Watermelon's aphrodisiac power discovered

Editorial Note

This article was previously published and has been updated according to evidence-based medicine criteria and responsible public communication. The text is for informational purposes only and does not replace medical advice. For clinical decisions or therapies, consult a healthcare professional.

In brief

• Watermelon is primarily water but contains biologically active compounds: citrulline (a precursor to arginine) and lycopene (a carotenoid).
• Consumption of watermelon or its preparations can increase plasma arginine/citrulline levels in high or concentrated doses, with modest cardiovascular effects in specific studies. [1][2][5]
• Citrulline in supplement form has shown improvements in erection in a clinical study on men with mild dysfunction; however, the results do not equate to the efficacy of approved drugs for erectile dysfunction. [3]
• The lycopene present in watermelon is bioaccessible, and observational data associate it with modest reductions in the risk of some cancers, but causal evidence is limited. [4][6]
• The glycemic profile of watermelon varies: it has relatively few calories per serving but a glycemic index that can be medium-high in the literature; it is important to consider portion size and dietary context. [7]

Abstract: what does science say?

Watermelon (Citrullus lanatus) is a fruit with a high water content that contains citrulline, arginine, and carotenoids such as lycopene. Clinical research shows that significant consumption or concentrated preparations can increase plasma arginine levels and, in small studies, improve some vascular parameters and, in concentrated form (citrulline supplements), the quality of erection in mild cases. Epidemiological evidence on lycopene suggests inverse associations with some cancers (e.g., prostate), but results are not consistent, and causality is not proven. The effect strongly depends on dose, form (whole fruit, juice, extract, or supplement), duration, studied population, and the presence of cardiometabolic risk factors. Methodological limitations (small sample sizes, heterogeneity of preparations, surrogate measures) require cautious interpretation: watermelon can contribute to a healthy diet, but it is not a miracle cure.

What do the main compounds mean?

Citrulline and arginine: how they work

Citrulline is an amino acid present in relatively high quantities in watermelon; in the body, it is converted into arginine, a precursor to the synthesis of nitric oxide (NO), a mediator that promotes vasodilation. Controlled clinical studies have shown that prolonged consumption of large quantities of watermelon juice or preparations can increase plasma arginine concentrations compared to control [1]. In subjects with high blood pressure or pre-hypertension, concentrated preparations based on citrulline/arginine have improved some measures of aortic hemodynamics and wave reflection, indicators related to cardiovascular risk [2]. These effects are dose-dependent and more evident in populations with risk factors; in healthy individuals, the results are more uncertain. [1][2][5]

Lycopene and antioxidants

Watermelon is a dietary source of lycopene, a fat-soluble carotenoid that gives the pulp its red color. It has been shown that the lycopene present in watermelon juice is absorbable and can increase plasma levels after regular consumption [4]. Observational studies and meta-analyses indicate associations between higher levels of lycopene (or consumption of lycopene-rich foods) and a reduced risk of some cancers, particularly prostate cancer; however, randomized studies have not provided definitive evidence of preventive or therapeutic efficacy, and bioavailability depends on the presence of fats in the diet. [4][6]

Evidence on sexual function and desire (aphrodisiac)

What clinical research has studied

The definition of "aphrodisiac power" includes biological and psychological aspects. Direct clinical literature on watermelon is limited; however, citrulline, found in watermelon, has been studied in purified form. In a clinical study on men with mild erectile dysfunction, oral L-citrulline supplementation (1.5 g/d for 1 month) improved the Hardness Score of erection compared to placebo in a small sample, suggesting a potential vasodilatory effect that can translate into improved erectile rigidity [3]. It is important to note that the study concerns a concentrated supplement and not the usual consumption of fruit slices; to obtain equivalent doses from portions, very high quantities of fruit would be needed. [3]

Cautious interpretation

The plausible mechanism is the increase in arginine availability and thus NO, which facilitates blood flow; this is a mechanism shared with PDE5 inhibitor drugs, but the effects of nutrients are generally more modest and less predictable. There is currently no solid evidence that eating normal portions of watermelon as a snack or salad is equivalent to using supplements or approved drugs for erectile dysfunction; therefore, it is not correct to present it as a therapeutic alternative. [3][5]

What research says about blood pressure and vascular function

Randomized clinical trials and pilot studies indicate that watermelon-based preparations or extracts rich in citrulline/arginine can reduce some measures of aortic pressure and wave reflection parameters in subjects with prehypertension or mild hypertension [2]. Recent meta-analyses comparing L-citrulline supplements and watermelon consumption show heterogeneous effects: some vascular endpoints improve, especially at high doses of citrulline; other studies, in healthy populations or at lower doses, do not report clinically significant changes [5][8]. In a study on postmenopausal women, two servings of watermelon juice per day for 4 weeks increased circulating lycopene but did not change indicators of vascular function, highlighting the variability of results depending on the studied population. [8]

Nutritional and glycemic considerations

Watermelon is low in energy per serving and provides water, some vitamins, and minerals; this often makes it suitable as a summer snack. However, the glycemic index (GI) value of watermelon reported in the literature can be medium-high: updated international tables show that some melons, including watermelon, can have a GI in the medium-high range, while the glycemic load (GL) per serving remains low due to the reduced carbohydrate content per serving. The practical implication is that, for people with diabetes or problematic glycemic control, the quantity consumed and the meal context matter more than the single food. [7]

