What the evidence says. Several controlled trials; effects real but modest or context-dependent.
Nutrition per serving 1 wedge (286 g)
Water261.5 g92%
Sugars17.7 g6%
Fibre1.1 g0%
Other carbs2.8 g1%
Protein1.7 g1%
Fat0.4 g0%
What's in one serving, by weight — average composition (USDA).One serving as % of the adult daily requirement (FDA Daily Values). The bold outer ring = 100% of a day's needs.
Watermelon (Citrullus lanatus) is a fruit used for modestly lowers blood pressure (citrulline/arginine pathway). NutriDex grades the human evidence as Moderate. Watermelon is best known among fruits for its L-citrulline content, which the body converts to L-arginine to support nitric-oxide-mediated vasodilation. A 2023 meta-analysis of 9 randomized trials found watermelon consumption significantly lowered systolic blood pressure and improved total cholesterol and LDL, though it unexpectedly raised fasting blood glucose. A 2025 meta-analysis of L-citrulline/watermelon trials in middle-aged and older adults confirmed modest reductions in systolic (~-4 mmHg) and diastolic (~-2.5 mmHg) blood pressure. Small RCTs of watermelon extract also show reduced arterial stiffness and aortic blood pressure in obese hypertensive adults, and watermelon juice may modestly aid post-exercise recovery, though evidence here is mixed. Most trials are small, short, and often use concentrated extracts or juice rather than typical whole-fruit servings. The fruit is largely water with a high glycemic index but low glycemic load per realistic portion. Overall the cardiovascular signal is consistent but modest, warranting a conservative "moderate" rating.
✓May reduce arterial stiffness in adults with prehypertension/hypertension
✓High water content supports hydration
✓Provides lycopene, an antioxidant carotenoid
✓May improve some cardiometabolic lipid markers (total cholesterol, LDL)
Dosing & Compounds
Typical Dose
A typical serving is one wedge (~286 g) or 1-2 cups of diced flesh; cardiovascular trials often use larger amounts (~2-3 cups daily or watermelon extract supplying ~1-6 g citrulline/arginine).
Active Compounds
L-Citrulline (non-protein amino acid)L-ArginineLycopene (carotenoid)Beta-carotene (provitamin A)Vitamin C (ascorbic acid)PotassiumMagnesiumCucurbitacin E
Safety & Cautions
⚠
Generally very safe as a food. The high glycemic index means large portions can spike blood glucose, relevant for people with diabetes (though glycemic load per serving is low). It is a high-FODMAP food (fructose, mannitol) and may cause bloating, gas, or diarrhea in sensitive individuals or those with IBS. Rare allergy can occur, sometimes via oral allergy syndrome cross-reacting with ragweed pollen. Concentrated citrulline/arginine supplements may add to the blood-pressure-lowering effect of antihypertensive drugs and PDE5 inhibitors; no notable CYP3A4/grapefruit-type interaction. Educational only — always check with your doctor or pharmacist before combining Watermelon with any medicine.
Watermelon is most often taken for Modestly lowers blood pressure (citrulline/arginine pathway), Supports nitric-oxide-mediated vasodilation, May reduce arterial stiffness in adults with prehypertension/hypertension, High water content supports hydration. Hydrating summer fruit rich in citrulline and lycopene
Does Watermelon work — what does the evidence say?
Moderate evidence. Several controlled trials; effects real but modest or context-dependent. Watermelon is best known among fruits for its L-citrulline content, which the body converts to L-arginine to support nitric-oxide-mediated vasodilation. A 2023 meta-analysis of 9 randomized trials found watermelon consumption significantly lowered systolic blood pressure and improved total cholesterol and LDL, though it unexpectedly raised fasting blood glucose. A 2025 meta-analysis of L-citrulline/watermelon trials in middle-aged and older adults confirmed modest reductions in systolic (~-4 mmHg) and diastolic (~-2.5 mmHg) blood pressure. Small RCTs of watermelon extract also show reduced arterial stiffness and aortic blood pressure in obese hypertensive adults, and watermelon juice may modestly aid post-exercise recovery, though evidence here is mixed. Most trials are small, short, and often use concentrated extracts or juice rather than typical whole-fruit servings. The fruit is largely water with a high glycemic index but low glycemic load per realistic portion. Overall the cardiovascular signal is consistent but modest, warranting a conservative "moderate" rating.
What is the typical dose of Watermelon?
A typical serving is one wedge (~286 g) or 1-2 cups of diced flesh; cardiovascular trials often use larger amounts (~2-3 cups daily or watermelon extract supplying ~1-6 g citrulline/arginine).
Is Watermelon safe? Any cautions or side effects?
Generally very safe as a food. The high glycemic index means large portions can spike blood glucose, relevant for people with diabetes (though glycemic load per serving is low). It is a high-FODMAP food (fructose, mannitol) and may cause bloating, gas, or diarrhea in sensitive individuals or those with IBS. Rare allergy can occur, sometimes via oral allergy syndrome cross-reacting with ragweed pollen. Concentrated citrulline/arginine supplements may add to the blood-pressure-lowering effect of antihypertensive drugs and PDE5 inhibitors; no notable CYP3A4/grapefruit-type interaction.
How many studies support Watermelon?
NutriDex cites 10 sources for Watermelon, graded "Moderate".
Cite this page
APA
Peh, D. (2026). Watermelon (Citrullus lanatus): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 16 Sept 2026, from https://nutridex.info/s/watermelon
BibTeX
@misc{nutridex_watermelon,
author = {Peh, Daryl},
title = {Watermelon (Citrullus lanatus): Benefits, Dosage, Side Effects \& Evidence},
year = {2026},
howpublished = {NutriDex --- The Supplement Research Compendium},
url = {https://nutridex.info/s/watermelon},
note = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-09-16}
}
For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.