zucchini
A low-calorie, high-water summer squash that adds potassium, fiber, and vitamin C to the plate.
Strong evidence
🥦Vegetables
Evidence tier
Strong
Research weight
Citations
11 verified / 11
Classification
Vegetables
❝
What the evidence says. Multiple high-quality RCTs / meta-analyses with consistent effects.
Nutrition per serving 1 medium, raw with skin (196 g)
- Sugars 4.9 g3%
- Fibre 2 g1%
- Protein 2.4 g1%
- Other 186.7 g95%
33 kcal2.4 g protein2 g fiber4.9 g sugar
| Nutrient | Per serving | % daily value |
|---|---|---|
| Vitamin C | 35 mg | 39% |
| Fiber | 2 g | 7% |
| Potassium | 512 mg | 11% |
| Folate | 47 µg | 12% |
| Vitamin A | 20 µg | 2% |
| Vitamin K | 8.4 µg | 7% |
| Vitamin B6 | 0.32 mg | 19% |
| Manganese | 0.35 mg | 15% |
| Copper | 0.11 mg | 12% |
| Vitamin E | 0.24 mg | 2% |
| Magnesium | 35 mg | 8% |
| Calcium | 31 mg | 2% |
Composition data: USDA FoodData Central ↗
What is zucchini?
zucchini is a vegetable used for supports a high-volume, low-calorie eating pattern. NutriDex grades the human evidence as Strong. Zucchini itself has not been the subject of dedicated clinical trials; the strongest human evidence comes from the food groups and nutrients it contributes to. Higher fruit-and-vegetable and dietary-fiber intakes are robustly linked in dose-response meta-analyses to lower all-cause and cardiovascular mortality, and increasing potassium intake significantly lowers blood pressure in randomized trials. The best-characterized Cucurbita pepo intervention literature concerns pumpkin-seed (not flesh) extracts for benign prostatic hyperplasia, where effects are modest and inconsistent.
Purported Benefits
✓Supports a high-volume, low-calorie eating pattern
✓Contributes potassium that helps lower blood pressure
✓Adds fiber linked to lower mortality and better glycemic control
✓Provides vitamin C and lutein/zeaxanthin carotenoids
✓Hydrating (~95% water) with minimal sugar
Dosing & Compounds
Typical Dose
Standard serving: 1 medium, raw with skin (196 g). Eat whole (with skin where edible); favour whole fruit over juice.
Active Compounds
Safety & Cautions
Very well tolerated. Rare bitter (high-cucurbitacin) zucchini can cause nausea, vomiting, and diarrhea ("toxic squash syndrome") — discard any unusually bitter squash. Modest oxalate and FODMAP content is tolerable for most; the skin contributes most of the fiber. No clinically significant vitamin-K/warfarin concern at typical intakes given the modest vitamin K content. Educational only — always check with your doctor or pharmacist before combining zucchini with any medicine.
Key Studies ★ 11 studies
Meta-analysis
Front Nutr 2023 (fiber & mortality)
✓ Full text
Dose-response meta-analysis of 32 cohorts (2,567,890 participants; 171,751 deaths) found vegetable fiber per 10 g/day was NOT significantly associated with all-cause (RR 0.88, 95% CI 0.73-1.05) or CVD mortality (RR 0.91, 95% CI 0.78-1.06), unlike cereal fiber.
Meta-analysis of RCTs (JAHA)
Filippou 2020
✓ Source
Dose-response analysis of 32 RCTs found increasing potassium intake reduced systolic BP, with the greatest effect in those with higher sodium intake.
Meta-analysis
Krieger 2022 (energy density meta-analysis)
✓ Full text
Meta-analysis of 38 RCTs (1,831 participants) found lowering dietary energy density (e.g., by adding low-calorie vegetables like zucchini) cut energy intake by 223 kcal (95% CI -259.7 to -186.0) while food weight stayed constant.
Dose-response meta-analysis
Aune 2017
✓ PubMed
Across 95 prospective studies, each 200 g/day of fruit and vegetables was associated with lower all-cause mortality, with risk reductions plateauing around 800 g/day (RR ~0.69 vs lowest intake).
Systematic review & meta-analysis (Lancet)
Reynolds 2019
✓ PubMed
Highest vs lowest dietary fiber intake was associated with a 15-30% reduction in all-cause and cardiovascular mortality, with benefit per 8 g/day; RCTs showed lower body weight and cholesterol.
Meta-analysis of RCTs (PLOS One)
Poorolajal 2017
✓ PubMed
Oral potassium supplementation lowered systolic/diastolic BP by ~4.5/3.0 mmHg in hypertensive adults across pooled randomized controlled trials.
Meta-analysis of 2 RCTs
Leibbrand 2019
✓ Full text
Pumpkin seed (Cucurbita pepo) soft extract improved IPSS lower-urinary-tract symptom scores vs placebo over 12 months in men with BPH, with modest quality-of-life gains.
Systematic review & meta-analysis (WHO, BMJ)
Aburto 2013
✓ PubMed
Increased potassium intake reduced systolic blood pressure by 3.49 mmHg (95% CI 1.82-5.15) in adults with hypertension and was associated with 24% lower stroke risk.
RCT
VESSEL study (Connolly 2025)
✓ Full text
In an 18-adult randomized crossover trial, root/squash vegetables (zucchini's class) did NOT improve glycemic variability, whereas cruciferous vegetables reduced 24h glucose variability by -2.0% (95% CI -2.8 to -1.1; p<0.001) over the squash arm.
RCT
Hong 2021 (pumpkin seed oil vs tamsulosin RCT)
✓ Full text
In a single-blind RCT (n=73), Cucurbita pepo seed oil reduced BPH IPSS symptoms (-3.19 at 3 months) but significantly less than tamsulosin (-5.33; p=0.020), with no side effects.
RCT secondary analysis (JAMA Ophthalmol)
AREDS2 Report No. 3, Chew 2014
✓ PubMed
In 4203 participants, adding lutein/zeaxanthin reduced progression to advanced AMD by ~26% among those in the lowest dietary lutein/zeaxanthin quintile (HR 0.74).