Arginine is an amino acid that plays many different important roles in the body. Among these include regulating blood pressure and circulation via nitric oxide, removing ammonia from the body, and healing of injuries. Read more to find out why this amino acid is critical to your health and if you need to be supplementing it.

What is L-Arginine?

Arginine is a conditionally essential amino acid that is used serves a variety of functions within the body. It is considered conditionally essential because healthy individuals can obtain enough of it from diet and from synthesizing it within the body via the kidneys.

Nearly all protein-containing foods have arginine in them, with the only exception being gelatin. Particularly rich sources of arginine include fish and walnuts, with as much of 15% of the amino acids being comprised of arginine in the latter. Arginine can also be made from citrulline via the proximal tubule cells in the kidneys.

The majority of arginine in the body is used to process ammonia into the less toxic urea, as well to synthesize creatine and ornithine. A small portion is then used as a precursor to nitric oxide (NO), a compound that dilates blood vessels, lowers blood pressure, and helps maintain a healthy cardiovascular system [1].

Supplemental arginine is therefore used to increase the conversion of arginine into nitric oxide.

L-Arginine Feedback Diagram


Possible Positive Effects of L-Arginine Supplementation

1) Helps Reduce Blood Pressure And Improve Blood Flow

Nitric Oxide is produced by cells in the body to reduce blood pressure and to increase blood flow [2].

Nitric Oxide works to expand and relax blood vessels to prevent blood clots [2].

L-Arginine increases the production of Nitric Oxide and stops its breakdown [3].

Supplementation with L-Arginine can, therefore, be useful in reducing blood pressure.

Reduced blood pressure can decrease the risk of hypertension and stroke.

2) Helps Reduce the Risk of Heart Disease

A controlled study done in humans found that L-Arginine levels were consistently lower in coronary heart disease (CHD) patients than they were in healthy controls [4].

The study also found that CHD patients had disrupted arginine metabolic pathways [4].

L-Arginine supplementation can bring L-Arginine levels back to normal and increase Nitric Oxide production (reducing the risk of heart disease).

3) Helps Reduce the Risk of Type 2 Diabetes

The same controlled human study found that Type 2 Diabetes patients consistently had lower levels of L-Arginine than healthy controls [4].

The patients once again had disrupted arginine metabolic pathways [4].

L-Arginine supplementation may be useful in restoring molecular imbalances in these patients.

4) Works as an Antioxidant in Type 2 Diabetic Patients

Type 2 Diabetes causes oxidative stress and damage in patients.

Controlled human studies have shown that L-Arginine supplementation can help decrease this effect in Diabetic (type 2) patients [5, 6].

The studies found that L-Arginine indirectly activated SOD (a free radical scavenger protein) to decrease oxidative damage [5, 6].

L-Arginine was also found to increase levels of Nitric Oxide, which decreased the damage caused by reactive oxygen species [5, 6].

5) Helps in Treating Diabetes

Diabetes results in increased glucose levels and insufficient insulin levels in the blood.

A controlled trial done in rats showed that L-arginine supplementation caused more pancreatic cells to form [7].

This helped increase insulin levels and decrease blood glucose levels in diabetic rats [7].

6) Works to Reduce Fat Mass and Triglycerides in Diabetics

A controlled study in rats found that L-Arginine supplementation reduced fat mass by increasing fatty acid breakdown in diabetic rats [8].

The same study found that L-Arginine supplementation reduced triglyceride levels in the rats [8].

7) Helps Increase Immune Response

Studies have shown that increased levels of Nitric Oxide will increase immune response in the body [2].

Nitric Oxide can stimulate the immune system to act on and destroy pathogens [2].

As discussed, L-Arginine has been shown to increase levels of Nitric Oxide.

8) Helps Reduce Anxiety

A controlled human trial experimented with L-Lysine and L-Arginine supplementation in healthy subjects with high anxiety levels.

The subjects were given 3 grams of Lysine and 3 grams of Arginine daily [9].

The results showed that the test group released more hormones in response to stressful situations [9].

These hormones worked to decrease stress and anxiety in the subjects [9].

9) Increases Stamina

Studies have shown that L-arginine can decrease the amount of oxygen needed by muscles during exercise.

This increases the amount of time a muscle can be exercised before it is exhausted.

10) Improves Wound Healing

L-arginine supplementation in mice improves wound healing by increasing Nitric Oxide [10].

Nitric Oxide increases blood vessel development to help in the recovery process [10].

Nitric Oxide can also increase collagen production, which helps in the wound healing process [11].

11) May Be Important In Maintaining Memory During Aging

Studies in rats have shown that maintaining Nitric Oxide levels seems to be important in memory function [12].

It has been seen that aging caused levels of L-Arginine to be decreased in areas of the brain associated with memory (controlled study using rats) [13].

This could lead to decreased Nitric Oxide levels and decreased memory function.

Supplementation could stop L-Arginine and Nitric Oxide levels from falling.

12) Helps Increase Fertility

In women, low fertility is often caused by a poor ovarian response to hormones [14].

A study in low fertility women found that when taken with other supplements, L-Arginine could increase pregnancy rates by increasing ovarian response to hormones [14].

In men, low fertility is often caused by low sperm count and low sperm motility.

These symptoms can be caused by L-Arginine deficiency.

A study done in men found that supplementation with L-Arginine leads to increased production of Nitric Oxide, which protects sperm from oxidative damage.

This protection has been seen to increase sperm motility and sperm count.

13) Fights Aging

A study in humans found that Nitric Oxide levels decrease with age [15].

This decrease can lead to serious conditions such as Heart Disease and Diabetes.

L-Arginine supplementation may be useful in maintaining normal Nitric Oxide levels in order to counterbalance the aging process.

Possible Negative Effects of L-Arginine Supplementation

1) Too Much May Encourage An Autoimmune Response

Nitric Oxide can react with Hydrogen Peroxide in the body to form free radicals [2].

These free radicals can cause oxidative damage and cell death.

Because of this, too much Nitric Oxide in the body can lead to an increased risk of an autoimmune response [2].

High levels of L-Arginine could encourage Nitric Oxide buildup, causing this response to occur.

2) Can Act as a Laxative When Taken On An Empty Stomach

There have been reports of L-Arginine causing diarrhea when it is taken on an empty stomach [16].

This is extremely uncommon but it is always best to take the supplement with food as a precaution.

L-Arginine: Safety, Dosage, Side Effects, and Cautions

L-Arginine is produced in the body but occurs at very low levels. For this reason, L-Arginine supplementation is can sometimes be useful as one ages. The enzyme Nitric Oxide Synthase uses L-Arginine to produce Nitric Oxide and L-Citrulline [17].

The average dietary intake of L-Arginine is 5.4 grams per day [2].

L-Arginine can be found in red meat, fish, dairy, nuts, and poultry.

The molecule can also be taken as a supplement in 500mg capsules.

Studies have shown determined that there are very few adverse side effects of taking L-Arginine at daily concentrations of 20 grams or below [18].

As mentioned above, it may be advised to take L-Arginine with food to avoid the laxative effects.

Because L-Arginine has very low absorption levels in the liver, intravenous supplementation of arginine may be recommended in extreme cases [2].

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