Melon: the trials named after it are testing a capsule

Most human trials with the word melon in them are not about the fruit. They test a patented freeze-dried melon juice concentrate swallowed as a capsule, and the 2025 systematic review of 47 supplement studies on protecting skin from sunlight that lists that concentrate among the supplements assessed called the evidence base limited by small samples and short duration. Bitter melon, which appears in the same searches, is a different plant. Take those away and the fruit itself has been measured in very few ways. In 10 healthy Malaysian volunteers eating portions that carried 50 g of available carbohydrate, watermelon came out at a glycaemic index of 55, at the top of the low range, against 82 for pineapple, with each food tested once per person. Two warnings travel with that number. Watermelon is Citrullus lanatus, a different genus from the Cucumis melo of cantaloupe and honeydew, and a portion holding 50 g of carbohydrate is a much larger plate of watermelon than anyone eats by accident. What this page holds most of is safety and handling. The sharpest finding there is allergy. Among 53 adults who came to a clinic saying melon affected them, a blinded challenge confirmed 36 percent, and two of those people had respiratory symptoms and a drop in blood pressure.

The numbers, per 100 g

What your body absorbs

• In 30 stone-forming patients with low urinary citrate, 385 mL of freshly blended melon juice raised urinary citrate as much as orange juice did, and it also raised urinary potassium, pH and net gastrointestinal alkali absorption. — 30 hypocitraturic stone-forming patients, fasting, given 385 mL of freshly blended melon juice (n = 10), orange juice (n = 10) or lime juice (n = 10); urine collected over 6 hours (n = 30) Evidence B source
  Urinary citrate rose in all three groups; urinary potassium, pH and net gastrointestinal alkali absorption rose only after melon and orange juice

What cooking and storage change

• A systematic review of 29 inoculation studies found that melons were one of the most studied surfaces for Listeria monocytogenes, and that whether the bacterium grows or dies depends on the commodity and on temperature. — 29 studies meeting inclusion criteria out of 3459 citations, covering 21 produce commodities, with melons among the most studied (n = 29 studies) Evidence D source
  Growth and survival differed substantially by commodity; temperature and surface characteristics had a considerable effect

What it does to your health

• Watermelon measured a glycaemic index of 55, at the top of the low range, despite its reputation as a sugary fruit. — 10 healthy Malaysian volunteers (5 women, 5 men, mean BMI 21.2) eating 50 g available carbohydrate portions of each test fruit and of glucose (n = 10) Evidence B source
  Glycaemic index 55 ± 3 for watermelon versus 82 ± 4 for pineapple, 58 ± 6 for papaya and 49 ± 5 for durian (p < 0.05 for pineapple against the rest)

Safety, limits and interactions

• Healthy volunteers who ate 250 g a day of organic melon for 15 days ended with higher red blood cell cholinesterase activity than those who ate market melon known to be sprayed with diazinon. — 53 healthy young volunteers in Mashhad, Iran, eating 250 g of melon a day for 15 days: organic (n = 22) versus market melon (n = 31) (n = 53) Evidence B source
  Red blood cell cholinesterase 5.86 ± 1.27 versus 5.11 ± 1.2 IU/mL (p = 0.002); plasma cholinesterase 58.7 ± 10.0% versus 50.5 ± 13.0% (p = 0.001)
• The largest recorded food-borne pesticide outbreak in North America came from watermelons treated with aldicarb, with 1376 illnesses reported in California in 1985 and 17 people admitted to hospital. — Residents of California and other western states after 4 July 1985; 1376 illnesses reported to the state health department (n = 1376 reported illnesses) Evidence C source
  1376 illnesses reported, 77% classified as probable or possible carbamate illness, 17 hospitalised
• Among 53 adults who reported reacting to melon, blinded food challenge confirmed a real allergy in 19 of them (36%), and two had life-threatening reactions. — 53 consecutive adult patients complaining of adverse reactions to melon (Cucumis melo) (n = 53) Evidence B source
  19 of 53 (36%) confirmed; oral allergy syndrome in 14; 2 with respiratory symptoms and hypotension; skin prick test positive predictive value 42%
• A survey of 428 cantaloupe samples from 13 commercial fields in Arizona and California found no Salmonella, Listeria or E. coli O157:H7 on any melon, soil, rhizosphere or air sample. — 428 cantaloupe composites (1284 fruits) plus 87 soil, 87 rhizosphere, 56 air and 18 water samples from 11 Arizona and 2 California fields, 2018 to 2021 (n = 428 melon composites) Evidence C source
  Zero detections of the three pathogens; indicator enterococci and coliforms up to 6.13 and 7.45 Log CFU per melon in Arizona

