Cucumber vs zucchini: mostly water, with more potassium in zucchini

The only trial we found that fed cucumber to adults used a powder. In a 30 day randomized pilot in 25 healthy adults over 60 in China, cucumber powder equal to 11 oz (300 g) of fresh cucumber a day lowered plasma uric acid by 45.1 percent from baseline, with no placebo group and 13 people on cucumber. Lotus root powder lowered it by 41.7 percent, and the two groups did not differ. On blood antioxidant markers the two powders were not remarkably different either, although lotus root and cucumber differ sharply in antioxidant capacity in the test tube. As food, both vegetables are about 95 percent water. Per 100 g raw, zucchini held 225.8 mg of potassium against 169.6 mg in cucumber in USDA samples, plus 15 mg of vitamin C and 71 mcg of folate, a folate figure that ranged from 20 to 147 mcg between samples.

How much is actually in it

• Per 100 g raw, zucchini held 225.8 mg potassium, 15 mg vitamin C and 71 mcg folate against 169.6 mg potassium in cucumber, both about 95% water. — USDA Foundation Foods, Cucumber with peel raw and Squash summer green zucchini includes skin, per 100 g (n = 8 samples each) Evidence E source
  Potassium 225.8 (182.5-284.0) vs 169.6 mg (136.0-211.0); water 95.01 vs 95.87 g; zucchini vitamin C 15.0 mg (10.4-19.3), folate 71 mcg (20-147); cucumber vitamin K1 24 mcg (16-32.2)
• By the UK composition tables raw zucchini has 16 calories and 341 mg potassium per 3.5 oz (100 g) against 14 calories and 156 mg in cucumber. — CoFID 2021 records 13-523 Cucumber, raw, flesh and skin and 13-627 Courgette, raw, per 3.5 oz (100 g) (n = 2 reference records) Evidence E source
  Cucumber 14 calories, water 96.5 g, sugars 1.2 g, potassium 156 mg, vitamin C 2 mg; zucchini 16 calories, water 95 g, sugars 2.2 g, potassium 341 mg, vitamin C 5 mg, folate 34 mcg

What a real portion looks like

• In a cluster RCT in 8 UK nurseries with 351 children, toddlers ate some of the cucumber sticks and carrot batons offered at breakfast in 62.4% of offers. — 351 children aged 18 months to 4 years in eight UK nurseries; three carrot batons and three cucumber sticks daily for three weeks (n = 351) Evidence B source
  Some vegetable eaten in 745 of 1194 offers (62.4%)
• In the US survey database one regular cucumber weighs 7.1 oz (200 g) and one green summer squash also 200 g, while a cup is 120 g and 115 g. — USDA FNDDS household measures for Cucumber, raw (75111000) and Summer squash, green, raw (75128010) (n = 6 and 4 measures) Evidence E source
  Cucumber 1 regular 200 g, 1 miniature 65 g, 1 cup 120 g, slice or stick 10 g, quantity not specified 60 g; green summer squash 1 whole 200 g, 1 cup 115 g, 1 slice 10 g, quantity not specified 58 g

What cooking and storage change

• Laboratory analysis in a Brazilian cardiology study found pressure-cooked zucchini at 93.62 mg potassium per 3.5 oz (100 g), among the lowest values tested. — Vegetables and legumes prepared by different cooking techniques for patients at risk of hyperkalemia Evidence D source
  Pressure-cooked zucchini 93.62 mg K/100 g; dry oven gave values far above recommended levels
• Boiling zucchini dropped its potassium from 341 to 238 mg and vitamin C from 5 to 1 mg per 3.5 oz (100 g) in the UK tables. — CoFID 2021 records 13-627 Courgette, raw and 13-628 Courgette, boiled in unsalted water, per 3.5 oz (100 g) (n = 2 reference records) Evidence E source
  Potassium 341 to 238 mg, folate 34 to 20.6 mcg, vitamin C 5 to 1 mg
• Boiling in water to cover and draining keeps 75 percent of vitamin C and 65 percent of folate by the USDA table for Vegetables and Vegetable Products, and 90 percent of potassium. — USDA Table of Nutrient Retention Factors Release 6, group Vegetables and Vegetable Products, method VEG,OTHER,BLD,WATER COVER,DRAINED, code 3775 (n = 16 nutrients in the method row) Evidence E source
  Folate 65% retained, vitamin C 75%, thiamin 80%, niacin vitamin B6 85%, phosphorus potassium riboflavin 90%, calcium iron magnesium sodium zinc copper 95%

What it does to your health

• In a randomized pilot of adults over 60, cucumber powder equal to 300 g fresh cucumber daily for 30 days cut plasma uric acid by 45.1% from baseline, in a trial with no placebo group. — 25 healthy non-smoking adults over 60 in Tianjin, China, randomized to lotus root or cucumber powder, 30 days (n = 25) Evidence B source
  Plasma uric acid down 41.7% (lotus root) and 45.1% (cucumber) from baseline; no between-group difference

