Di-Citrulline Malate
Mechanism of Action +
### Pharmacokinetics and Hepatic Bypass Unlike oral L-arginine, which is subject to extensive first-pass metabolism by the enzyme arginase in the liver and intestines, L-citrulline largely bypasses hepatic metabolism. Upon ingestion, citrulline is absorbed in the enterocytes and transported to the kidneys. In the renal proximal tubules, it is converted into L-arginine through a two-step enzymatic process involving argininosuccinate synthetase (which condenses citrulline and aspartate to form argininosuccinate) and argininosuccinate lyase (which cleaves argininosuccinate into arginine and fumarate). This makes citrulline a significantly more effective and bioavailable precursor for elevating systemic plasma arginine levels than arginine itself.
### Nitric Oxide Synthase (eNOS) Activation The newly synthesized L-arginine is released into systemic circulation where it serves as the primary substrate for endothelial nitric oxide synthase (eNOS). eNOS catalyzes the oxidation of L-arginine to produce nitric oxide (NO) and L-citrulline (which can be recycled). Nitric oxide is a potent signaling molecule that diffuses into adjacent smooth muscle cells, activating soluble guanylyl cyclase (sGC). This increases intracellular cyclic guanosine monophosphate (cGMP), leading to the relaxation of smooth muscle and subsequent vasodilation. This widening of blood vessels enhances blood flow, oxygen delivery, and nutrient transport to working skeletal muscles, creating the physiological 'pump' experienced during resistance training.
### The Role of Malic Acid (Malate) Di-Citrulline Malate is typically bonded in a 2:1 ratio (two molecules of L-citrulline to one molecule of malic acid). Malate is a key intermediate in the tricarboxylic acid (TCA) cycle, also known as the Krebs cycle. By providing exogenous malate, supplementation may anaplerotically replenish TCA cycle intermediates, thereby supporting aerobic ATP production. Furthermore, malate facilitates the malate-aspartate shuttle, which is crucial for transferring reducing equivalents (NADH) from the cytosol into the mitochondria. This process helps maintain the NAD+/NADH ratio required for continuous glycolysis, potentially delaying the accumulation of lactic acid and reducing muscular fatigue during high-intensity anaerobic exercise.
### Ammonia Clearance and the Urea Cycle L-citrulline is an integral component of the urea cycle, a hepatic pathway responsible for detoxifying ammonia—a metabolic byproduct of amino acid catabolism and intense muscular exertion. Elevated ammonia levels can cross the blood-brain barrier, contributing to central fatigue, and can also interfere with oxidative metabolism in the muscle. By increasing the pool of urea cycle intermediates, citrulline supplementation enhances the clearance of ammonia and blood lactate, further contributing to its anti-fatigue properties.
What does citrulline malate do for your body? +
Is it safe to take citrulline malate daily? +
Does L-citrulline lower cholesterol? +
Does L-citrulline lower blood sugar? +
What not to take with citrulline malate? +
Does L-citrulline interact with any medications? +
Is citrulline safe for the heart? +
What happens if you take citrulline malate every day? +
How much citrulline malate should I take for a workout? +
What is the difference between L-citrulline and citrulline malate? +
Why is citrulline better than L-arginine? +
Does citrulline malate help with erectile dysfunction? +
Can citrulline reduce muscle soreness? +
Does citrulline improve aerobic exercise like running? +
Should I take citrulline malate on rest days? +
Does citrulline need to be taken with food? +
Are there any side effects of citrulline malate? +
Can women take citrulline malate? +
Everything About Di-Citrulline Malate Article
## The Ultimate Guide to Di-Citrulline Malate
Di-Citrulline Malate is arguably the most reliable, evidence-backed non-stimulant pre-workout ingredient on the market today. Originally discovered in watermelon (the Latin term for watermelon is *Citrullus vulgaris*), this unique compound combines the non-essential amino acid L-citrulline with malic acid. While it doesn't build muscle protein directly, its role in the body is profound: it is a master regulator of blood flow, a tireless scavenger of metabolic waste, and a proven enhancer of muscular endurance.
Whether you are a bodybuilder chasing skin-tearing pumps, a powerlifter looking to squeeze out an extra rep, or someone seeking cardiovascular health benefits, Citrulline Malate has a robust portfolio of clinical data to support its use. Examine.com tracks over 53 references, 46 trials, and 5 meta-analyses on this ingredient, giving it a Grade A rating for elevating plasma arginine.
### The Science of the Pump: How Citrulline Works
To understand why Citrulline Malate is so effective, you have to understand the Nitric Oxide (NO) pathway. For years, the supplement industry sold L-arginine as the ultimate pump ingredient. The logic was sound: L-arginine is the direct precursor to nitric oxide. However, the pharmacokinetics were flawed. When you consume L-arginine orally, it is subjected to the 'first-pass effect.' An enzyme in the liver and intestines called arginase aggressively breaks down L-arginine before it can ever reach your bloodstream.
