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Citrulline: The Amino Acid that Benefits Blood Flow & Performance (+ Foods & Dosage Info)

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Citrulline - Dr. Axe

Citrulline is an amino acid often used to improve overall health and ramp up your fitness routine. Although it’s not considered an essential amino acid, it is still incredibly important to health and boasts a wide array of health benefits.

Getting in your fix of foods rich in this key compound can help support better blood flow, enhance oxygen uptake, promote muscle growth and more.

So what is citrulline malate, and how can it impact your health? Keep reading for everything you need to know about this important amino acid, plus some simple ways to quickly boost your intake.

What Is Citrulline? How Does It Work?

Citrulline is a type of amino acid that has been associated with a long list of health benefits. It was first discovered in 1914 when it was isolated from watermelon, but it wasn’t actually identified until the year 1930.

This important amino acid is integral to the urea cycle, which is a pathway that helps excrete ammonia out of the body through the urine. Like alanine, arginine and glycine, it’s considered non-essential, meaning your body can produce it on its own.

It can also be found in many different foods and supplements, which can help give your levels a boost to enhance the potential health benefits of this powerful amino acid.

This amino acid plays a key role in several processes within the body. For starters, it helps increase blood flow and reduce blood pressure by widening the arteries.

It also acts similar to nitric oxide supplements to increase levels of nitric oxide in the body, which is a compound that acts as a vasodilator to relax the muscles in the blood vessels and promote circulation. This is because it’s converted into arginine, another amino acid that is used to produce nitric oxide in the body.

Because of its ability to promote proper blood flow, it’s been linked to several possible health benefits. In particular, it is thought to decrease blood pressure, prevent erectile dysfunction and boost oxygen uptake to optimize exercise performance.

L-Citrulline vs. L-Arginine

What are the key differences between arginine vs. citrulline?

Both arginine and citrulline are non-essential amino acids that are necessary for several aspects of health. However, citrulline is actually converted into arginine, which is used to produce nitric oxide, an important compound that helps support better circulation by relaxing the muscles within the blood vessels.

Because of their similarities, L-citrulline and L-arginine taken together is common in supplements geared toward treating conditions like high blood pressure and erectile dysfunction. Interestingly enough, however, some studies have actually found that taking citrulline could increase arginine levels more effectively than arginine supplements alone.

In fact, one of the biggest differences between citrulline vs. arginine is in the way that these two amino acids are absorbed in the body. One study published in Nutrition notes that citrulline is absorbed especially well when taken orally.

Many supplements also combine these important amino acids to help treat issues like high blood pressure and impotence. However, more research is needed to determine the best L-arginine and L-citrulline dosage for ED and other conditions, as well as whether you should take L-arginine and L-citrulline before bed, with meals or at other times throughout the day.

Citrulline Benefits

1. Reduces Blood Pressure

Several promising studies have found a close connection between L-citrulline and blood pressure levels. It’s been shown to help improve the function of the cells that line the blood vessels and act as a natural nitric oxide booster.

One study out of Japan showed that taking a citrulline supplement improved endothelial dysfunction and reduced lipoprotein oxidation, which can lead to the development of atherosclerosis, or fatty plaque in the arteries. Another study published in European Journal of Applied Physiology showed that taking this amino acid reduced systolic and diastolic blood pressure by 6 percent and 14 percent, respectively.

2. May Help Treat Erectile Dysfunction

Erectile dysfunction (ED) is the inability to get or maintain an erection, which can be caused by medical issues like high blood pressure as well as mental and emotional issues like stress. Citrulline is one of the most popular natural alternatives to prescription ED supplements thanks to its ability to improve blood flow and decrease blood pressure levels.

A 2011 study conducted by the University of Foggia in Italy found that, although this amino acid was not quite as effective as other prescription supplements for ED like sildenafil, it was able to improve several symptoms of erectile dysfunction after just one month.

So how long does it take for L-citrulline to work for ED? Although individual results can vary, most people experience symptom improvements within the  first few weeks of starting supplementation.