What people believe that the data does not support

• The European Union register lists every antioxidant claim filed for watermelon extract as non-authorised, so none of them may be used on a label in the EU. — EU register of nutrition and health claims, snapshot of 2026-09-21: 2330 claims, of which 262 authorised and 2067 non-authorised (n = 9 melon claims in the register, 0 authorised) Evidence E source
  Status Non-authorised for claim POL-HC-6934 and for all eight other melon entries

Who this works differently for

• In a 2023 outbreak in the United Kingdom and Portugal, cases of Salmonella Saintpaul had 14 times the odds of having eaten cantaloupe compared with controls, and 46% of the 98 cases were children under 10. — 98 outbreak cases (93 UK, 5 Portugal); the case-control analysis used 25 UK cases and 100 age-matched controls (n = 25 cases vs 100 controls) Evidence C source
  Adjusted odds ratio 14.22 (95% CI 2.83 to 71.43) for the odds of cantaloupe consumption, p = 0.001
• The 1985 aldicarb watermelon outbreak included 47 reports of illness in pregnant women, two of whom later had a stillbirth, and no further stillbirths were found among the 35 followed up nine months later. — Pregnant women among the reported cases of the 1985 California watermelon outbreak (n = 47 pregnant women, 35 followed up) Evidence C source
  2 stillbirths reported among 47 affected pregnancies; no additional stillbirths at 9 month follow-up of the other 35
• Among 222 adults treated for seasonal hay fever, 14% reported pollen-food allergy syndrome, and melon was one of the five foods that triggered it most often. — 222 adults with seasonal allergic rhinitis at a university allergy clinic in Ankara over ten months (n = 222) Evidence C source
  31 of 222 (14%) reported the syndrome; isolated oropharyngeal symptoms in 58.1% and urticaria in 51.6%; melon among the five most frequent trigger foods

What is still unknown

• A 2025 systematic review of 47 supplement studies on protecting skin from sunlight listed a patented freeze-dried melon juice concentrate among the supplements assessed and called the evidence limited by small samples and short duration. — 47 human studies of dietary supplements and photoprotection retrieved from PubMed, Embase and Cochrane, among them the melon concentrate trials (n = 47 studies) Evidence A source
  Strongest evidence for polyphenols, carotenoids and Polypodium leucotomos; melon concentrate listed among the supplements assessed, with the overall evidence base limited by small sample size and short duration

The bottom line

The USDA table here covers raw cantaloupe, casaba and honeydew. One small trial used melon in a medical way. Thirty patients who form kidney stones and run low on urinary citrate drank 385 mL of freshly blended melon, orange or lime juice, ten to each arm, and over the following 6 hours citrate rose in all three groups while urinary potassium, pH and net alkali absorption rose only after melon and orange. That is an acute test in ten people per arm, on juice rather than whole fruit, and it measured urine chemistry rather than whether anyone went on to form fewer stones. Handling is the better documented half of this fruit. A review of 29 laboratory inoculation studies put melons among the most studied surfaces for Listeria monocytogenes and found that growth or die-off depends on the commodity and the temperature, all of it on inoculated intact rind rather than naturally contaminated fruit, with cut produce excluded by design. Cut fruit is where the risk to a shopper concentrates. In the field the picture is clean. Across 428 cantaloupe composites covering 1284 fruits from 13 commercial fields in Arizona and California between 2018 and 2021, no melon, soil, rhizosphere or air sample carried Salmonella, Listeria or E. coli O157:H7, though that is sampling in the field and the recorded outbreaks began after harvest. In the 2023 Salmonella Saintpaul outbreak in the United Kingdom and Portugal, 25 cases set against 100 age-matched controls had 14 times the odds of having eaten cantaloupe (95% CI 2.83 to 71.43, p = 0.001), which is odds and not risk, on a very wide interval and on food histories recalled after people were already ill. Pesticide contamination has its own record, and it is old. California logged 1376 reported illnesses in 1985 from watermelons treated with aldicarb, 17 of them admitted to hospital and 77 percent classed as probable or possible carbamate illness, through passive reporting that leaves the true count unknown in both directions. Aldicarb was already illegal on watermelon, so the story is contamination rather than the fruit. Among those reports were 47 pregnant women, two of whom had a stillbirth, and the 35 others followed up nine months later had none, with no comparison group and no background rate to pin anything on the pesticide. More recently, 53 healthy young volunteers in Mashhad ate 250 g of melon a day for 15 days, and red blood cell cholinesterase finished higher in the 22 given organic melon than in the 31 given market melon known to be sprayed with diazinon (5.86 against 5.11 IU/mL, p = 0.002), in an open label trial whose authors say the health meaning of that change is undetermined. Allergy is the caution to take seriously. Of 53 adults reporting reactions to melon, a randomised double-blind placebo-controlled challenge confirmed 19 of them, 36 percent, with oral allergy syndrome in 14 and two who had respiratory symptoms and hypotension. That share belongs to people who already suspect melon, and a positive skin prick test was right only 42 percent of the time. In a separate clinic survey, 31 of 222 adults with seasonal hay fever, 14 percent, reported pollen-food allergy syndrome and named melon among the five most frequent triggers, by questionnaire without any food challenge, in one clinic over one pollen season. Children appear in the outbreak record and in no trial: 46 percent of the 98 cases in that 2023 outbreak were under 10. The EU register lists nine melon claims and authorises none, including every antioxidant claim filed for a watermelon extract, which records evidence judged insufficient at the time of assessment rather than an effect shown to be absent.

