Watermelon Seeds - Beneficial Foods

Table of Contents

1. Introduction
2. A Snack in China, the Middle East and West Africa
3. What the Seed Is: Snack Watermelons and Egusi
4. Nutritional Profile
5. Protein and Amino Acids
6. The Oil: Mostly Linoleic Acid
7. Magnesium, Iron, Zinc and Phosphorus
8. What the Research Actually Shows
9. Seed Oil and Blood Fats in Rats
10. The Citrulline Mix-Up: Fruit Research Is Not Seed Research
11. Roasting, Sprouting, Buying and Storing
12. Amounts Used in Studies
13. Who the Research Raises Cautions For
14. Connections
15. Key Research Papers
16. Featured Videos

Introduction

Most people in Europe and North America think of watermelon seeds as something to spit out, or as the thing seedless watermelons were bred to get rid of. Across much of the rest of the world they are a food in their own right. In China, roasted watermelon seeds are cracked between the teeth by the bagful; in the Middle East and Iran they sit in bowls beside nuts and tea; and in West Africa the seeds of watermelon-type melons, ground into a meal called egusi, thicken some of the region's best-known soups.

Nutritionally, the shelled kernel is a dense little package: by the USDA's figures, about 28 grams of protein and 47 grams of fat per 100 grams, with large amounts of magnesium, zinc, iron and phosphorus. Those numbers are solid, because they come from direct laboratory measurement of the food.

What is not solid is the long list of health claims that circulates online. When the published research on watermelon seeds is actually read, it turns out to be almost entirely composition analysis, food-technology work, studies in rats and studies in cell culture. There are no controlled trials in people that test eating watermelon seeds and measure a health outcome. This page lays out the composition, the traditional uses and the laboratory findings, and labels each kind of study for what it is.

A Snack in China, the Middle East and West Africa

China: guazi and the seed-snack watermelon

In Chinese, guazi (瓜子, "melon seeds") is the general word for roasted snack seeds — today usually sunflower, pumpkin or watermelon. China grows a dedicated watermelon variety, known as ZiGua, purely for its seeds. A 2023 note in the Cucurbit Genetics Cooperative Report by the botanist Susanne Renner describes it: the fruits carry large, numerous red or black seeds, which "are eaten lightly salted, roasted, or sometimes coated in licorice extract," while the rind and pulp have traditionally been discarded. Black-seeded types are grown mainly in northwest China (Gansu, Xinjiang, Inner Mongolia and Ningxia), and red-seeded types are more popular in the south. The same note reports that the area planted to seed watermelons rose from about 140,000 hectares in 1996 to 320,000 hectares by 2015, and that the variety is thought to have been cultivated for some 350 years (Renner, Cucurbit Genetics Cooperative Report 46, 2023).

Eating seeds this way is slow and social. The shell is cracked with the front teeth, the kernel extracted with the tongue, and the shell discarded — a habit that makes a handful last a long time, and bowls of seeds are a familiar sight when guests visit.

The Middle East and Iran

Roasted, salted watermelon seeds are a familiar snack across the eastern Mediterranean, Egypt, the Gulf and Iran, sold in markets alongside pumpkin and sunflower seeds and eaten in the shell in the same crack-and-discard style. As in China, the seeds are usually roasted with salt, which matters for anyone tracking sodium (see the cautions below).

West Africa: egusi

In West Africa the seeds are not a nibble but a staple ingredient. The US National Research Council's Lost Crops of Africa, Volume II: Vegetables (2006), chapter "Egusi" describes how the shelled seeds are ground coarsely to thicken stews and soups, made into steamed dumplings, fermented into a seasoning, and roasted into a spread similar to peanut butter. It notes that "in West Africa, a region where soups are integral to life, they are a major soup ingredient and a common component of daily meals," and lists Mali, Burkina Faso, Ghana, Benin, Nigeria and Cameroon among the main growing countries. A study of watermelon genetics adds that the egusi seed type is "widely cultivated in Nigeria for the high protein and carbohydrate content of the edible seeds" (Gusmini 2004).

