Watermelon rind: what research says about the part most people throw away

On 7 April 2026 the lifestyle desk of the Bengali news site Jagonews24 published a report urging readers to think again before dropping watermelon rind into the bin after eating the fruit. The report, which credited the US health website Verywell Health for its information, said the rind, the firm pale layer between the red flesh and the green skin, holds fibre, vitamins A, C and B6, potassium and amino acids, and that it can be eaten in smoothies, pickles, salads or curries. This account keeps the report's message and sets each of its claims beside peer-reviewed research and the advice of US health authorities published before that date. Where the research says something narrower than the report did, the narrower finding is given, and readers with a health condition are advised to ask a doctor before changing their diet.

The report began from a habit it said almost everyone shares: the rind goes straight to the dustbin. It argued that a little awareness would show that what people treat as useless can be a valuable food. It listed five groups of benefits.

• Fibre: the rind contains plenty of insoluble fibre, which the report said helps keep digestion normal, gives a feeling of fullness for longer and so can help people who want to control their weight.
• Citrulline: the report said the white part of the rind holds about 60 percent more citrulline than the red flesh, and that citrulline helps blood circulation, helps keep blood pressure under control and eases muscle pain after exercise.
• Vitamins A and C: the report described the rind as an important source of these vitamins, which it said strengthen immunity, keep skin healthy and act as antioxidants.
• The heart: it said citrulline is turned into arginine in the body, which improves the working of blood vessels, and that eating rind regularly may help lower the risk of heart disease.
• Other compounds: it said the rind contains chlorophyll and lycopene, which help reduce inflammation and fight oxidative stress.

The sections below take these claims one by one. Some are well supported by laboratory measurements, some rest on small trials that used concentrated watermelon products rather than ordinary rind, and two could not be confirmed in any source read for this report and are therefore not repeated as fact.

Watermelon, Citrullus lanatus, belongs to the gourd family, Cucurbitaceae, and is described in a 2023 study in the journal Heliyon as originally a fruit of tropical and subtropical countries. The same study put world production at almost 103 million tonnes in 2018 and called watermelon the second-largest fruit in the world by production.

Researchers divide the fruit into the outer peel or skin, the rind, the flesh and the seeds. Estimates of the rind's share differ with the variety and with how the layers are cut. The Heliyon study gave the flesh as about 68 percent of the fruit's weight, the rind about 30 percent and the seeds about 2 percent. A team at Texas Woman's University, writing in the journal Molecules in April 2022, gave the rind as approximately 40 percent and the flesh approximately 60 percent. A Spanish study of five fresh-cut cultivars, published in the Journal of the Science of Food and Agriculture in 2011, found the by-product left after cutting ranged from 31.27 to 40.61 percent of the fruit's initial fresh weight, depending on the cultivar.

The outer skin is dark green or pale green with stripes and can turn yellowish-green after ripening, the Heliyon study noted. The rind itself is about 95 percent water, which makes it spoil quickly once cut. Its taste is mild: the Texas researchers reported that consumer tests found fresh rind's sweet and sour taste and watermelon-like aroma very different from the flesh, that the rind's total aroma compounds came to only 15 percent of the flesh's, and that its aroma was fresh, green and cucumber-like. The Heliyon authors added that although the rind is edible, many people avoid it because they dislike the flavour.

What happens to the rind matters beyond the kitchen. The Texas team wrote that the rind is often discarded before serving or processing, and that the waste is sent to landfill, burned, used as animal feed or composted, all of which they described as low in value, costly or harmful to the environment. The Heliyon study described rind as frequently thrown into the environment without care.

In Bangladesh the volume of rind left over has grown with the crop. Data from the Bangladesh Bureau of Statistics (BBS), reported by The Financial Express on 23 December 2025, showed watermelon production of 1.98 million metric tonnes in fiscal year 2024-25, up from 581,677 tonnes in 2023-24, a rise the paper called nearly four-fold. The area under the crop rose to 142,817 acres from 64,718 acres, according to the same BBS data, and agricultural experts quoted by the paper said good weather and strong summer demand had led farmers, particularly in coastal and char areas, to switch from traditional cereals to watermelon.

The Business Standard reported in February 2025 that the leading watermelon districts were Patuakhali, Khulna, Bhola, Noakhali and Barguna. The same report described the crop's spread to new areas such as Jaintapur upazila in Sylhet, where, according to the local office of the Department of Agricultural Extension (DAE), 650 farmers grew watermelon on 130 hectares in six unions that season, with popular varieties including Banglalink, Anarkali and Glory.

