Zucchini: the pan sets the potassium, and bitter means bin it

In one study, how zucchini was cooked mattered for its potassium as much as the vegetable itself. Cooked under pressure, zucchini held 93.62 mg of potassium per 3.5 oz (100 g), the second lowest of the vegetables measured in a trial with 68 cardiology patients. In the same study every sautéed vegetable except beetroot came out above 200 mg per 3.5 oz (100 g), and those baked in a dry oven far above recommended levels. The abstract gives no separate sautéed or oven figure for zucchini. It also says the tests found no significant difference between cooking methods for legumes and only a similar trend for vegetables, so the paper contradicts itself, and we show both sides. These are laboratory measurements of the cooked food. What the trial randomized was the order in which meals reached the patients. The researchers picked foods against a cut-off of 201 mg per 3.5 oz (100 g) for raw high potassium foods, a rule for the study menu and not a clinical limit. The number matters for one group above all. The NIH Office of Dietary Supplements says high dietary potassium is no risk for healthy people with normal kidneys, but in chronic kidney disease or on drugs such as ACE inhibitors or potassium-sparing diuretics even intakes below the adequate intake can cause hyperkalemia. On such a diet, pressure-cooked zucchini and sautéed or oven-baked zucchini are not the same food, and what counts is the potassium in the portion you actually eat. Past that, our evidence base thins out. Nothing in it measures how well the body takes up anything from zucchini, and no trial in it has fed zucchini to people and watched their health.

The numbers, per 3.5 oz (100 g)

As people eat it, per 3.5 oz (100 g)

What a real portion looks like

• Zucchini was named by 39 percent of 1944 Spanish caregivers as one of the foods they most often use for children under two, and 63 percent of them boil that food. — 1944 adults in Spain who usually prepare food for children under 2 years, mean age 37.4 years, 65.5 percent women (n = 1944) Evidence C source
  Zucchini used by 39 percent of respondents, boiling used by 63 percent
• In a survey of 419 parents zucchini fell into the group of green vegetables that children eat hidden inside other dishes rather than on their own. — 419 parents of children aged 6 to 12 years in Montevideo, Uruguay, plus a preliminary sample of 162 parents (n = 419) Evidence C source
  Zucchini grouped with spinach, chard and peas as vegetables usually eaten camouflaged or under pressure
• An Italian total diet study counted zucchini among the vegetables carrying beta-carotene and lutein into the diet, where all carotenoids together reached 14.3 mg per person per day. — Italian total diet market basket, national level intake estimate Evidence C source
  14.3 mg of carotenoids per person per day across the whole Italian diet, of which lutein and zeaxanthin 4 mg per day and beta-carotene 2.6 mg per day; the share coming from zucchini was not reported

What cooking and storage change

• In the same study that measured 93.62 mg potassium per 3.5 oz (100 g) in pressure cooked zucchini, every sauteed vegetable except beetroot came out above 200 mg per 3.5 oz (100 g), and oven-dried ones far above recommended levels. The authors also report no statistically significant difference between cooking methods. — vegetables and legumes cooked for 68 patients of a cardiology institute in Porto Alegre, Brazil; potassium measured in the foods themselves (n = 68) Evidence B source
  Pressure cooking gave the lowest values (zucchini 93.62 mg per 3.5 oz (100 g)); sauteed vegetables above 200 mg per 3.5 oz (100 g) except beetroot (196.23); dry oven far above recommended levels; ANOVA found no significant difference between methods for legumes and a similar trend for vegetables
• Pressure cooked zucchini held 93.62 mg potassium per 3.5 oz (100 g), the second lowest value among the vegetables measured in a randomized crossover trial run with 68 cardiology patients. — 68 patients of a cardiology institute in Porto Alegre, Brazil, who tasted the prepared foods; potassium measured in the foods themselves (n = 68) Evidence B source
  93.62 mg potassium per 3.5 oz (100 g) after pressure cooking, against a selection threshold of 201 mg per 3.5 oz (100 g) for raw high potassium foods
• In the same trial ANOVA showed no statistically significant difference in potassium across cooking methods for legumes, and the authors reported that a similar trend was observed for vegetables. — vegetables and legumes prepared by pressure cooking, boiling in one or two waters, sauteing and dry oven, tested with 68 patients (n = 68) Evidence B source
  ANOVA found no statistically significant difference across cooking methods for legumes (significance level 5 percent); for vegetables the authors reported only a similar trend, without a test result

What it does to your health

• A review building a food pyramid for eye health places cooked zucchini among the fruit and vegetable portions it advises, at 5 portions of at least 200 g a day. — people at risk of diabetic retinopathy, age related macular degeneration and cataracts Evidence E source
  5 portions of at least 200 g per day of fruits and vegetables, zucchini named among the preferred ones