What the Seed Is: Snack Watermelons and Egusi

The watermelon is Citrullus lanatus, a member of the gourd family (Cucurbitaceae), the same family as pumpkins, squash, cucumbers and melons. Its seed has two parts: a hard outer hull (the part spat out or cracked off) and the pale inner kernel, which holds almost all of the protein and oil. The USDA figures on this page are for the dried kernel, with the hull removed.

The white, soft "seeds" in a seedless watermelon are a different thing again: they are immature seed coats that never developed, not edible mature seeds, and they are not what the snack or the research is about.

Which plant is "egusi"?

This is where the research gets confusing, and it matters when reading studies. The word egusi is used for the seeds of several different gourd-family plants. The Lost Crops of Africa chapter says the name applies primarily to a watermelon type, Citrullus lanatus, but also to seeds of Cucumeropsis mannii, the bottle gourd Lagenaria siceraria and the fluted pumpkin Telfairia occidentalis, observing that "the name egusi is applied generally to any of several similar looking seeds."

Within the watermelon itself, "egusi" also names a specific seed type. Plant geneticists at North Carolina State University found that the egusi seed — a seed with an unusual thick, fleshy coating that appears in the second to third week of fruit development — is controlled by a single recessive gene, which they named eg (Gusmini 2004). A USDA genebank survey of watermelon seed found that these egusi types carried markedly more oil than ordinary watermelon seed (an average of 35.6% versus about 23%) and had a lower ratio of hull to kernel — more food, less shell (Jarret 2012). Some botanists now place the West African "seed watermelon" in its own species, Citrullus mucosospermus, a name used in recent laboratory work on the plant (Fujita 2025).

Studies also use older or looser names. A contamination study of egusi bought in Ireland and the UK, for instance, identifies its samples as "Colocynthis citrullus L." (Somorin 2016), while research on "melon seed" from Cucumis melo (cantaloupe-type melons) concerns a different plant altogether. Wherever this page reports a study, it names the species the authors said they used.

Nutritional Profile

The figures below are from the USDA FoodData Central entry "Seeds, watermelon seed kernels, dried" (FDC ID 169407, SR Legacy). The 1-ounce column (28.35 g) is calculated from the 100 g values. One ounce is roughly a small handful of shelled kernels. The "daily value" shares use the US FDA daily values for adults (protein 50 g, magnesium 420 mg, iron 18 mg, zinc 11 mg, phosphorus 1,250 mg, potassium 4,700 mg, copper 0.9 mg, manganese 2.3 mg) and are rounded.

Energy and macronutrients

The USDA entry does not give a usable dietary-fiber figure for the hulled kernel, so none is listed here. Most of the seed's fiber is in the hull, which is usually discarded.

Minerals

B vitamins

In short: per ounce, the shelled kernel offers about as much protein as an egg and a little more, over a third of a day's magnesium, a quarter of a day's zinc, and a modest amount of iron — in about 158 calories, most of them from fat. It is not a notable source of vitamins.

Protein and Amino Acids

At 28 grams of protein per 100 grams, the dried kernel is in the same range as pumpkin seeds and peanuts, and well above most tree nuts. The USDA amino-acid figures for the same entry list arginine as one of the most abundant amino acids, at roughly 4.9 grams per 100 grams of kernel. Arginine is the amino acid the body uses to make nitric oxide, a molecule that relaxes blood vessels; see Arginine.

Food scientists have looked at the seed as a possible plant-protein ingredient, often using the seeds left over from juice processing:

• Protein concentrate (lab study). A Polish team extracted a protein concentrate from defatted watermelon seeds that was 82.5% protein and 1.5% fat. It dissolved well at high pH and absorbed water and oil, but foamed and emulsified poorly — properties that decide what foods it could be used in (Hahn 2025).
• Protein fractions (lab and cell study). Researchers in India separated the seed protein into its four classical fractions (albumins, globulins, prolamins and glutelins), measured their amino-acid make-up, and tested them in the test tube: the prolamin fraction slowed the growth of the bacterium Acinetobacter baumannii, and the globulin fraction showed the strongest antioxidant activity in chemical assays (Dash 2017). These are test-tube results only; they say nothing about what happens when the seeds are eaten.
• Seed flour in baking (food-technology study). Watermelon seed flour and the "pomace" left after pressing oil were added to wheat flour at 10–30% and improved several dough-handling measurements; the seed materials had about double the protein of teff flour (Jaroszewska 2023).

