How does L-Citrulline Boost Nitric Oxide Levels?

L-citrulline is a nonessential amino acid which was first discovered in high concentrations in watermelons. It is also synthesized inside the body and has been shown to increase levels of L-arginine in the blod.

People use L-citrulline supplements for diabetes mellitus, Alzheimer’s disease, dementia, heart disease, hypertension (high blood pressure), ED (erectile dysfunction) and certain other conditions and diseases.

Bodybuilders and other athletes use L-citrulline to decrease fatigue, combat muscle weakness, upregulate energy and improve markers of athletic performance.

L-Citrulline

Amino Acid

Pre- Workout

Body- building

Stamina

How It Works:

• Shown to raise blood arginine levels
• Increases Nitric Oxide & Growth Hormone
• Delays onset of fatigue during intense training

Dosage:

Between 1 - 3 g per day

Safety:

Rated Possibly Safe

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L-citrulline and Nitric Oxide

Along with L-arginine and L-ornithine, L-citrulline is an intermediate in the urea cycle; a set of biochemical processes which convert toxic ammonia into less toxic urea. This process occurs mainly in the liver, and to a small degree in the kidneys.

Accumulations of ammonia and other nitrogenous waste substances can lead to the development of hepatic encephalopathy (brain dysfunction stemming from the liver).

In one step of the urea cycle, L-citrulline is converted into L-arginine inside the kidneys. It is then released into the blood. L-arginine is then used to synthesize NO inside the endothelium of circulatory vessels, as well as some other organs and tissues.

NO is a vasodilator which helps to open and expand circulatory vessels. This allows more blood to be delivered throughout the body with no associated elevations in blood pressure.

Along with increased blood delivery; more beneficial enzymes, hormones, proteins and other vital nutrients are transported.

Citrulline Malate

Citrulline malate supplements are sold as athletic performance enhancers. Esters and salts residues from malic acid are called malates. When malates are added to L-citrulline, citrulline malate results. This substance is preferred by athletes who train for strength.

Citrulline malate has been clinically shown to:

• Upregulate ATP (adenosine triphosphate);
• Increases phosphocreatine recovery;
• Reduce lactic acid and ammonia;
• Increase NO synthesis;

Citrulline malate supplement users report increased energy during workouts, less fatigue, longer-lasting muscular pumps and enhanced post-workout recovery.

L-Citrulline Foods

L-citrulline is named after the botanical name for watermelon (Citrullus vulgaris). It is also found in lesser amounts in certain other melons, cucumbers, eggs and some meats. Watermelon contains between 0.7 and 3.6 mg of L-citrulline per 1-gram serving.

Research shows that ingesting 1 or 2 cups of watermelon juice daily causes increases in fasting levels of L-arginine. However, it does not increase fasting L-citrulline levels.

Roughly an hour and a half after ingesting watermelon juice, plasma levels of L-citrulline are increased. However, these levels return to baseline amounts after about 8 hours.

In order to successfully elevate L-citrulline levels consistently, supplementation is used. Even if an individual ate watermelon with every meal, every day, significant increases in L-citrulline would be unlikely.

L-Citrulline for Erectile Dysfunction

Phosphodiesterase-5 (PDE-5) inhibitors are a class of drugs used to treat erectile dysfunction. Viagra contains sildenafil, Levitra contains vardenafil and Cialis contains tadalafil.

These substances block the degrading actions of PDE5 inside the smooth muscle cells which line the blood vessels of the corpus cavernosum in the penis. This promotes blood delivery to the penis, and may result in erections.

Research shows that L-citrulline supplements naturally act to inhibit PDE-5. While the effects are not quite as potent as those of prescription PDE-5 inhibitors (at least in short term studies), they are safer.

There are no adverse effects associated with L-citrulline. PDE-5 inhibitor drugs are associated with various possible side effects; some very serious.

In one double-blind trial, 24 men between 46 and 66 years of age were studied. Relative to a placebo agent, L-citrulline caused significant improvements in erection hardness.

Subjects also reported strong decreases in the psychological stress associated with possible side effects of taking mainstream PDE-5 inhibitors. No adverse effects were experienced by any subjects in this trial.

L-Citrulline Safety

The Natural Medicines Comprehensive Database states that L-citrulline is possibly safe for proper oral use in adults and children. In adults, 0.13 g/kg/day doses have been used safely for 9 months. This amounts to roughly 9 grams daily for an individual weighing 70 kilos (154 pounds).

In infants, oral doses of 0.17 g/kg/day have been used with apparent safety. In 2-year olds, intravenous L-citrulline has been administered at 5.7 grams daily for 20 months without side effects.

There is insufficient data available to rate the safety of L-citrulline supplementation in women who are nursing or pregnant. Usage is not advised.

L-Citrulline Side Effects

There are not any adverse effects associated with proper L-citrulline supplementation.

However, because L-citrulline may increase NO and thereby vasodilation, conjunctive usage with antihypertensive drugs, nitrates for heart disease and/or phosphodiesterase-5 inhibitors is not recommended.

Also, use caution if taking a L-citrulline supplement with herbal supplements with antihypertensive potentials.

Conclusions

Proper usage of a quality L-citrulline supplement can help to increase L-arginine levels; subsequently increasing NO in the serum. This can induce vasodilation, increase blood delivery and have a positive effect on blood pressure modulation.

The full scope of L-citrulline therapeutic effects is still being explored. If you have any medical conditions or are taking prescription drugs, then it is best to discuss using a L-citrulline supplement with your doctor before beginning.

Although no side effects are associated, and usage seems very well tolerated in healthy individuals, not all natural substances are safe for all people.

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