Citrulline - NutraPedia

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Citrulline: An Overview

1. Conditions Studied for Citrulline Use

Citrulline has been studied for various health conditions, including:

  • Cardiovascular diseases such as hypertension and heart failure
  • Erectile dysfunction
  • Muscle weakness
  • Certain metabolic disorders
  • Exercise performance and recovery

2. Efficacy in Treating Conditions

Research on the efficacy of citrulline in treating the aforementioned conditions has shown mixed results:

  • Some studies suggest it may help lower blood pressure and improve heart function.
  • It may aid in treating erectile dysfunction by increasing blood flow.
  • For exercise performance, it may reduce fatigue and improve endurance.
  • Results are varied and more research is needed to confirm these findings.

3. Health Benefits of Citrulline

Citrulline has several potential health benefits:

  • It may boost nitric oxide production, improving blood flow and cardiovascular health.
  • Could help enhance exercise performance and muscle recovery.
  • May play a role in reducing muscle soreness after exercise.
  • Some evidence suggests it can support the immune system.

4. Downsides of Citrulline

While citrulline is generally considered safe, there are some potential downsides:

  • Some people may experience stomach discomfort or other gastrointestinal issues.
  • High doses could potentially cause imbalances in other amino acids.
  • Long-term effects are not well-studied.
  • It could interact with certain medications, such as nitrates or erectile dysfunction drugs.

5. Citrulline in Relation to Genetic Variations

Genetic variations can influence how individuals respond to citrulline supplementation:

  • Some genetic mutations may affect the absorption and metabolism of citrulline.
  • Genetic variations in nitric oxide synthase genes could modify the efficacy of citrulline in promoting nitric oxide production.
  • Personalized genetic testing may help determine if citrulline could be particularly beneficial or harmful, but more research is needed in this area.

Effects of Citrulline Supplementation on Exercise Performance and Recovery

High-Intensity Strength and Power Performance

Citrulline supplementation has been shown to have a statistically significant, but small, benefit on strength and power during short-duration, high-intensity exercises. This could be meaningful for high-level athletes.

Post-Exercise Recovery

Citrulline supplementation significantly reduces the rating of perceived exertion during exercise and muscle soreness at 24 and 48 hours post-exercise, but does not significantly reduce muscle soreness at 72 hours post-exercise or affect blood lactate levels.

Strength Training Performance

Acute Citrulline Malate (CitMal) supplementation can modestly increase the number of repetitions performed before voluntary muscular failure during high-intensity strength training, particularly in lower body exercises.

Blood Pressure Reduction

L-citrulline supplementation leads to a statistically significant reduction in systolic blood pressure and may also reduce diastolic blood pressure when taken at higher doses.

Nitric Oxide Synthesis and Exercise Performance

Supplements related to nitric oxide production, like Citrulline and GPLC, show mixed results on exercise performance, with the potential for improved exercise tolerance in untrained or moderately trained individuals.

Citrulline in Medical Treatments and Diagnostics

Citrulline supplementation is used for various medical conditions and as a biomarker for intestinal pathologies and early diagnosis of rheumatoid arthritis.

Watermelon as a Natural Source of Citrulline

Watermelon, including the rind, is a valuable source of natural citrulline, which can lead to elevated plasma citrulline and arginine levels upon consumption.

Pharmacokinetics of L-Arginine

L-arginine administered intravenously and orally to healthy volunteers shows a biphasic elimination pattern, with oral administration having an absolute bioavailability of about 20%.

Citrulline and Arginine in the Human Body

Citrulline is involved in key metabolic pathways, including the conversion of ammonia to urea in the liver, the creation of arginine from glutamine in the gut and kidney, and the production of nitric oxide.

Impact of Citrulline Malate on Muscle Strength

Citrulline malate supplementation does not significantly improve muscle strength in healthy, resistance-trained individuals.

Aerobic Exercise Performance

Citrulline supplementation does not show significant benefits on aerobic performance, RPE, VO2 kinetics, or lactate levels.

Metabolism and Amino Acid Utilization

L-citrulline-malate supplementation before intense exercise can improve the utilization of amino acids and enhance the production of arginine-derived metabolites.