None of these studies measured how well people digest or use watermelon seed protein. That question — protein digestibility in humans — is not answered by the papers in this page's research list.

The Oil: Mostly Linoleic Acid

Almost half the kernel's weight is oil, and most of that oil is polyunsaturated. The main fatty acid is linoleic acid, the omega-6 fat that also dominates sunflower, corn and grapeseed oils. The USDA lists about 28 grams of linoleic acid per 100 grams of kernel.

The largest survey of watermelon seed oil comes from the USDA's plant genebank in Georgia. Researchers measured the oil in intact seed from 475 genebank samples and the fatty acids in 96 of them (Jarret 2012):

• Seed oil content ranged from 14.8% to 43.5% across all the plant material tested.
• Egusi-type watermelon seed averaged 35.6% oil, significantly more than ordinary sweet watermelon seed (23.2%) or the citron-type watermelon (22.6%).
• Linoleic acid was the main fatty acid in every watermelon sample, at 43.6–73% of the fat. Wild relatives tested for comparison, including the bitter colocynth, were similarly high.
• Nearly all samples contained only traces (under 0.5%) of arachidonic acid.

A Nigerian analysis of the seed oil reported the same pattern: linoleic acid at about 52%, a sixteen-carbon fatty acid at about 21% and oleic acid (the main fat of olive oil) at about 10% (Eke 2021).

Watermelon seed oil contains essentially no omega-3 fat. Whether a diet high in linoleic acid is helpful, neutral or harmful is one of the more argued questions in nutrition; the Seed Oils page covers that debate. Eaten as whole seeds by the handful, the amounts are far smaller than those supplied by cooking oils.

Magnesium, Iron, Zinc and Phosphorus

The mineral content is the most clearly established nutritional strength of the seed, because it rests on direct measurement rather than on biological studies.

• Magnesium. At 515 mg per 100 g (146 mg per ounce), the dried kernel is among the richest common food sources of magnesium, a mineral used in hundreds of enzyme reactions, in muscle and nerve function and in bone.
• Zinc. At 10.2 mg per 100 g, roughly 2.9 mg per ounce. Zinc is needed for immune function, wound healing, taste and the activity of many enzymes.
• Iron. At 7.3 mg per 100 g, about 2.1 mg per ounce. This is plant (non-heme) iron, which the body absorbs less efficiently than the heme iron in meat; vitamin C eaten at the same meal increases its absorption.
• Phosphorus. At 755 mg per 100 g. Phosphorus is plentiful in most diets; for people with kidney disease it is a mineral that is often restricted (see the cautions).

Independent lab work agrees that the seed is mineral-dense. The Polish baking study measured, in the pressed seed "pomace," 7.5 g of phosphorus, 1.7 g of magnesium, 124 mg of iron and 27 mg of zinc per kilogram (Jaroszewska 2023). The same study found the seed materials' total polyphenols were low (under 2 mg gallic-acid equivalents per gram) and their antioxidant capacity correspondingly low — a useful corrective to claims of the seed as an "antioxidant powerhouse." The pomace did contain melatonin, at 60 micrograms per kilogram.

One factor the USDA figures do not capture is phytic acid, a compound in most seeds, nuts and grains that binds zinc, iron and calcium and reduces how much is absorbed. None of the studies in this page's research list measured phytic acid in watermelon seed or tested how much of the seed's zinc and iron people actually absorb.

What the Research Actually Shows

The studies most often cited for watermelon seed "benefits" fall into four groups. Sorted by type, the picture is clear:

The human watermelon trials that do exist test the fruit — its flesh, juice or rind — not the seed (see the citrulline mix-up below). A broad 2024 review of foods marketed as "superfoods," which included watermelon and several seeds, concluded that although many such foods are sought out by consumers, "scientific evidence for their beneficial effectiveness and their 'superpower' are yet to be provided" (Hassoun 2024).

