Zucchini is a summer squash, which means it is a squash picked young. It is the same species, Cucurbita pepo, as many pumpkins and pattypan squash. But it is harvested while the rind and seeds are still soft, and left to mature it is called a marrow. Botanically it is a fruit, and in the kitchen it is a vegetable.
Zucchini is also one of the youngest vegetables. A study of old Italian farming and cooking books traces it to the area around Milan, perhaps as early as 1850. The word zucchini first named a small dried bottle gourd used to store tobacco.
A raw zucchini is about 95% water, with 17 calories and 18 mg of vitamin C per 100 g. It also holds 2,125 µg (micrograms) of lutein and zeaxanthin, two yellow plant pigments called carotenoids, per 100 g.
Almost no research has tested zucchini on health outcomes in people. The one thing to watch for is a bitter taste, which means the fruit should not be eaten.
Health benefits of zucchini
The top findings from 13 studies, strongest evidence first
What the stars mean
- Strong. Several randomized trials, pooled in a meta-analysis, point the same way, or regulators (FDA or EFSA) have approved the claim.
- Moderate. Good randomized trials support it, but there are fewer of them, or their results vary.
- Limited. Small, short or single trials, or mixed results. Promising, but it needs confirmation.
Population and lab studies get no stars: they show a link or a mechanism, not proof.
How we rate evidence →- ★★Lower late macular degeneration risk, from pillsIn people with intermediate macular degeneration, an eye disease of aging, lutein and zeaxanthin pills lowered the risk of the late stage by 9%. Zucchini contains these carotenoids, but pills were tested.
- ★More vegetables eaten by young childrenChildren aged 3 to 5 ate 52 to 73 g more vegetables a day when they were hidden in dishes such as zucchini bread. Zucchini was one of five vegetables used.
- Population studyLutein in food linked to less macular degenerationPeople who got the most lutein and zeaxanthin from food had 26% less late macular degeneration. Zucchini is one source of these carotenoids.
All 13 studies, strongest evidence first
Lutein and zeaxanthin pills lowered late macular degeneration risk 9%
This 10-year follow-up of the AREDS2 randomized trial tested supplements, not zucchini, in 3,882 people (6,351 eyes) with intermediate age-related macular degeneration. Compared with beta carotene, the two carotenoids did better (0.85 times the risk). They did not clearly raise lung cancer risk, while beta carotene did (odds ratio 1.82). The follow-up years were not randomized, because everyone took lutein and zeaxanthin.
Hidden vegetables raised children’s vegetable intake 52 to 73 g daily
In this randomized crossover trial, 40 children aged 3 to 5 ate all meals and snacks one day a week for 3 weeks. Vegetables were puréed and hidden in dishes such as zucchini bread; zucchini was one of five, with broccoli, cauliflower, tomatoes and squash. Daily energy fell by 142 kcal (12%) when the vegetable content was quadrupled, and the children liked the dishes about the same. This is not a test of zucchini alone.
Top lutein and zeaxanthin intake went with 26% less late macular degeneration
This meta-analysis pooled six cohort studies, which follow people over time. The risk of neovascular (wet) macular degeneration was 32% lower, while early macular degeneration showed no link (0.96 times the risk). It covers these carotenoids from all foods, of which zucchini is one source, and the authors say more studies are needed.
Boiling and steaming courgettes kept more carotenoids than frying
This lab study boiled, steamed or fried carrots, courgettes (zucchini) and broccoli. Boiling and steaming also kept vitamin C in courgettes, while fried vegetables kept their antioxidants less well. Antioxidant readings rose after all three methods, probably because softening makes compounds easier to extract. These are measurements of the cooked vegetable, not a study in people.
Of 20 vegetables, zucchini lost the most antioxidant activity boiled or fried
Lab study of 20 vegetables cooked six ways. Overall, griddling, microwaving and baking caused the smallest losses, while pressure-cooking and boiling caused the largest. Results depended on the antioxidant test used, and this was not a study in people.
