Understanding L-Citrulline: The Daily Supplement
L-citrulline is a non-essential amino acid naturally produced by the body and also found in foods like watermelon. It plays a crucial role in the urea cycle, which helps the body get rid of harmful ammonia. Supplementing with L-citrulline can increase plasma L-arginine levels more effectively than supplementing with L-arginine itself, which in turn boosts the production of nitric oxide (NO). This increase in NO promotes vasodilation—the widening of blood vessels—leading to improved blood flow throughout the body. The daily use of L-citrulline is most commonly considered for enhancing exercise performance and supporting cardiovascular health, including lowering blood pressure in some individuals.
Safety and Side Effects of Daily L-Citrulline
For most healthy individuals, L-citrulline is considered safe for daily use within appropriate amounts. Studies involving daily intake over several weeks or months have generally shown good tolerability with minimal side effects. However, some people might experience mild gastrointestinal discomfort, such as stomach upset or heartburn, especially with larger quantities. One study noted that amounts exceeding what is necessary might not significantly increase blood arginine levels further, and could increase the risk of gastrointestinal issues. Long-term safety for chronic, high-level use is still an area that needs more research.
Important Considerations for Daily Intake
The optimal daily amount for L-citrulline depends on the intended purpose, such as improving athletic performance or managing blood pressure. The supplement is available in two main forms: L-citrulline and citrulline malate. For reference, citrulline malate contains both L-citrulline and malic acid.
- Benefits: L-citrulline is often taken to support general blood flow or enhance athletic performance. It is also being studied for its potential effects on mild erectile dysfunction.
It is always best to start with a smaller quantity to assess your body's tolerance before increasing the amount.
Comparison: L-Citrulline vs. Citrulline Malate
| Feature | L-Citrulline | Citrulline Malate |
|---|---|---|
| Composition | Pure L-citrulline amino acid. | L-citrulline bound to malic acid, a compound found in apples. |
| Purity | Considered the pure amino acid form. | A combined form, meaning you get less pure L-citrulline per gram. |
| Potential Added Benefits | Focuses solely on the benefits of L-citrulline (e.g., nitric oxide production). | Malic acid may have additional benefits for energy production (ATP) and muscular endurance. |
| Dosing Consideration | Amounts are based on the pure L-citrulline content. | Dosing must account for the malic acid content. You may need more citrulline malate to get the same amount of pure L-citrulline. |
| Common Use | Often used for boosting nitric oxide and blood flow. | Frequently chosen for performance-enhancing effects during weight training due to potential ATP-boosting properties. |
Important Precautions and Drug Interactions
While L-citrulline is generally safe, certain individuals should exercise caution or avoid it entirely, particularly those with specific health conditions or who are taking certain medications.
- Blood Pressure Medications: Because L-citrulline can lower blood pressure, combining it with antihypertensive drugs (e.g., lisinopril, metoprolol, and nitrates) could cause blood pressure to drop too low (hypotension).
- Erectile Dysfunction (ED) Medications: L-citrulline interacts with phosphodiesterase-5 (PDE-5) inhibitors like sildenafil (Viagra) and tadalafil (Cialis), potentially causing an unsafe drop in blood pressure.
- Kidney Issues: Individuals with kidney dysfunction should be cautious, as very high amounts could potentially overload the kidneys' creatine production.
- Surgery: Since L-citrulline can affect blood pressure, it's recommended to stop taking it at least two weeks before any scheduled surgery.
- Pregnancy and Breastfeeding: There is insufficient evidence to determine the safety of L-citrulline during pregnancy or breastfeeding, so avoidance is recommended as a precaution.
Always consult a healthcare provider before starting a daily L-citrulline regimen, especially if you have pre-existing health conditions or take other medications. For more information, the National Institutes of Health provides resources on dietary supplements.
Conclusion
For most healthy adults, taking L-citrulline every day within appropriate amounts appears to be a safe practice. Its benefits for enhancing exercise performance and promoting cardiovascular health are supported by research, though results for some applications can be mixed. The key to safe daily use lies in proper use and awareness of potential drug interactions, especially concerning blood pressure. As with any supplement, professional medical advice is essential to ensure it's the right choice for your individual health needs.