In September 2025 the national news agency BSS, in a report carried by The Business Standard, described how saline-prone land in the Khulna region, comprising Khulna, Bagerhat, Satkhira and Narail, that had been left fallow after the Aman rice season was being planted with watermelon. Khulna DAE officials said farmers in the zone had sown 1,176.75 hectares that season, including 965.75 hectares in Khulna district, and expected 36,446 tonnes. For the 2024-25 Rabi season the DAE had set a target of 13,432 hectares, and farmers planted more than 18,000 hectares. Farmers were using mulching polythene, drip irrigation and hybrid seed, the report said, while price swings and a lack of cold storage forced many to sell quickly.

Every one of those fruits carries a rind that, by the estimates above, makes up between about 30 and 40 percent of its weight, and, as the Jagonews24 report observed, most people throw it away.

The report's claim that the rind is rich in fibre is supported by laboratory work on dried rind. A Brazilian team at Fluminense Federal University, writing in the Journal of Food Science in November 2023, turned rind into a flour and measured a fibre content of 27.15 percent. Bread in which that flour replaced 40 percent of the wheat flour contained 3.06 grams of insoluble fibre, enough, the authors said, to count as a source of fibre. A Turkish study published in the same journal in March 2025 analysed powders made from the by-products of the Crimson Sweet variety and found 48.66 percent dietary fibre in the rind powder and 78.55 percent in the powder made from the outer peel.

These figures are for dried powders. Fresh rind, being about 95 percent water, carries much less fibre in each bite, and the studies above measured rind products in the laboratory; they did not test rind as a weight-control food in people.

What fibre does in the body is set out by MedlinePlus, the consumer health service of the US National Library of Medicine, in its encyclopedia entry on fibre (reviewed in July 2024). It says dietary fibre adds bulk to the diet and, because it makes people feel full faster, can help with weight control. Fibre aids digestion and helps prevent constipation. There are two forms: soluble fibre attracts water and turns to gel during digestion, slowing it, while insoluble fibre, found in foods such as wheat bran, vegetables and whole grains, appears to speed the passage of food through the stomach and intestines and adds bulk to the stool.

MedlinePlus recommends 21 to 38 grams of fibre a day for older children, adolescents and adults, and notes that taking the peels off fruits and vegetables reduces the fibre a person gets from them. It also warns that eating a large amount of fibre in a short time can cause gas, bloating and cramps, advises adding fibre gradually over a few weeks, and says water helps fibre pass through the digestive system.

Citrulline is the compound that has drawn most scientific interest in watermelon rind. A 2022 review in the journal Nutrients, by researchers at the Federal University of Rio de Janeiro and Texas Tech University, describes it as a neutral, non-essential amino acid, one the body can make for itself. It was first isolated from watermelon, which gave it its name, after the genus Citrullus.

The review explains why citrulline matters. In the body it can be converted into another amino acid, arginine, and arginine is the raw material from which the cells lining blood vessels make nitric oxide, a molecule that regulates the tone of the vessels. The authors note that studies have found citrulline can raise blood arginine more effectively than arginine itself, because, unlike arginine, citrulline is not broken down by the enzyme arginase in the intestine and liver.

How much citrulline the rind holds compared with the flesh has been measured in several studies, and the answer depends on how it is counted.

• Scientists at the US Department of Agriculture's Agricultural Research Service, Rimando and Perkins-Veazie, reported in the Journal of Chromatography A in June 2005 that citrulline across the watermelons they tested ranged from 3.9 to 28.5 milligrams per gram of dry weight. Rind held more than flesh on a dry-weight basis, 24.7 against 16.7 milligrams per gram, but a little less on a fresh-weight basis, 1.3 against 1.9 milligrams per gram. Red-fleshed watermelons had less citrulline than yellow or orange ones.
• The Spanish study of five fresh-cut cultivars (2011) found much more citrulline in the rind than in the flesh, 3.34 against 2.33 grams per kilogram of fresh weight, and singled out Fashion, a dark-skinned seedless cultivar, as an especially good source.
• The Texas Woman's University study (2022) measured 61.4 milligrams of citrulline per 100 grams of fresh rind against 39.7 milligrams in the flesh, which the authors described as approximately a 1.5-fold difference. Arginine followed the same pattern, 53.8 against 36.7 milligrams. The rind held more free amino acids in total, 165 against 146 milligrams per 100 grams, but significantly lower amounts of the essential amino acids.

