Best L-Citrulline Supplement

If you're among the nearly 50% of Americans trying to lose weight and get in shape, you've likely considered pre-workout supplements. Thousands of brands on the market promise everything from bulking you up to burning fat and boosting metabolism. But which ones work? And how do they work?

L-citrulline and citrulline malate supplements enhance athletic performance by boosting the body's nitrous oxide production, increasing blood flow, and providing endurance and strength for deeper, more strenuous workouts. These supplements are taken pre-workout and can even benefit heart health, sexual performance, and immunity.

We tested the top brands of citrulline supplements and determined six clear winners in terms of quality, effectiveness, cost, and customer service.

If you don't have time to read our complete guide, glance over our top picks below.

We considered four primary criteria to evaluate our top citrulline supplements: quality, cost, safety, and customer experience. Read our descriptions below to help you choose the right supplement for you.

Quality

Winner: Transparent Labs

Quality is our top priority when testing products. How well-manufactured is the supplement? Is the product effective and worth buying? It's a rarity when our winner for quality also beats out the competition in terms of cost, but that's precisely what Transparent Labs has done with its L-Citrulline Fermented powder.

We admire Transparent Labs as a company based on its commitment to providing scientifically backed ingredients and clearly labeling ingredient amounts on all its products. L-Citrulline Fermented is no different in this regard. It provides 2,000mg of high-quality fermented L-citrulline in every serving — with no fillers, additives, flavorings, or colorings.

Topping off its many attributes, Transparent Labs stands by the quality of its products, providing a 60-day, 100% money-back guarantee on everything it sells. If you're not completely satisfied with L-Citrulline Fermented, simply contact customer service for a full refund.

Cost

Winner: NOW Sports

Cost is an essential consideration for everything we purchase because we want to make sure we’re buying the best product available at the best cost. This includes the product’s price, value, and any offers for deeper discounts provided by the company.

NOW Sports L-Citrulline 1200mg comes in a tablet formula that costs just $0.45 per serving. It provides an effective dosage in a vegan, keto-friendly, gluten-free, and non-GMO tablet that's easy to carry and take on the go. NOW Sports also provides additional savings options when you buy bundles or opt-in to the auto-delivery subscription service. However, you can buy NOW Sports products from many local retailers, saving you shipping costs. If you order from the manufacturer, shipping is free on orders over $50.

Safety

Winner: NOW Sports

We all want to know if the product we're considering is safe, and it's essential to keep in mind that dietary supplements are regulated differently than food or drugs by the FDA. When testing supplements, we look at several factors, including:

• Where it's manufactured
• If the manufacturer is cGMP-certified (meaning it follows Current Good Manufacturing Practice regulations)
• If the company produces known allergens at the same facility
• If the product has undergone third-party testing
• Whether the product is certified by official sports organizations for safety and purity

Answering these questions leads us to find the safest products available. And yet again, in this category, we chose NOW Sports L-Citrulline 1200mg as our winner based on its cGMP and Informed Sports certifications and third-party testing.

Customer experience

Winner: Jacked Factory

Customer experience is an important factor when choosing a new product or continuing with a product you’ve already tried. If you're investing money in a supplement that doesn't work for you, your risk is significantly reduced when you purchase a product with a customer satisfaction guarantee. This level of protection also gives you a sense that the company truly believes in what it's selling.

Jacked Factory is our winner in this category because they provide a 90-day money-back guarantee. You can also quickly contact representatives by phone, email, or live chat. In our interactions with customer service representatives, they offered quick and helpful responses to our queries. The only downside is the lack of free shipping for subscription or bulk orders, which we hope Jacked Factory introduces soon.

The chart below shows how our top recommendations compare in terms of cost, transparency, ingredients, safety, and more. Your product choice depends on your lifestyle, budget, and dietary needs.

These price comparisons are based on single purchases of each product and do not account for subscription plans or bulk purchases, which can often earn significant savings.

