L–Citrulline is an amino acid that has been found to play an important role in nitric oxide (NO) metabolism and regulation. L-Citrulline is converted to L-Arginine in the body, leading to increases in both L-Arginine and nitric oxide. Increased production of nitric oxide promotes vascular dilation, which helps support normal oxygen and blood circulation throughout the body.
The pharmacokinetic advantage of L-Citrulline is that it is not subject to any elimination by the liver prior to entering the bloodstream. Conversely, L-Arginine is subject to extensive elimination by the gut wall and liver. (26)
The majority of L-Citrulline is converted to L-Arginine in the kidney. (3)
Once in circulation, L-Arginine is readily converted into L-Citrulline and nitric oxide, which in turn serves as an L-Arginine precursor (see figure below). (10)
* Citrulline Malate is mixed 1:1 (Malic Acid + L-Citrulline). Basically, the L-Citrulline is cut in half!
** Most brands use Citrulline Malate 1:1 ratio due to cost (cheap) – 50% less per kg than pure L-Citrulline.
Other Ingredients: None
As I travel the country, I lecture on the topic of the benefit of L-Citrulline and the role of nitric oxide (NO) within the human body. It is amazing how many medical doctors and professionals are blown away with the research supporting the role of citrulline to help support optimal nitric oxide levels. It was in 1998 that the researchers that discovered the effects of nitric oxide won the Nobel Prize. They received the accolades of the President of the American Heart Association in 1998 when he proclaimed:
"The discovery of NO and its function is one of the most important
in the history of cardiovascular medicine.”
Beating the NO Challenge
Nitric oxide is a gas molecule, not to be confused with nitrous oxide (laughing gas). It only has a half-life within the body of three to five seconds. This means that the moment NO is made it starts degrading. Bottom line, if you don’t have a constant supply of raw ingredients to rebuild your NO, you will fall short to gleaning its full benefits. To compound the NO challenge is the fact that as we get older our innate ability to make this critical substance drops, from as early as our 20s and steadily dropping that point onwards unless we take charge and do something about it. Clinically I have seen many of my patients by age 40 as low as the 50% level of optimal, and believe these drops don’t happen overnight. The consequence is that one or more the body functions below are impacted with the decreased NO, remembering we are not just looking to limp along and survive, we are looking to THRIVE!
Test Don’t Guess
In my clinical practice I routinely test my patients’ nitric oxide levels. The NO molecule that helped the researchers win the Nobel Prize is definitely worth testing. At the American Heart Association, the president stated in 1998 that NO is one of the most important discoveries of cardiovascular medicine. Let’s think about that for a moment. Nitric oxide helps control blood pressure, enhances blood flow to the heart, brain, muscles, and entire body. NO is involved in immune function, respiratory performance, sexual performance, mental capacity, blood pressure, and so much more. I can tell you that I test my nitric oxide levels routinely, not only before I work out, but a few times a week, which, in my opinion, is on the same list as checking my pulse, blood pressure, blood sugar, and pH of my body. These are all data points essential for true wellness and peak performance. Think of each day as a race to the finish line. If you were to race a performance car (your body) you would check the oil pressure, fuel tank, tire pressure, etc. Unlike a car, you can’t replace your body; your body is the ultimate and largest investment you can ever make.
Clinical Presentations of Low Nitric Oxide
I routinely see patients that aren’t eating sufficient veggies, have excess stress, work out hard, have a high sugar diet, are overweight, aging, and have high blood pressure, which are among several saboteurs to optimized NO levels.
Many conditions I have seen in clinical practice over the last 20 years have been associated at least in part with lower NO, including mental fog, high blood pressure, suboptimal muscle recovery, inflammatory dysregulation, decreased sexual performance, and the list goes on.
When we ask our bodies to perform athletically we all know our tissues demand abundant oxygen, blood supply, and fuel. How do these “exercise essentials” get to your muscles and target tissues? Through the 60,000 plus miles of blood vessels that irrigate your body.
Now let’s make a comparison of your blood vessels and a multi-lane highway. If you are stuck in rush hour, do you want to be on a two-lane freeway or a six-lane freeway with the same number of cars? The answer is simple—you want more room to maneuver and get to your destination. Likewise, NO helps vasodilate your blood vessels (expand your superhighway) and get the “exercise essentials” delivered as promised and demanded.
