Benefits
Blood pressure with daily cucumber juice
In a nonrandomized 6-week study of 45 adults with stage 1 high blood pressure not on medication, juice from 100 g of cucumber each morning lowered systolic pressure by about 4 mmHg and diastolic by about 8 mmHg, while a water group did not change. Groups were chosen by purposive sampling and had only 15 people each.
A low-calorie source of water and potassium
Per 100 g raw with peel, cucumber supplies about 95 g of water, 15 kcal, 147 mg of potassium, 2.8 mg of vitamin C and 16 micrograms of vitamin K, according to USDA data; peeled cucumber has less vitamin K. These figures describe content only; no trial has tested cucumber for hydration.
Antioxidant markers with cucumber powder in older adults
In 25 healthy adults over 60, 30 days of freeze-dried cucumber juice powder (about 300 g of fresh cucumber a day) or lotus root powder raised plasma glutathione peroxidase, vitamin C and total phenolics within both groups. Several other markers did not change, and there was no group without a vegetable.
Knee comfort scores with Q-Actin cucumber extract
This is a standardized cucumber extract studied mainly at 20 mg a day, not the fresh fruit. In three randomized trials in adults with knee or joint discomfort, each sponsored, part-funded or authored by groups linked to the extract, pain questionnaire scores favored it over glucosamine and chondroitin or placebo in two; in the third, the main pain score did not differ significantly from placebo. Details are on the Q-Actin page.
Blood lipids with a cucumber seed extract
This was a seed extract, not the fruit. In a 6-week placebo-controlled trial in 47 adults with mildly raised blood lipids who completed it, 500 mg a day lowered total cholesterol, LDL cholesterol, triglycerides and BMI and raised HDL cholesterol compared with placebo. It is a single small trial.
Mechanism of action
Potassium and water content (proposed, not measured)
Cucumber is mostly water and supplies potassium. The authors of the juice study proposed that potassium lowers renin release and sodium retention, but they did not measure potassium intake, urine sodium or renin, so this explanation is untested in cucumber trials.
The iminosugar idoBR1 (laboratory work)
idoBR1 is an iminosugar amino acid isolated from certain cucumbers and used to standardize Q-Actin. In cell and ex vivo blood tests it lowered TNF-alpha release after a bacterial toxin and inhibited sialidase enzymes; it is excreted unchanged in urine. These findings come from PhytoQuest, a research company whose staff also led the Q-Actin knee trials, not from human outcome trials.
Cucurbitacins make cucumbers bitter
Cucurbitacins are bitter triterpenoids found in gourd family plants. In cucumber the main one is cucurbitacin C; genetic work traced its pathway and showed that selection on a fruit bitterness gene during domestication produced nonbitter fruit.
Clinical trials
Quasi-experimental pretest and posttest control group design with purposive sampling at a health center in Bandung, Indonesia: tomato juice, cucumber juice (100 g cucumber blended with 200 mL water) or 200 mL mineral water each morning for 6 weeks. (Sutriyawan et al. 2025, Acta Med Philipp)
45 adults aged 40 to 70 with stage 1 hypertension who were not taking blood pressure medication, 15 per group.
Systolic pressure fell 4.2 mmHg with cucumber juice versus no change with water, and diastolic 7.6 versus 0.4 mmHg; Bonferroni tests showed cucumber differed from water for both (P = 0.001 and 0.0001). Tomato juice lowered systolic pressure more than cucumber. Groups were chosen by purposive sampling with a matched control rather than randomized, the sample was small, no blinding was described, and the report lists two dropouts while its tables still show 15 per group.
Quasi-experimental nonequivalent pretest and posttest comparison in villages of Aravalli District, India: juice from about 200 g of fresh cucumber or tea from about 10 g of drumstick leaves once daily for 15 days, with standard lifestyle advice. (Bharatbhai et al. 2026, Bioinformation)
200 adults with hypertension, 100 per group.
Blood pressure fell within both groups (cucumber group systolic from about 152 to 130 mmHg) and the two groups did not differ after 15 days. With no group that received neither drink and lifestyle advice given to everyone, the change cannot be attributed to cucumber.
Randomized pilot comparison of freeze-dried cucumber juice powder (12.5 g a day, about 300 g fresh) and lotus root powder (25 g a day) dissolved in warm water each morning. (Ji et al. 2015, J Nutr Health Aging)
25 healthy adults over 60 (16 men, 9 women) in Tianjin, China.
Plasma glutathione peroxidase, vitamin C and total phenolics rose and uric acid fell within both groups; plasma antioxidant power (FRAP), vitamin E, malondialdehyde, oxidized LDL and superoxide dismutase did not change. The two vegetables did not differ much, and with no non-vegetable control the changes cannot be credited to cucumber.
Randomized, double-blind, parallel multicenter trial of Q-Actin, an aqueous cucumber extract, 10 mg twice daily, versus glucosamine-chondroitin 1,350 mg twice daily. Sponsored by IminoTech, which supplied the extract; the first author is from PhytoQuest. Extract, not fresh fruit. (Nash et al. 2018, Clin Interv Aging)
122 adults aged 40 to 75 with moderate knee osteoarthritis, 61 per group.
WOMAC scores fell 70% with the extract versus about 33% with glucosamine-chondroitin by day 180, with significant between-group differences reported at every follow-up time point; visual analog and Lequesne scores followed the same pattern. There was no placebo group and no adverse effects were reported.
Placebo-controlled study of Q-Actin, standardized to more than 1% idoBR1, at 20 mg or 100 mg a day against cellulose capsules. The first and fifth authors are from PhytoQuest, the company behind the idoBR1 research. Extract, not fresh fruit. (Nash et al. 2023, Curr Rheumatol Rev)
101 adults with moderate knee osteoarthritis enrolled, 91 completed.
The abstract reports a significant, dose-dependent improvement over time in pain-related measures and concludes the extract outperformed placebo, but gives no effect sizes or between-group numbers.
Randomized, double-blind, placebo-controlled trial (NCT06246383) of standardized cucumber extract (Q-Actin, more than 1% idoBR1) 20 mg a day versus rice protein for 60 days. Gateway Health provided partial funding. Extract, not fresh fruit. (Hausenblas et al. 2025, Cureus)
80 adults, mean age 50, with mild to moderate joint pain.
WOMAC, the primary outcome, improved 31.8% by day 60 with the extract while placebo scores worsened 14.3%, but the group by time interaction was not significant (p = 0.13). The Brief Pain Inventory pain interference subscale favored the extract (interaction p = 0.05); Pain Disability Index differences were not significant. All outcomes were self-reported questionnaires.
Randomized, double-blind, placebo-controlled trial of one 500 mg capsule of Cucumis sativus seed extract or placebo daily with food for 6 weeks. Seed extract, not the fruit. (Soltani et al. 2017, J Food Sci)
Adults with mild hyperlipidemia in Isfahan, Iran; 24 extract and 23 placebo participants completed.
Compared with placebo, the extract lowered total cholesterol (P = 0.016), LDL cholesterol (P < 0.001), triglycerides (P < 0.001) and BMI (P < 0.001) and raised HDL cholesterol (P = 0.012). A single small trial; no replication was found.