Microwaved courgette gave human gut-like cells the most lutein
This lab digestion model tested courgette (zucchini), red pepper and tomato, plus Caco-2 cells, a human intestinal cell line. For lutein uptake by the cells, microwaving beat raw, boiled, grilled and steamed courgette. Every cooking method lowered beta-carotene in the digested food but made more of it transferable to micelles, the tiny fat clusters that carry it. Grilling and microwaving were the worst for beta-cryptoxanthin, and transfer ranged from 1.7% to 100% depending on the food, carotenoid and method.
Oil added to a raw courgette meal raised carotenoid transfer into micelles
This lab digestion model added olive, peanut or rapeseed oil to a raw meal of courgette, red pepper and spinach. The gain did not grow with the amount of oil. In a meal of tomato, red pepper and spinach, adding oil or fiber lowered carotenoid transfer, so the effect depends on the vegetables. This is a lab model, not a study in people.
Stir-fried zucchini showed higher antioxidant capacity; steamed won on looks and texture
This lab and tasting study used zucchini cubes (10 and 20 mm) that were raw, stir-fried or steamed. The higher antioxidant capacity of stir-fried zucchini came partly from the oil. Total phenolics stayed stable across sizes and methods, and smaller cubes were preferred in the sensory test. Stir-frying also raised dry matter, protein and fat, which is mostly the oil.
Microwaving kept more minerals in zucchini than grilling or steaming
Lab study of two zucchini varieties, eggplant and potatoes that were grilled, microwaved or steamed. Some minerals, such as sodium, calcium, manganese and iron, were gained or lost more than others. The authors call for more research on how heat changes the mineral content.
Organic and conventional courgettes did not differ in vitamin C, carotenoids or chlorophylls
This field comparison grew two cultivars in organic and conventional systems. Organic fruit had more sugars, and manure-fertilized organic fruit had more of some polyphenols. The authors say the trends need confirming on other varieties.
Zucchini had 30 to 50% of its carotenoids as lutein and zeaxanthin
This lab analysis tested 33 fruits and vegetables. Egg yolk and corn had the highest share (over 85%). Kiwi, grapes, spinach, orange juice, zucchini (vegetable marrow) and several squashes came next. The authors say vegetables of many colors, not only dark greens, can raise lutein and zeaxanthin intake.
Zucchini extracts were not toxic to DNA and shielded cells from peroxide
This cell study tested yellow and light green zucchini, plus lutein, beta-carotene, zeaxanthin and dehydroascorbic acid. The protection was against hydrogen peroxide, and it did not hold for the highest lutein dose. Light green zucchini skin triggered DNA fragmentation in HL60 leukemia cells. This was done in cells, not in people.
Dayangua zucchini reduced weight gain in mice on a high-fat diet
This study was in mice, not people. Obese mice got 600 mg per kg of the variety for 14 weeks. It also lowered fat in the liver and fat tissue, improved blood lipids and glucose handling, and shifted gut bacteria. One author works for a biotech company.
Who should be careful with zucchini
Most people can eat zucchini freely. Take a little care if one of these applies:
- Bitter zucchini. Wild squashes make bitter, toxic cucurbitacins, and breeding has greatly reduced them in zucchini from shops and bought seed. Rarely, a fruit from a home garden turns bitter and toxic, for example after drought or when saved seed cross-pollinated with ornamental gourds. If a zucchini tastes bitter, throw it away, because cooking does not make it safe. French poison centers reported 353 people over about 5 years after exposure to non-edible bitter squash, almost all by eating it. Of these, 57.8% had diarrhea, vomiting or stomach pain, and none died.
- Allergy to zucchini. It is rare, and the first four cases were reported in 2000. Cases have been linked to pollen and latex allergy, so itching in the mouth after eating zucchini is worth mentioning to an allergist.
- Babies under 3 months. Two infants aged 1 and 2 months developed methemoglobinemia, a blood oxygen problem. Their formula had been made with a high concentration of courgette soup to treat constipation. The authors advise against using nitrate-rich vegetables such as courgette to relieve constipation in very young babies, who are more sensitive to nitrates.