So the honest summary is that watermelon seeds are a nutritious food by composition — protein, magnesium, zinc, iron — and that specific claims about blood sugar, cholesterol, heart health, skin, hair or fertility are not backed by studies in people who ate the seeds.

The skin-cell study

One recent study is sometimes quoted for skin. Japanese researchers isolated a compound called coniferyl alcohol from an extract of the fruit of the West African seed watermelon (Citrullus mucosospermus) and found that, at 300 micromolar, it roughly doubled (about 2.2-fold) fat production in human sebaceous-gland cells grown in a dish when those cells were stimulated with linoleic acid (Fujita 2025). The authors proposed it as a cosmetic ingredient for dry skin; the paper declares that two authors were employed by a company that grows the plant. It is a cell-culture study of a fruit extract, not a study of eating seeds.

Seed Oil and Blood Fats in Rats

The most-quoted "health" study of watermelon seed is a rat study from Nigeria (Eke 2021). Researchers analysed the seeds, pressed out the oil and gave the oil to rats by mouth for 28 days. They reported:

• No sign of toxicity at the highest dose tested, 50 ml of oil per kilogram of body weight — an enormous amount by human food standards.
• Lower blood cholesterol, triglycerides and LDL cholesterol, and higher HDL cholesterol, in treated rats.
• Lower levels of the liver enzyme ALT and of MDA (a marker of fat oxidation), and higher levels of the antioxidant enzymes SOD and catalase.
• Better blood-sugar handling in a glucose-tolerance test.

The authors concluded the seeds and oil "could have a beneficial effect on man" but also called for further studies on the oil's biological activity and long-term safety. These are results in rats given extracted oil; they have not been tested in people eating the seeds.

A second rat study pointed the other way. Rats were fed diets containing 2.5% or 5% watermelon seed for 21 days (Oyenihi 2022). Blood cholesterol, triglycerides and liver enzymes did not change. Male rats lost body weight; testis weights rose and ovary weights fell; blood urea and creatinine — markers of kidney function — rose significantly in both sexes; and sperm abnormalities were seen. The authors concluded that the seed diet "may elicit negative effects in organs particularly on the kidney and testes in rats."

Two short rat studies with opposite-leaning results, using different preparations (pressed oil versus whole seed in the diet), are the full extent of the animal evidence in this page's research list. Neither can show what a handful of roasted seeds does for a person.

The Citrulline Mix-Up: Fruit Research Is Not Seed Research

Watermelon is famous in nutrition research for citrulline, an amino acid the body converts into arginine and then nitric oxide. Articles about watermelon seeds often borrow this research. It does not belong to the seed. The citrulline studies use the red flesh, juice or rind:

• Flesh (puree). Overweight and obese postmenopausal women given 100% watermelon puree daily for 6 weeks had a 6% fall in sVCAM-1, a blood marker linked to hardening of the arteries, and higher blood arginine and lycopene; blood sugar, insulin and insulin resistance did not differ from controls (Shanely 2020).
• Juice concentrate. In 15 resistance-trained men, a watermelon juice concentrate supplying 2.2 g of citrulline a day did not improve strength, bench-press performance or blood-vessel diameter compared with placebo, apart from a small difference in muscle oxygenation (Gonzalez 2022).
• Rind. In 11 young adults, a single 30 g dose of microencapsulated watermelon rind containing 4 g of citrulline improved flow-mediated dilation (a measure of how well an artery widens) at 60 minutes, without changing tissue oxygen levels (Volino-Souza 2023).

None of these trials used seeds, and the USDA does not report citrulline as a notable component of the seed kernel. The seed's own nitric-oxide connection, if any, would come through its arginine content — and that has not been tested in a trial either. For the fruit research in full, see Watermelon and Watermelon: Citrulline and Blood Flow.

Roasting, Sprouting, Buying and Storing

Roasting

Roasting is the traditional way the seeds are eaten in China and the Middle East, usually with salt. Roasting dries the seed, develops flavour and makes the hull brittle enough to crack. Commercial snack seeds are sold both in the shell and shelled; the shell itself is generally cracked off and discarded rather than eaten, though some people swallow seeds whole. In West Africa the seeds are shelled and ground raw or lightly toasted for soup.

