L-Citrulline Guide: Everything you need to know

Bodybuilding dietary supplements

An important part of your diet and overall health is amino acids. Our body can make some amino acids, while others have to be ingested in our diets or with supplements. How much do you know about amino acids and their benefits to your body and its growth? Now it is time to find out. One important amino acid your body needs is L-citrulline. This complete guide to L-citrulline will help you add it to your diet.

All About Amino Acids

Amino acids are the basic building blocks for the body. They are organic compounds that combine to form proteins, which the body then uses to support the body. Organic compounds means they are part of a large group of chemical compounds that have one or more atoms of carbon that are linked to other elements such as nitrogen, oxygen or hydrogen with a covalent bond.

amino acids
20 amino acids. A life basis.

Types of Amino Acids

There are 20 amino acids, but not all of them are the same [1]. Amino acids are broken up into three different categories. Amino acid classifications depends on whether or not your body can synthesize them and the ones you need to get from your diet. The three types of amino acids are: essential amino acids, non-essential amino acids, and conditional amino acids.

Essential and Conditional Amino Acids

Essential amino acids are the ones that your body needs but it cannot make [2]. These amino acids are essential to your diet [3]. There are nine essential amino acids:

  • Histidine (H)
  • Isoleucine (I)
  • Leucine (L)
  • Lysine (K)
  • Methionine (M)
  • Phenylalanine (F)
  • Threonine (T)
  • Tryptophan (W)
  • Valine (V)

Non-Essential Acids

Don’t let the name fool you. Even though I they are non-essential doesn’t mean your body doesn’t need them. Non-essential amino acids are the ones that your body can produce the amino acids even if you don’t get them from your food. There are 4 non-essential amino acids:

  • Alanine (A)
  • Asparagine (N)
  • Aspartic acid (D)
  • Glutamic acid (G)

The rest of the 20 amino acids are called conditional amino acids. Conditional amino acids are acids that your body doesn’t necessarily need everyday like it does essential acids, but they still play a role in overall health and well-being during times of sickness and stress.

The conditional amino acids are:

  • Arginine (R)
  • Cysteine (C)
  • Tyrosine (Y)
  • Glycine (G)
  • Ornthine 
  • Proline (P)
  • Serine (S)

All amino acids are organic compounds that build proteins in the body. Every single function, cell, structure of the human body contains protein. We can thank amino acids for everything from forming muscle, tissue, bone, organs, and skin. Protein is critical not only for development but for tissue repair and regeneration.

Protein and Your Body

Food high in protein close-up

Your body needs protein. It is essential for active people, athletes, bodybuilders, and couch junkies [3]. The amount of protein your body needs depends on three important factors: gender, activity level, and diet demands.

The RDA for protein intake is 0.8 grams of protein for each kilogram of body weight [4]. But you need to figure out what that means in pounds. One kilogram equals about 2.20 pounds. If you weigh 150 lbs., you are about 68 kilograms. So, a 150-pound person requires about 54.4 grams of protein per day. The catch to that is the RDA assumes you are “average” Maybe it figures you work a desk job, you are moderately active, and you meet the recommended dietary guidelines for calorie intake per day.

If you landed here, you are not “average.” You are active, you push your body, and your body demands more protein because it has to work harder and build muscle to support your fitness plans.

How much protein do bodybuilders need?

For bodybuilders and athletes, protein is a key nutrient that helps build muscle, regenerate tissue, aid in recovery, and support endurance [5]. The issue here is that the bodybuilding community doesn’t seems to be at odds with dieticians and physicians about protein demands.

An article in Men’s Fitness addressed this issue not too long back.  The article tackled 5 myths or claims about protein, and then it backed it up with research. What the article revealed was these main takeaways:

  • Those with high-protein diets have less  body fat
  • Unless you have a pre-existing kidney condition, to much protein won’t damage your kidneys or impede kidney function
  • Too much fatty animal protein may actually be the worst, instead of too much protein. Consuming lean proteins is ideal.
  • Protein you consume in your diet actually works with calcium to improve retention of the important building block for strong bones.

With those points in mind, how much protein do bodybuilders need. The RDA recommendations may not be sufficient enough for active individuals. It is possible that too little protein inhibits the body’s ability to offset the oxidation of amino acids during vigorous activity such as cardio and lifting. Ideally active individuals, such as bodybuilders and athletes, should be anywhere from 1.0 gram to 1.6 -2.0 grams per kilogram of bodyweight. The harder you push yourself, the higher on the scale you should be.