Safety, limits and interactions

• Observational data from a hepatitis E outbreak in China link eating cucumber in sauce to infection after cross-contamination from raw pork. — 80 people exposed at a funeral dinner in Yantai, 18 acute infections, 1:2 case-control (n = 80) Evidence C source
  AOR 4.44, 95% CI 1.23 to 16.06
• Observational data tie a UK outbreak of E. coli O157 in 36 people to a fast-food product whose only specific ingredient was imported cucumber. — 36 cases of STEC O157:H7, United Kingdom, August 2020 (n = 36) Evidence C source
  Case-control aOR 9.19, 95% CI 1.0 to 82.8; case-case aOR 31.8
• A case report describes a 66-year-old woman hospitalized with bloody colitis and low blood pressure after eating a bitter zucchini containing cucurbitacin. — One 66-year-old woman, Germany (n = 1) Evidence D source
  Tachycardia, hypotension, hemorrhagic colitis; recovered on IV fluids within 2 days
• A case report describes food protein-induced enterocolitis syndrome caused by zucchini in a child, later outgrown on a second food challenge. — One child with FPIES to zucchini, two oral food challenges (n = 1) Evidence D source
  First challenge positive, second tolerated
• A meta-analysis of pesticide residue data in Iran ranked cucumber first among foods by disease burden from residues, at 5.9 DALYs per 100,000. — Iranian foodstuffs, pooled residue measurements Evidence C source
  DALY rate cucumber 5.9, fish 3.9, date 2.1

What people believe that the data does not support

• In the same 30-day randomized pilot, cucumber matched lotus root on antioxidant markers in older adults although the two differ sharply in test-tube antioxidant capacity. — Healthy aged subjects over 60, 30-day cucumber or lotus root powder (n = 25) Evidence B source
  No significant change in plasma FRAP, vitamin E, MDA, ox-LDL, SOD or catalase in either group

Who this works differently for

• In a cluster RCT of 598 Dutch toddlers over 3 months, only repeated tasting with non-food rewards raised willingness to try vegetables including cucumber. — 598 children aged 1-4 years in 26 day-care centers in the Netherlands, 3-month program (n = 598) Evidence B source
  Willingness to try increased only in the exposure plus reward arm; recognition rose in both exposure arms

The bottom line

British tables show the same direction with a wider gap, 341 mg of potassium per 3.5 oz (100 g) in raw zucchini against 156 mg in cucumber, so the two databases differ by more than 100 mg on zucchini alone. A regular cucumber and a whole green summer squash both weigh 7.1 oz (200 g) in US survey data. Boiling zucchini took its potassium from 341 to 238 mg per 3.5 oz (100 g) and its vitamin C from 5 to 1 mg, comparing two separate table records. For patients at risk of high blood potassium, a laboratory analysis in a Brazilian cardiology study found pressure-cooked zucchini at 93.62 mg potassium per 3.5 oz (100 g), among the lowest values tested. The abstract gives no raw value to compare, and the analysis found no significant difference between cooking methods. With toddlers the question is getting the vegetable eaten. In a cluster trial in 8 UK nurseries with 351 children, toddlers ate some of the cucumber sticks and carrot batons offered at breakfast in 62.4 percent of offers, a feasibility measure that counted no grams. Among 598 Dutch toddlers over 3 months, only repeated tasting paired with non-food rewards raised willingness to try vegetables, cucumber being one of six. Cucumber is usually eaten raw, and two outbreaks show what can ride on it. Observational data from a hepatitis E outbreak among 80 guests at a funeral dinner in China tie infection to cucumber in sauce (aOR 4.44, 95% CI 1.23 to 16.06), with raw pork as the source of the virus. A UK outbreak of E. coli O157 in 36 people was traced to a fast-food product whose only specific ingredient was imported cucumber, with a confidence interval running from 1.0 to 82.8. Zucchini has its own warning sign. A 66 year old woman in Germany was hospitalized with bloody colitis and low blood pressure after eating a bitter zucchini containing cucurbitacin, a toxin rare in commercial varieties, and the report names bitter taste as the key to diagnosis. One child had a rare food allergy reaction, FPIES, to zucchini and tolerated it at a second food challenge. In Iran, a meta-analysis of residue data ranked cucumber first among foods for disease burden from pesticides, at 5.9 DALYs per 100,000, a modeled estimate for one country. We found no study of how the body absorbs nutrients from either vegetable, and no trial comparing the two directly. Neither the EU register nor US federal labeling rules carry a health claim for cucumber or zucchini.