Sources

1. mlon-r1-06 · randomised trial
   Significant and comparable increases of mean urinary citrate were observed in all groups, whereas mean urinary potassium, pH, and NGIA were significantly increased only after consumption of melon and orange juices.
   J Endourol, 2012 · checked 2026-09-24
2. mlon-r1-09 · systematic review of laboratory studies
   Included studies represented 21 commodities, with the majority of studies focusing on melons, leafy greens, berries, or sprouts. Synthesis of the reviewed studies suggests L. monocytogenes growth and survival on intact produce surfaces differ substantially by commodity.
   J Food Prot, 2020 · checked 2026-09-24
3. mlon-r1-07 · randomised crossover
   Similarly, the glycemic index of pineapple, 82+/-4, was significantly greater than those of papaya, 58+/-6, watermelon, 55+/-3, and durian, 49+/-5 (p<0.05).
   Asia Pac J Clin Nutr, 2008 · checked 2026-09-24
4. mlon-r1-02 · randomised trial
   RBC [5.86 ± 1.27 vs. 5.11 ± 1.2 IU/mL] and plasma cholinesterase activities [58.7 ± 10.0 vs. 50.5 ± 13.0%] significantly increased in organic melon-exposed vs. market melon-exposed participants (p = 0.002 and p = 0.001, respectively).
   Eur Rev Med Pharmacol Sci, 2016 · checked 2026-09-24
5. mlon-r1-03 · case series
   Within California, a total of 1,376 illnesses resulting from consumption of watermelons was reported to the California Department of Health Services (CDHS)...Seventeen individuals required hospitalization.
   Arch Environ Health, 1990 · checked 2026-09-24
6. mlon-r1-05 · randomised double-blind challenge
   Actual clinical reactivity was confirmed in 19 (36%) of 53 patients. The most frequent symptom was oral allergy syndrome (n = 14), but two patients experienced life-threatening reactions, including respiratory symptoms and hypotension.
   J Allergy Clin Immunol, 2000 · checked 2026-09-24
7. mlon-r1-08 · prevalence survey
   No Escherichia coli O157:H7, Listeria species, or Salmonella enterica were detected in any melon, rhizosphere, soil, or air samples from either Arizona or California.
   Food Microbiol, 2026 · checked 2026-09-24
8. mlon-r1-11 · regulatory register entry
   POL-HC-6934 Citrullus lunatus (Watermelon) extract - ACTI-08 Good source of antioxidants Contains naturally occuring antioxidants Has antioxidant properties Acts as an antioxidants Contributes to the protection against oxidation Helps increase the antioxidative capacity of the body Helps preventing oxidation Antioxidants help protect you from free radicals Antioxidants help protect your cells and tissues from oxidation Antioxidants contribute to the total antioxidant capacity of the body Antioxidants help to protect your body by reinforcing the body's natural defence against the effects of free radicals Non-authorised
   EU Register on nutrition and health claims, claim POL-HC-6934, snapshot 2026-09-21 · checked 2026-09-24
9. mlon-r1-01 · case-control
   Multivariable logistic regression analysis of food exposures in cases and controls identified a strong association with cantaloupe consumption (adjusted odds ratio: 14.22; 95% confidence interval: 2.83-71.43; p-value: 0.001).
   Epidemiol Infect, 2024 · checked 2026-09-24
10. mlon-r1-04 · case series
    There were 47 reports of illness involving pregnant women, two of whom reported having subsequent stillbirths. Thirty-five of the remaining pregnant women were followed-up 9 mo after the epidemic; no additional stillbirths were found.
    Arch Environ Health, 1990 · checked 2026-09-24
11. mlon-r1-10 · cross-sectional
    Among 222 patients with a diagnosis of SAR, 31 had patient reported PFAS (31/222, 14%)...The most frequent culprit foods were eggplant, walnut, kiwi, peach, and melon.
    Eur Rev Med Pharmacol Sci, 2023 · checked 2026-09-24
12. mlon-r1-12 · systematic review
    A total of 47 studies were included in the systematic review. Studied supplements included carotenoids, polyphenols, Polypodium leucotomos (PL), melon concentrate, vitamins, coenzyme Q, squalene, and omega-3 and omega-6 fatty acids...Dietary supplements may promote enhanced photoprotection, although current evidence is limited by small sample size and short duration.
    J Med Food, 2025 · checked 2026-09-24