The Need for L-Citrulline!


L-CitrullineWhat’s a picture of a watermelon have to do with L-citrulline? I’ll answer that in a little bit. Let’s first start with nitric oxide and L-arginine.

So much of the buzz about improved nitric oxide production centers on L-arginine. Unfortunately, many forget about L-citrulline. While L-arginine is the main amino acid used by the endothelial cells to create nitric oxide, some feel that L-citrulline is actually more important for long term nitric oxide production and improved cardiovascular health.

I bring this to your attention because I’m in the process of developing an educational module designed to help those with sickle cell anemia. One complication for those who have sickle cell anemia is the negative effects of the enzyme arginase.

Arginase is an enzyme located primarily in the liver. It is used to help complete the fifth and final step in the urea cycle. This urea cycle helps your body dispose of harmful ammonia. It is also found in the kidneys and prostate. Some research indicates that arginase is located in the mitochondria of most cells. The mitochondria are the portions of your cells that produce the bulk of your energy.

Arginase and Circulation!

While arginase has a useful role in the body it can also play a negative role in circulation. Why? Because arginase destroys L-arginine. Your endothelial cells convert the amino acid L-arginine to nitric oxide. Nitric oxide is the master signaling molecule of your cardiovascular system. It regulates blood pressure, helps to improve blood flow, keeps blood platelet cells from sticking together, prevents LDL cholesterol from adhering to the vascular walls and is a factor in a host of other very important health issues.

Everyone carries arginase in their bloodstream which can have some affect on lowering nitric oxide production. This is a bigger problem in the African American community especially for those with sickle cell disease. Thankfully, your body has an alternative pathway that enables the endothelial cells to create nitric oxide. It’s through the amino acid L-citrulline.

How Important is L-citrulline?

Well, let me introduce you to Dr. Louis J. Ignarro to answer that question. Dr. Ignarro is the 1998 Nobel Laureate in Medicine. He, and two other American researchers, were awarded the Nobel Prize for their discovery of how the endothelial cells create nitric oxide (NO) from the essential amino acid L-arginine. In Dr. Ignarro’s book, NO More Heart Disease, he makes the following statement:

My research shows that if you take only L-arginine, which is the dominant producer of NO, you will not receive the maximum benefit. I have found that by including the synergistic partner L-citrulline, your ability to boost NO production is greatly enhanced over the effects of L-arginine alone.”

Your endothelial cells use an alternative pathway to convert L-citrulline to nitric oxide. This helps bypass the arginase enzyme so that good nitric oxide production can be restored. Plus, L-citrulline provides a 24 to 36 hour window for enhanced nitric oxide production whereas L-arginine by itself usually only has a 30 minute to 2 hour window of enhanced nitric oxide production.

This means that L-arginine can help start the process of nitric oxide production to improve circulation. Then the L-citrulline can take over to continue the improved nitric oxide production helping to maintain improved circulation.

Dr. Ignarro goes on to say, “Any supplement program that does not contain L-citrulline and antioxidants to augment the L-arginine – and most on the market do not – is missing out on a major piece of the potential of NO to improve your cardiovascular health.” This statement and the information I shared so far leads to two important questions:

What foods contain L-arginine and L-citrulline?

Is it better to get these critical amino acids through food or supplementation?

I’m preparing two new videos to help answers these questions and to visibly show you the best and most effective method for enhanced nitric oxide production. But the first question brings me back to the picture of the watermelon.

The Watermelon!

In March of 2007 there was a study published in the Journal of Nutrition. The article was entitled “Watermelon consumption increases plasma arginine concentrations in adults.” This article created a significant buzz on the internet because L-arginine is needed to produce nitric oxide which is needed for a male erection. In the media, watermelon became the new and natural Viagra. While this study didn’t examine the effects on male anatomy it did provide some very important information confirming the body’s ability to convert L-citrulline to L-arginine to improve nitric oxide production.