3. Supports Muscle Growth

Amino acids like this one are absolutely essential when it comes to muscle growth. Studies show that this important compound stimulates muscle protein synthesis and plays a central role in maintaining protein homeostasis.

One trial out of Mallorca, Spain, even demonstrated that taking L-citrulline malate could improve the use of branched-chain amino acids during exercise and increase levels of human growth hormone, a type of protein hormone that is thought to improve physical capacity and muscle strength.

4. Enhances Exercise Performance

Some research suggests that this amino acid can help improve oxygen usage in the muscles, which can bring some big benefits when it comes to your workout routine. For example, a study in Journal of the International Society of Sports Medicine found that taking a citrulline supplement improved physical performance for cyclists and even improved feelings of fatigue and concentration immediately after exercise.

Another study showed that it was effective at enhancing endurance and high-intensity exercise performance by increasing oxygen uptake.

Citruline Foods and How to Get It in the Diet

What foods have citrulline? It can be found in a number of natural food sources, making it easy to meet your needs of this important amino acid by making a few simple switches to your diet.

Some of the top food sources of this amino acid include:

  • Watermelon
  • Bitter gourd
  • Onions
  • Garlic
  • Nuts
  • Chickpeas
  • Liver
  • Peanuts
  • Salmon
  • Pumpkin
  • Cucumbers
  • Gourds

There are many different ways to start adding these nutritious foods to your diet. Here are a few recipe ideas to help get you going:

Supplements and Dosage Info

There are two common types of citrulline supplements available: L-citrulline and citrulline malate.

What’s the difference between L-citrulline and citrulline malate?

The main difference between citrulline vs. citrulline malate is the different compounds that they contain. While L-citrulline contains citrulline alone, citrulline malate contains L-citrulline and DL-malate, a compound that aids in energy production during exercise.

How much citrulline should you take a day, and when should I take it?

The L-citrulline dosage can vary based on the type of supplement that you take and the condition you’re trying to treat.

L-citrulline powder has been generally studied in doses of three to five grams per day. The citrulline malate dosage tends to be slightly higher, with a dosage ranging from six to eights grams daily for maximum results.

The L-citrulline dosage for ED may be a bit lower, with doses ranging between 1.5 to three grams per day.

There are no specific guidelines for citrulline malate dosage timing, but it’s recommended to take around one hour before exercise if you’re looking to increase muscle recovery and endurance. For other conditions, you can split your supplement into several smaller citrulline dosages, which can be taken with meals throughout the day.

Precaution, Side Effects and Interactions

In most cases, this important amino acid is safe, effective and associated with very few L-citrulline side effects. In fact, one study out of Paris showed that taking even high doses up to 15 grams per day was safe and well-tolerated by participants.

Women who are pregnant or breastfeeding should avoid supplementation to prevent any potential citrulline side effects. It’s also not recommended for those taking other medications like nitrates for high blood pressure, heart disease or erectile dysfunction.

Taking it combination with these medications can cause dangerous drops in blood pressure, which could potentially be harmful.

Therefore, it’s best to talk to your doctor before starting supplementation if you are taking any medications or have any underlying health conditions. Additionally, be sure to use only as directed to prevent any adverse effects on health.

Final Thoughts

  • What is L-citrulline? It is an important non-essential amino acid that plays a key role in several aspects of health.
  • It’s converted into arginine in the body, which is used to make nitric oxide, a compound that helps dilate and relax the blood vessels to promote proper circulation.
  • Potential benefits include decreased blood pressure, increased muscle growth and improved exercise performance. Citrulline malate benefits certain health conditions like erectile dysfunction as well, thanks to its ability to increase blood flow through the body.
  • Although it’s generally safe and associated with very few side effects, it’s not recommended for those taking nitrates or medications for high  blood pressure, heart disease or erectile dysfunction as well as women who are pregnant or breastfeeding.

Read Next: Tyrosine Benefits for Brain & Thyroid Health (+ Foods & Dosage Info)


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