L-citrulline (or just citrulline) is a nonessential amino acid that the kidneys transform into L-arginine and nitric oxide in the body. These compounds benefit heart and blood vessel health and may boost the immune system.

One of the primary reasons people take citrulline supplements is for boosted endurance during intense workouts. Others take them to help lower blood pressure or ease symptoms of erectile dysfunction.

L-citrulline naturally occurs in foods, mainly watermelon, and it has no reported side effects. Some of the benefits you'll likely encounter from taking a citrulline supplement include:

• Reduced hypertension
• Improved sexual function
• Reduced intestinal problems
• Improved muscle protein levels
• Greater endurance in the gym
• Reduced fatigue
• Reduced post-workout soreness

L-citrulline (CIT) is an organic nonessential amino acid primarily derived from watermelons. It is also naturally produced in the body through endogenous synthesis in the liver and intestines. It is rarely attained from a regular diet (unless you live on a watermelon farm).

Citrulline's primary functions in the body are helping eliminate harmful substances like ammonia through the urine and promoting nitrous oxide production and vasodilation.

Taking a single dose of CIT is unlikely to have any significant effect. Still, studies examining longer-term use have demonstrated that supplementation may reduce systolic blood pressure at doses of up to six grams per day. For individuals at risk of heart disease and hypertension, supplementing citrulline may help prevent the need for medications down the line.

How do citrulline supplements aid athletic performance? By promoting nitric oxide production in the body, citrulline supplements increase the amount of oxygen in your muscle tissues. Nitric oxide modulates:

• Mitochondrial respiration
• Muscle energy
• Metabolism
• Blood flow

Thus, increasing nitric oxide production can improve endurance and reduce muscle soreness during and after workouts. It can also increase blood flow to the sexual organs, reducing symptoms of erectile dysfunction.

In studies of CIT supplementation in elderly and malnourished rats, researchers showed that those who received supplements gained muscle protein content, especially when supplemented with branched-chain amino acids (leucine, valine, and isoleucine) as well.

How citrulline malate is different

Citrulline malate (CM) combines L-citrulline with DL-malate, a compound derived from apples that may assist in converting food to energy. Developed originally for treating asthenia (abnormal physical weakness and lack of energy), citrulline malate supplements have been shown to improve athletic performance in numerous scientific trials.

This 2016 study showed that CM supplementation improved tennis match-play performance in women subjects, improving power and endurance. A 2015 study showed that CM supplementation improved muscle performance while having no significant impact on lactic acid levels for advanced weightlifters during repeated bouts of lower-body exercise.

L-citrulline and citrulline malate supplements improve athletic performance over time, so you likely won't feel immediately like the Hulk when kicking off a new regimen. They may boost your workouts and endurance, but these stimulant-free products won't give you an immediate rush or cause unwanted jitters.

We found that we had greater ease at the gym when taking the supplements about an hour before workouts. Over time, we extended our training sessions with more intensity. After about two weeks, we noticed a significant change in our endurance levels. And for those interested — the male testers among our panel did experience improved sexual performance in about this time frame as well.

Who shouldn't use citrulline supplements

Individuals taking vasodilators or other medications for high blood pressure should not take citrulline supplements without consulting their doctor. These supplements can lower blood pressure to dangerous levels when combined with certain medications.

Examples of vasodilators include:

• Alprostadil IV
• Corlopam
• Deponit
• Fenoldopam
• Glyceryl trinitrate transdermal
• Hydralazine
• Loniten
• Minitran

Other medications that interact with citrulline supplements include those prescribed for erectile dysfunction, including:

• Tadalafil (Cialis)
• Sildenafil (Revatio, Viagra)
• Vardenafil (Levitra, Staxyn)

Pregnant or nursing individuals should also avoid citrulline supplements. Anyone with a chronic medical condition or those taking medications should talk to their doctor before beginning any new dietary supplement.

