A few studies indicate that lemons and other citrus fruits have naturally occurring substances that may have cancer fighting properties, namely modified citrus pectin and limonoids. These properties have not been tested in humans. widely circulating e-mail claiming to be from the Institute of Health Sciences (or the Health Sciences Institute) in Baltimore states that lemons are a “proven remedy against cancers of all types” and that lemons are 10,000 times stronger than chemotherapy.