Sources of Protein in Your Diet

Remember to stay away from fatty slabs of beef to increase protein and bulk up. You are asking for increased fat instead and heart disease. I also encourage you to avoid the pre-packaged foods and snacks the boast about added protein. In most cases they come with more sugar than they do protein. It isn’t worth it. Stick to these healthy sources of protein for added muscle and muscle performance.

  • Dairy
  • Leans meats such as turkey and chicken
  • Dish
  • Nuts and legumes
  • Protein powder
  • Amino acid supplements

Find the best protein powder for your needs and dietary restrictions.

What is L-Citrulline and Its Role in Building Muscle?

Earlier I told you that L-Citrulline is an amino acid, but you might notice that it isn’t on the essential, non-essential, or conditional amino acids lists [3]. L-citrulline is a non-essential amino acid, which means your body needs it but cannot produce it. So, you must add L-citrulline to your diet through other means. The kidneys convert L-citrulline into yet another amino acid called L-arginine.

About L-Arginine

L-arginine is yet another component of a urea cycle. L-arginine is a nonessential amino acid. The amino acid has antiatherogenic (preventing accumulation of lipids that contain plaque), anti-ischemic (reduced blood flow to heart), and anti-thrombotic (reduces blood clots) properties. L-arginine is safe for most populations, but if you suffer from allergies, asthma, or frequent stomach discomfort, L-arginine may exacerbate these concerns. Generally, the low toxicity of l-arginine is why many use it.

L-arginine is used for common heart-related issues and diseases, to improve memory health, for erectile dysfunction, and to improve blood flow to muscle and the skin to shorten recovery time. However, too much l-arginine can lead to cramping, stomach pain, bloating, and nausea.

Foods that contain L-arginine are red meats, pork, turkey breasts, dairy, soy beans, oats, rice, and seeds.

About L-Citrulline

L-citrulline is a dietary amino acid that plays an important role in a urea cycle with L-arginine and L-ornithine. In most circles, citrulline is replacing arginine for improved blood flow and exercise performance [6]. It also bypasses the liver. Arginine does not.

Uses for L-Citrulline

L-citrulline plays many roles in overall body health. L-citrulline increases the among of nitric oxide in your body.

Nitric oxide (NO) is a gas that your body produces on its own. Enzymes in your body break down arginine to produce nitric oxide. The role of nitric oxide in your body is to deliver messages back and forth among cells in the body. This control the circulation of blood through vital and non-vital organs: everything from your stomach and liver to your lungs, brain and kidneys. This boosts recovery time, healthy cell production,and it releases hormones and adrenaline thanks to increased and efficient blood flow throughout the body.

In the lab, L-citrulline has been used for several reasons. Uses for and studies about l-citrulline include:

  • Lowering blood pressure in people who suffer from hypertension (high blood pressure). Those who suffer hypertension often become patients who have trouble controlling high blood pressure, which increases the risk for heart disease.
  • Reducing blood pressure concerns in patients, specifically children, who have undergone heart surgery.
  • Controlling the symptoms and concerns of erectile dysfunction
  • In animals, promoting wound healing and aiding in recovery time in diabetes sufferers.
  • Improving protein in the muscles in those who suffer from muscle wasting diseases and undernourishment.
  • Treating intestinal and GI issues such as celiac disease, short bowel syndrome, and damage to the small bowel.
  • Boosting athletic performance, muscle mass, endurance, and muscle recovery.

How to Add L-Citrulline to Your Diet

Because L-citrulline is a nonessential amino acid, you need to add it to your diet. There are a couple ways you can do so: food and supplements. Foods that have high levels of L-citrulline are:

  • watermelon


  • Onions
  • Garlic
  • Chickpeas
  • Peanuts
  • Red meat, especially liver
  • Salmon
  • Almonds
  • Seeds

As you can see, the list is limited. The other way to increase L-citrulline levels in your body is to take an L-citrulline supplement, but the recommendation comes with a couple suggests: talk to your physician about adding any new supplement to your regimen. If you have any pre-existing conditions, you take herbal supplements, or your have a prescription medication, you need to know if you are taking the correct dose. You also need to be aware of possible drug interactions.

