This complete guide explores the benefits and dosages of L-citrulline supplements. Learn about citrulline and citrulline malate and how they can help you reach your goals.
- About the physiological role and benefits of citrulline.
- Who should consider taking a citrulline supplement.
- When to take citrulline malate, and what the recommended dosage is.
- Physiological role of citrulline
- Primary benefits of citrulline (malate) supplementation
- Possible side effects of citrulline supplementation
- Who should or should not use citrulline
- When to take citrulline
- Recommended dosing
- Citrulline Malate FAQs
Citrulline is a nonessential alpha-amino acid that is not coded for by human DNA but is still present in certain proteins and the urea cycle (either as a by-product of arginine oxidation or from reaction of carbamoyl phosphate and ornithine). Citrulline appears to have a variety of synergistic effects with other popular peri-workout supplements, such as branched-chain amino acids (BCAAs).
It is naturally produced in the rind and flesh of watermelon and is gaining ground as a useful ingredient in the field of dietary/sports supplements.
Citrulline plays a variety of physiological roles, but is primarily relegated to augmentation of nitric oxide-dependent signaling. (1) Citrulline is manufactured by a variety of other amino acids in the liver and is an important component of the urea cycle; the urea cycle facilitates the elimination of ammonia and other nitrogenous toxins from the blood (most of which takes place in the liver of mammals). Nitrogen metabolites accrue from digestion, absorption, and metabolism of proteins.
Oral citrulline supplementation has been shown to increase increase plasma arginine concentration and thus enhances production of arginine-derived metabolites (i.e. nitrite, ornithine, creatinine, etc). (2) As aforementioned, this is crucial as synthesis and elimination of urea is necessary for removing toxic nitrogen metabolites from the body. Citrulline works along with citric acid, aspartic acid, and magnesium to improve nitrogen metabolite excretion.
A rare disorder in humans called citrullinemia may cause buildup of ammonia in the blood; this occurs when there is a deficiency of the enzyme necessary to catalyze the [citrulline-arginine] reaction of the urea cycle. Research seems to indicate that zinc supplementation can improve the conversion of citrulline to arginine in the liver and lower blood ammonia levels. (3)
Moreover, since pyridoxine (vitamin B-6) activates transaminases (i.e. enzymes that convert an amino acid to a different amino acid) in the urea cycle, it may be useful to supplement with if there is a suspected malfunction in the liver. As always though, these clinical abnormalities should be addressed by your personal care physician.
Citrulline supplementation, generally in malic acid salt form, has been garnering attention in the realm of physical performance enhancement and its benefits are numerous. Aside from being a necessary biomolecule in the urea cycle, citrulline may enhance health and performance by:
- Increasing intracellular NO production which is a positive regulator of vasodilation and blood flow (2)
- Enhancing the utilization of essential amino acids during exercise (1)
- Improving recovery time after exercise by attenuating delayed-onset muscle soreness (4)
- Enhancing elimination of toxic nitrogen metabolites (2)
- Increasing growth hormone levels to a higher degree in individuals after resistance training as compared to a placebo group (1)
- Reducing/inhibiting the increase in plasma insulin levels that usually arises after high-intensity exercise (3)
Thankfully, citrulline is a rather safe compound and the side effects are limited and generally benign. The most prevalent side effect for people supplementing with citrulline tends to be gastrointestinal distress, but this can be ameliorated by taking citrulline on an empty stomach.
- Physique competitors
- Athletes involved in aerobic and/or anaerobic events/sports
- Those looking for increased blood flow and “pumps” during training
- Avoid use if you have citrullinemia as this would only compound the issue
- Optimally, citrulline should be ingested about 15-30 minutes before training.
- May also take citrulline during and/or after training if desired
- Start with a once-daily dose of 6-7g
- If desired, dose may be increased to 15-20g split into multiple doses throughout the day
A: Most of the citrulline content in watermelons is found in the rind of the fruit, therefore it is not very practical to obtain the doses of citrulline suggested herein through diet.
A: This is actually another nice “benefit” of citrulline supplementation as the increase in nitric oxide will relax blood vessels and increase blood flow (which can help improve erections, among other things).
A: This is likely due to the rare occurrence of stomach distress that may occur after ingesting citrulline; it is fine to take citrulline at meal times if you tolerate it well.
A: This will vary for most individuals, but acute effects such as endotoxin removal will happen after the first dose; more latent benefits such as strength increases and decreased DOMS may take a few weeks to notice.