Watermelon is rich in carotenoids. Some of the carotenoids in watermelon include lycopene, phytofluene, phytoene, beta-carotene, lutein, and neurosporene. Lycopene makes up the majority of the carotenoids in watermelon. The carotenoid content varies depending on the variety of the watermelon. Depending on the variety, carotenoid content in red fleshed watermelon varies from 37 – 121 mg/kg fresh weight, where as lycopene varies from 35 – 112 mg/kg fresh weight.

Carotenoids have antioxidant activity, free-radical scavenging property. Several researches have reported an association between dietary lycopene consumption and lower incidence in diseases such as prostate and oral cancers. Lycopene may also help reduce risks of cardiovascular disease.

Watermelon seeds are excellent sources of protein (both essential and non-essential amino acids) and oil. Watermelon seed is about 35% protein, 50% oil, and 5% dietary fiber. Watermelon seed is also rich in micro- and macro-nutrients such as magnesium, calcium, potassium, iron, phosphorous, zinc etc.

Besides, the red flesh, in the Arab world, salted and roasted watermelon seeds are also consumed as a snack.

Nutritional Facts of Watermelon

Table: List of nutrients in watermelon (flesh, raw) and their content. Nutrient values and weights are for edible portion of watermelon.

Nutrients
Units
Nutrient content per 100 grams
Water
g
91.45
Energy
kcal
30
Energy
kj
127
Protein
g
0.61
Total lipid (fat)
g
0.15
Ash
g
0.25
Carbohydrate, by difference
g
7.55
Fiber, total dietary
g
0.4
Sugars, total
g
6.20
Sucrose
g
1.21
Glucose (dextrose)
g
1.58
Fructose
g
3.36
Lactose
g
0.00
Maltose
g
0.06
Galactose
g
0.00
Starch
g
0.00
Minerals
Calcium, Ca
mg
7
Iron, Fe
mg
0.24
Magnesium, Mg
mg
10
Phosphorus, P
mg
11
Potassium, K
mg
112
Sodium, Na
mg
1
Zinc, Zn
mg
0.10
Copper, Cu
mg
0.042
Manganese, Mn
mg
0.038
Fluoride, F
mcg
1.5
Selenium, Se
mcg
0.4
Vitamins
Vitamin C, total ascorbic acid
mg
8.1
Thiamin
mg
0.033
Riboflavin
mg
0.021
Niacin
mg
0.178
Pantothenic acid
mg
0.221
Vitamin B-6
mg
0.045
Folate, total
mcg
3
Folic acid
mcg
0
Folate, food
mcg
3
Folate, DFE
mcg_DFE
3
Choline, total
mg
4.1
Betaine
mg
0.3
Vitamin B-12
mcg
0.00
Vitamin B-12, added
mcg
0.00
Vitamin A, IU
IU
569
Vitamin A, RAE
mcg_RAE
28
Retinol
mcg
0
Vitamin E (alpha-tocopherol)
mg
0.05
Vitamin E, added
mg
0.00
Tocopherol, beta
mg
0.00
Tocopherol, gamma
mg
0.00
Tocopherol, delta
mg
0.00
Vitamin K (phylloquinone)
mcg
0.1
Fatty acids (Lipids)
Fatty acids, total saturated
g
0.016
4:0
g
0.000
6:0
g
0.000
8:0
g
0.000
10:0
g
0.001
12:0
g
0.001
14:0
g
0.000
16:0
g
0.008
18:0
g
0.006
Fatty acids, total monounsaturated
g
0.037
16:1 undifferentiated
g
0.000
18:1 undifferentiated
g
0.037
20:1
g
0.000
22:1 undifferentiated
g
0.000
Fatty acids, total polyunsaturated
g
0.050
18:2 undifferentiated
g
0.050
18:3 undifferentiated
g
0.000
18:4
g
0.000
20:4 undifferentiated
g
0.000
20:5 n-3
g
0.000
22:5 n-3
g
0.000
22:6 n-3
g
0.000
Cholesterol
mg
0
Phytosterols
mg
2
Amino acids
Tryptophan
g
0.007
Threonine
g
0.027
Isoleucine
g
0.019
Leucine
g
0.018
Lysine
g
0.062
Methionine
g
0.006
Cystine
g
0.002
Phenylalanine
g
0.015
Tyrosine
g
0.012
Valine
g
0.016
Arginine
g
0.059
Histidine
g
0.006
Alanine
g
0.017
Aspartic acid
g
0.039
Glutamic acid
g
0.063
Glycine
g
0.010
Proline
g
0.024
Serine
g
0.016
Other nutrients
Alcohol, ethyl
g
0.0
Caffeine
mg
0
Theobromine
mg
0
Carotene, beta
mcg
303
Carotene, alpha
mcg
0
Cryptoxanthin, beta
mcg
78
Lycopene
mcg
4532
Lutein + zeaxanthin
mcg
8
Watermelon nutritional facts source: USDA National Nutrient Database for Standard Reference, Release 19 (2006)

Watermelon related:
Nutritional value of watermelon seeds
Eating watermelon increases arginine level

Antioxidant and fruits related articles:
Goji berry antixoxidant activity and health benefits
Blueberry antioxidant and health benefits
Pomegranate juice: antioxidant source
Apple fruit, juice (cider) and health benefits on cancer, diabetes, and cardiovascular diseases

References:

Perkins-Veazie, P.; Collins, J. K.; Davis, A. R.; Roberts, W. 2006. Carotenoid Content of 50 Watermelon Cultivars. J. Agric. Food Chem.; (Article); 2006; 54(7); 2593-2597.

El-Adawy, T. A.; Taha, K. M. Characteristics and Composition of Watermelon, Pumpkin, and Paprika Seed Oils and Flours. J. Agric. Food Chem.; (Article); 2001; 49(3); 1253-1259.