L-Citrulline Safety and Dosage

What is the recommended dose for L-citrulline. The answer is not as cut and dry. In fact, clear dosing of l-citrulline is yet to be established. When researchers study l-citrulline, they do so with intent and doe specific conditions. Just because one study suggests a dose for erectile dysfunction, it doesn’t mean that is the right dose of l-citrulline to build muscle.

How to Take L-Citrulline

Recently, Men’s Fitness looked at suggested intake recommendations for l-citrulline. The author provides readers with a snapshot of a study that stated 5.2 grams of both l-citrulline and l-arginine. Studies in both the British Journal of Nutrition and British Journal of Sports Medicine made attempts to establish a directed dosage for l-citrulline. A 2008 study in the British Journal of Nutrition found that doses between 2 grams and 15 grams is safe and generally tolerated by the body. The British Journal of Sports Nutrition published a 2002 study about l-citrulline and its effect of aerobic energy. The study discovered that as much as 6 grams of citrulline per day improved healthy muscle metabolism when using supplements.

It is important to ALWAYS read the labels on your supplements. Many supplements are mixed with other ingredients. You must know what you are ingesting and the effects it may have on your body or current medications.

Drug Interactions

As with any other supplement, you must consult your pharmacist or physician about possible drug interactions.

One notable concern with taking l-citrulline is the effect it can have on medications you may already be taking for ED (erectile dysfunction). Early studies have found that l-citrulline may improve blood flow to the penis. Of course, I don’t have to explain what happens when you get a little more pumping down there. Let’s just say your muscles aren’t the only thing getting big and hard. What’s good for the heart is good for the erection.

Before you get to eh hem “excited,” I offer a word of caution: watch your meds. If you already suffer from erectile dysfunction, you probably take a supplement or medication already to control your symptoms. You may want to make the switch to a natural supplement like l-citrulline for sexual dysfunction, but don’t do it without professional support and guidance. Always talk to your doctor to see if l-citrulline interacts with any phosphodiesterase type 5 inhibitors you may already be taking. Erectile dysfunction medications include Viagra, Cialis, and Levitra.

Side Effects of L-Citrulline

No considerable side effects have been studied or observed in users who take l-citrulline. You might experience GI discomfort if you take too much l-citrulline or you don’t balance l-citrulline correctly with l-arginine. More l-arginine than l-citrulline can make you nauseous and bloated.

If you are pregnant or plan to become pregnant, don’t take supplements such as l-citrulline without first consulting your doctor. Not enough research has been done on the supplement in such populations to see if there are any side effects or adverse reactions to l-citrulline.

To find learn more about optimal body health and the ways you can improve performance, check out the blog. Share your stories of success wit us. Find Vaxxen Labs on Facebook, Pinterest, and Instagram. We want to see how supplements like l-citrulline are improving your performance and physique. We also want to hear how your cycle is going.


  1. Amino Acid
    PubMed Health Glossary
    (Source: NIH – National Institute of General Medical Sciences)
  2. Protein and Amino Acids
    National Research Council (US) Subcommittee on the Tenth Edition of the Recommended Dietary Allowances.
    Washington (DC): National Academies Press (US); 1989.
  3. Essential amino acids are primarily responsible for the amino acid stimulation of muscle protein anabolism in healthy elderly adults
    Elena Volpi, Hisamine Kobayashi, Melinda Sheffield-Moore, Bettina Mittendorfer, and Robert R Wolfe Am J Clin Nutr. Author manuscript; available in PMC 2011 Oct 13.
    Published in final edited form as: Am J Clin Nutr. 2003 Aug; 78(2): 250–258. doi: [10.1093/ajcn/78.2.250]
  4. Dietary Protein Intake and Human Health.
    Wu G1. Food Funct. 2016 Mar;7(3):1251-65. doi: 10.1039/c5fo01530h.
  5. Macronutrient Considerations for the Sport of Bodybuilding.
    Lambert CP1, Frank LL, Evans WJ. Sports Med. 2004;34(5):317-27.
  6. Influence of L-Citrulline and Watermelon Supplementation on Vascular Function and Exercise Performance.
    Figueroa A1, Wong A, Jaime SJ, Gonzales JU. Curr Opin Clin Nutr Metab Care. 2017 Jan;20(1):92-98.
Leave a Reply

Your email address will not be published.