The Nutrients review also cites earlier work by Akashi and colleagues showing that the central part of the fruit has a lower citrulline concentration than the outer part, the rind. Taken together, the studies support the report's point that the rind is a rich source of citrulline. The precise figure of about 60 percent more than the flesh was not found in the studies read for this report; their own comparisons range from more on a dry-weight basis but slightly less on a fresh-weight basis, in the 2005 USDA study, to about one and a half times, in the 2022 study.

The report linked citrulline to better circulation, lower blood pressure, a healthier heart and less muscle pain after exercise. The research supports a narrower version of these claims.

The 2022 Nutrients review concluded that watermelon products such as juice, extract, powder and puree can lower blood pressure and arterial stiffness when they contain enough citrulline, particularly in people with cardiometabolic risk factors. But it also reported divergent findings: studies that found no benefit had given low doses of citrulline, and in some cases more than 700 millilitres of watermelon would be needed to reach a useful dose. For that reason the authors called for food technologies that concentrate the fruit's compounds into a smaller volume.

Two small trials have tested rind directly.

• At the Illinois Institute of Technology, six overweight or obese adults were given 100 kilocalories of watermelon flesh, rind or seeds, or a control meal, in a pilot study published in the Journal of Agricultural and Food Chemistry in 2020. Blood citrulline peaked significantly higher after the flesh and rind meals than after the control, but flow-mediated dilation, a standard measure of how well the lining of the arteries works, was not different among the test meals.
• In Brazil, 11 healthy young adults took 30 grams of microencapsulated watermelon rind powder containing 4 grams of citrulline, or a placebo, in a trial reported in the European Journal of Clinical Nutrition (published online in September 2022). Flow-mediated dilation improved 60 minutes after the rind powder, and blood citrulline rose, but tissue oxygen saturation did not change. The authors concluded that a single dose with 4 grams of citrulline seemed adequate to improve the measure in healthy adults.

On muscles, a study at the Technical University of Cartagena in Spain, published in the Journal of Agricultural and Food Chemistry in August 2013, gave seven athletes 500 millilitres of natural watermelon juice containing 1.17 grams of citrulline, a juice enriched with extra citrulline, or a placebo, in a maximum-effort test on a cycle ergometer. Both watermelon juices helped reduce the recovery heart rate and muscle soreness 24 hours later. That study used juice, not rind.

None of the studies read for this report tested whether eating rind regularly lowers the risk of heart disease, so that claim is not repeated here. The trials were small and short, and the positive results came from concentrated products or juice in measured doses. Anyone with high blood pressure or heart disease, or who takes regular medicine, should ask a doctor before changing their diet or taking any citrulline or watermelon supplement, and should not replace prescribed treatment with food.

The report called the rind an important source of vitamins A and C. MedlinePlus lists watermelon among the fruits with the highest vitamin C content in its entry on the vitamin (reviewed in January 2025), though measurements of vitamins in the rind itself were not found in the sources read for this report. MedlinePlus explains that vitamin C is needed for the growth and repair of tissues in all parts of the body: it is used to form collagen, a protein used to make skin, tendons, ligaments and blood vessels, to heal wounds and to help the body absorb iron. It is one of many antioxidants. The body cannot make or store it, so it must come from food, and raw fruits and vegetables are the best sources because cooking and long storage reduce it.

Vitamin A, according to MedlinePlus, helps form and maintain healthy teeth, bones, soft tissue, mucous membranes and skin, and promotes good eyesight, especially in low light. Plants supply it as provitamin A carotenoids such as beta-carotene, which the body converts into the vitamin, and the deeper or brighter the colour of a fruit or vegetable, the more carotenoids it usually holds.

Measurements of the rind itself give a mixed picture on antioxidants. The 2011 Spanish study found that the watermelon cultivars it tested were poor sources of total antioxidant capacity, and that rind and flesh were similar, at 46.96 and 43.46 milligrams of ascorbic acid equivalent per kilogram. The rind did have a moderate phenolic content, higher than the flesh's, at 458 against 389 milligrams of chlorogenic acid equivalent per kilogram. The Heliyon study measured total phenolics of 35.83 milligrams and total flavonoids of 8.71 milligrams per 100 grams in fresh rind, and found that both fell when the rind was turned into sugar-dried candy.