Safety, limits and interactions

• Among 353 people reported to French poison centers after eating bitter, non-edible squash in 2012 to 2016, 57.8% had symptoms, mostly diarrhea, vomiting and abdominal pain. 4.0% were moderately ill and none died. The authors advise throwing away any squash that tastes bitter. — 353 patients reported to French poison control centers after exposure to non-edible (bitter) squash, 1 January 2012 to 12 December 2016 (n = 353) Evidence C source
  204 (57.8%) symptomatic, mostly diarrhea, vomiting, abdominal pain; no deaths and no severe cases; 14 (4.0%) moderate; 95.5% exposed through food
• A 66-year-old woman was hospitalized with tachycardia, hypotension, diarrhea and hemorrhagic colitis after eating bitter zucchini, and the bitter taste was what pointed to cucurbitacin poisoning. — one 66-year-old female patient admitted to an emergency department in Germany (n = 1) Evidence D source
  Acute cucurbitacin poisoning, self limiting, eating resumed after 2 days of intravenous fluids
• The zucchini allergen described in one reported patient was stable to both heat and pepsin. — one middle aged male patient, mono-sensitized (n = 1) Evidence D source
  Sensitization to a heat stable and pepsin stable zucchini allergen

Who this works differently for

• The NIH Office of Dietary Supplements says high dietary potassium is no risk for healthy people with normal kidneys, but in chronic kidney disease or on drugs such as ACE inhibitors or potassium-sparing diuretics even intakes below the adequate intake can cause hyperkalemia. — people with chronic kidney disease or on ACE inhibitors or potassium-sparing diuretics; also type 1 diabetes, congestive heart failure, adrenal insufficiency, liver disease Evidence E source
  No UL for healthy people with normal kidneys; with impaired potassium excretion even intakes below the AI can cause hyperkalemia, which in severe cases causes life-threatening arrhythmias
• Zucchini caused food protein induced enterocolitis syndrome in one child, and a repeat oral food challenge later showed the child had outgrown it. — one child followed with two oral food challenges (n = 1) Evidence D source
  First oral food challenge positive, second one tolerated

The bottom line

The one rule worth carrying out of here is about taste: a zucchini that tastes bitter goes in the bin. French poison centers recorded 353 people who ate bitter, non-edible squash between 2012 and 2016. 57.8% had symptoms, mostly diarrhea, vomiting and abdominal pain, 4.0% were moderately ill and none died, and the authors advise throwing away any squash that tastes bitter. Those reports have no count of everyone who ate squash, so they give no rate, and they do not say how many of the squashes were zucchini. One case shows how bad it can get. A 66-year-old woman in Germany ate a bitter zucchini and was admitted with a racing heart, low blood pressure, diarrhea and bleeding from the colon. She improved on intravenous fluids and was eating again after two days, and the bitter taste was the sign that told the doctors it was cucurbitacin poisoning. Allergy appears in the record only as single patients. In one reported patient the zucchini allergen was stable to heat and to pepsin, so heating would not be expected to remove it. In another case a child reacted with food protein induced enterocolitis syndrome and passed a repeat oral food challenge later, having outgrown it. Two patients show the thing can happen and say nothing about how often. Children are where zucchini turns up most. Of 1944 Spanish adults who cook for a child under two, 39 percent named it among the foods they use most often, and 63 percent of them boil what they make. In a survey of 419 parents in Montevideo, zucchini sat with spinach, chard and peas in the group of green vegetables children swallow hidden inside something else or under pressure. That is a description of how it gets eaten, and we would not read it as advice to hide vegetables. The usual reasons given for eating zucchini are thinner than they sound. An Italian total diet study counted it among the vegetables carrying beta-carotene and lutein into the national diet, where all carotenoids together came to 14.3 mg per person per day, with lutein and zeaxanthin at 4 mg and beta-carotene at 2.6 mg. Those figures describe a whole national shopping basket. How much of any of it came from zucchini was never reported. A review on eye health lists cooked zucchini among its preferred vegetables inside five portions of at least 7.1 oz (200 g) of fruit and vegetables a day. That is the opinion of the people who wrote the review, and nobody has measured what zucchini itself does to the eyes of the people eating it. What is missing deserves naming, because a quiet gap reads like a clean record. We searched for absorption and came back with nothing, so how much of what is in a zucchini reaches you is unknown. Outside potassium, our evidence base holds nothing on what cooking takes out of it or leaves behind, and nothing on whether cooking changes the bitter compound. There is no second independent set of composition numbers to check the first against. And our drug interaction layer is built around nutrients rather than foods, so the blank there describes our data and says nothing about zucchini. A poison-center series, three case reports and one potassium study are what our evidence base holds on this vegetable so far.