The study subjects were given either 780 grams (equivalent of 1 g of citrulline) of watermelon or 1560 grams (equivalent of 2 g of citrulline) of watermelon. The study lasted three weeks. At the end of the study the 780 grams of watermelon group saw a 12% increase in fasting plasma arginine concentrations. The 1560 grams of watermelon group saw a 22% increase when compared to a control group that received no watermelon.

This clearly shows that your body has an alternative pathway for creating the necessary L-arginine from the amino acid L-citrulline.

So, is eating watermelon an effective way to improve nitric oxide production?

Well, the 780 grams of watermelon is equal to 1.72 pounds. The 1560 grams of watermelon is equal to 3.43 pounds. That’s a lot of watermelon to eat even if you like it. Plus, it includes the rind, that thick green outer covering of the watermelon. I believe there’s an easier way to achieve an even better result. I’ll show you in one of my upcoming videos.

Together we can work to save a million lives!

Dan Hammer

Dan Hammer has a background in biology, chemistry and exercise physiology. He used to run one of the largest health club operations in the Chicagoland area and has been helping people with their wellness issues for more than 25 years.
The information contained in this article is for general information purposes only and never as a substitute for professional medical advice or medical exam. The information contained in this article about L-Citrulline has not been evaluated by the Food and Drug Administration and should not be used to diagnose, treat, cure or prevent any disease without the supervision of a qualified medical doctor.

13 comments to The Need for L-Citrulline!

  • [...] foods for L-citrulline. Watermelon is your one and only good food choice. You can read my article, “The Need for L-Citrulline!” to get more information on this [...]

  • jared

    I’m looking for a scientific reference to the claim, “L-citrulline provides a 24 to 36 hour window for enhanced nitric oxide production whereas L-arginine by itself usually only has a 30 minute to 2 hour window of enhanced nitric oxide production.”
    There is no question that l-citrulline is a precursor to l-arginine and that it enhances NO production, but I can’t find information about the 24-36 hour time frame.

  • Hi Jared – Thank you for your post about the time frame for the L-arginine and L-citrulline as it applies to improved nitric oxide production. I’ll provide you with two references although you might not consider them “scientific reference.” The first would be Dr. Louis J. Ignarro’s national bestseller NO More Heart Disease. Pages 73-75 and 93-95 talk about this synergistic effect of combining L-arginine with L-citrulline to extend the body’s ability to enhance its production of nitric oxide over a much longer period of time. However, Dr. Ignarro does not quantify the time period like I did.

    My statement of the “24 to 36 hour window” versus the “30 minutes to 2 hour window” comes from an indepth interview of Dr. J. Joseph Prendergast who is the product formulator of ProArgi-9 Plus. Here is a link to the interview:
    I didn’t time it but it is about 12-14 minutes into the interview as Dr. Prendergast is talking about the synergistic relationship between L-arginine and L-citrulline in nitric oxide production. You may not feel that this is “scientific reference” but Dr. Prendergast in an international authority on L-arginine therapy. He has been using it in his practice since 1991. His track record in helping over 7,000 patients is amazing. He has had less than 1% hospital admissions for cardiovascular concerns over 15 plus years. This is even more amazing when you realize that 80% of his patients are diabetics who typically have cardiovascular issues.

    Because of his amazing health record the American Diabetic Association awarded Dr. Prendergast the 2008 Father of the Year Award. So, I put a lot of stock in what Dr. Prendergast has to say since he has helped thousands of people personally and ten of thousands of people world wide.

    I hope this helps provide you with your need for additonal information.


  • Paul Kanyer

    Solgar has come out with a product that combines Arginine and Orinithine. Does this product also have citruline in it. If it doesn’t, does the orinithine act a seffectively to time release the argine?

  • Hi Paul – Thank you for your question about the product from Solgar. I’ve looked at this product and done some research to answer your questions. First off let me say that I’m not going to disrespect Solgar as a company. They make good products. But, if you are looking to use this product to improve nitric oxide production then I think there are better products in the marketplace.