L-citrulline elegantly bypasses this problem. When you ingest citrulline, it slips past the liver's arginase enzymes untouched. It travels directly to the kidneys, where it is converted into L-arginine. Because of this 'backdoor' mechanism, supplementing with citrulline actually raises blood arginine levels higher and for a longer duration than supplementing with arginine itself.
Once converted, this arginine is released into the bloodstream where endothelial cells use it to synthesize nitric oxide. Nitric oxide signals the smooth muscles around your blood vessels to relax (vasodilation). The result? Wider pipes, massive blood flow to working muscles, enhanced oxygen delivery, and the legendary 'pump.'
### The Malic Acid Advantage
Why take Citrulline Malate instead of pure L-Citrulline? The answer lies in the 'Malate' (malic acid).
In a Citrulline Malate supplement, the amino acid is bonded to malic acid, typically in a 2:1 ratio (two parts citrulline to one part malate). Malic acid is a naturally occurring organic acid that plays a critical role in the Tricarboxylic Acid (TCA) cycle, also known as the Krebs cycle. This is the primary engine of cellular energy (ATP) production in the human body.
During intense exercise, your muscles rapidly burn through ATP and accumulate lactic acid and ammonia, leading to the burning sensation and eventual muscular failure. Malate acts as an anaplerotic agent—meaning it replenishes depleted intermediates in the Krebs cycle. It also facilitates the malate-aspartate shuttle, which helps clear out lactic acid.
When you combine the blood-flow-enhancing properties of Citrulline with the energy-producing, fatigue-delaying properties of Malate, you get a synergistic effect. This is why WebMD notes studies showing that men taking citrulline malate were able to perform 53% more repetitions during weight training compared to a placebo, while also experiencing significantly less muscle soreness two days later.
### Clinical Dosing vs. Industry Reality
The benefits of Citrulline Malate are highly dose-dependent. According to Examine.com and clinical literature, the optimal dose for sports performance is **6,000 to 8,000 mg** taken about one hour before exercise.
However, label literacy is crucial here. Because Citrulline Malate is heavier than pure L-Citrulline, you need more of it to get the same amount of the base amino acid. Specifically, you must take 1.76 grams of citrulline malate to equal 1 gram of L-citrulline.
Unfortunately, the supplement industry is rife with underdosing. Catalog data reveals that some products contain a mere 100mg to 200mg of Citrulline Malate. At these micro-doses, the ingredient is nothing more than 'label dressing'—included solely so the manufacturer can put the name on the bottle, but providing absolutely zero physiological benefit. If your pre-workout doesn't have at least 6,000mg (6 grams) of Citrulline Malate, you are being shortchanged.
### Health Benefits Beyond the Gym
While athletes use it for performance, Citrulline has profound clinical applications for general health:
**Cardiovascular Health and Blood Pressure:** Examine.com assigns a Grade B (Moderate confidence) rating to Citrulline for improving blood pressure. By promoting vasodilation, it reduces the resistance against which the heart must pump. WebMD notes that long-term use has been shown to provide results for those with, or at risk for, heart disease, particularly in lowering blood pressure in individuals with hypertension.
**Erectile Dysfunction (ED):** The mechanism that causes a muscle pump is the exact same mechanism required for an erection: nitric oxide-mediated vasodilation. WebMD highlights that L-citrulline helps boost L-arginine and NO production, which aids in blood vessel relaxation. Studies show it can provide a measurable improvement in mild erectile dysfunction scores, making it a popular natural alternative or adjunct for male sexual health.
**Ammonia Clearance:** Citrulline is a vital component of the urea cycle. When you consume high amounts of protein or engage in brutal workouts, your body produces ammonia as a toxic byproduct. Citrulline helps the liver convert this toxic ammonia into urea, which is safely excreted in urine.
### Safety, Side Effects, and Interactions
Citrulline Malate is generally recognized as highly safe and well-tolerated. It does not need to be taken with meals. However, WebMD notes that some people might experience mild stomach discomfort or heartburn.
The primary safety concerns revolve around drug interactions due to its blood-pressure-lowering effects.
* **PDE5 Inhibitors:** Medications for erectile dysfunction (like Viagra or Cialis) also lower blood pressure by acting on the nitric oxide pathway. Combining these with high doses of Citrulline can cause a dangerous, synergistic drop in blood pressure. * **Antihypertensive Drugs:** If you are on medication for high blood pressure, adding Citrulline could cause your blood pressure to drop too low. * **Surgery:** Because of its effects on blood flow and pressure, WebMD advises stopping Citrulline supplementation at least two weeks before any scheduled surgery.
### The Bottom Line
Di-Citrulline Malate is a powerhouse ingredient. It has 'No effect' on aerobic exercise metrics like VO2 max or blood glucose, but for anaerobic capacity, muscle size, strength, and cardiovascular blood flow, it is top-tier. Ensure you are taking a clinical dose of 6-8 grams, take it 45-60 minutes before you lift, and enjoy the endurance and pumps that follow.