Supplement Face Off: L-Citrulline vs. Citrulline Malate

Supplement Face Off: L-Citrulline vs. Citrulline Malate

When you want to accelerate muscle growth, one of the best ways is to increase your body’s nitric oxide (NO) production while training. NO is a minuscule gas molecule that encourages your blood vessels to relax, allowing a greater flow of blood and nutrients to your working muscles. The immediate benefit is a better muscle pumps and a killer workout. But the more important, long-term benefit is faster recovery and more efficient muscle growth.

The best way to boost NO production is to supplement pure L-citrulline, an amino acid contained in Kaged Muscle products, including Pre-Kaged, In-Kaged, and our standalone fermented Citrulline. While some “experts” claim that other aminos and forms of citrulline work better, here’s more about citrulline and the science that supports why Kaged Muscle relies on the pure L-citrulline form in their products.


Citrulline is a non-essential amino acid that was first isolated from watermelon and was named “citrulline” based on the Latin term for watermelon: Citrullus lanatus. Interestingly, non-essential amino acids, including citrulline, can be made by the human body. But our bodies don’t make citrulline in the quantity that supports ideal muscle growth.

Because citrulline is not a constituent of proteins, dietary proteins are not a direct source of this amino acid for the body, either. That means you don’t get significant amounts of it from the protein foods you consume. So the best way to boost citrulline levels for better muscle growth is to supplement it.

In the body, citrulline is formed in the urea cycle from ornithine and carbamoyl phosphate. The urea cycle is a natural process that rids the body of ammonia, lactic acid, and other harmful compounds, many of which are generated by stress, including intense weight-training sessions. As such, it stands to reason that taking supplemental citrulline enhances the removal of these toxic byproducts (ammonia, lactic acid) that accumulate during exercise.
The ammonia-sequestering effect of citrulline is one of the reasons why people notice less fatigue when they supplement citrulline before and during workouts [1].

Citrulline is also synthesized in intestinal absorptive cells (called enterocytes) from amino acids including proline, arginine, and glutamine. In fact, most of the naturally occurring citrulline in our blood is formed from glutamine conversion through the glutamate to ornithine pathway in enterocytes [2]. Still, the main purpose of this conversion is for basic physiological function. Again, the amount our bodies make isn’t enough to spur maximal muscle growth.
Once citrulline is in your system, your kidneys convert it to arginine (another amino acid). This increased blood-level of arginine boosts NO production. Then this gas promotes vasodilation, which you may witness as increased vascularity, as well as remove metabolic waste from your body.


So if arginine does all that, why not just supplement it instead of citrulline? While your goal is to boost arginine production rather than citrulline itself, it’s interesting that citrulline supplementation is better at boosting arginine levels than is supplementing arginine. That’s because your gut and liver contain enzymes called arginases, which break down and eliminate supplemental arginine. That means citrulline supplementation is more beneficial in elevating blood arginine and nitric oxide (NO) than arginine itself [3]! In fact, a 2006 study demonstrated that acute ingestion of citrulline elevated plasma arginine levels by approximately 227% (within 4 hours of ingestion) compared to only 90% with the equivalent dose of arginine [4].

Contrary to what some supplement gurus tell you, citrulline malate is not the same supplement as pure L-citrulline. In fact, citrulline malate is a blend (usually 1:1) of L-citrulline and malic acid (malate). So, if you take 2 g of a 1:1 blend of citrulline malate, you’re only getting in about 1 g of pure L-citrulline and about 1 g of malic acid.

Malate is found naturally in many sour fruits, such as green apples and sour grapes, and it gives them their tartness. In the body, malate is an intermediate in the Kreb’s cycle (i.e., the citric acid cycle), giving it an important role in ATP (energy) production. It is this property of malate that some capitalize on when promoting citrulline malate as superior to pure L-citrulline. However, malate doesn't appear to be a rate-limiting substrate in the Kreb’s cycle, which is probably why there is a lack of peer-reviewed scientific evidence showing that pre-workout malate supplementation (on its own) results in greater ATP/energy production during exercise.

So, what’s our point? Simply that malate has not been demonstrated by research to provide muscle-building benefits while citrulline itself has. When you “cut” citrulline with malate, you’re getting in less of the supplement that research demonstrates best supports NO production and muscle growth.


Here are some more reasons why you should seek out pure L-citrulline over other forms:

1. In order to know exactly how much L-citrulline you are getting from citrulline malate, you must know and trust the ratio at which it was blended and formulated. This ratio probably will not be disclosed on the label (rendering it the same as a proprietary blend). This leaves you with no idea how much of this blend contains actual citrulline. Remember, it’s the “citrulline” in “citrulline malate” that produces the greatest increases in exercise performance. 

    2. Malate is less expensive than pure citrulline. So, gram-for-gram citrulline malate costs far less to formulate. This is likely why many supplement companies promote the use of citrulline malate over citrulline: It increases profit margins by basically diluting the most expensive (and active) ingredient—L-citrulline. 

    3. There are no human exercise studies that have directly evaluated and compared the performance benefits of supplementing citrulline malate versus pure L-citrulline. In fact, there are no compelling exercise studies showing that malate, on its own, provides any ergogenic effect whatsoever. So, when companies and “experts” make claims that citrulline malate provides greater citrulline-based performance enhancements over pure L-citrulline, they are simply making this up! Think about it, if malate does provide performance benefits, why not just formulate it as a separate ingredient and list exactly how much L-citrulline and malate the product has per serving? Almost no product does that because, to date, malate has no proven benefits for supporting muscle building. 


    At Kaged Muscle, we understand that you want the purest and most efficacious ingredients your money can buy. This is why we use full disclosure labeling, no proprietary blends, and patented ingredients that are backed by real science in our products. When it comes to citrulline supplementation, using pure fermented L-citrulline assures that you are getting every gram of science-backed pump support and fatigue resistance you paid for. This is true for Pre-Kaged, In-Kaged and our stand-alone fermented Citrulline product. 

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