Compared with other foods

Sources

1. zuc-r3-06 · cross-sectional survey
   Zucchini (39 %), chicken (62 %), hake (64 %) and banana (44 %) were the most commonly used foods...Boiling (63 %) and freezing (59 %) were the most widely used culinary and preservation practices.
   Nutr Hosp, 2021 · checked 2026-09-23
2. zuc-r3-07 · cross-sectional survey
   Group D consists of green vegetables: zucchini, spinach, chard and peas. Vegetables of this group are added to other foods and the child usually ingests them camouflaged or obliged.
   BMC Public Health, 2018 · checked 2026-09-23
3. zuc-r3-08 · total diet study
   Furthermore the contribution to the dietary intake of beta-carotene and lutein of the most consumed vegetables in the market basket of the Italian total diet (beets, brassica vegetables, carrots, chicory, courgette (zucchini), green beans, lettuce, peas, pepper, spinach, tomatoes) was also investigated...The Italian total diet provided 14.3 mg/person/day of carotenoids; lycopene was the highest (7.4 mg/day), followed by lutein + zeaxanthin (4 mg/day), beta-carotene (2.6 mg/day), alpha-carotene (0.15 mg/day), and beta-cryptoxanthin (0.17 mg/day).
   Int J Vitam Nutr Res, 2006 · checked 2026-09-23
4. hf2-zuc-1 · randomized crossover trial
   Pressure cooking resulted in the lowest K losses, followed by boiling in two waters and one water, respectively. These techniques were most effective in preserving potassium. The sautéed method resulted in values above 200 mg/100 g for all vegetables except beetroot (196.23 mg/100 g), while the dry oven method consistently showed values far above recommended levels. ANOVA tests revealed no statistically significant differences in potassium content for legumes across soaking durations or cooking methods. A similar trend was observed for vegetables.
   Clin Nutr ESPEN, 2025 · checked 2026-10-08
5. zuc-r3-01 · randomized crossover trial
   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 2026-09-23
6. zuc-r3-02 · randomized crossover trial
   ANOVA tests revealed no statistically significant differences in potassium content for legumes across soaking durations or cooking methods. A similar trend was observed for vegetables.
   Clin Nutr ESPEN, 2025 · checked 2026-09-23
7. zuc-r3-09 · narrative review, opinion of authors
   5 portions (each portion: ≥200 g/day) of fruits and vegetables (spinach, broccoli, zucchini cooked, green leafy vegetables, orange, kiwi, grapefruit for folic acid, vitamin C, and lutein/zeaxanthin content, at least ≥42 μg/day, are to be preferred)
   Front Med (Lausanne), 2023 · checked 2026-09-23
8. hf2-zuc-3 · retrospective case series
   353 patients were included, with 71.7% belonging to collective cases of poisoning. ... The circumstances of exposure were dietary for 337 patients (95.5%). The majority of the squash consumed was purchased at a store (55.8%) but some also came from the garden (25.5%). 204 patients (57.8%) mostly presented with diarrhea, vomiting, abdominal pain, sometimes with the consequent dehydration, hypotension, tachycardia, headaches, or vertigo. There were no deaths or severe (Poisoning Severity Score (PSS) 3) cases, but there were 14 patients (4.0%) of moderate severity, 190 patients (53.8%) of minor severity (PSS 1), and 149 patients (42.2%) without severity (PSS 0) but among which we include the bitter taste of the squash. ... In terms of prevention therefore, we recommend disposing of any squash with a bitter taste.
   Clin Toxicol (Phila), 2018 · checked 2026-10-08
9. zuc-r3-03 · case report
   A 66-year-old female patient was admitted to the emergency department following bitter zucchini ingestion...Bitter taste is essential to diagnose cucurbitacin intoxications.
   Dtsch Med Wochenschr, 2020 · checked 2026-09-23
10. zuc-r3-05 · case report
    A case of mono-sensitization to a heat- and pepsin-stable allergen in zucchini is described.
    Eur Ann Allergy Clin Immunol, 2012 · checked 2026-09-23
11. hf2-zuc-2 · fact sheet
    In healthy people with normal kidney function, high dietary potassium intakes do not pose a health risk because the kidneys eliminate excess amounts in the urine [1]. ... However, in people with impaired urinary potassium excretion due to chronic kidney disease or the use of certain medications, such as angiotensin converting enzyme (ACE) inhibitors or potassium-sparing diuretics, even dietary potassium intakes below the AI can cause hyperkalemia [11]. Hyperkalemia can also occur in people with type 1 diabetes, congestive heart failure, adrenal insufficiency, or liver disease [7]. Individuals at risk of hyperkalemia should consult a physician or registered dietitian about appropriate potassium intakes from all sources.
    NIH Office of Dietary Supplements, Potassium Health Professional Fact Sheet · checked 2026-10-08
12. zuc-r3-04 · case report
    We report an unusual case of FPIES due to zucchini...The first OFC was positive and in the second the child tolerated the food without problems.
    Allergol Immunopathol (Madr), 2021 · checked 2026-09-23