So picture this, you are healthy, fit and looking to get the most out of your latest physical venture, yet due to stress you are all clamped down, in the proverbial “Saber-Toothed Tiger Mode”, and your blood vessels aren’t dilated like they could be. Thus your protein rich meals, carbs, and BCAA, carnitine, glutamine, etc. are now stuck in rush hour, rather than getting to the muscles that are screaming for fuel. Well, you get the idea of how Kaged Muscle L-Citrulline, a high-quality bioavailable citrulline that fuels nitric oxide levels, can put you in the driver’s seat.
Clinical findings have pointed to the ability for sustained healthy NO levels to have a side benefit in many to lessen fatigue and help feel calmer and more focused. Instead of making this a medical claim, let’s actually think about it. An individual gets their nitric oxide levels in the “sweet zone” thus they have better blood supply throughout their entire body, their trillions of cells are nurtured better, toxins are better able to leave the body due to better blood flow, muscles are able to breath and recuperate better than in a low NO state. Thus is it no wonder that a person feels better. Isn’t it great when common sense and science meet on the same page?!
A Look at Scientific Studies
Any athlete knows blood supply is foundational for performance and nutrient delivery when working out. Yet we know other parts of the body need great blood supply as well, for instance for erectile performance.
A 2011 study in the Journal of Urology supported the quantifiable benefits of citrulline and performance. 1
To test the efficacy and safety of oral L-citrulline supplementation in improving erection hardness in patients with mild erectile dysfunction (ED). L-arginine supplementation improves nitric oxide-mediated vasodilation and endothelial function; however, oral administration has been hampered by extensive presystemic metabolism. In contrast, L-citrulline escapes presystemic metabolism and is converted to L-arginine, thus setting the rationale for oral L-citrulline supplementation as a donor for the L-arginine/nitric oxide pathway of penile erection.
In the present single-blind study, men with mild ED (erection hardness score of 3) received a placebo for 1 month and L-citrulline, 1.5 g/d, for another month. The erection hardness score, number of intercourses per month, treatment satisfaction, and adverse events were recorded.
Although less effective than phosphodiesterase type-5 enzyme inhibitors (Erectile Drugs), at least in the short term, L-citrulline supplementation has been proved to be safe and psychologically well accepted by patients. Its role as an alternative treatment for mild to moderate ED, particularly in patients with a psychological fear of phosphodiesterase type-5 enzyme inhibitors, deserves further research.
Watermelon Juice to the Rescue
Picture this: go to the store and pick up a cart full of watermelons for the week and juice one per day. Sure, it is messy, lots of work, and is definitely going to cost an arm and leg; yet look at the clinical findings in this 2013 article. P.S. I find using high quality, bioavailable vegetable-derived citrulline powder a whole lot more reliable and affordable. That’s just my personal bias.*
*Remember not all supplements are created equal. Just because it says “X” on the bottle doesn’t mean “X” is getting delivered to your cells. This concept is what I have coined “The Real Nutritional X Factor.”
L-Citrulline is an excellent candidate to reduce muscle soreness, and watermelon is a fruit rich in this amino acid. This study investigated the potential of watermelon juice as a functional drink for athletes.
An in vitro study of intestinal absorption of l-citrulline in Caco-2 cells was performed using unpasteurized (NW), pasteurized (80 °C for 40 s) watermelon juice (PW) and, as control, a standard of l-citrulline.
L-citrulline bioavailability was greater when it was contained in a matrix of watermelon and when no heat treatment was applied. In the in vivo experiment (maximum effort test in a cycloergometer), seven athletes were supplied with 500 mL of natural watermelon juice (1.17 g of l-citrulline), enriched watermelon juice (4.83 g of l-citrulline plus 1.17 g from watermelon), and placebo. Both watermelon juices helped to reduce the recovery heart rate and muscle soreness after 24 h. 2
Dosing and Targeting Your NO Goals
When using citrulline, look to fuel your body with a pure pharmaceutical grade derived from a vegetable fermented source. Remember we each only have one body for a lifetime, so making sure you make the right choice is essential. I tell my patients to hold citrulline in their mouth and swish it around and not to drink other liquids for about 10 to 15 minutes. This allows the normal friendly bacteria in the mouth to begin forming nitric oxide giving your body a head start in ramping up its ever fleeting NO stores.
1.Cormio L et al., Oral L-citrulline supplementation improves erection hardness in men with mild erectile dysfunction. Urology. 2011 Jan;77(1):119-22
2.Tarazona-Díaz MP1 et al., Watermelon juice: potential functional drink for sore muscle relief in athletes. J Agric Food Chem. 2013 Aug 7;61(31):7522-8