Roasting high-linoleic seeds at high heat can begin to oxidize their fat, which shows up as a bitter or stale taste. None of the studies in this page's research list measured how roasting changes the seed's nutrients.

Sprouting

"Sprouted" watermelon seeds are marketed with claims that sprouting increases protein or reduces anti-nutrients such as phytic acid. Sprouting does change the chemistry of many seeds and grains, but no study in this page's research list measured sprouted watermelon seed in particular, so these claims cannot be confirmed here. Sprouted seeds of any kind, kept warm and moist, are also a known setting for bacterial growth.

Buying and storing

• Salt. Many roasted snack seeds are heavily salted; the USDA's 99 mg of sodium per 100 g is for unsalted kernels, and salted products can carry many times that.
• Mould and mycotoxins. Like peanuts and other oil seeds, melon seeds can carry aflatoxins — toxins made by moulds during warm, damp drying and storage. In a survey of egusi melon seed sold and stored in Ireland and the UK, aflatoxin B1 was found in every sample, and 68% exceeded the EU limit of 2 micrograms per kilogram for oilseeds; retail samples were more contaminated than household ones (Somorin 2016). Mouldy, shrivelled or discoloured seed is the visible end of this problem; aflatoxins themselves cannot be seen or tasted. See Mould and Mycotoxins and Peanuts: Aflatoxin and Safe Sourcing.
• Rancidity. With nearly half their weight as polyunsaturated oil, shelled kernels go rancid faster than seeds in the shell. Cool, dark, airtight storage slows this; refrigeration or freezing slows it further.

Amounts Used in Studies

Because there are no human trials of watermelon seeds, there is no studied human "dose." The amounts in the literature are:

• Rats, whole seed: 2.5% or 5% of the diet, eaten freely for 21 days (Oyenihi 2022).
• Rats, seed oil: up to 50 ml per kilogram of body weight by mouth, over 28 days (Eke 2021).
• Baking: watermelon seed flour or pomace replacing 10–30% of wheat flour (Jaroszewska 2023).

For reference only, the USDA's standard serving size for comparison is 1 ounce (28 g) of dried kernels — about 158 calories. Typical snacking amounts vary widely, and seeds eaten in the shell give much less kernel per handful than the shelled weight suggests.

Who the Research Raises Cautions For

• People with kidney disease. The kernel is high in phosphorus (755 mg per 100 g) and potassium (648 mg per 100 g), two minerals commonly restricted in chronic kidney disease, and salted snack seeds add sodium. Separately, the one rat feeding study found rises in urea and creatinine, markers of kidney strain, at 2.5–5% of the diet (Oyenihi 2022). That is an animal finding, not evidence of harm in people, but it is the only toxicity feeding study in the list. See Kidney Disease.
• Male fertility questions. The same rat study reported sperm abnormalities and altered testis weight at high dietary levels (Oyenihi 2022). This has not been studied in men. It contrasts with online claims that the seeds boost fertility, for which no human evidence was found.
• People eating stored or imported egusi regularly. The aflatoxin survey above found widespread contamination of egusi above the EU limit (Somorin 2016). Aflatoxin B1 is a recognised liver carcinogen, and regular intake matters most where diets already include other contaminated staples such as maize and groundnuts.
• People watching sodium or calories. Roasted snack seeds are often heavily salted, and at about 158 calories per ounce of kernel the energy adds up quickly when seeds are eaten by the bowl.
• Allergy. No allergy study of watermelon seed is in this page's research list, so how often watermelon seed causes allergic reactions is not reported here; see Food Allergy.
• Pregnancy and young children. There is no safety data from human studies on watermelon seed in pregnancy. Whole hard seeds are a choking hazard for young children, as with nuts.

This is general food information, not medical advice. Decisions about diet in kidney disease, pregnancy or allergy belong with a clinician.

