As a nutritionist, I frequently recommend my weight loss clients enjoy watermelon whenever they wish, as it has next to no calories and is a great option to snack on. So, it is known for being a low-calorie food, but did you know that it could make an impact on how you perform in the gym as well?
Watermelon is the best food source of the amino acid L-citrulline. Keep reading to learn more about L-citrulline workout benefits and what other foods you could incorporate into your diet!
What is L-citrulline?
According to ScienceDirect, “L-citrulline is a naturally occurring nonessential amino acid (AA) [that is] conditionally essential in stress and diseases.” It plays an important role in the body’s production of nitric oxide, a compound that relaxes blood vessels and improves circulation.
Unlike essential amino acids, it is considered “non-essential,” meaning the body can produce it on its own. However, increasing your intake through foods or supplements may lead to enhanced performance and recovery.
When you consume L-citrulline, it is converted into another amino acid called L-arginine in the kidneys, which then supports nitric oxide production. This process helps improve oxygen delivery and nutrient transport to working muscles during exercise. Because of its effects on blood flow, energy metabolism, and waste removal, L-citrulline has become popular among athletes, bodybuilders, and endurance enthusiasts.
Interestingly, the amino acid gets its name from watermelon (Citrullus vulgaris), where it was first discovered and its most abundant food source. Today, it’s recognized as one of the most promising natural performance boosters available.
How does L-citrulline benefit athletes and lifters?
Athletes and lifters often look for safe, effective ways to improve performance and speed recovery, and L-citrulline offers multiple advantages. One of the most researched benefits is its ability to increase nitric oxide production, which enhances blood flow to muscles. Better circulation means more oxygen and nutrients are delivered during workouts, leading to improved endurance and reduced fatigue. This makes it especially helpful for long-distance runners, cyclists, and anyone tackling high-rep sets in the gym.
Another benefit is reduced muscle soreness. Studies have shown that supplementing with L-citrulline may decrease post-exercise soreness by helping remove ammonia and other waste products that build up during strenuous activity. For lifters, this means recovering faster and being ready for the next session sooner. L-citrulline may also support greater strength and power output, allowing athletes to push harder during workouts. Together, these effects make it a valuable tool for anyone aiming to maximize training results.
Best natural food sources of L-citrulline
While supplements are popular, you can also boost your intake of L-citrulline through diet. Some of the best natural sources include the following:
- Watermelon – The richest natural source, especially in the rind and white flesh near the skin
- Cucumbers – Contain modest amounts, particularly when eaten fresh
- Pumpkin – Seeds and flesh both contribute small amounts of citrulline
- Squash – Varieties like zucchini and yellow squash provide a mild boost
- Bitter melon – Less common, but also a decent source of L-citrulline
- Nuts and legumes – Chickpeas, peanuts, and almonds contain trace levels
Although none of these foods match watermelon’s concentration, incorporating a mix of them into your diet can naturally raise L-citrulline intake, as well as other nutrients. For those seeking performance benefits, whole foods can be paired with supplementation for an even greater effect.
When should you supplement L-citrulline?
Timing plays a big role in getting the most from L-citrulline supplementation. Most research suggests taking it about 30 to 60 minutes before exercise to maximize blood flow and endurance during training. This pre-workout window allows your body enough time to convert citrulline into arginine and increase nitric oxide levels before muscles are pushed to their limits.
For strength athletes and lifters, supplementing before workouts can reduce fatigue during heavy sets and improve recovery between training sessions. Endurance athletes may also find it useful to take L-citrulline before long runs, cycling, or competitions. Typical doses for performance benefits range from six to eight grams of citrulline malate or three to five grams of pure L-citrulline.
Some individuals also take smaller daily doses to maintain steady nitric oxide levels, supporting heart health and circulation. However, for workout-focused results, pre-training supplementation remains the most effective approach.
Frequently asked questions
What happens if I take L-citrulline every day?
Taking L-citrulline every day can support healthy blood flow, improve workout endurance, and reduce post-exercise soreness. Daily use may also promote heart health by maintaining nitric oxide levels. Most people tolerate it well, but results vary. Consistency matters—regular intake often provides more noticeable benefits than occasional use.
Does L-citrulline reduce belly fat?
L-citrulline does not directly reduce belly fat. Its main benefits are improved blood flow, endurance, and recovery. While it can help you work out harder and longer, fat loss comes from a consistent calorie deficit through diet and exercise. L-citrulline supports performance but isn’t a fat-burning supplement.
How long until L-citrulline kicks in?
L-citrulline typically kicks in within 30 to 60 minutes after consumption. This is the time it takes for the body to convert it into L-arginine and increase nitric oxide production. Athletes often take it before workouts to maximize blood flow, endurance, and performance during training or competition.