How to choose, store and eat zucchini
- With a little oil: in a lab digestion test, olive, peanut or rapeseed oil raised carotenoid transfer from a raw courgette meal.
- Steamed or microwaved: microwaved courgette gave gut-like cells the most lutein in a lab test, and microwaving kept the most minerals in another.
- Boiled or fried: lab results conflict. Boiling kept more carotenoids than frying in one study, while another found zucchini lost the most antioxidant activity after boiling and frying.
Pick glossy, firm squash that are small to medium and heavy for their size. Keep them unwashed in a plastic bag in the fridge for up to 5 days.
Residues are no reason to skip it. In USDA tests of 698 summer squash samples (zucchini, yellow and crookneck squash) in 2021, none had a residue above the legal limit.
Sources
- Le Roux G, Leborgne I, Labadie M, et al. Poisoning by non-edible squash: retrospective series of 353 patients from French Poison Control Centers. Clin Toxicol (Phila). 2018.
- Jung C, Steuber B, Schwörer H. Food poisoning by cucurbitacines. Dtsch Med Wochenschr. 2020. In German.
- Vergiftungsfälle durch bittere Zucchini. Bavarian State Office for Health and Food Safety (LGL). 2015. In German.
- Reindl J, Anliker MD, Karamloo F, Vieths S, Wüthrich B. Allergy caused by ingestion of zucchini (Cucurbita pepo): characterization of allergens and cross-reactivity to pollen and other foods. J Allergy Clin Immunol. 2000.
- Pereira C, Tavares B, Loureiro G, Lundberg M, Chieira C. Turnip and zucchini: new foods in the latex-fruit syndrome. Allergy. 2007.
- Savino F, Maccario S, Guidi C, et al. Methemoglobinemia caused by the ingestion of courgette soup given in order to resolve constipation in two formula-fed infants. Ann Nutr Metab. 2006.
- Ryan L, O’Connell O, O’Sullivan L, Aherne SA, O’Brien NM. Micellarisation of carotenoids from raw and cooked vegetables. Plant Foods Hum Nutr. 2008.
- O’Connell O, Ryan L, O’Sullivan L, Aherne-Bruce SA, O’Brien NM. Carotenoid micellarization varies greatly between individual and mixed vegetables with or without the addition of fat or fiber. Int J Vitam Nutr Res. 2008.
- Miglio C, Chiavaro E, Visconti A, Fogliano V, Pellegrini N. Effects of different cooking methods on nutritional and physicochemical characteristics of selected vegetables. J Agric Food Chem. 2008.
- Jiménez-Monreal AM, García-Diz L, Martínez-Tomé M, Mariscal M, Murcia MA. Influence of cooking methods on antioxidant activity of vegetables. J Food Sci. 2009.
- Lisciani S, Aguzzi A, Gabrielli P, et al. Effects of household cooking on mineral composition and retention in widespread Italian vegetables. Nutrients. 2025.
- Summer squash. University of Nebraska–Lincoln Extension.
- Pesticide Data Program annual summary, calendar year 2021. USDA Agricultural Marketing Service.
History of zucchini
Squashes were among the first crops people grew in the Americas. At El Gigante Rockshelter in Honduras, radiocarbon dating shows people used wild squash and bottle gourds about 10,950 years ago. They used them mostly as watertight containers.
Domesticated Cucurbita pepo seeds appear there about 2,190 years ago. They fall into at least three types, one like present-day zucchini and another like vegetable marrow.
Wild squashes are bitter, and that may be part of their story. Researchers have suggested that large animals that once ate wild squash and spread its seeds died out. That left the wild plants without helpers, and people took over that role. The wild ancestors of several squash crops are now scarce or unknown.
Squash reached Italian kitchens by the mid-16th century. Within about 50 years, young elongated C. pepo fruits were cooked as their own item. They had largely replaced the centuries-old use of young bottle gourds.
