Description 

Citrullus lanatus is an annual, prostrate or climbing vine belonging to the Cucurbitaceae (gourd) family. The stems can reach up to 10 meters in length and are covered with coarse, woolly hairs—a characteristic reflected in the species name lanatus, meaning “woolly”. The leaves are alternately arranged, ovate to triangular in outline, measuring 5–20 cm in length, and are deeply palmately 3–5-lobed, with the central lobe being the largest . Both surfaces bear short, stiff hairs, particularly along the veins. The tendrils are 2- to 3-fid (branched).

The plant is monoecious, bearing separate male and female flowers on the same plant. Both flower types are solitary in the leaf axils and pale yellow in color. Male flowers have pedicels (flower stalks) 12–45 mm long, while female flowers have shorter pedicels (3–45 mm) and an inferior, villous (hairy) ovar. The fruit is a large, fleshy berry known botanically as a pepo. Wild forms produce small fruits (1.5–20 cm in diameter), while cultivated varieties can reach up to 60 × 30 cm. The rind is smooth and varies in color from golden-yellow to dark green, often mottled or striped. The inner flesh is typically red or yellow, though orange, pink, and white varieties also exist, and is juicy and sweet. The fruit contains numerous flattened, smooth seeds that vary in color (white, brown, black, red, or mottled), measuring approximately 9–11 × 5–6 mm.

The plant is monoecious and thrives in warm, sunny tropical/subtropical climates with well-drained soil. It is native to Africa, with evidence of cultivation in ancient Egypt dating back over 5,000 years. It is now cultivated extensively in tropical, subtropical, and warm temperate regions worldwide.

Common names (including Nigerian) 

  • English: Watermelon, Afghan melon, Egusi melon (for seed types), Wild watermelon (for bitter types), Preserving melon, Citron melon
  • Chinese: 西瓜 (Xī guā)
  • French: Pastèque, Melon d’eau
  • Spanish: Sandía, Albudeca
  • German: Wassermelone, Futtermelone
  • Nigerian Names:
  • Yoruba: Egusi agbe (refers specifically to seed-type watermelons)
  • Hausa: Kankana, Guna, Gunar shanu
  • Fula-Fulfulde: Cikilje pahe
  • Igbo: Anyụ or Anyụ mmiri

Health Benefits 

Citrullus lanatus is is nutrient-dense and low in calories, offering hydration (over 90% water) along with potassium, magnesium; and rich in bioactive compounds, including vitamins (especially vitamin C and A), phenolic compounds, flavonoids, lycopene, and the amino acid L-citrulline, which contribute to its wide range of pharmacological activities .

  • Cardiovascular Health: L-citrulline, found abundantly in watermelon, is effective in treating cardiovascular diseases and has beneficial effects on metabolic diseases . It is converted to L-arginine in the body, which helps produce nitric oxide, relaxing blood vessels and improving blood flow.
  • Hepatoprotective (Liver Protection): Studies have demonstrated that watermelon seed extracts possess significant hepatoprotective properties, helping to reduce liver enzymes (SGOT, SGPT, ALP) and protect against non-alcoholic fatty liver disease (NAFLD) . The presence of compounds such as hexadecanoic acid methyl ester (methyl palmitate) and 9,12-octadecadienoic acid (linoleic acid) is thought to be responsible for this activity .
  • Antihyperlipidemic (Cholesterol-Lowering): Seed extracts have shown substantial antihyperlipidemic effects, reducing serum cholesterol, triglycerides, and LDL levels while increasing HDL (“good”) cholesterol . These effects were comparable to the standard drug Atorvastatin in animal studies.
  • Antioxidant Effects: The fruit flesh is rich in lycopene, a potent antioxidant that gives red watermelon its color, and other phenolic compounds. These compounds help combat oxidative stress by increasing antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT).
  • Antidiabetic and Metabolic Benefits: Watermelon consumption has been associated with reduced blood glucose levels and beneficial effects on metabolic diseases. The presence of L-citrulline contributes to improved metabolic parameters.
  • Anti-inflammatory and Analgesic Effects: Extracts from the roots and leaves of C. lanatus have demonstrated significant anti-inflammatory activity in animal models, including inhibition of ear edema, paw edema, and granuloma formation. Analgesic (pain-relieving) effects were also observed through increased pain threshold in hot-plate tests and reduced writhing responses to acetic acid.
  • Antiurolytic and Diuretic Effects: Traditional uses for treating urinary tract infections and kidney stones are supported by scientific findings, with steroids and alkanes in the plant linked to its in vivo antiurolytic (kidney stone-preventing) and diuretic activities .
  • Exercise recovery and muscle health: L-citrulline may reduce muscle soreness and improve performance by aiding blood flow. 
  • Skin and Eye Health: Vitamins A and C contribute to healthy skin and good vision.
  • Safety Profile: Toxicity studies have demonstrated that C. lanatus seed extract is safe with an LD50 greater than 2000 mg/kg body weight and no observed adverse effects at doses up to 1000 mg/kg in animal studies. This supports its use in further preclinical and clinical evaluations.

