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Citrulline Nitrate

Also known as: Citrulline, L-Citrulline

Overview

L-Citrulline is a non-essential, non-protein amino acid that plays a vital role in the urea and nitric oxide cycles. Naturally found in watermelon, it is used as a dietary supplement primarily to enhance exercise performance by increasing nitric oxide production and buffering ammonia levels in the body. L-Citrulline is noted for its superior absorption compared to arginine, effectively bypassing first-pass metabolism. Research on its ergogenic effects is ongoing, with systematic reviews indicating mixed results on performance enhancement, especially in endurance and high-intensity exercise contexts. The use of l-citrulline is growing in popularity among athletes and fitness enthusiasts as part of training regimens aimed at improving performance.

Benefits

L-Citrulline has several evidence-based benefits: it has been shown to improve high-intensity exercise performance in athletes with a small but statistically significant effect size (SMD = 0.20). Some systematic reviews found no significant improvements in endurance performance metrics like time-to-exhaustion and time-to-completion. Long-term supplementation may also enhance vascular function, improving nitric oxide bioavailability and having favorable cardiometabolic effects. Athletes may find the benefits of citrulline particularly relevant, as competitive scenarios often hinge on small performance gains. However, many findings suggest longer supplementation periods yield more pronounced benefits, emphasizing regular intake over acute doses.

How it works

L-Citrulline functions by being converted into arginine in the kidneys, thus increasing plasma levels of arginine and subsequently enhancing nitric oxide (NO) synthesis. Through this increase in NO, citrulline improves blood flow, which can enhance exercise capacity and recovery. It also buffers ammonia build-up during exercise, potentially mitigating fatigue. L-Citrulline targets key pathways involved in the urea cycle and nitric oxide synthase (NOS) pathway, which regulates vascular function and metabolic performance.

Side effects

L-Citrulline is generally regarded as safe when taken within the recommended dosages, and it is associated with minimal side effects. Most users tolerate it well, with no commonly reported adverse effects exceeding 5%. Uncommon side effects are not well-documented, and rare side effects are virtually nonexistent. While significant drug interactions have not been reported, caution is advised when combining with other athletic supplements. Individuals with specific health conditions should consult healthcare providers prior to commencing supplementation. Pregnant or breastfeeding women and those with chronic illnesses are encouraged to seek medical guidance.

Dosage

The minimum effective dose for performance enhancement of L-Citrulline is typically around 3 grams. Optimal dosing ranges from 3 to 9 grams daily, with several studies indicating sustained benefits from longer-term use (about 7 days). While no maximum safe dose is set, caution should be practiced as doses exceeding 9 grams have not been sufficiently researched. Citrulline can be administered before workouts; however, due to its mechanism of action, exact timing may not critically affect outcomes. It is available in various forms, including pure powder supplements and blends with other performance-enhancing ingredients.

FAQs

Is L-Citrulline safe to use?

Yes, L-Citrulline is generally safe when consumed in recommended doses, but those with medical conditions should consult a healthcare provider.

When is the best time to take L-Citrulline?

L-Citrulline can be consumed before exercise; however, optimal timing is not definitively established due to its mode of action.

What results can I expect from using L-Citrulline?

Users may experience small improvements in high-intensity exercise performance and potential long-term vascular health benefits.

Is it true that L-Citrulline greatly improves endurance?

Current evidence does not support significant improvements in endurance performance from L-Citrulline; benefits are more evident in high-intensity efforts.

Research Sources

https://www.tandfonline.com/doi/full/10.1080/15502783.2023.2209056 – This systematic review and meta-analysis assesses the effects of L-Citrulline on endurance performance, revealing no significant difference in performance measures after acute supplementation.
https://pubmed.ncbi.nlm.nih.gov/30895562/ – Another meta-analysis focused on the impact of L-Citrulline on high-intensity exercise performance, presenting small but statistically significant improvements with supplementation.
https://pubmed.ncbi.nlm.nih.gov/37155582/ – The study highlights the vascular benefits of long-term L-Citrulline supplementation, primarily through improved nitric oxide levels and arginine bioavailability.
https://www.mdpi.com/2072-6643/14/1/40 – Meta-analysis findings demonstrating the role of L-Citrulline in enhancing cardiovascular function and metabolic health through increased NO production.
https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/effects-of-lcitrulline-supplementation-and-watermelon-consumption-on-longerterm-and-postprandial-vascular-function-and-cardiometabolic-risk-markers-a-metaanalysis-of-randomised-controlled-trials-in-adults/1873E93CFF6015FD63F34CBDF5DFAE3C – This article reviews the benefits of L-Citrulline and watermelon consumption for long-term vascular health and metabolic profiles in adults, supporting its role in managing cardiometabolic risks.