Like watermelons, pumpkins, zucchini and other types of squash, cucumbers (Cucumis sativus) belong to the cucurbitaceae (gourd) family. Cucumbers have a high water content and are low in calories and relatively low in nutrients compared to most other vegetables. The flesh of the cucumber contains some vitamin C and vitamin A. Cucumber components which have been shown to have some anticancer activities include fisetin, lutein, caffeic acid and cucurbitacins. The skin of the cucumber is a source of dietary fiber and contains minerals such as potassium, magnesium, and molybdenum. Cucumbers have been shown to have some antioxidant activities, but these are low compared to those of intensely colored vegetables and do not appear to be the source of its apparent anticancer properties. Cucumber consumption may help reduce cholesterol. Cucumber fruit and leaf extracts have been found to be useful in lightening and soothing the skin, and to treat inflammatory skin conditions such as rosacea.
Cucumbers with excessive bitterness are typically rejected by the consumer and cultivated species have been selected for low bitterness. The bitterness is caused by a class of phytochemicals called cucurbitacins (oxygenated tetracyclic triterpenes), which have been shown to have some anticancer properties, but which also can be highly toxic when ingested. Fisetin, a flavonoid found in cucumbers, has been shown to reduce the viability of postate cancer cells in the laboratory without harming normal prostate cancer cells. Consumption of cucumbers has been found to be associated with lower risk of lung cancer among tin miners in China.
Breast cancer-related effects of eating cucumbers
Caffeic acid has been shown to have antiproliferative and apoptotic effects on human breast cancer cells in the laboratory. A Korean case-control study comparing the diets of breast cancer patients with a healthy control group of women found that the breast cancer patients consumed a significantly lower quantity of vegetables, including cucumbers, than the control group. A Greek study also found that women with breast cancer consumed significantly less cucumber than those without breast cancer. A Swiss study found that consumption of cucumbers, among other fruits and vegetables, was associated with significant protection against breast cancer.
Gherkins are a different cultivar of Cucumis sativus and have a similar nutritional profile as cucumbers. Seedless cucumbers typically are longer in length, have thinner skins, and are grown in greenhouses. The sodium content of commercial dill pickles, sweet pickles, bread and butter pickles, pickle relish and pickled gherkins can be high.
Although cucumber skin is nutritious, waxed cucumbers should always be peeled before consumption since the wax can trap pesticide residue and other contaminants. Non-organic cucumbers must be washed very thoroughly to remove pesticides as much as possible before cutting or peeling even if not waxed. Non-organic greenhouse cucumbers were found to incorporate unacceptably high levels of cadmium, lead, and chromium in one 2009 study.
Colocynth (Citrullus colocynthis), also known as bitter apple or bitter cucumber, is related to cucumber, but contains a much higher fraction of cucurbitacins. Colocynth and other high-cucurbitacin cucurbits are sometimes sold as herbal remedies, including for cancer. However, while chemotherapy based on cucurbitacins may eventually be developed, these are toxic chemicals whose safety profiles and appropriate dosages have not been determined.
Below are links to recent studies concerning this food. For a more complete list of studies, please click on cucumber.