Cucumber: water, vitamin K, and one trial about a capsule

A cucumber is 95.87 g of water per 100 g, and across eight USDA samples that figure moved by 1 percent. Almost nothing else in it held still. Copper ran from zero to 0.325 mg, a spread of 516 percent. Zinc moved 345 percent and sodium 349 percent. Vitamin K is the one nutrient here that both stays put and matters, at 24 µg per 100 g, so a whole 200 g cucumber is 48 µg, which is 40 percent of the Daily Value. If you take anticoagulants, steady matters more than low. People taking warfarin and similar anticoagulants need a consistent vitamin K intake rather than a low one: sudden changes in either direction can increase or decrease the effect of the medicine. So the thing worth watching is a sudden change in how much cucumber you eat, and not the cucumber itself. For everyone else the number carries no instruction at all. The one trial on this page that improved blood lipids did not feed anybody a cucumber. It gave 47 people a 500 mg capsule of cucumber seed extract once a day for six weeks, and every lipid measured moved in the good direction. A single small trial of a seed extract says nothing about the vegetable in your salad.

The numbers, per 100 g

How much is actually in it

• The only steady number about a cucumber is that it is ninety-six percent water. — 8 USDA Foundation Foods samples of Cucumber, with peel, raw (FDC 2346406), against CoFID Cucumber, raw, flesh and skin (code 13-523) (n = 8 samples) Evidence E source
  Water 95.87 g per 100 g with a range of 95.38 to 96.38 and a spread of 1%; copper mean 0.063 mg with a range of 0.0 to 0.325, a median of 0.038 and a spread of 516%; zinc spread 345%, sodium 349%, molybdenum 239%, vitamin K 24.0 µg over a range of 16.0 to 32.2 with a spread of 68%, potassium 169.6 mg over 136.0 to 211.0; CoFID gives copper 0.03 mg, potassium 156 mg and vitamin K1 20.9 µg

What a real portion looks like

• A whole cucumber carries about two fifths of a day's vitamin K, which matters to one group of readers and to nobody else. — one FNDDS food with six household measures (n = fdc_id 2709784) Evidence E source
  Vitamin K as phylloquinone 24 µg per 100 g; 1 regular cucumber = 200 g = 48.0 µg, which is 40% of the 120 µg Daily Value; 1 cup = 120 g = 28.8 µg; 1 slice or stick = 10 g = 2.4 µg; 1 miniature = 65 g = 15.6 µg

What cooking and storage change

• Cooking losses are the least useful thing to know about a vegetable that almost nobody cooks. — group 11, Vegetables and Vegetable Products; 25 method rows carry a potassium factor (n = 25 method rows) Evidence E source
  Boiled under a cover of water and drained retains 85% of potassium, and boiling in little water, boiling under water and cooking from frozen all retain 90%

What it does to your health

• A capsule of cucumber seed extract improved every blood lipid measured in a small six-week trial, which is a result to treat with caution rather than repeat. — adults with mild hyperlipidaemia; 24 completed in the extract group and 23 in the placebo group (n = 47) Evidence B source
  Against placebo the extract lowered total cholesterol (P = 0.016), LDL (P < 0.001), triglycerides (P < 0.001) and BMI (P < 0.001) and raised HDL (P = 0.012), at a daily dose of 500 mg

Safety, limits and interactions

• Pooled contamination surveys put cucumber at the bottom of the range for iron among fruits. — published surveys of fresh and processed fruits across WHO regions (n = not stated in the abstract) Evidence C source
  The highest arsenic, cadmium and lead were in pineapple, mango and cherry and the lowest in berries and pineapple; peach and cucumber held the highest and lowest iron concentrations; the total hazard quotient in infants came out below 1 and the authors conclude consumption is safe and poses no risk to consumers
• A bitter cucumber, courgette or squash can genuinely poison someone, and the bitterness is the warning. — one 66-year-old woman admitted to an emergency department after eating bitter courgette (n = 1) Evidence D source
  Tachycardia, hypotension, somnolence, diarrhoea, bloody stool, dehydration, nausea and vomiting, with leukocytosis and a thickened sigmoid colon wall on ultrasound read as acute colitis; she recovered on intravenous fluids and was eating again after two days

Who this works differently for

• Preschoolers ate more vegetables when offered three kinds at once than when offered one, and still ate four times more fruit than vegetables. — 61 children aged 3 to 5 in a childcare facility; vegetables were cucumber, sweet pepper and tomato, fruit was apple, peach and pineapple (n = 61) Evidence B source
  Variety raised the likelihood of selecting anything from 70% of snacks to 94% (P < 0.0001) and raised consumption of both food types (P < 0.0002) by a mean 31 ± 5 g, about one sixth of the recommended daily amount; independently of variety, children were less likely to choose vegetables than fruit (P < 0.0001) and ate 22 ± 1 g of vegetables against 84 ± 3 g of fruit

