What are the benefits of l-citrulline?
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Benefits of L-Citrulline: A Comprehensive Overview
Introduction to L-Citrulline
L-Citrulline is a non-essential amino acid that plays a crucial role in the urea cycle and is a precursor to L-arginine, which is essential for nitric oxide (NO) production. This amino acid has garnered attention for its potential health benefits, particularly in enhancing exercise performance, cardiovascular health, and metabolic functions.
Enhanced Exercise Performance
Improved Cycling Performance
Several studies have demonstrated that L-citrulline supplementation can significantly enhance exercise performance. For instance, a study involving trained male cyclists showed that one week of L-citrulline supplementation improved their 40-km time trial performance by 5.2% and increased their average power output and heart rate during the trial. Another study found that L-citrulline supplementation reduced the time taken to complete a 4-km cycling time trial and improved subjective feelings of muscle fatigue and concentration immediately after exercise.
Oxygen Uptake and High-Intensity Exercise
L-citrulline has also been shown to improve oxygen uptake kinetics and exercise performance during high-intensity activities. Research indicates that L-citrulline supplementation lowers the mean response time of oxygen uptake during severe-intensity exercise and increases the total amount of work completed. This suggests that L-citrulline can enhance endurance and performance in high-intensity workouts.
Cardiovascular Health Benefits
Blood Pressure and Vascular Function
L-citrulline is effective in improving cardiovascular health by enhancing nitric oxide production, which helps in vasodilation and blood flow. Studies have shown that L-citrulline supplementation can lower blood pressure in adults with pre-hypertension and hypertension. Additionally, it has been found to improve splanchnic perfusion and reduce gut injury during strenuous exercise, which can be beneficial for athletes.
Endothelial Function in Older Adults
In older adults, L-citrulline supplementation has been linked to improved vascular function and muscle protein synthesis, potentially mitigating age-associated cardiovascular diseases and sarcopenia. This makes L-citrulline a promising supplement for maintaining cardiovascular health in aging populations.
Metabolic and Antioxidant Effects
Glucose Homeostasis and Lipid Profile
L-citrulline supplementation has shown positive effects on glucose homeostasis and lipid profiles in overweight and obese patients with type 2 diabetes. It significantly decreases serum levels of insulin, fasting glucose, hemoglobin A1c (HbA1c), and inflammatory markers such as TNF-α and hs-CRP. These findings suggest that L-citrulline can be beneficial in managing diabetes and improving metabolic health.
Antioxidant Properties
L-citrulline also exhibits antioxidant properties. It has been found to increase the levels of antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GPx) following high-intensity interval exercise, thereby reducing oxidative stress. This antioxidant effect can help in protecting cells from damage and improving overall health.
Muscle Protein Synthesis and Growth
Fetal Growth and Protein Synthesis
In animal models, L-citrulline supplementation has been shown to enhance fetal growth and muscle protein synthesis in cases of intrauterine growth restriction (IUGR). This indicates that L-citrulline can stimulate protein synthesis and support growth in conditions of undernutrition.
Immune Function and Oxidative Damage
L-citrulline has also been found to alleviate oxidative damage and immune dysfunction caused by iron overload in the thymus. It reduces iron deposition and enhances antioxidative capacity, thereby protecting against oxidative stress and inflammation.
Conclusion
L-citrulline offers a wide range of health benefits, from enhancing exercise performance and cardiovascular health to improving metabolic functions and antioxidant defenses. Its ability to increase nitric oxide production and support muscle protein synthesis makes it a valuable supplement for both athletes and individuals with metabolic or cardiovascular conditions. As research continues, L-citrulline's potential therapeutic applications are likely to expand, offering new avenues for health optimization.
Sources and full results
Most relevant research papers on this topic
L-Citrulline Supports Vascular and Muscular Benefits of Exercise Training in Older Adults.
Oral L-citrulline supplementation enhances cycling time trial performance in healthy trained men: Double-blind randomized placebo-controlled 2-way crossover study
l-Citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans.
L-Citrulline Supplementation Enhances Fetal Growth and Protein Synthesis in Rats with Intrauterine Growth Restriction.
L-citrulline improves splanchnic perfusion and reduces gut injury during exercise.
One Week of L-Citrulline Supplementation Improves Performance in Trained Cyclists.
Effects of l-citrulline supplementation on nitric oxide and antioxidant markers after high-intensity interval exercise in young men: a randomised controlled trial
l-Citrulline Supplementation: Impact on Cardiometabolic Health
L-Citrulline Supplementation Restrains Ferritinophagy-Mediated Ferroptosis to Alleviate Iron Overload-Induced Thymus Oxidative Damage and Immune Dysfunction
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