Other benefits 

  • Culinary Uses (Beyond Fresh Fruit):
    • Seeds: Watermelon seeds are highly nutritious, containing approximately 20% oil with a fatty acid profile dominated by linoleic acid (60–70% of total). They can be eaten raw, roasted as a snack, or ground into a coarse, nutty-tasting meal. In West Africa, the seeds of “egusi” type watermelons are made into a pulp and added as a thickener to soups.
    • Rind and Peels: The rind serves as a source of pectin and melanin, which are being explored for use as edible biofilms and natural sweeteners in the food industry. Candied or dried rind is also marketed as a snack.
    • Oil: Cold-pressed seed oil is produced for culinary use; the residual seed meal is used as animal feed or fertilizer.
  • Industrial Applications:
    • Natural Colorants: Lycopene extracted from the red flesh is used as a natural red food colorant (E160d) in processed foods.
    • Fiber and Composites: Rind fiber is being investigated for biodegradable composites and as a cellulose source for papermaking.
    • Pectin Production: The rind provides pectin (approximately 0.5–1% dry weight), a gelling agent used in jams and jellies.
  • Beverages: Watermelon juice is consumed fresh, concentrated, or pasteurized. The fruit is also used to produce fermented beverages such as watermelon wine.
  • Cosmetics: Watermelon aroma extracts are incorporated into flavorings, fragrances, and cosmetic formulations for their characteristic sweet-muscat scent.
  • Animal Feed: Wild, bitter forms of watermelon (containing cucurbitacins) are fed to cattle, and seed meal from oil extraction serves as animal feed.
  • Sustainability: Global watermelon production exceeds 200 million tons annually, and processing by-products (seeds, rind, pulp) into oil, pectin, or fiber reduces waste and adds economic value, supporting integrated utilization of fruit biomass.
  • Economic and agricultural: A valuable cash crop in Nigeria and globally, supporting livelihoods through fresh fruit sales, juice production, and seed processing. High-yield potential on suitable land; by-products (rind and seeds) have further uses. 
  • Environmental/cultural: Grows on marginal or sandy soils in warm climates; provides ground cover and supports biodiversity in traditional farming systems. In parts of Africa, wild or semi-wild forms contribute to food security during dry seasons.

How it is used 

– Food: Eaten fresh as slices for hydration and refreshment; juiced or blended into smoothies/drinks; added to salads or fruit bowls. Rind can be stir-fried, pickled, or made into preserves. Seeds are roasted as snacks, ground into flour for thickening soups/sauces, or pressed for oil. In Nigeria, seeds from certain varieties are processed into local delicacies. 

– Medicinal/traditional (including Nigerian/West African use): 

  – Fresh fruit or juice: Consumed for hydration, cooling effect, fever, inflammation, or as a general tonic/diuretic. 