On minerals, the 2025 Turkish study found potassium and magnesium in much greater amounts than iron and sodium in all the watermelon by-product powders, and more potassium and magnesium in the rind powder than in the peel or seed powders. On lycopene, a 2025 review by researchers at Clemson University in the journal Frontiers in Genetics explains that lycopene is the main carotenoid of red-fleshed watermelon, making up as much as 97 percent of its carotenoids, and gives the flesh its colour. The report's statement that the rind holds chlorophyll and lycopene that reduce inflammation was not confirmed in the sources read for this report and is left out.

The rind has long been eaten in some places. The Heliyon authors note that watermelon rind is typically consumed as pickles in the southern United States and is also used in jellies, fruit preserves and conserves. The Texas team listed rind pickles and jams, rind powder in cakes, cookies, noodles and meat patties, and the extraction of pectin, a setting agent, from the rind. Its own earlier consumer tests had found a juice with 20 percent rind blended into the flesh acceptable to tasters.

Researchers in Iran, writing in Heliyon in June 2023, made a rind candy by soaking pieces in sugar syrup before drying them. Tasters preferred the sample soaked for five hours in a 70 percent syrup and dried at 40 degrees Celsius, and the authors suggested the product could serve as a snack with a long shelf life, though the process reduced its antioxidant activity from 61 to 40 percent.

The Jagonews24 report suggested smoothies, pickles, salads and curries. For a pickle that keeps, the US National Center for Home Food Preservation, based at the University of Georgia, publishes a tested recipe for watermelon rind pickles, taken from its guide So Easy to Preserve (6th edition, 2014). Its main steps are:

• Ingredients: about 3 quarts (about 6 pounds) of rind, three-quarters of a cup of salt, 3 quarts of water for the brine, 2 trays of ice cubes, 9 cups of sugar, 3 cups of white vinegar of 5 percent acidity, 3 cups of water, a tablespoon of whole cloves, six one-inch pieces of cinnamon stick and one thinly sliced lemon with the seeds removed. The yield is about four or five pints.
• Trim the pink flesh and the outer green skin from thick rind and cut it into one-inch squares.
• Cover with a brine of the salt and 3 quarts of cold water, add the ice and leave for three to four hours; drain and rinse in cold water.
• Cover with cold water and cook until fork-tender, about 10 minutes, without overcooking; drain.
• Boil the sugar, vinegar, water and spices, tied in a clean thin white cloth, for five minutes; pour over the rind, add the lemon slices and leave overnight in the refrigerator.
• Heat the rind in the syrup to boiling and cook slowly for one hour, then pack hot into clean hot pint jars with a piece of cinnamon in each, cover with boiling syrup leaving half an inch of headspace, and process in a boiling-water canner for 10 minutes at elevations up to 1,000 feet.

Eating the rind means eating the part of the fruit that touched the soil, the field and the market, so washing matters. The US Food and Drug Administration's consumer page on selecting and serving produce safely (content current as of 5 March 2024) warns that harmful bacteria in the soil or water where produce grows can contaminate fruits and vegetables, and that produce can also be contaminated after harvest, during storage or preparation.

The FDA advises the following:

• Wash hands for at least 20 seconds with soap and warm water before and after preparing produce.
• Cut away damaged or bruised areas, and throw away produce that looks rotten.
• Wash produce thoroughly under running water; do not use soap, detergent or commercial produce wash, which the fruit can absorb.
• Wash produce even when the skin will not be eaten, so that dirt and bacteria are not carried from the surface to the inside by the knife.
• Scrub firm produce, such as melons and cucumbers, with a clean produce brush, then dry it with a clean cloth or paper towel.
• Buy cut produce, such as half a watermelon, only if it has been kept refrigerated or on ice, and refrigerate all cut produce; cooking kills harmful bacteria.

For cooking, the outer green skin is usually trimmed off and the pale rind used, as in the pickle recipe above. Because the rind adds fibre, MedlinePlus's advice to increase fibre gradually and drink enough water applies to anyone who starts eating it in quantity.

Photo: Scott Bauer, USDA / Wikimedia Commons (public domain)

Sources: Jagonews24, Journal of Chromatography A (USDA Agricultural Research Service, 2005), Journal of the Science of Food and Agriculture (2011), Journal of Agricultural and Food Chemistry (2013 and 2020), Molecules (2022), Nutrients (2022), European Journal of Clinical Nutrition (2022), Heliyon (2023), Journal of Food Science (2023 and 2025), Frontiers in Genetics (2025), MedlinePlus (US National Library of Medicine), US Food and Drug Administration, National Center for Home Food Preservation (University of Georgia), The Financial Express, The Business Standard, BSS