Antioxidant and Vasodilatory Benefits

Citrulline has potential antioxidant and vasodilatory benefits and is found in various watermelon varieties.

Arginine and Citrulline Supplementation

Combining L-citrulline with reduced glutathione (GSH) can significantly increase indicators of nitric oxide synthesis.

Citrulline Malate and Fatigue Reduction

Citrulline malate (Stimol) can reduce fatigue by protecting against acidosis and ammonia toxicity through its effect on liver and kidney functions.

References:


  1. Acute Effects of Citrulline Supplementation on High-Intensity Strength and Power Performance: A Systematic Review and Meta-Analysis
  2. Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis
  3. Acute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-Analysis
  4. Effects of L-citrulline supplementation on blood pressure: A systematic review and meta-analysis
  5. The effect of nitric-oxide-related supplements on human performance
  6. Citrulline: pharmacological perspectives and its role as an emerging biomarker in future
  7. Determination of citrulline in watermelon rind
  8. Elevated plasma citrulline and arginine due to consumption of Citrullus vulgaris (watermelon)
  9. Pharmacokinetics of intravenous and oral L-arginine in normal volunteers
  10. Watermelon consumption increases plasma arginine concentrations in adults
  11. Effects of Citrulline Malate Supplementation on Muscle Strength in Resistance-Trained Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
  12. Effects of Citrulline Supplementation on Different Aerobic Exercise Performance Outcomes: A Systematic Review and Meta-Analysis
  13. Almost all about citrulline in mammals
  14. Metabolism of citrulline in man
  15. Arginine synthesis from enteral glutamine in healthy adults in the fed state
  16. Intestinal and hepatic metabolism of glutamine and citrulline in humans
  17. Interorgan amino acid exchange in humans: consequences for arginine and citrulline metabolism
  18. Manipulation of citrulline availability in humans
  19. Amino acid handling in uremic rats: citrulline, a reliable marker of renal insufficiency and proximal tubular dysfunction
  20. Whole body nitric oxide synthesis in healthy men determined from [15N] arginine-to-[15N]citrulline labeling
  21. Effects of leucine and citrulline versus non-essential amino acids on muscle protein synthesis in fasted rat: a common activation pathway?
  22. Citrulline modulates muscle protein metabolism in old malnourished rats
  23. Leucine and citrulline modulate muscle function in malnourished aged rats
  24. Leucine and citrulline: two major regulators of protein turnover
  25. Oral citrulline does not affect whole body protein metabolism in healthy human volunteers: results of a prospective, randomized, double-blind, cross-over study
  26. Dose-ranging effects of citrulline administration on plasma amino acids and hormonal patterns in healthy subjects: the Citrudose pharmacokinetic study
  27. Nitric oxide synthesis leads to vascular endothelial growth factor synthesis via the NO/cyclic guanosine 3',5'-monophosphate (cGMP) pathway in human corpus cavernosal smooth muscle cells
  28. Effects of icariin on cGMP-specific PDE5 and cAMP-specific PDE4 activities
  29. Validation of the erection hardness score
  30. Adverse gastrointestinal effects of arginine and related amino acids
  31. Growth hormone responses to varying doses of oral arginine
  32. L-citrulline-malate influence over branched chain amino acid utilization during exercise
  33. Leucine and citrulline: two major regulators of protein turnover
  34. Combined L-citrulline and glutathione supplementation increases the concentration of markers indicative of nitric oxide synthesis
  35. L-citrulline-malate influence over branched chain amino acid utilization during exercise
  36. Activity of citrulline malate on acid-base balance and blood ammonia and amino acid levels. Study in the animal and in man
  37. Activity of citrulline malate on acid-base balance and blood ammonia and amino acid levels. Study in the animal and in man
  38. Arginine or citrulline associated with a statin stimulates nitric oxide production in bovine aortic endothelial cells
  39. The role of eNOS, iNOS, and NF-kappaB in upregulation and activation of cyclooxygenase-2 and infarct size reduction by atorvastatin
  40. Statin treatment upregulates vascular neuronal nitric oxide synthase through Akt/NF-kappaB pathway
  41. 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors upregulate inducible NO synthase expression and activity in vascular smooth muscle cells


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