Squash: thin evidence and one bitter warning

Almost nothing here was tested on squash by itself, and that is the first thing to know. In the one trial built around it, squash was the comparison food. Eighteen older adults with raised blood pressure ate 300 g of soup a day for two weeks, and the cruciferous soups left their post-meal glucose 0.14 mmol/L lower than the root and squash soups. That is a small gap in a small study, and it tells you about the cabbage family more than about squash. The biggest number on this page is also the weakest. Among 177,148 UK Biobank adults, people who said they strongly liked butternut squash had 25 percent lower mortality over 3.4 years. The questionnaire asked what people liked. It never asked what they ate, and people who enjoy vegetables differ from everyone else in many ways at once. The finding you can use is about fat. Filipino schoolchildren fed carrots, squash and leafy greens for 9 weeks roughly doubled their body's vitamin A stores with 2.4 g of fat per meal, as well as the group given 10 g did. Those were mixed vegetables, so squash's own share is unknown, but in these children a little oil with the meal was enough.

Every statement here is tied to a source. The badge says what kind of evidence stands behind it: A is a meta-analysis or systematic review, E is the position of an expert body without its own analysis. How we verify →

The numbers, per 100 g

USDA entry	kcal	Protein	Carbs	Fiber
Squash, summer, zucchini, includes skin, raw	17	1.21 g	3.11 g	1 g
Squash, Indian, cooked, boiled (Navajo)	16	0.31 g	3.22 g	1.5 g
Squash, Indian, raw (Navajo)	26	0.52 g	5.64 g	— g
Squash, pie pumpkin, peeled, seeded, raw	—	0.85 g	— g	2.3 g
Squash, spaghetti, peeled, seeded, raw	—	0.79 g	— g	1.4 g
Squash, summer, all varieties, cooked, boiled, drained, with salt	20	0.91 g	4.31 g	1.4 g
Squash, summer, all varieties, cooked, boiled, drained, without salt	20	0.91 g	4.31 g	1.4 g
Squash, summer, all varieties, raw	16	1.21 g	3.35 g	1.1 g
Squash, summer, crookneck and straightneck, canned, drained, solid, without salt	13	0.61 g	2.96 g	1.4 g
Squash, summer, crookneck and straightneck, cooked, boiled, drained, with salt	19	1.04 g	3.79 g	1.1 g
Squash, summer, crookneck and straightneck, cooked, boiled, drained, without salt	19	1.04 g	3.79 g	1.1 g
Squash, summer, crookneck and straightneck, frozen, cooked, boiled, drained, with salt	25	1.28 g	5.54 g	1.4 g

These are the USDA entries that are squash, not foods made from it. Follow a name for the full profile and per-portion figures. Showing 12 of 49 USDA entries that are squash; the rest differ only in cut, pack or preparation.

What your body absorbs

In 116 Filipino schoolchildren fed carrots, squash and leafy greens for 9 weeks, 2.4 g fat per meal doubled total-body vitamin A as well as 10 g did. — children aged 9 to 12, three fat groups of 38 to 39 (n = 116) Evidence B source
Vitamin A pool about 2-fold, serum beta-carotene 5-fold, low liver vitamin A 35% to 7%

What cooking and storage change

Pressure-cooked squash held 237.83 mg potassium/100 g versus 460.25 mg when dry-oven cooked, and pressure-cooked zucchini only 93.62 mg, in a food analysis within a study for heart patients. — squash and other vegetables analysed after several cooking methods (Brazil); sensory arm 68 heart disease patients (n = 68 (sensory panel, not the potassium measurement)) Evidence D source
Squash potassium 237.83 vs 460.25 mg/100 g, zucchini 93.62 mg/100 g

What it does to your health

In 18 older adults with raised blood pressure, 2 weeks of 300 g/day cruciferous soups gave 0.14 mmol/L lower post-meal glucose than root and squash soups. — 18 non-diabetic adults with elevated blood pressure, median age 68, 89% women (n = 18) Evidence B source
2-h postprandial glucose -0.14 mmol/L (95% CI -0.24 to -0.04) on cruciferous vs root/squash
Observational data from 177,148 UK Biobank adults link a strong liking for butternut squash with 25% lower all-cause mortality over 3.4 years. — 177,148 UK Biobank participants with a food preference questionnaire (n = 177148) Evidence C source
HR 0.75 (95% CI 0.68 to 0.83)

Safety, limits and interactions

A case report describes haemorrhagic colitis, low blood pressure and vomiting in a 66-year-old woman after eating bitter, cucurbitacin-containing zucchini. — one 66-year-old woman (n = 1) Evidence D source
Self-limiting haemorrhagic colitis, recovered within 2 days on IV fluids
Among 2197 plant food-confusion cases at a French poison centre over 22 years, the squash family (Cucurbitaceae) was the second most frequent cause at 3.3%. — food confusion events, Marseille poison control centre, 2002 to 2023 (n = 2197) Evidence C source
Cucurbitaceae 3.3% of events, 0.5% of all events severe

