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Nutrition and daily life

Watermelon — fruit card: summer fluid

Watermelon is over 90% water, a refreshing source of fluid on hot days and when appetite is low. But it grows on the ground and is large, so cutting it correctly matters. This card explains how.

Last updated: ~1 min read
A whole watermelon and a wedge on a dark board.
Figure 1.Watermelon, summer fluid.

01Short answer

Watermelon provides water, few calories, vitamin C and lycopene. The rind touches the soil, so scrub it with a brush under running water before cutting, or the knife will carry germs into the flesh. Buy whole watermelons; avoid cut halves and slices sold loose. Keep cut watermelon in the fridge and eat it within 1–2 days. If your fluids are restricted, watermelon counts.

02Simple explanation

Watermelon is over 90% water.

Scrub the rind.

Buy it whole.

Cut pieces in the fridge.

03Scientific explanation

CDC/FDA: thick-rinded fruits such as watermelon and melon have been linked to Salmonella and Listeria outbreaks; washing the rind before cutting matters.

WHO: at least 400 g of fruit and vegetables a day is recommended; during treatment the amount may vary with appetite and your doctor’s advice.

FDA: wash produce under running water before cutting or peeling, because a knife can carry germs from the skin into the flesh.

04What happens in the body?

Cutting

Wash and dry the rind, then cut with a clean knife on a clean board.

A watermelon rind scrubbed under running water.
Figure 2.Scrub the rind — Watermelon — fruit card: summer fluid

Nausea

Cold watermelon cubes are pleasant for some people with nausea.

Watermelon cubes in a covered glass container.
Figure 3.Keep cut pieces in the fridge.

Washing and peeling

Wash your hands, rub the fruit under running water, dry it with a clean towel, then peel or cut it. Soap or bleach solutions are not needed.

Cut fruit

Keep cut fruit in the fridge and eat it within 1 day; do not leave it at room temperature for more than 2 hours.

05Fruit: four steps

Whole fruit, swap bruised, wash and peel, eat cut fruit soon.

Whole fruit — No spots.1Whole fruitNo spots.
Not bruised — Fresh and whole.2Not bruisedFresh and whole.
Wash and peel — Running water.3Wash and peelRunning water.
Eat soon — Fridge, 1 day.4Eat soonFridge, 1 day.
VitaminsA natural source.
FibreFor the gut.
SafetyWashing.

06Key points at a glance

TopicIn brief
CuttingWash and dry the rind, then cut with a clean knife on a clean board.
NauseaCold watermelon cubes are pleasant for some people with nausea.
Washing and peelingWash your hands, rub the fruit under running water, dry it with a clean towel, then peel or cut it. Soap or bleach solutions are not needed.
Cut fruitKeep cut fruit in the fridge and eat it within 1 day; do not leave it at room temperature for more than 2 hours.

07Key terms

Lycopene
The pigment that gives red colour.
Listeria
A bacterium that can grow even in the cold.
Neutropenia
Low neutrophils, raising infection risk.
Potassium
A mineral for the heart and muscles.
Fibre
The part of plants that helps the gut work.

08Key points

  • Wash the rind before cutting.
  • Buy whole watermelons.
  • Eat cut pieces soon.
  • Wash under running water.
  • Eat cut fruit soon.

09Frequently asked questions

Does watermelon strain the kidneys?

With fluid or potassium limits, agree it with your doctor.

Can I buy a cut half?

Not during neutropenia; buy it whole.

Does this fruit treat leukemia?

No. It is a pleasant part of eating, not a treatment.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Does watermelon strain the kidneys?

  2. Can I buy a cut half?

  3. Does this fruit treat leukemia?

My questions

12Sources

  1. Leukemia & Lymphoma Society. Diet Guidelines for Immunosuppressed Patients
  2. U.S. FDA. Selecting and Serving Produce Safely
  3. NHS. 5 A Day: what counts?
  4. National Cancer Institute. Eating Hints: Before, During, and After Cancer Treatment
  5. USDA. FoodData Central
  6. American Cancer Society. Dietary Supplements: What Is Safe?
  7. U.S. Food and Drug Administration (FDA). Dietary Supplements
  8. Clinical Pharmacology & Therapeutics, 2004. Effect of St John’s wort on imatinib mesylate pharmacokinetics
  9. Journal of Clinical Oncology, 2020. Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients With Breast Cancer Enrolled in a Cooperative Group Clinical Trial (SWOG S0221)
  10. Macmillan Cancer Support. Tiredness (fatigue) and cancer
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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