Zucchini is a low-calorie vegetable that delivers a surprisingly broad range of vitamins, minerals, and protective plant compounds. One medium zucchini (about 196 grams) contains just 33 calories while providing meaningful amounts of vitamin C, potassium, and B vitamins. It’s also 95% water by weight, making it one of the most hydrating foods you can eat.
Calories, Carbs, and Fiber
Zucchini is one of the lightest vegetables in terms of calorie density. A medium zucchini has 33 calories, 6 grams of carbohydrates, 2 grams of fiber, and 2 grams of protein. One cup of cooked zucchini (180 grams) is even lower at 27 calories, since some water cooks off and the squash compresses. Fat content is negligible.
The fiber in zucchini is a mix of soluble and insoluble types. Two grams per medium zucchini isn’t a blockbuster number on its own, but zucchini is the kind of vegetable people eat in volume, tossed into stir-fries, soups, or spiralized as a pasta substitute. That makes its fiber contribution add up quickly in a real meal.
Key Vitamins
Vitamin C is zucchini’s standout micronutrient. A single medium zucchini provides 35 milligrams, which covers 39% of the daily value. That puts it in the same general range as an orange segment for segment, though most people don’t think of zucchini as a vitamin C source. This vitamin supports immune function and helps your body build collagen for skin and connective tissue.
Vitamin B6 is the other notable vitamin, at 0.32 milligrams per medium zucchini (19% of the daily value). B6 plays a role in over 100 enzyme reactions in the body, particularly in protein metabolism and the production of neurotransmitters like serotonin and dopamine. Getting nearly a fifth of your daily B6 from a single vegetable is uncommon outside of starchy foods like potatoes.
Zucchini also contains smaller amounts of folate, riboflavin, and vitamin A, mostly in the form of beta-carotene concentrated in the skin.
Minerals Worth Noting
Potassium is the dominant mineral in zucchini. One medium zucchini delivers 512 milligrams, covering 11% of the daily value. Potassium helps regulate fluid balance and blood pressure, and most people fall short of the recommended intake. Eating zucchini regularly is an easy, low-sodium way to close that gap.
Zucchini provides trace amounts of manganese, magnesium, and copper as well. None of these hit dramatic percentages on their own, but they contribute to your overall mineral intake in the same way that all whole vegetables do: steadily, across multiple meals.
Antioxidants and Carotenoids
Beyond standard vitamins and minerals, zucchini contains carotenoids that act as antioxidants. The most significant are lutein and zeaxanthin, two compounds known for protecting eye health. One cup of cooked zucchini with the skin on provides about 2,070 micrograms of lutein and zeaxanthin combined. These carotenoids accumulate in the retina, where they filter harmful blue light and reduce the risk of age-related macular degeneration over time.
The skin is where much of this antioxidant value lives. Studies on squash in the same species (Cucurbita pepo) show the peel contains roughly 60% more fiber than the flesh and higher concentrations of certain protective compounds. If you peel your zucchini, you lose a meaningful share of its nutritional value. The skin is thin and tender enough to eat without any special preparation.
How Cooking Changes the Nutrition
Because zucchini is rich in vitamin C, a water-soluble vitamin that breaks down with heat, your cooking method matters. Research comparing different techniques found that nutrient retention follows a clear hierarchy: microwaving preserves the most, followed by steaming, with boiling at the bottom. Boiling draws water-soluble vitamins and phenolic compounds out of the zucchini and into the cooking water, which most people discard.
That said, cooking isn’t purely a loss. Antioxidant activity in zucchini actually increases after cooking, particularly with stir-frying. Heat breaks down cell walls and releases compounds that are otherwise locked inside the plant tissue. In one study, stir-fried zucchini had nearly three times the measured antioxidant activity of raw zucchini. So while you lose some vitamin C, you gain better access to other protective compounds.
Raw zucchini has a similar overall profile to cooked, with more vitamin C but less available vitamin A. For the broadest nutritional benefit, eating zucchini both raw (in salads or with dips) and lightly cooked (sautéed or steamed) gives you the best of both worlds.
Why the Nutrient Density Is Deceptive
Zucchini’s 95% water content means its nutrients look modest when you measure them per gram. But that same water content is exactly why people eat large portions of it without thinking twice. Nobody stops at a quarter cup of zucchini. A typical serving in a stir-fry or a bowl of zucchini noodles can easily reach two cups, which doubles or triples all the values above. At that volume you’re getting a meaningful dose of vitamin C, potassium, B6, and carotenoids for fewer than 60 calories. Few foods offer that ratio.