What people believe that the data does not support

A case report describes orange skin and abnormal liver function tests in a 20-year-old woman who had eaten pumpkin and very little else daily for 2 years. — one 20-year-old woman with an eating disorder (n = 1) Evidence D source
Aurantiasis cutis and abnormal liver function tests

Who this works differently for

A case report describes food protein-induced enterocolitis syndrome caused by zucchini in a child, confirmed and later cleared by oral food challenge. — one child (n = 1) Evidence D source
Positive first oral challenge, tolerance on the second

The bottom line

How you cook squash changes how much potassium stays in it. In a Brazilian lab analysis of cooked vegetables, part of a study for heart patients, pressure-cooked squash held 237.83 mg of potassium per 100 g and oven-cooked squash held 460.25 mg. Pressure-cooked zucchini held 93.62 mg. Many of the differences in that study did not reach statistical significance, and it measured Brazilian produce, so read it as a direction. If a doctor has told you to limit potassium, cooking method is a fair thing to ask them about. The one safety rule here is simple. If a squash or zucchini tastes bitter, stop eating it. Bitterness is the sign of cucurbitacins, natural plant toxins, and a 66-year-old woman who ate bitter zucchini developed bleeding colitis, low blood pressure and vomiting. She recovered within two days on a drip. That is a single case report, but it is part of a pattern. Over 22 years a French poison centre handled 2197 cases of people eating the wrong plant, and the squash family was the second most common cause, at 3.3 percent. The one pumpkin case we hold is a 20-year-old woman who had an eating disorder and for two years ate little besides pumpkin. Her skin went orange and her liver tests were abnormal. That is one person on a very narrow diet, so it tells you nothing about pumpkin as part of ordinary meals. Children can react to squash, rarely. One child had food protein-induced enterocolitis syndrome, a delayed allergy-like reaction in the gut, from zucchini. A supervised feeding test confirmed it, and a second test later found the child had outgrown it. If your child reacts, that test is one to do with a doctor. Some questions have no answer yet. We found no human trial of how well carotenoids are absorbed from squash itself, nothing in our cards on squash in pregnancy or alongside medicines, and no approved health claim in the US or the EU that names squash.

Sources

sqsh-b1-03 · RCT
The meals provided 4.2 mg provitamin A carotenoids/d (mainly beta-carotene) from yellow and green leafy vegetables [carrots, pechay (bok choy), squash, and kangkong (swamp cabbage)] and 7, 15, or 29 g fat/d (2.4, 5, or 10 g fat/meal) ... The overall prevalence of low liver vitamin A (<0.07 mumol/g) decreased from 35% to 7%.
Am J Clin Nutr, 2007 · checked 2026-09-23
sqsh-b1-02 · laboratory 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. Among the lowest values, only squash (237.83 mg/100 g), also pressure-cooked, exceeded 200 mg/100 g. ... for squash (p = 0.037) between pressure cooking (237.83 mg/100 g) and dry oven (460.25 mg/100 g; p = 0.055).
Clin Nutr ESPEN, 2025 · checked 2026-09-23
sqsh-b1-01 · RCT
Overall PPGR 2-h and AUC were lower in the active versus control (mean difference: -0.14 mmol/L, 95% CI -0.24, -0.04, p = 0.005 and -20.1 mmol/L × min, 95% CI -34.1, -6.1, p = 0.005, respectively)
Diabetes Obes Metab, 2025 · checked 2026-09-23
sqsh-b1-07 · cohort
Higher preference for asparagus (hazard ratio (95% confidence interval)): 0.69 (0.62, 0.77)), aubergine (0.79 (0.72, 0.87)), black pepper (0.72 (0.64, 0.81)), broccoli (0.69 (0.61, 0.79)), butternut squash (0.75 (0.68, 0.83))
Sci Rep, 2026 · checked 2026-09-23
sqsh-b1-04 · 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
sqsh-b1-05 · retrospective cohort
Over 22 years, 2197 food confusion events were managed with 321 different species. The most frequently involved plant was Nerium oleander (289 cases, 13.1%), then Cucurbitaceae genus (3.3%)
Toxins (Basel), 2024 · checked 2026-09-23
sqsh-b1-06 · case report
A 20-year-old Japanese woman had been eating pumpkin and only a very limited amount of other foods on a daily basis for 2 years. ... Aurantiasis cutis and abnormal liver function tests were noted by her family doctor
J Hepatol, 1999 · checked 2026-09-23
sqsh-b1-08 · 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

Review. Reviewed on 2026-09-23 for evidence level, dose and population context, and claims a reader could misread. Bioma Learn has no human medical reviewer at this time, and we say so rather than invent one. Methodology. This is information, not medical advice.