Practical section

What it means in practice

For the general public: watermelon is a refreshing, hydrating, and low-calorie fruit ideal for balanced diets. It can provide lycopene and citrulline, nutrients with plausible beneficial effects on vascularity and oxidative stress; however, possible "aphrodisiac effects" derive mainly from the presence of citrulline and are only demonstrated when citrulline is administered in concentrated form or in high doses, not with a single slice of fruit. [1][3][4][5]

Non-prescriptive practical indications:

• Consume watermelon as part of a varied diet: accompanying it with healthy fats (extra virgin olive oil, seeds, avocado) improves lycopene absorption. [4]
• Those taking medications for blood pressure or erectile function should speak with their doctor before using citrulline-based supplements or large quantities of extracts. [2][3]
• For those with diabetes, moderate portions and pairing with protein/fiber reduce the glycemic impact. [7]

Key takeaways

• Watermelon contains citrulline (a precursor to arginine) and lycopene; these compounds have plausible biological mechanisms to influence vascular function and oxidative stress. [1][4]
• High doses or concentrated preparations have shown measurable effects on some vascular parameters in limited studies and on symptoms of mild erectile dysfunction with citrulline supplements. [2][3]
• Observational associations between lycopene and the risk of some cancers do not prove causality; more quality RCTs are needed. [6]
• The nutritional value of the fruit as a hydrator and source of micronutrients makes it a valid choice in a balanced diet, but it is not a cure. [4][7]
• Effects depend on the form, dose, duration, and health status of the studied population. [5][8]

Limitations of the evidence

It is essential to distinguish between types of studies: observational studies show associations and suggest biological hypotheses, but cannot establish cause-and-effect. Randomized clinical trials represent the best level for evaluating causal effects, but many trials on watermelon or citrulline are small, short-duration, or use different preparations (juice, purees, extracts, synthetic supplements), making it difficult to generalize the results. The variability in the dose of citrulline available in food products compared to supplements makes the translation of experimental effects into dietary recommendations problematic. Furthermore, endpoints are often surrogate measures (e.g., blood flow, hemodynamic parameters) rather than established clinical outcomes (heart attack, mortality, long-term improvement in sexual function). For these reasons, any interpretation requires caution and contextualization. [2][3][5][8]

Editorial conclusion

Watermelon is a hydrating and nutritious food that provides citrulline and lycopene with plausible biological benefits. Experimental and clinical literature suggests potential favorable effects on some vascular parameters and, at concentrated doses of citrulline, on aspects of erectile function. However, the evidence is not sufficient to translate these observations into therapeutic recommendations. For the general population, including watermelon in a varied and balanced diet is reasonable; those seeking treatments for specific conditions (hypertension, erectile dysfunction, cardiovascular diseases) should rely on healthcare professionals and treatments with consolidated evidence.

Editorial Note

This update was carried out with criteria of transparency and citation of peer-reviewed sources. The article aims to inform the reader about current literature without replacing personalized medical advice.

SCIENTIFIC RESEARCH

1. Collins JK, Wu G, Perkins‑Veazie P, Spears K, Claypool PL, Baker RA, Clevidence BA. Watermelon consumption increases plasma arginine concentrations in adults. Nutrition. 2007 Mar;23(3):261‑266. https://doi.org/10.1016/j.nut.2007.01.005
2. Figueroa A, Sanchez‑Gonzalez MA, Perkins‑Veazie P, Arjmandi BH. Effects of watermelon supplementation on aortic blood pressure and wave reflection in individuals with prehypertension: a pilot study. Am J Hypertens. 2011 Jan;24(1):40‑44. https://doi.org/10.1038/ajh.2010.142
3. Cormio L, De Siati M, Lorusso F, Selvaggio O, Mirabella L, Sanguedolce F, Carrieri G. Oral L‑citrulline supplementation improves erection hardness in men with mild erectile dysfunction. Urology. 2011 Jan;77(1):119‑122. https://doi.org/10.1016/j.urology.2010.08.028
4. Edwards AJ, Vinyard BT, Wiley ER, Brown ED, Collins JK, Perkins‑Veazie P, Baker RA, Clevidence BA. Consumption of watermelon juice increases plasma concentrations of lycopene and β‑carotene in humans. J Nutr. 2003 Apr;133(4):1043‑1050. https://doi.org/10.1093/jn/133.4.1043
5. Smeets JSJ, Mensink GBM, Joris PJ, et al. Effects of L‑citrulline supplementation and watermelon consumption on longer‑term and postprandial vascular function and cardiometabolic risk markers: a meta‑analysis of randomised controlled trials in adults. Br J Nutr. 2022;128(9):1758‑1770. https://doi.org/10.1017/S0007114521004803
6. Shi M, et al. Effect of Carotene and Lycopene on the Risk of Prostate Cancer: A Systematic Review and Dose‑Response Meta‑Analysis of Observational Studies. PLoS One. 2015;10(7):e0137427. https://doi.org/10.1371/journal.pone.0137427
7. Atkinson FS, Foster‑Powell K, Brand‑Miller JC. International tables of glycemic index and glycemic load values 2021: a systematic review. Am J Clin Nutr. 2022;116(1):xx‑xx. https://doi.org/10.1093/ajcn/nqab233
8. Ellis AC, Mehta T, Nagabooshanam VA, Dudenbostel T, Locher JL, Crowe‑White KM. Daily 100% watermelon juice consumption and vascular function among postmenopausal women: a randomized controlled trial. Nutr Metab Cardiovasc Dis. 2021;31(10):2959‑2968. https://doi.org/10.1016/j.numecd.2021.06.022