L-citrulline and citrulline malate supplements have no known side effects and are safe for most healthy adults. However, these supplements can interact with blood pressure and erectile dysfunction medications (see above: "Who shouldn't take citrulline supplements"). If you are pregnant, nursing, or have any chronic medical condition, you should consult with your doctor before beginning any new supplement.

Best overall and best budget pick (powder)

When shopping for L-citrulline supplements, simplicity is critical. Transparent Labs L-Citrulline Fermented provides 2,000mg of fermented L-citrulline in every scoop with no additives, flavorings, colorings, or sweeteners. While not the best-tasting powder available, it was comparable to the other brands we tested. We also found that mixing it with apple juice or other flavored beverages made it more palatable. Transparent Labs stands behind its products, providing a 60-day 100% money-back guarantee for anyone who's dissatisfied.

Ingredients and benefits

Transparent Labs L-Citrulline Fermented comes in a 0.52-pound tub containing 120 servings. Each 2g scoop provides 2,000mg of fermented L-citrulline and absolutely nothing else.

This supplement promises the following health benefits:

• Increased nitric oxide production and blood flow
• Improved physical performance
• Better endurance
• Improved muscle recovery
• Reduced soreness

Pricing

Transparent Labs currently only offers L-Citrulline Fermented as a one-time purchase with no subscription or bulk savings options. One container with 120 servings costs $14.99, or $0.13 per serving. However, you can save money by purchasing this product as part of Transparent Labs' pre-made bundles.

Buying from the company website ensures you get the 60-day customer satisfaction guarantee, and all orders over $99 include free shipping in the U.S. Shipping for orders under $99 starts at $7.99.

Runner-up overall

Some studies indicate that citrulline malate may be easier to absorb and contribute to more energy production during athletic training than L-citrulline alone (see "How citrulline malate is different" above). And no product provides a more significant dosage than Swolverine. This supplement may be the most expensive single-purchase product on our list, but it wins on effectiveness and flavor. Swolverine also provides clinical studies and research on its website to support its ingredients and efficacy.

Ingredients and benefits

Swolverine provides a synergistic 2:1 ratio of L-citrulline and malic acid in each 5g serving. It includes no additives, flavorings, or colorings.

It provides the following benefits:

• Increases nitric oxide production
• Improves physical strength and power
• Enhances muscle recovery and supports tissue repair
• Provides energy for longer, more intense training sessions
• Reduces muscle fatigue

Pricing

Swolverine offers a subscription membership option for 15% savings on each order. By enrolling in this program, you can drop your price per serving from $0.95 to $0.81.

Domestic shipping for Swolverine products starts at $6.99, although the company provides free shipping on all U.S. orders over $99.

Best budget pick (capsules or tablets) and best for athletes

NOW Sports manufactures a regular strength version of L-Citrulline that contains 750mg per tablet, but we opted for the maximum strength version providing 1,200mg of CIT per serving. This convenient tablet form is easy to take before hitting the gym, and it is a number one choice for those who can't stand the taste or texture of the unflavored powder options. NOW Sports products are also Informed Sport-certified, meaning they are third-party tested for banned substances by the world class sports anti-doping laboratory, LGC.

Ingredients and benefits

Like our other top choices for citrulline supplements, NOW Sports L-Citrulline 1200mg has clear ingredient transparency. It provides 1,200mg of L-citrulline in each tablet, which you can take one to two times daily. It offers the following benefits:

• Boosted nitric oxide production
• Easier, more intense workouts
• Immunity support
• Improved muscle recovery and reduced post-workout soreness

Pricing

NOW Sports products are widely available from pharmacies, big box stores, and online retailers. Ordering directly from the company can earn some savings on bulk purchases, although we had to buy elsewhere due to this product being sold out. When in stock, NOW Sports L-Citrulline 1200mg costs $39.99 for 120 tablets or $0.45 per serving.

Shipping on single orders costs $6.95 in the contiguous U.S. NOW Sports provides free shipping on all orders over $50.