The bottom line

Eat cucumber if you like it, and expect water, a useful amount of vitamin K and very little else. Two things here are worth acting on. If a cucumber, courgette or squash tastes bitter, stop eating it and throw it out. Cucurbitacin poisoning is rare and real: a 66-year-old woman reached an emergency department with a fast pulse, low blood pressure, bloody stools and a thickened colon wall after eating bitter courgette, and she needed intravenous fluids and two days before she could eat again. The bitter taste is the warning, and it is the thing doctors use to recognise the poisoning. The second is for anyone feeding small children. Among 61 preschoolers, offering cucumber, sweet pepper and tomato together rather than one of them raised the chance a child took anything from 70 percent to 94 percent, and added about 31 g to what they ate, roughly a sixth of a recommended day. Those same children still ate 22 g of vegetables against 84 g of fruit, so variety helps and does not close the gap. On contamination, a pooled review of trace element surveys in fruits put cucumber at the lowest end for iron, which is a fact about how little the vegetable holds rather than about how clean it is. As for cooking losses, boiled vegetables keep 85 to 90 percent of their potassium, which is the least useful fact we can offer you about a food hardly anybody boils.

Sources

1. cuc-p1-05 · reference dataset comparison
   Cucumber, with peel, raw · Water 95.87 G діапазон 95.38–96.38 (медіана 95.94), зразків 8, розкид 1% · Copper, Cu 0.06299 MG діапазон 0.0–0.325 (медіана 0.03825), зразків 8, розкид 516% · Vitamin K (phylloquino 24.0 UG діапазон 16.0–32.2 (медіана 24.8), зразків 8, розкид 68% · Potassium, K 169.6 MG діапазон 136.0–211.0 (медіана 169.8), зразків 8, розкид 44% · Zinc, Zn 0.204 MG діапазон 0.0921–0.795 (медіана 0.119), зразків 8, розкид 345%
   USDA FoodData Central, Foundation Foods, release 2026-04-30 (FDC 2346406) and CoFID 2021, Public Health England / OGL v3.0 (code 13-523) · checked 2026-09-22
2. cuc-p1-06 · reference dataset
   Cucumber, raw · Vitamin K (phylloquinone) 24 UG на 100 г [fdc_id 2709784] · 1 piece/slice 10 г 2.4 UG · 1 stick 10 г 2.4 UG · 1 regular 200 г 48.0 UG · 1 miniature 65 г 15.6 UG · 1 cup 120 г 28.8 UG
   USDA FNDDS 2021-2023, Cucumber, raw (fdc_id 2709784) · checked 2026-09-22
3. cuc-p1-07 · reference dataset
   potassium_mg · група 11 Vegetables and Vegetable Products · 3005 VEG,GREENS,BOILED,WATER COVER DRAIN — 85% · 3004 VEG,GREENS,BOILD,LITTLE WATER DRAIN — 90% · 3774 VEG,OTHER,BLD,LITTLE WATER,DRAINED — 90% · 3775 VEG,OTHER,BLD,WATER COVER,DRAINED — 90% · 3789 VEG,OTHER,CKD FROM FRZN(BLD,DRAIND) — 90%
   USDA Table of Nutrient Retention Factors, Release 6 (2007) · checked 2026-09-22
4. cuc-p1-02 · randomised double-blind placebo-controlled trial
   Cucumis seed extract resulted in significant reduction of total cholesterol (P = 0.016), LDL-C (P < 0.001), TG (P < 0.001), and BMI (P < 0.001) as well as significant increase of HDL-C (P = 0.012) compared to placebo.
   Journal of Food Science, 2017 · checked 2026-09-22
5. cuc-p1-03 · systematic review and meta-analysis of contamination surveys
   Regarding trace elements, peach and cucumber represented the highest and lowest concentrations of Fe, respectively.
   Biological Trace Element Research, 2023 · checked 2026-09-22
6. cuc-p1-04 · case report
   Acute food poisoning due to cucurbitacin - containing pumpkin is rare but can occur in small gardening units in association with higher outside temperatures...Bitter taste is essential to diagnose cucurbitacin intoxications.
   Deutsche Medizinische Wochenschrift, 2020 · checked 2026-09-22
7. cuc-p1-01 · randomised crossover trial
   Offering a variety of vegetables or fruit increased the likelihood of selection (P < 0.0001); children chose some pieces in 94% of snacks with variety and in 70% of snacks without variety...the mean intake was substantially less for vegetables than for fruit (22 ± 1 compared with 84 ± 3 g).
   The American Journal of Clinical Nutrition, 2013 · checked 2026-09-22