The citrulline amino acid is very popular these days as a health and exercise performance supplement. The body can produce it naturally and also available in some foods. However, taking supplements increases the body’s citrulline content above typical levels. While some people are aware of its efficacy for health and performance in exercise, others are skeptical. Here are the health benefits of citrulline supplements.
Citrulline Supplements May Reduce Blood Pressure
Citrulline supplements can lower blood pressure, especially in those with high blood pressure levels. Studies in 40 participants show the effects of citrulline supplements in adults with high blood pressure or other heart conditions.
They found that after eight weeks the blood pressure of participants had decreased by 4–15 percent (1).
Moreover, researchers found that citrulline reduced blood pressure by 6–16 percent after 7 days in a small study examining 12 adults with normal blood pressure (2).
The evidence is not conclusive in healthy individuals, as other researchers found no benefit from citrulline over periods of four weeks (3).
Overall, it is unclear whether it significantly affects healthy individuals’ blood pressure.
Citrulline May Widen Your Blood Vessels
Improving the ability of the blood vessels to enlarge can potentially improve blood pressure and its flow. Studies have shown that a single dose of L-citrulline does not improve the ability of the arteries to enlarge on individuals who are healthy or ill (4, 5).
However, the ability of their arteries to widen has improved when people who have heart disease or are at risk of heart disease have consumed L-citrulline for seven days or more (6).
So, while a single dose may not be very effective in widening your blood vessels. Therefore, taking supplements may be more effective over the longer term.
Can Boost Exercise Performance
Citrulline was studied in both endurance and strength-based exercise because of its ability to increase blood flow. Several endurance exercise studies have used L-citrulline, while much of the resistance-based research has used citrulline malate.
It can also increase oxygen in muscle tissue. This means that while the amino acid may not allow the body to use more oxygen. However, it may improve the usage of oxygen in the exercising muscle. This may allow for better results in exercise (9, 10).
Cyclists taking citrulline could cycle 12 percent longer before exhaustion than those taking placebo in one study (11).
Taking seven days of these supplements can also improve power output during cycling. In a certain amount of time, that is how much force it can produce (12).
Generally, citrulline can affect the oxygen in the muscle which can improve stamina.
Citrulline May Boost Growth Hormone (GH)
Citrulline may boost growth hormone (GH) after exercise. It may involve the rise in GH and other hormones after exercise in the beneficial adaptations that your body experiences when you are exercising (13, 14).
The amino acid may also improve erections in men with erectile dysfunction, possibly by increasing blood flow (15).
May Help You Build Muscle Faster
Several studies have shown that citrulline malate can improve performance in weight training. One study in 41 men on the ability to perform repetitions during upper-body exercise.
After the ingestion of citrulline malate, participants could perform 53 percent more repetitions than the placebo. When they consumed citrulline malate before exercising the muscle soreness of participants in the two days after exercise was 40 percent less (16).
Other researchers also found that citrulline malate can reduce tiredness and increases the performance of the lower body in weight training. Participants had taken the supplement 60 minutes before exercise in both studies (17).
Forms Of Citrulline Supplements
In dietary supplements, there are two primary forms of citrulline:
L-Citrulline: This refers to citrulline by itself, with nothing else attached.
Citrulline Malate: This refers to the combination of citrulline and another compound called malate, which is important for the production of energy (18).
The two forms may produce some similar effects. However, citrulline’s malate form is more common in sport. It is not clear which form can better affect human health L-Citrulline or Citrulline Malate.
Supplements Safety and Side Effects
However, the highest doses of arginine in the blood did not appear to increase as much as expected, meaning there is a limit to how much of this supplement your body can use.
Overall, the study showed that excessive doses are greater than 10 grams. Blood tests conducted in participants after taking citrulline supplements revealed no harmful changes to normal body functions or blood pressure (19).
The Bottom Line
Citrulline has several health benefits and is an amino acid. It also seems to be healthy, and no known side-effects exist. This supplement can promote healthy blood vessels and lower blood pressure, especially in people with heart or high blood pressure conditions. Citrulline malate was researched the most for weight training.
An 8-gram dose could reduce fatigue and boost workout performance. Citrulline may be the next medication you should consider if you want to support heart health or boost your workout results. Before taking any supplements, we strongly recommend consulting with your dietician.
Frequently Asked Questions
Citrulline is an amino acid first discovered in watermelon. It’s considered non-essential, meaning your body can produce it naturally. You can, however, increase your levels by eating citrulline rich foods or by taking dietary supplements rather than relying on the production of your body alone.
There are some citrulline rich foods, but your body can produce it on its own. Most of these foods are not analyzed for their amino acid content. However, citrulline foods such as cucumber, Watermelon, pumpkins, gourds, and bitter melon.
Citrulline has several significant effects on your body. One important way that it works is by increasing vasodilatation. Vasodilatation implies the expansion of arteries or veins. Linked to lower blood pressure and increased blood flow. Ironically, taking citrulline in the body will increase arginine more than eating arginine alone. This is because of differences in how arginine and citrulline are processed and absorbed by the body. The increase in nitric oxide and blood flow may be one process involved in the beneficial effects of citrulline on exercise performance.
A recommended dose, based on current studies, are 3–6 grams of L-citrulline per day, or about 8 grams of citrulline malate per day. The dosage varies as 1.75 grams of citrulline malate contains 1 gram of L-citrulline, depending on the type. The 0.75 grams that are left are malate.
In weight training, eight grams of citrulline malate provides approximately 4.5 grams of citrulline, an important dose for weight training success. For blood pressure, the daily dose of L-citrulline used in studies usually is a 3–6 grams per day to raise blood pressure.
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