Doses of 3–8 g/day appear to be safe in humans (40). Here are the recommended doses for a few cases:
Cardiovascular disease – 3 to 6 grams, divided into two parts (mornings and evenings) (41)
Erectile dysfunction – 3 to 6 grams, divided into two parts (mornings and evenings) (42)
Exercise performance – 5 to 9 grams, once a day (43)
L-arginine may also cause side effects in some cases. We will explore more in the following section.
What Are The Side Effects Of L-Arginine?
Excess intake of l-arginine may lead to side effects ( these are rare and mostly dose-dependent). These include unstable blood pressure, aggravated diabetes symptoms, allergies, abdominal pain and bloating, chemical imbalances in the blood, or an increased risk of bleeding in pregnant women.
Nausea and diarrhea have been reported infrequently at higher doses ranging from 15 to 30 g per day (16). Intake of l-arginine in normal food amounts seems to be safe, and no side effects have been reported in this regard. However, lactating and pregnant women should avoid the use of l-arginine.
For a certain group of individuals, l-arginine may pose a serious risk. L-arginine may lead to an increased risk of death after a heart attack. It also may make blood pressure control during surgeries more difficult. The amino acid may cause serious illness to infants and children and may also show negative interactions with certain medications meant for blood pressure control. However, the intake of L-arginine in limited doses appears to be safe. Concrete research is limited in this area. Consult your doctor.
Foods High In L-Arginine
This amino acid can easily be found in a number of food sources like nuts and fish. The rich food sources of l-arginine include:
- Dairy products like yogurt, kefir, and cheese
- Beef and chicken liver
- Wild-caught fish (they also provide you with essential omega-3 fatty acids that are great for heart health)
- Pumpkin seeds
- Sesame seeds
- Sunflower seeds
- Sea vegetables
L-arginine is an essential amino acid with many health benefits. From reducing the risk of heart disease to enhancing exercise performance, this amino acid has many advantages. It is readily available in foods that you consume. However, be wary of the dosage if you are taking it as a supplement. Excess intake of l-arginine may cause several side effects. If you are pregnant or lactating or have any medical condition, you may want to check with your doctor before taking l-arginine supplements.
Expert’s Answers For Readers’ Questions
Does l-arginine burn belly fat?
L-arginine may be effective in reducing central adiposity in obese patients (44). Previous studies showed that dietary l-arginine supplementation decreased white fat mass in genetically obese rats. Thus, dietary arginine supplementation may promote muscle over fat gain. It may be useful for improving metabolic profile and reducing body white fat (45).
Can you take l-arginine every day?
There is no recommended daily amount established for l-arginine because the human body normally makes enough of it. If taken as a supplement, higher doses of arginine are often needed. Doses of 1200 mg (per day) in the supplement form could be helpful.
How long does arginine take to work?
The single dose of 5-6 grams of l-arginine can be administered 2-3 times a day. It may take 2 to 3 months to work and should be taken continuously or as directed by the health care expert.
Should l-arginine supplement be taken on an empty stomach?
L-arginine is usually recommended to be taken on an empty stomach. Take the supplement with lots of water to avoid nausea.
Can you take l-citrulline and l-arginine supplements together?
Yes; this combination of the two amino acids is said to possess anti-atherosclerotic properties. It also may rapidly increase nitric oxide (NO) bioavailability and lower blood pressure levels (46).
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