Cucumbers contain small amounts of several vitamins, with vitamin K as the standout nutrient. They’re not a powerhouse source of any single vitamin, but their combination of vitamins, minerals, and exceptionally high water content (96%) makes them a useful addition to your diet, especially during warmer months.
Vitamin K Is the Main Event
Vitamin K is the most significant vitamin in cucumbers by a wide margin. A half-cup of unpeeled cucumber slices (about 52 grams) provides roughly 8.5 micrograms, which covers about 7% of your Daily Value. That number climbs quickly if you eat a whole cucumber, which weighs around 300 grams, pushing you closer to 50% of your daily vitamin K needs in a single snack.
Vitamin K plays a central role in blood clotting and helps your body maintain strong bones by regulating calcium. Most people get enough vitamin K from leafy greens, but cucumbers are an easy, mild-tasting way to top up your intake, especially if you’re not a fan of kale or spinach.
Vitamin C in Smaller Amounts
Cucumbers contain vitamin C, though far less than citrus fruits or bell peppers. You’ll get a few milligrams per serving, enough to contribute to your daily intake but not enough to rely on as a primary source. Vitamin C supports immune function and helps your body absorb iron from plant-based foods.
One practical consideration: vitamin C in cucumbers degrades over time. Research published in Applied Sciences found that cucumber juice stored in a refrigerator lost about 13% of its vitamin C after two weeks and over 15% after three weeks. At room temperature, losses were slightly faster. Eating cucumbers soon after buying them gives you the most vitamin C, and refrigeration helps slow the decline.
B Vitamins Across the Board
Cucumbers provide a spread of B-complex vitamins, none in large quantities, but collectively meaningful. One cup of peeled, chopped cucumber contains:
- Folate: 18.62 mcg
- Pantothenic acid (B5): 0.32 mg
- Vitamin B6: 0.07 mg
- Thiamin (B1): 0.04 mg
- Riboflavin (B2): 0.03 mg
- Niacin (B3): 0.05 mg
These B vitamins collectively support energy metabolism, helping your body convert the food you eat into usable fuel. Folate is the most notable of the group here, playing a key role in cell division and DNA synthesis. Cucumbers contain no vitamin B12, which only comes from animal products or fortified foods.
The Peel Makes a Difference
If you peel your cucumbers, you lose some of their nutritional value. A comparison from MyFoodData shows that unpeeled cucumber contains more vitamin K per gram than peeled cucumber. The skin also holds more fiber. When you account for the serving-size difference (a half-cup of unpeeled slices versus a full cup of peeled, chopped cucumber), the vitamin K content is comparable, at 8.5 mcg versus 9.6 mcg, but the unpeeled version delivers that from a much smaller portion.
The skin also contains beta-carotene, which your body converts into vitamin A. Peeling removes most of this. If you’re eating cucumbers for their nutritional value, leave the skin on whenever you can. Just give them a good rinse first.
Minerals Worth Noting
Beyond vitamins, cucumbers carry a useful mineral profile. One whole unpeeled cucumber (about 301 grams) provides approximately 442 milligrams of potassium, 39 micrograms of magnesium, and 0.2 milligrams of manganese, according to data from North Carolina State’s Cooperative Extension.
Potassium is the standout here. At 442 mg per cucumber, that’s roughly 9% of the recommended daily intake. Potassium helps regulate blood pressure by counteracting the effects of sodium, and it supports normal muscle and nerve function. The combination of potassium with cucumbers’ 96% water content makes them a particularly effective hydrating snack, since your body needs both water and electrolytes to stay properly hydrated.
How Cucumbers Fit Into Your Diet
Cucumbers are not a substitute for nutrient-dense vegetables like broccoli, sweet potatoes, or leafy greens. Their vitamin concentrations are modest across the board. What they offer instead is a low-calorie, high-water vehicle that delivers a broad spectrum of micronutrients with almost no downside. A whole cucumber has only about 45 calories.
Their real strength is versatility. Because they’re so mild and hydrating, most people eat them in quantities large enough to make those small vitamin amounts add up. A few slices in a salad won’t move the needle, but eating a full cucumber as a snack delivers meaningful amounts of vitamin K and potassium alongside traces of vitamin C, several B vitamins, and a burst of hydration that most people could use more of.