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. The flesh of cucumbers contain some vitamin C and vitamin A. Cucumbers are a good source of lupeol and lutein, both of which have been shown to have anticancer activities. The skin of the cucumber is a source of cucurbitacins, as well as dietary fiber and 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 their chemopreventive 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 toxic when ingested in large amounts or concentrated form. 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
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 fewer cucumbers 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.
Organic cucumbers are preferable to conventionally grown cucumbers. Cucumber skin is nutritious, but conventional cucumbers are normally coated with wax that may be petroleum-based and can trap pesticide residue and other contaminants. Therefore, conventionally grown cucumbers should always be peeled, which eliminates the best source of cucurbitacin D. In addition, non-organic greenhouse cucumbers were found to incorporate unacceptably high levels of cadmium, lead, and chromium in one study.
Slicing cucumbers (the common cucumber found in supermarkets) appear to be the best choice of cucumber. Pickling cucumbers and gherkins also incorporate cucurbitacin D. However, the sodium content of commercial dill pickles, sweet pickles, bread and butter pickles, pickle relish and pickled gherkins can be high. Burpless cucumbers such as Persian and English cucumbers have low levels of cucurbitacins, including cucurbitacin D.
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 highly 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.