    From what I could learn about the Solgar L-Arginine 500 mg / L-Ornithine 250 mg there is no L-citrulline in the product. In answer to your second question, “does the orinithine act as effectively to time release the argine?” my answer would be NO! Here is why:

    1.L-ornithine is one of the products of the action of the enzyme arginase on L-arginine, creating urea. The enzyme arginase destroys L-arginine to reduce the endothelial cells’ ability to produce nitric oxide. Thus, L-ornithine is important for the disposal of excess nitrogen but it is also involved in the process of reducing L-arginine and your endothelial cells’ ability to create nitric oxide. Can your body use L-ornithine to create L-arginine? Yes, but it’s usually in specific situations like wound-healing and auto immune stresses.

    2.Most vascular researchers will tell you that L-citrulline is more important for the creation of nitric oxide then L-ornithine. The reason why is that L-citrulline can bypass the negative effects of the enzyme arginase to provide the endothelial cells with a valuable alternative pathway for changing L-citrulline into L-arginine to convert it into nitric oxide. This is also important because L-citrulline provides a long term benefit in the improve production of nitric oxide to help repair the endothelial cells and the cardiovascular system.

    3.I’ve never seen any recommendation from Dr. Louis Ignarro (the 1998 Nobel Laureate in Medicine) for the inclusion of L-ornithine as a pathway for nitric oxide production and he won the Nobel Prize in this area.

    Here is another factor to consider. To get a therapeutic effect you need to consume 5 grams of pharmaceutical grade L-arginine. The Solgar product contains 500 mg of L-arginine per tablet. Thus, you would need to take 10 tablets. The price for this product is $24.95 to a low of $20.00 online. There are 100 tablets in a bottle. Thus, this bottle is a 10 day supply at a therapeutic level or $60 to $75 per month. It is one of the reasons why I like the ProArgi-9 Plus product. One serving gives you a therapeutic level of both L-arginine and L-citrulline plus all the others heart healthy ingredients it contains. It is more cost effective plus it has proven short and long term clinical data to support its ability to properly repair the endothelial cells that line all of your cardiovascular system to improve their ability to properly product nitric oxide – the master signaling molecule of your cardiovascular system.

    I hope this information helps. Dan

  • peter

    Hi Sir,

    i purchased the book from Dr. Ignarro NO more heart disease.

    i am 29 yrs old and is detected with high BP, as a counter attack battle plan, i learn to adopt all the amino asid and antioxidant supplements explain by Dr. Ignarro in his book. but sadly to say, its hard for me to find L citrulline in my local pharmacy, i am from malaysia, and its hard for me to purchase via internet cause they wont send the item to my country. my question is, is there supplement i can use to replace L Citrulline?

  • Hi Peter,
    Dr. Ignarro’s book is a vitally important book that I recommend to everyone. The need for L-citrulline is very important since it helps to recylce the L-arginine. This recycling process helps the body to go from a 30 minute to 2 hour window of improved nitric oxide production with just L-arginine to a 24 to 36 hour window of improved nitric oxide production when L-citrulline is included. This has huge therapeutic benefits to your cardiovascular system. Unfortunately there is not another supplement that can replace L-citrulline. Hopefully your local pharmacy can work with you to find an L-citrulline supplier.

