Lemons (Citrus limon) are a good source of vitamin C. Lemons and lemon peel are also a source of chlorogenic acid, didymin, diosmin, eriocitrin, hesperidin, hesperetin, limonene, limonin and γ-terpinene, all of which have been reported to have anti-cancer properties. Lemons have been shown to have antioxidant, anti-inflammatory and antimicrobial properties. Consumption of lemons and lemon juice may improve cholesterol profile and reduce blood pressure. Hesperidin has been shown to inhibit androgen-dependent prostate cancer cell growth and to have chemopreventive action against carcinogen-induced lung cancer in mice. Limonin has been shown to suppression colon carcinogenesis in rats. Lemon consumption has been found to be associated with lower risk of thyroid cancer.
Lemon peel contains the monoterpene D-limonene, which is metabolized into perillic acid and some other components. D-limonene has been used in patients to dissolve cholesterol-containing gallstones and for the relief of heartburn and gastroesophageal reflux (GERD). D-limonene and its metabolites have been shown to inhibit the growth of human leukemia and lung cancer cells in the laboratory, as well as opposing lymphoma and skin, stomach, pancreatic, colon, and liver cancer in animals. D-limonene has been shown to enhance the antitumor effect of the chemotherapy drug docetaxel against prostate cancer cells without being toxic to normal prostate cells. Perillyl alcohol has been shown to inhibit androgen-induced prostate cancer cell growth and carcinogen-induced colon cancer in rats.
Consumption of lemon peel has been found to be associated with lower risk of squamous cell carcinoma of the skin. However, one major 2015 study reported that people with diets high in lemons (but not lemon juice) may be at slightly increased risk for malignant melanoma, possibly from ingesting photosensitizing compounds called psoralens found in citrus fruits.
Breast cancer-related effects of eating lemons
Perillyl alcohol, hesperidin and limonin have all been shown to inhibit the proliferation of breast cancer cells in the laboratory. Lemon extract has been shown to induce apoptosis (programmed cell death) of hormone receptor positive (ER+/PR+) breast cancer cells. D-limonene, which is a fat-soluble compound, has been shown to accumulate in breast tissue in levels much higher than levels in the systemic circulation, thus potentially impacting breast cancer risk.
However, a phase II clinical trial of perillyl alcohol (an important D-limonene metabolite) in the treatment of advanced breast cancer reported in 2008 that there was no benefit for the treatment. No population studies have been performed that directly assess the association between consuming lemons or lemon rind and the risk of breast cancer.
Hesperidin has the potential to interfere with cyclophosphamide treatment. Cyclophosphamide is an alkylating agent frequently used in combination with anthracyclines (Adriamycin, epirubicin) and/or taxanes (Taxol, Taxotere) to treat breast cancer. Examples of chemotherapy regimens incorporating cyclophosphamide include TEC (docetaxel, epirubicin, and cyclophosphamide), TAC (taxotere, adriamycin and cyclophosphamide), and FEC (cyclophosphamide, epirubicin and 5-fluorouracil). Hesperidin is found most abundantly in the peel, pith and membranous parts of oranges and other citrus fruits.
Non-organic lemons should be washed thoroughly before using to prevent a transfer of pesticides and other contaminants to the flesh during cutting.
Fresh lemonade has been shown to be a good source of D-limonene.
Limes (Citrus aurantifolia) are closely related to lemons, with similar nutritional characteristics. Limes are green rather than yellow, and normally are smaller and more acidic than lemons.
Below are links to recent studies concerning this food. For a more complete list of studies, please click on lemon.