Sources

1. cuzc-daily-r6-11 · reference dataset
   Cucumber, with peel, raw: Potassium 169.6 mg (136.0-211.0, n 8), Vitamin K (phylloquinone) 24.0 ug (16.0-32.2, n 8), Water 95.87 g | Squash, summer, green, zucchini, includes skin: Potassium 225.8 mg (182.5-284.0, n 8), Vitamin C 15.0 mg (10.4-19.3, n 8), Folate, total 71.0 ug (20.0-147.0, n 8), Water 95.01 g
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-10-02
2. cuzc-daily-r6-12 · reference dataset
   CoFID 13-523 Cucumber, raw, flesh and skin: Energy 14 kcal, Total sugars 1.2 g, Water 96.5 g, Potassium 156 mg, Vitamin C 2 mg, AOAC fibre 0.7 g | CoFID 13-627 Courgette, raw: Energy 16 kcal, Total sugars 2.2 g, Water 95 g, Potassium 341 mg, Folate 34 µg, Vitamin C 5 mg, AOAC fibre 0.5 g
   CoFID 2021, Public Health England, records 13-523 and 13-627 · checked 2026-10-02
3. cuzc-daily-r6-03 · Cluster RCT
   Both the feasibility and acceptability of the intervention to nursery staff and the willingness of children to consume the vegetables met the green stop-go criteria, with children eating some part of the vegetables in 62.4% (745/1194) of instances where vegetables were offered.
   Int J Behav Nutr Phys Act, 2023 · checked 2026-10-02
4. cuzc-daily-r6-15 · reference dataset
   Cucumber, raw, FNDDS 75111000: 1 piece/slice 10 g | 1 stick 10 g | 1 regular 200 g | 1 miniature 65 g | 1 cup 120 g | Quantity not specified 60 g || Summer squash, green, raw, FNDDS 75128010: 1 slice 10 g | 1 whole 200 g | 1 cup 115 g | Quantity not specified 58 g
   USDA FNDDS, Cucumber raw 75111000 and Summer squash green raw 75128010 · checked 2026-10-02
5. cuzc-daily-r6-05 · In vitro food analysis
   The vegetables with the lowest potassium values were spinach (74.85 mg/100 g) and zucchini (93.62 mg/100 g), both cooked under pressure.
   Clin Nutr ESPEN, 2025 · checked 2026-10-02
6. cuzc-daily-r6-13 · reference dataset
   CoFID 13-627 Courgette, raw: Energy 16 kcal, Water 95 g, Potassium 341 mg, Folate 34 µg, Vitamin C 5 mg | CoFID 13-628 Courgette, boiled in unsalted water: Energy 15 kcal, Water 95 g, Potassium 238 mg, Folate 20.6 µg, Vitamin C 1 mg
   CoFID 2021, Public Health England, records 13-627 and 13-628 · checked 2026-10-02
7. cuzc-daily-r6-14 · nutrient retention factor dataset
   USDA-RETN-R6:3775 | Vegetables and Vegetable Products | VEG,OTHER,BLD,WATER COVER,DRAINED | folate_total_ug 65% | vitamin_c_mg 75% | thiamin_mg 80% | niacin_mg 85% | vitamin_b6_mg 85% | phosphorus_mg 90% | potassium_mg 90% | riboflavin_mg 90% | calcium_mg 95% | iron_mg 95% | magnesium_mg 95% | sodium_mg 95% | zinc_mg 95% | copper_mg 95% | choline_mg 100% | vitamin_b12_ug 100%
   USDA Table of Nutrient Retention Factors, Release 6, 2007, Retn_Code 3775 · checked 2026-10-02
8. cuzc-daily-r6-01 · RCT
   During the intervention period, the subjects received daily 25g of lotus root powder or 12.5g of cucumber powder, which was equivalent to 300g of fresh lotus root or cucumber, respectively. ... Meanwhile, the content of uric acid was significantly decreased in the two groups by 41.7% and 45.1%, respectively.
   J Nutr Health Aging, 2015 · checked 2026-10-02
9. cuzc-daily-r6-06 · Case-control
   Multifactorial analysis showed that the infection was significantly associated with the consumption of cucumber in sauce (aOR = 4.44, 95%CI = 1.23-16.06).
   Int J Food Microbiol, 2025 · checked 2026-10-02
10. cuzc-daily-r6-07 · Case-control
    Consumption of a specific fast-food product was a likely cause of this outbreak. The only ingredient specific to the product was cucumbers.
    Int J Infect Dis, 2021 · checked 2026-10-02
11. cuzc-daily-r6-08 · Case report
    Bitter taste is essential to diagnose cucurbitacin intoxications.
    Dtsch Med Wochenschr, 2020 · checked 2026-10-02
12. cuzc-daily-r6-09 · Case report
    We report an unusual case of FPIES due to zucchini.
    Allergol Immunopathol (Madr), 2021 · checked 2026-10-02
13. cuzc-daily-r6-10 · Meta-analysis of contamination data
    The three food items with the highest DALY rates from pesticide residues were cucumber (5.9), fish (3.9), and date (2.1).
    Food Chem Toxicol, 2025 · checked 2026-10-02
14. cuzc-daily-r6-02 · RCT
    These results suggest that lotus root and cucumber are not remarkably different in improving antioxidant function in aged subjects, though they are significantly different in antioxidant capacity in vitro.
    J Nutr Health Aging, 2015 · checked 2026-10-02
15. cuzc-daily-r6-04 · Cluster RCT
    The willingness to try vegetables only increased significantly in the 'exposure/reward' group.
    Appetite, 2023 · checked 2026-10-02