Best for sexual health

BulkSupplements provides a clean and pure powder with 3g of L-citrulline in each dose, which you can take once or twice daily. It is manufactured to cGMP standards and is onsite-lab and third-party tested for safety. This natural nitric oxide booster can increase energy and stamina at the gym and in the bedroom, contributing to sexual wellness and libido.

Ingredients and benefits

BulkSupplements L-Citrulline Powder comes in an unflavored formula. Each 3g scoop contains nothing but L-citrulline to provide the following benefits:

• Improved endurance and strength
• Better muscle repair
• Reduced soreness during and after workouts
• Healthy immunity
• Improved sexual performance

Pricing

BulkSupplements L-Citrulline Powder comes in several sizes, from 100g (3.5oz) to 25kg (55lbs). Buying in greater bulk earns savings, as does the company's Subscribe & Save program. Enrolling in this program will earn 5% off all orders.

Pricing below is for the 100g (3.5oz) package as a single and subscription order.

BulkSupplements provides free shipping in the contiguous U.S. for orders over $59. For orders under this amount, shipping starts at $8.95.

Best for dietary restrictions

Doctor's Best L-Citrulline is a powder formula that may appeal to those with dietary restrictions, as it is vegan and does not contain:

• GMOs
• Gluten
• Soy
• Artificial flavors or colors
• Preservatives

This nitric oxide-promoting supplement supports vascular dilation and blood circulation, and it has the second-lowest price for powder formulas on our list.

Ingredients and benefits

Doctor's Best provides 3g of Kyowa Quality (KQ) L-citrulline in each daily dose and includes no other ingredients. Kyowa Hakko is a high-quality and long-established manufacturer of amino acids and related compounds that stands as a global leader in the nutraceutical and pharmaceutical industries.

Benefits of Doctor's Best L-Citrulline include:

• Improved strength and endurance
• Boosted nitric oxide levels
• Improved muscle repair and reduced soreness
• Better sexual performance
• Healthy immunity

Pricing

Doctor's Best L-Citrulline is widely available from pharmacies, big box stores, and online retailers. While there are no bulk purchase or subscription savings benefits by ordering directly from the manufacturer, you do get the added advantage of free shipping on all orders over $20. A single tub of this supplement contains 66 servings for $20.99, or $0.32 per scoop.

Best customer service

Jacked Factory is a highly rated and respected brand manufacturing several supplements aimed at weightlifters, athletes, and everyday people looking to improve their physical performance in the gym. N.O. XT Nitric Oxide Booster provides more ingredients than just L-citrulline, and it works synergistically to boost muscle protein synthesis and nitric oxide metabolism. Jacked Factory also offers excellent customer service and a 100% 90-day money-back guarantee on all products.

Ingredients and benefits

Unlike the other products in our top picks, Jacked Factory contains three additional ingredients alongside L-citrulline. Among them is L-arginine, a semi-essential amino acid also serving as a substrate for nitric oxide production. In studies, L-arginine has demonstrated its potential as a treatment to reduce systolic and diastolic blood pressure in hypertensive adults.

The complete list of Jacked Factory N.O. XT Nitric Oxide Booster ingredients includes:

• L-citrulline (1.5g)
• Inositol-stabilized arginine silicate (Nitrosigine) (500mg)
• L-glutathione (200mg)
• Bioperine (black pepper fruit extract) (5mg)

Other ingredients include hypromellose (capsule) and L-leucine.

This supplement supports:

• Muscle growth and recovery
• Nitric oxide production
• Healthy immunity
• Reduced muscle soreness after workouts
• Sexual health

Pricing

Jacked Factory offer a subscription program that takes 25% off your first order and 15% off subsequent orders. Enrolling in this membership drops the price of N.O. XT Nitric Oxide Booster from $1 per serving to just $0.85.

The pricing below is for a 90-capsule bottle, which covers 30 days.

Jacked Factory does not provide free shipping on single or subscription orders. For orders to the United States, shipping is $9.99 and up.

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Additionally, like all health-related content on this website, this review was thoroughly vetted by one or more members of our Medical Review Board for accuracy.