Get Your Personalized Supplement StackSupplement Stack Quiz

Watermelon Extract

Also known as: Citrullus lanatus, Watermelon extract, Watermelon concentrate, Watermelon juice powder

Overview

Watermelon extract is derived from the fruit *Citrullus lanatus*, primarily valued for its high L-citrulline content. L-citrulline is a non-essential amino acid that acts as a precursor to L-arginine and nitric oxide (NO). It is used to support cardiovascular health, improve vascular function, and potentially enhance exercise performance. The extract is rich in L-citrulline, antioxidants (lycopene, beta-carotene), and polyphenols, and is generally well-tolerated. Research suggests it can decrease systolic blood pressure (SBP), total cholesterol (TC), and low-density lipoprotein (LDL). While several RCTs and meta-analyses exist, sample sizes are often limited and long-term data are lacking. Evidence is strongest for cardiovascular and vascular effects, with less robust evidence for exercise performance and testosterone.

Benefits

Watermelon supplementation has been shown to significantly decrease systolic blood pressure (SBP), total cholesterol (TC), and low-density lipoprotein (LDL). A meta-analysis of 9 RCTs found statistically significant reductions in SBP, TC, and LDL. Some evidence suggests improved vascular function (reduced arterial stiffness, improved endothelial function) due to increased nitric oxide production from L-citrulline. Limited evidence suggests increased testosterone in animal models, but human data are lacking. Most evidence is in adults with or at risk for cardiovascular disease. Reductions in SBP, TC, and LDL are modest but clinically relevant for cardiovascular risk reduction. Acute effects on vascular function may be seen within hours, while chronic benefits (blood pressure, lipids) typically require several weeks of supplementation.

How it works

L-citrulline in watermelon extract is converted to L-arginine in the kidneys, which is then used to synthesize nitric oxide (NO). NO is a potent vasodilator that improves endothelial function and reduces arterial stiffness. The extract primarily affects the cardiovascular system by improving vascular tone and reducing blood pressure. It may also have antioxidant effects due to lycopene and polyphenols. L-citrulline is well-absorbed orally and efficiently converted to L-arginine, bypassing first-pass metabolism in the liver. The known molecular targets include nitric oxide synthase (NOS), endothelial cells, and vascular smooth muscle.

Side effects

Watermelon extract is generally safe and well-tolerated in clinical studies. Common side effects have not been reported in clinical trials. Mild gastrointestinal discomfort may occur in sensitive individuals. Rare side effects include allergic reactions. No significant drug interactions have been reported, but there is a theoretical potential to enhance the effects of antihypertensive medications. There are no established contraindications, but caution is advised in individuals with severe hypotension. It is considered safe in adults, but there is insufficient data in children, pregnant, or lactating women.

Dosage

The minimum effective dose is not well-established; most studies use 1–2 g L-citrulline daily, equivalent to 300–700 mL watermelon juice. Optimal dosage ranges are 1–3 g L-citrulline per day for cardiovascular and vascular benefits. There is no established upper limit, but doses up to 6 g L-citrulline daily have been used safely in short-term studies. It can be taken at any time of day; acute vascular effects may be seen within 1–2 hours. Juice, powder, or extract forms are available. Powder/extract is more concentrated and practical for higher L-citrulline doses. L-citrulline is well-absorbed, and no specific cofactors are required.

FAQs

How much watermelon juice do I need to drink to get the benefits?

Most studies use the equivalent of 300–700 mL of watermelon juice to achieve an effective L-citrulline dose. Extracts are a more practical way to get higher doses.

Is watermelon extract safe to take with blood pressure medication?

It is generally safe, but monitor your blood pressure if you are taking antihypertensive medications, as watermelon extract may enhance their effects.

When is the best time to take watermelon extract?

It can be taken at any time of day, with or without food. The timing is flexible and depends on individual preference.

Will watermelon extract improve my athletic performance?

Benefits are primarily cardiovascular. There is no clear benefit for exercise performance in trained individuals.

Is watermelon extract a performance-enhancing supplement for athletes?

No, the benefits are primarily cardiovascular. It is not considered a performance-enhancing supplement for athletes.

Research Sources

https://pubmed.ncbi.nlm.nih.gov/37369281/ – A meta-analysis of 9 RCTs on watermelon supplementation found significant reductions in systolic blood pressure (SBP), total cholesterol (TC), and low-density lipoprotein (LDL) in adults with or at risk for cardiovascular disease. The study noted an increase in fasting blood sugar (FBS), but the clinical significance was unclear. The authors concluded that the evidence was limited by small sample sizes and short follow-up periods.
https://examine.com/research-feed/study/dnBLOd/ – A randomized controlled crossover trial found that watermelon supplementation had no effect on resistance exercise performance, muscle oxygen saturation, or blood vessel function in resistance-trained men. The study was limited to trained men and had a short duration. The authors concluded that watermelon supplementation does not enhance resistance exercise performance in this population.
https://www.mdpi.com/2072-6643/14/14/2913 – A review of watermelon ingestion on vascular function found that watermelon-derived L-citrulline improves vascular function and reduces arterial stiffness. The authors noted that the effects depend on the dose and may require large volumes of juice. The review cited multiple RCTs but was limited by variability in study designs and doses.
https://austinpublishinggroup.com/nutrition-food-sciences/fulltext/ajnfs-v7-id1127.pdf – This study investigates the potential of watermelon extract to enhance testosterone levels. The research suggests a possible link between watermelon consumption and increased testosterone, warranting further investigation into the underlying mechanisms and clinical implications.
https://pubmed.ncbi.nlm.nih.gov/35889869/ – This review discusses the potential of L-citrulline from watermelon to improve vascular function. It highlights that L-citrulline is efficiently converted to L-arginine, bypassing first-pass metabolism in the liver, and improving nitric oxide production, which is crucial for vascular health.