What Is the Best Time to Take L-arginine and L-citrulline?

Studies suggest L-citrulline is more effective at raising blood arginine levels than L-arginine itself due to better absorption. Knowing what is the best time to take L-arginine and L-citrulline is key to maximizing their combined impact on nitric oxide production and overall health.

Quick Summary

The optimal timing for taking L-arginine and L-citrulline varies based on your specific goal, such as taking it before a workout for athletic performance or at different times of day for cardiovascular health. Consistency and dosage are also critical factors.

Key Points

• Pre-Workout Timing: Take L-citrulline 30-60 minutes before a workout to maximize muscle pumps and endurance.

• General Health Timing: For cardiovascular benefits, consistent daily intake of L-citrulline, possibly in divided doses, is more important than specific timing.

• L-Citrulline Absorption: L-citrulline is more effective at increasing blood arginine levels than L-arginine because it bypasses digestive breakdown.

• Synergistic Combination: Combining L-arginine with L-citrulline can provide a powerful and prolonged nitric oxide boost for both immediate and lasting effects.

• For Erectile Dysfunction: Consistency over several weeks is necessary for noticeable improvements from L-citrulline, though some see benefits one hour before activity.

• Empty Stomach: Taking L-citrulline on an empty stomach may improve absorption, though it is not strictly necessary and depends on personal preference.

Understanding L-Arginine and L-Citrulline

L-arginine and L-citrulline are two amino acids that play a crucial role in the body's nitric oxide (NO) pathway. Nitric oxide is a signaling molecule that causes blood vessels to relax and widen, a process known as vasodilation. This increased blood flow can benefit various bodily functions, including exercise performance, cardiovascular health, and even erectile function. However, their effectiveness and absorption rates differ significantly, making the timing of supplementation a strategic consideration.

L-arginine is a direct precursor to nitric oxide. Unfortunately, it is poorly absorbed when taken orally because it is rapidly broken down by enzymes in the gut and liver. This poor bioavailability limits its ability to effectively increase plasma arginine levels. In contrast, L-citrulline bypasses this digestive breakdown. It is absorbed more efficiently and then converted into L-arginine in the kidneys. This indirect pathway allows L-citrulline to produce higher and more sustained plasma arginine levels, often making it the more effective supplement for boosting nitric oxide.

Optimal Timing for Different Goals

For Enhanced Athletic Performance (Pre-Workout)

If your primary goal is to maximize muscle pumps, increase endurance, and reduce fatigue during your workout, strategic pre-exercise timing is essential. The increase in nitric oxide from L-citrulline takes time to build up in the system. For this reason, it is generally recommended to take L-citrulline 30 to 60 minutes before your training session. This provides enough time for the amino acid to be absorbed and converted to L-arginine, peaking its nitric oxide-boosting effects when you need them most. Taking the supplement on an empty stomach may further enhance absorption for some individuals.

For Overall Cardiovascular Health and Blood Pressure

For general health benefits like supporting healthy blood pressure, consistency is more important than precise timing. L-citrulline's ability to be absorbed better and provide a more sustained increase in arginine levels makes it an excellent choice for daily intake. Some people choose to split their total daily dosage into smaller, multiple doses throughout the day to maintain elevated nitric oxide levels. For example, a common approach is to take it with meals to aid with consistency, though it can be taken at any time of day. A typical dosage for general health might be 3-5 grams daily.

For Erectile Dysfunction (ED)

In cases of mild to moderate erectile dysfunction, L-citrulline can help improve blood flow to erectile tissues. Some studies have shown positive results with daily, consistent use over a period of weeks or months, indicating that long-term supplementation is more effective than a single dose. For individuals looking for more immediate results, anecdotal evidence and some preliminary studies suggest taking the supplement about an hour before sexual activity. Consistent daily dosing is still recommended to support overall circulatory health, which is the underlying mechanism for the benefit.

For Muscle Recovery (Post-Workout)

While L-citrulline is best known as a pre-workout supplement, some evidence suggests a post-workout dose can aid recovery. The enhanced blood flow helps deliver nutrients and oxygen to tired muscles, while also helping clear metabolic waste products like ammonia. Combining a post-workout dose with a recovery protein shake can maximize nutrient delivery and kickstart the muscle repair process. For this purpose, a 6-gram dose of L-citrulline is often recommended.

