First recorded in the Himalayan foothills of India, Cucumber has been cultivated for over 4,000 years. This long, cylindrical, green-skinned fruit of the gourd family has edible seeds surrounded by a mild, crisp flesh. Leading countries in the cultivation of Cucumbers include Britain, China, India, Iraq, Java, Kurdistan, Turkey, and Venezuela.

Cucumber is among the most widely grown vegetables, common in home gardens, on truck farms and as a greenhouse crop. It consists of around 96% water. The plant is trailing, usually on the ground in the open, but on trellises in greenhouses. The Cucumber is called a Gherkin when small and used in preserves and pickles, often with dill-flavoured vinegar. Cucumbers are available year-round, with the peak crop from late spring to late summer.

Cucumbers grow only under cultivation. They are used for fresh consumption, or for preservation, marinated with vinegar, salt, or spices. The thin skin, unless waxed, does not require peeling.

Cucumbers contain 5 calories per ounce and only very small amounts of nutrients. But some cultivars have significantly higher levels of vitamins A and C. Many people find the fruit to be indigestible: this is due to the high cellulose content. Oil from the seed is used in salad dressings and French cooking.The leaf juice is emetic and used to treat dyspepsia in children.

The fruit may be used as a natural remedy. The fruit is applied to the skin as a cleansing cosmetic to soften and whiten it. The juice is used in many beauty products.

Cucumber skins have been shown to repel cockroaches in laboratory experiments. The roots of Cucumber plants secrete a substance that inhibits the growth of most weeds.

Allergens

The following allergen has been characterised:

• Cuc s 2, a profilin (1-2).

The activity of a chitinase has been detected in xylem sap from Cucumber stems. Cucumber roots produce a chitinase and secrete it into xylem sap for delivery to aboveground organs (3). Whether this chitinase is found in the Cucumber fruit, and whether it has panallergen activity, are questions that have not been investigated yet. Cucumber leaves may contain a chitinase protein following a plant infection (4).

A beta-1,3-glucanase protein, a PR panallergen, was shown to be activated by plant stress in Cucumbers. Whether this panallergen has any clinical significance, or whether it occurs in the Cucumber fruit, has not been determined yet (5).

Cross Reactivity

An extensive cross-reactivity among the different individual species of the genus could be expected, as well as to a certain degree among members of the family Cucurbitaceae, such as Watermelon, Melon, and Cucumber (6).

An association between Ragweed pollinosis and hypersensitivity to Cucurbitaceae vegetables and Banana has been reported (7). Six of 26 patients who had Watermelon IgE antibodies reported developing oropharyngeal symptoms (itching and/or swelling of the lips, tongue, or throat) after ingesting at least 1 of the study foods of the gourd family (Watermelon, Cantaloupe, Honeydew melon, Zucchini, and Cucumber), or Banana (8).

There is cross-allergenicity among Celery, Cucumber, Carrot, and Watermelon. Immuno-blots of individual sera showed a 15 kDa protein band common to all 4 foods (9).

Cross-reactivity was demonstrated among Pumpkin, Pumpkin seed, Muskmelon, Watermelon, Cucumber and Zucchini (10). Cuc m 3 from Melon shares a sequence identity of 60% or more with PR-1 proteins from Grape and Cucumber (11).

Hevamine, an enzyme with lysozyme/chitinase activity from Hevea brasiliensis Latex, has a sequence identity of about 60% with a chitinase from Cucumber, and 95% with the N-terminal sequence of the lysozyme/chitinase of Parthenocissus quinquefolia. The differences in cellular location, charge properties and sequence between hevamine and Cucumber chitinase are similar to those between class I and class II chitinases from Tobacco and other plant species (12).

Last reviewed: June 2022