  – Seeds: Boiled or ground for decoctions/teas to support urinary tract health, kidney/bladder cleansing, hypertension, or as a vermifuge/diuretic in folk medicine. Roasted seeds may stimulate appetite or relieve constipation. 

  – Rind or whole fruit: Occasional use in remedies for skin issues, oedema, or gastrointestinal complaints. 

Preparation examples: For seed tea — grind dried seeds, steep 1–2 tablespoons in hot water for 20–30 minutes, strain and drink. Fruit juice is consumed fresh. Oil is extracted by pressing or traditional methods for culinary/medicinal use. Dosages in traditional practice vary; modern supplements often concentrate L-citrulline.

### How it is Used

  • As Food:
    • Fresh Fruit: The ripe fruit flesh is the most common form of consumption, eaten raw, in fruit salads, or as a refreshing snack.
    • Juice: Fresh, concentrated, or pasteurized watermelon juice is a popular beverage.
    • Frozen/Canned: Watermelon pieces are frozen for use in drinks or canned for preservation.
    • Seeds: Roasted watermelon seeds are consumed as a snack. In West Africa, seeds (egusi) are ground and used as a soup thickener.
    • Rind: The rind is candied, dried as a snack, or used to make preserves.
    • Fermented Beverages: Watermelon wine is produced through fermentation.
  • As Medicine (Traditional and Scientific Applications):
    • Seed Extract: Oral administration of seed extracts has been studied for hepatoprotective, antihyperlipidemic, and antioxidant effects.
    • Root and Leaf Extract: Used in traditional medicine for their anti-inflammatory and analgesic properties; scientific studies have validated these effects in animal models.
    • L-citrulline Content: The natural L-citrulline in watermelon is utilized for cardiovascular health and metabolic disease management.
  • Industrial and Other Uses:
    • Natural Colorant: Lycopene is extracted from the flesh for use as a natural red food colorant (E160d).
    • Pectin Extraction: Pectin is extracted from the rind for use as a gelling agent.
    • Seed Oil Production: Cold-pressed oil is extracted for culinary or cosmetic use; the remaining seed meal is used as animal feed or fertilizer.
  • Traditional Medicine: Used in some communities to support hydration, reduce heat in the body, and promote urination (mild diuretic effect).
  • Topical Use: Occasionally used in homemade skin treatments for hydration.

Side Effects/Caution 

  • Generally Recognized as Safe: Citrullus lanatus is widely consumed as a food and is generally safe. Toxicity studies have confirmed that seed extracts are non-toxic below 1000 mg/kg body weight, with an LD50 greater than 2000 mg/kg in animal models. Acute toxicity studies on root and leaf extracts also showed no apparent toxic reactions at high doses (87 g extract per kg body weight).
  • Moderate Consumption: Due to its high water and fiber content, excessive consumption may cause digestive discomfort such as bloating or diarrhea in sensitive individuals.
  • Wild Bitter Types: Wild forms of C. lanatus contain high levels of cucurbitacins, making them very bitter and potentially toxic. These are typically only fed to cattle and should not be consumed by humans. The edible watermelon has been selectively bred to remove these compounds.
  • Pesticide Residues: As the fruit is often grown conventionally, the rind may contain pesticide residues. Washing thoroughly before consuming the rind or using it for preserves is recommended.
  • Blood Sugar and Cholesterol Monitoring: Due to its demonstrated hypoglycemic and antihyperlipidemic effects, individuals taking medications for diabetes or high cholesterol should monitor their levels when consuming large, consistent amounts of watermelon products and consult their healthcare provider. However, it contains natural sugars (fructose/glucose); large portions can raise blood glucose levels—people with diabetes should monitor intake and prefer whole fruit over juice. 
  • Allergies: Rare, but possible reactions include itching, hives, or swelling (particularly in those with related fruit/pollen allergies). 
  • Other: High potassium may pose risks for individuals with kidney disease or on certain medications (e.g., affecting electrolyte balance).
  • Pregnancy and Breastfeeding: Individuals and children can enjoy it as food; consult a healthcare provider for medicinal use or if you have underlying conditions. Moderation (e.g., 1–2 cups/300g daily) is recommended.