Taking L-Arginine and L-Citrulline Together

Emerging research suggests a combination of L-arginine and L-citrulline may offer synergistic benefits. By combining the two, you can leverage L-arginine's quicker, albeit less sustained, effect while taking advantage of L-citrulline's superior absorption and longer-lasting impact. This can lead to a rapid initial increase in plasma arginine, followed by a more prolonged elevation. For this reason, some pre-workout supplements now include both amino acids. A good strategy is to use a combination product or take them together, timed for 30-60 minutes before exercise.

L-Arginine vs. L-Citrulline: A Comparison

Feature	L-Arginine	L-Citrulline
Absorption	Poor due to extensive breakdown in the gut and liver.	Superior, as it bypasses the liver and is converted in the kidneys.
Nitric Oxide Production	Acts directly, but systemic levels are hard to sustain orally.	Acts indirectly by converting to L-arginine, leading to sustained NO levels.
Onset	Quicker initial effect, but less durable.	Slower onset, but more reliable and longer-lasting effect.
Side Effects	Higher risk of gastrointestinal issues, especially at higher doses.	Minimal side effects, better tolerated by the stomach.
Best For	Short-term, acute NO boost, often combined with L-citrulline.	Sustained NO boost, endurance, pumps, and general cardiovascular support.

How to Strategize Your Supplementation

1. Assess Your Goal: Define whether you're targeting athletic performance, general health, or another specific outcome. This is the most crucial step for determining the correct timing.
2. Choose the Right Amino Acid: If you are taking a single supplement, L-citrulline is generally the more effective option for raising nitric oxide levels systemically due to its superior absorption.
3. Consider Combination: For the most comprehensive effect, a combination of L-arginine and L-citrulline can provide both immediate and sustained benefits. Many high-quality pre-workout formulas already incorporate this blend.
4. Listen to Your Body: Start with a lower dose to assess your tolerance, especially if you have a sensitive stomach. Adjusting your dose or timing based on personal experience is key to finding what works best for you. Some find taking arginine with a meal helps with tolerability.
5. Be Consistent: For long-term benefits related to cardiovascular health or ED, regular, consistent daily intake is more important than timing the dose perfectly with an event.

Conclusion

While L-arginine and L-citrulline both play a role in nitric oxide production, their distinct absorption profiles mean timing and selection matter. L-citrulline is often the more effective choice for raising plasma arginine levels due to its better bioavailability, making it ideal for sustained benefits. For those seeking peak athletic performance, taking L-citrulline 30-60 minutes before a workout is best, while consistent daily intake is recommended for cardiovascular health and ED management. Combining L-arginine and L-citrulline can offer a synergistic effect, providing both quick and lasting nitric oxide enhancement. Always consult a healthcare professional before beginning any new supplement regimen, particularly if you have underlying health conditions.

For more detailed information on supplement research, see the comprehensive supplement encyclopedia at Examine.com.

Frequently Asked Questions

Can I take L-arginine and L-citrulline at the same time?

Yes, taking L-arginine and L-citrulline together can create a synergistic effect, leading to a faster and more sustained increase in nitric oxide levels compared to taking either amino acid alone.

Is it better to take L-citrulline or L-arginine for a workout?

Most evidence suggests L-citrulline is more effective as a pre-workout supplement. It is absorbed more efficiently and leads to higher, more consistent blood arginine and nitric oxide levels, which directly benefit athletic performance.

How long does L-citrulline take to work?

For exercise performance, the effects of L-citrulline can typically be felt within 30 to 60 minutes after ingestion. For sustained benefits like those for erectile function, consistent daily use over several weeks may be necessary to see significant results.

Should I take L-citrulline on an empty stomach?

Taking L-citrulline on an empty stomach is generally considered optimal for absorption. However, if you experience any stomach discomfort, you can take it with a light meal, though it may slightly delay absorption.

What is the best time to take these supplements for blood pressure?

For cardiovascular health and blood pressure regulation, consistency is paramount. You can take L-citrulline at any time of day, but it is often recommended to split the total daily dose and take it consistently, such as with meals.

Can I take L-citrulline for exercise recovery after a workout?

Yes, taking L-citrulline post-workout can assist with muscle recovery by increasing blood flow to deliver nutrients and helping to clear out metabolic waste products. This can help reduce muscle soreness.

What are the common side effects of L-arginine and L-citrulline?

While L-citrulline is generally well-tolerated, L-arginine is known to cause more gastrointestinal side effects like bloating or diarrhea, particularly at higher doses. This is one reason L-citrulline is often preferred.