Cucumber supplements arrive as powders, juice concentrates, or extracts. The vegetable is mostly water and carries small amounts of vitamin K plus antioxidant compounds like cucurbitacins and flavonoids.
People take these supplements mainly for hydration and a light antioxidant boost. Some choose them to raise fluid intake or to fold plant phytonutrients into a daily routine without eating whole vegetables.
Solid evidence for any specific health effect is missing. Taking cucumber extracts has not been shown to change skin appearance, digestion, or other functions beyond what a hydrating, low-calorie food would do.
Most people tolerate cucumber well. Supplements can contain vitamin K, so anyone on blood thinners (warfarin, for example) should keep their intake steady and speak with their healthcare provider before starting.