  • Erny

    Hi Dan. I am 18 years old and just graduated from high school and I am attending college. I was a varsity soccer player and captain of the varsity wrestling team. I understand the importance of exercise and keeping a good diet. However, I have high blood pressure, and although I have limited my diet to simple foods like tuna and a variety of vegetables and fruits, high blood pressure still has the effect of tiring me out before the rest of my friends and making me gasp for air. I’ve tried many things including endurance training but I can’t seem to get over that plateau. But, as I was weight training one day, I met a friend who seemed to do the same weights as me but many more repetitions and he was about 20 lbs lighter and 5 inches shorter. I asked him how he did it, and he told me he was using “NO Explode” a supplement marketed in many food & drug stores. I researched how it worked and learned of the NO gas and how L-arginine and L-citrulline helped. Although I am against unnatural supplements, I couldn’t help coming across your article and videos which state that it improves your cardiovascular system by alleviating blood pressure and opening arteries.
    So I was wondering if L-argenine and L-citrulline could be used to produce NO and to improve exercise and athletic ability for someone as young as me.
    Also, my mom is overweight and has high blood pressure and is under serious stress from work. She has been hospitalized a couple times for risk of a stroke. I was also wondering of argenine and citrulline would help her in re-establishing her blood pressure and giving her more energy to exercise. Because I believe that if I help my mom exercise she will lose some weight and become healthier.
    Thank you

  • Hi and thank you for your questions about using L-Arginine and L-Citrulline to create Nitric Oxide to improve your workouts. These are natural supplements, at least the ones used in ProArgi-9 Plus that I promote on my website. To help you better understand the science of how to heal and nourish your endothelium for improved nitric oxide production and how that can improve your circulation, I’ve two links for you to review.

    The first link will help you understand how these two amino acids, at proper therapeutic levels, will help you with athletic training, performance, and recovery. While this article and videos are directed towards competitive cycling, the information directly applies to any form of exercise and training:

    The second link will help you understand how these two amino acids and nitric oxide production directly impacts blood pressure. Especially for those like yourself and your mom. Here is the link:

    I’ve also include one final link for a new video in which I help people understand how the ProArgi-9 Plus can be properly used for weigth management and improved energy. Here is the link:

    I hope this information helps both you and your mom. I’ve many satisfied customers who are both athletes and non-athletic. Please feel free to call me at 630-936-8079 or email me if you have any additional questions. Dan

  • John

    Hi! Dan

    Please advise. There is a product by V-extreme called Citruaid. They claim to have the Citru-line that’s been spoken about.

    Can you advise on the integrity of this product?

  • Hi John,

    Thank you for the question about Citruaid. I’ve checked out their website and information. They seem to be a legitimate company with a product that is completely focused on L-citrulline. As you can tell by my article, L-citrulline is a vital ingredient in the production of Nitric Oxide. And, it is difficult to obtain this amino acid at health food stores. At the time of this response to your question, even major nutritional supplement stores like Whole Foods don’t even care this amino acid as a stand alone product.

    Pricing seems to be reasonable.

    My question to you is what is your purpose for taking this stand alone ingredient? If you looking to improve energy then you should see some benefits from this single ingredient. If you’re wanting to improve your cardiovascular health then you need to consider additional ingredients that can have a synergistic effect like L-arginine, Vitamin D3, Vitamin K2, Folic Acid, Pomegranate Concentrate, Red Wine Extract. These ingredients will help the endothelium to more effectively produce Nitric Oxide.

    Since Nitric Oxide is the master signaling molecule of your cardiovascular system, it will help to improve blood flow. It will also help to repair damage done to the endothelium. All of this enhances the health of the cardiovascular system, which then helps all your tissues and organs to function better by delivering needed nutrients and more effectively removing waste products. I personally feel the best L-arginine / L-citrulline complexer in the marketplace today is ProArgi-9 Plus from Synergy WorldWide. This product has clinic application with remarkable results for the cardiovascular system.


  • Phil

    In what ratio should arginine and citrulline br combined?

  • Hi Phil! Thank you for a great question. If you look at the research of the 1998 Nobel Laureate in Medicine Dr. Louis J. Ignarro then your are looking at the following amounts: 4-6 grams of L-arginine and 200 to 1000 mg of L-citrulline. My recommendation from experience in working with people would be 5 grams of L-arginine and at least 250 mg of L-citrulline. Please note that 1 gram is the equivalent of 1000 mg. This would mean 5000 mg of L-arginine to 250 mg of L-citrulline or a 20 to 1 ratio. I hope this helps. Dan

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