Connections

• Seeds — all the seed pages
• Watermelon — the fruit, its flesh and rind
• Watermelon: Citrulline and Blood Flow — the fruit research, which is not about the seed
• Pumpkin Seeds — the closest relative, also a gourd seed rich in magnesium and zinc
• Sunflower Seeds — the other guazi, also high in linoleic acid
• Sesame Seeds
• Chia Seeds
• Peanuts — similar protein and the same aflatoxin issue
• Magnesium
• Zinc
• Iron
• Arginine
• Citrulline
• Seed Oils — the linoleic-acid debate
• Mould and Mycotoxins
• Kidney Disease

Key Research Papers

1. Gusmini G, Wehner TC, Jarret RL. Inheritance of egusi seed type in watermelon. The Journal of heredity. 2004;95(3):268-70. PubMed PMID: 15220396
2. Jarret RL, Levy IJ. Oil and fatty acid contents in seed of Citrullus lanatus Schrad. Journal of agricultural and food chemistry. 2012;60(20):5199-204. PubMed PMID: 22540530
3. Eke R, Ejiofor E, Oyedemi S, et al. Evaluation of nutritional composition of Citrullus lanatus Linn. (watermelon) seed and biochemical assessment of the seed oil in rats. Journal of food biochemistry. 2021;45(6):e13763. PubMed PMID: 34002399
4. Oyenihi OR, Afolabi BA, Oyenihi AB, et al. Toxicity assessment of watermelon seed supplemented diet in rats. Drug and chemical toxicology. 2022;45(4):1891-1898. PubMed PMID: 33682546
5. Jaroszewska A, Jedrejek D, Sobolewska M, et al. Mineral, Nutritional, and Phytochemical Composition and Baking Properties of Teff and Watermelon Seed Flours. Molecules (Basel, Switzerland). 2023;28(7). PubMed PMID: 37050018
6. Hahn A, Liszka J, Maksym J, et al. Preliminary Data of the Nutritive, Antioxidative, and Functional Properties of Watermelon (Citrullus lanatus L.) Flour and Seed Protein Concentrate. Molecules (Basel, Switzerland). 2025;30(1). PubMed PMID: 39795237
7. Dash P, Ghosh G. Fractionation, amino acid profiles, antimicrobial and free radical scavenging activities of Citrullus lanatus seed protein. Natural product research. 2017;31(24):2945-2947. PubMed PMID: 28393615
8. Somorin Y, Akinyemi A, Bertuzzi T, et al. Co-occurrence of aflatoxins, ochratoxin A and citrinin in "egusi" melon (Colocynthis citrullus L.) seeds consumed in Ireland and the United Kingdom. Food additives & contaminants. Part B, Surveillance. 2016;9(3):230-5. PubMed PMID: 27134068
9. Fujita S, Inoue S, Zouboulis CC, et al. Seed Watermelon (Citrullus mucosospermus (Fursa))-Derived Coniferyl Alcohol as a Functional Ingredient in Remedies for Dry Skin: Evidence of Facilitated Lipogenesis in Human Sebocytes. Molecules (Basel, Switzerland). 2025;30(16). PubMed PMID: 40871513
10. Hassoun A, Harastani R, Jagtap S, et al. Truths and myths about superfoods in the era of the COVID-19 pandemic. Critical reviews in food science and nutrition. 2024;64(3):585-602. PubMed PMID: 35930325
11. Shanely RA, Zwetsloot JJ, Jurrissen TJ, et al. Daily watermelon consumption decreases plasma sVCAM-1 levels in overweight and obese postmenopausal women. Nutrition research (New York, N.Y.). 2020;76:9-19. PubMed PMID: 32142970
12. Gonzalez AM, Pinzone AG, Lipes SE, et al. Effect of watermelon supplementation on exercise performance, muscle oxygenation, and vessel diameter in resistance-trained men. European journal of applied physiology. 2022;122(7):1627-1638. PubMed PMID: 35429293
13. Volino-Souza M, de Oliveira GV, Conte-Junior CA, et al. Effect of microencapsulated watermelon (Citrullus Lanatus) rind on flow-mediated dilation and tissue oxygen saturation of young adults. European journal of clinical nutrition. 2023;77(1):71-74. PubMed PMID: 36109652

PubMed Topic Searches

1. Watermelon seed composition
2. Egusi melon seed
3. Watermelon seed oil
4. Melon seed aflatoxin
5. Watermelon seed protein

Featured Videos