References 

  • “Citrullus lanatus (Thunb.) Matsum. & Nakai (species) – Taxonomy, Distribution, Uses & Phytochemicals.” PlantaeDB, 3 Apr. 2026, https://plantaedb.com/taxa/phylum/angiosperms/order/cucurbitales/family/cucurbitaceae/genus/citrullus/species/citrullus-lanatus.
  • “Citrullus lanatus (Thunb.) Matsum. & Nakai.” Plazi.org, http://tb.plazi.org/GgServer/html/03C2A72C32135C56FF1FD3B6A904FAC1. Accessed 16 Apr. 2026.
  • “西瓜 [Watermelon].” 中国数字植物标本馆 (CVH), https://www.cvh.ac.cn/spms/detail.php?id=c27c6f54. Accessed 16 Apr. 2026.
  • “Citrullus lanatus (Thunb.) Matsum. & Nakai.” Plants of the World Online, Royal Botanic Gardens, Kew, powo.science.kew.org/taxon/urn:lsid:ipni.org:names:292146-1. Accessed 16 Apr. 2026. 
  • “Citrullus lanatus (Watermelon).” Missouri Botanical Garden, www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=279562. Accessed 16 Apr. 2026. 
  • “Watermelon – Uses, Side Effects, and More.” WebMD, www.webmd.com/vitamins/ai/ingredientmono-1492/watermelon. Accessed 16 Apr. 2026. 
  • Belemkar, Sateesh, and Parshuram Nivrutti Shendge. “Toxicity Profiling of the Ethanolic Extract of Citrullus lanatus Seed in Rats: Behavioural, Biochemical and Histopathological Aspects.” Bioscience Reports, vol. 41, no. 1, 2021. OUCI, https://ouci.dntb.gov.ua/?backlinks_to=10.1042%2Fbsr20192536&sort=issued-desc.
  • Collins, J. K., et al. “Watermelon Consumption Increases Plasma Arginine Concentrations in Adults.” Nutrition, vol. 23, no. 3, 2007, pp. 261–266.
  • FAO. Production and Utilization of Watermelon in Tropical Regions. Food and Agriculture Organization, 2018.
  • Nimed Health. “Amazing Health Benefits of Watermelon (Citrullus lanatus).” Nimed Health Blog, 3 Dec. 2019, https://nimedhealth.com.ng/2019/12/03/amazing-health-benefits-of-watermelon-citrullus-lanatus/?amp.
  • Paris, Harry S. “Origin and Emergence of the Sweet Dessert Watermelon, Citrullus lanatus.” Annals of Botany, vol. 116, no. 2, 2015, pp. 133–48. 
  • Perkins-Veazie, Penelope, et al. “Watermelon: Nutrition and Health Benefits.” Horticultural Reviews, vol. 36, 2009, pp. 231–264.
  • Tarazona-Díaz, María P., et al. “Watermelon Juice: Potential Functional Drink for Sore Muscle Relief.” Journal of Agricultural and Food Chemistry, vol. 61, no. 31, 2013, pp. 7522–7528.
  • United States Department of Agriculture (USDA). “Watermelon, Raw.” FoodData Central, 2019.
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  • Younus, Iqra, et al. “Cumulative Hepatoprotective, Antihyperlipidemic and Antioxidant Effects of Methanolic Seeds Extract of Citrullus lanatus, Cucumis melo, Cucumis sativus, and Cucurbita maxima With GC–MS Profile.” Food Science & Nutrition, vol. 13, no. 1, 2025. Wiley Online Library, https://onlinelibrary.wiley.com/doi/full/10.1002/fsn3.70358.