The cylindrical zucchini is much newer. Its group traces back to the area around Milan, perhaps as early as 1850. The earliest known description is in a horticulture book published in Milan in 1901.
The name arose separately. In Tuscany, near the start of the 19th century, zucchini meant small dried bottle gourds used to store tobacco. By the 1840s the word was used for young, mostly elongated C. pepo fruits. It is a diminutive of zucca, the Italian word for gourd, pumpkin or squash.
Courgette is the French-derived name used in Britain and France. The Académie française lists it as a 20th-century coinage from the 14th-century word courge.
The first records of zucchini in the United States date to the early 1920s, and Italian immigrants probably brought it to California. In Britain, the food writer Elizabeth David recalled that courgettes were rare and expensive imports from France when she wrote Italian Food in 1954. A Surrey nursery began growing them for the British market in 1957.
Sources
- Domic AI, VanDerwarker AM, Thakar HB, et al. Archaeobotanical evidence supports indigenous cucurbit long-term use in the Mesoamerican Neotropics. Sci Rep. 2024.
- Kistler L, Newsom LA, Ryan TM, Clarke AC, Smith BD, Perry GH. Gourds and squashes (Cucurbita spp.) adapted to megafaunal extinction and ecological anachronism through domestication. Proc Natl Acad Sci U S A. 2015.
- Lust TA, Paris HS. Italian horticultural and culinary records of summer squash (Cucurbita pepo, Cucurbitaceae) and emergence of the zucchini in 19th-century Milan. Ann Bot. 2016.
- Zucchini. Wikipedia.
Frequently asked questions about zucchini
Is zucchini good for you?
For most people, yes, though no trial has tested it on health outcomes. Per 100 g it has 17 calories, 17.9 mg of vitamin C (20% of the Daily Value) and 1 g of fiber. It is about 95% water.
Lutein and zeaxanthin, which it contains, were linked as supplements to a 9% lower risk of late macular degeneration in a trial follow-up. That is not proof that zucchini does the same.
Is zucchini healthier raw or cooked?
No study in people compares them, and lab results differ by nutrient. In lab tests, boiling and steaming kept more carotenoids than frying, and microwaving gave gut-like cells the most lutein. Zucchini also lost the most antioxidant activity after boiling and frying.
Raw zucchini is safe to eat, and a little oil helped carotenoid transfer in a lab digestion test.
Why is my zucchini bitter, and can it make you sick?
A bitter zucchini contains cucurbitacins, and eating it can cause vomiting, diarrhea and stomach pain. Bavarian food safety officials link it to drought and to saved seed that cross-pollinated with ornamental gourds. They advise against eating bitter zucchini raw or cooked.
In 353 French poison center cases of bitter squash, 57.8% had symptoms and none died. But one 66-year-old woman needed hospital care with bloody diarrhea. If it tastes bitter, throw it away.
Is zucchini good for weight loss?
No study tested weight loss with zucchini. It is 94.8 g of water per 100 g and only 17 calories, so it fills a plate cheaply.
In a trial of 40 children, hiding puréed vegetables including zucchini in meals cut daily energy by 142 kcal (12%). That is a swap effect, not a proven effect of zucchini itself.
How many carbs are in zucchini, and is it keto?
Zucchini is low in carbs, with 3.1 g per 100 g, of which 1 g is fiber, leaving about 2.1 g of net carbs. A cup (124 g) has 3.9 g of carbs and about 2.6 g net.
That makes it a common stand-in for pasta when cut into spirals. How it fits your plan depends on your own targets.
Is zucchini a fruit or a vegetable?
Both, depending on who is asking. Botanically it is a fruit, the young fruit of Cucurbita pepo, and in cooking it is a vegetable. Zucchini and courgette are the same thing, with the name differing by country.
Can you be allergic to zucchini?
Yes, but it is rare. The first four cases were reported in 2000, with symptoms such as itching in the mouth, nausea, diarrhea and itchy skin. They were confirmed by a double-blind food challenge.
Some of the allergen survives heat, and cases have been tied to pollen and latex allergy, so see an allergist if you react.