A recently concluded study, utilizing more than twenty years of data collection, may come as the worst news yet for lovers of grapefruits and oranges. The study, published in the Journal of Clinical Oncology stated that people who consume high amounts of orange juice and whole grapefruit are at a higher risk of developing skin cancer (melanoma). This is not the first research to link citrus fruits to melanoma. Past researches have shown that tanning lotions containing psoralen (a naturally occurring substance found in citrus fruits) sensitize the skin to UV radiation effects hence increasing the risk of melanoma.
The research analyzed data from over 40000 men and 60000 women for 26 years with people filling questionnaires on their diets every four years. In the course of the research, 1840 participants were diagnosed with melanoma. The researchers found that people who consumed citrus fruits more than 1.6 times a day were 36% more likely to be diagnosed with melanoma.
Though the research did not dwell on the mechanisms that link citrus fruits consumption and skin cancer, the theory suggests that the link is similar to the one between tanning lotions and cancer. Dr. Wu speculates that the furocoumarins and psoralens present in the fruits make the skin sensitive to UV and stimulate proliferation of skin cancer cells. However, citrus fruits are not the only sources of furocoumarins, yet people consuming vegetables rich in the substance did not show increased risk of melanoma. The simple explanation for this is that furocoumarin level is reduced by heat when the vegetables are cooked.
Statistics from the American Cancer Society show that over 73000 people in USA were diagnosed with skin cancer in 2015 and almost 10000 of them will die from the disease.
One thing that is clear is that proliferation of melanoma cells requires a combination of citrus fruits consumption and exposure to UV. Therefore, people who consume a lot of citrus fruits should avoid over-exposure to the sun.
While the benefits of citrus fruits in weight loss and prevention of heart diseases and other conditions cannot be ignored, there are other dietary options that can provide the same nutrients as citrus fruits and do not contain psolaren. To maintain the health benefits of fruits, people should consume a wide variety.
The controversy surrounding citrus fruits is likely to continue before doctors find a balance. Researchers have to consider the fact that citrus fruits have anti-cancer properties and there is evidence showing they have a chemo-preventive effect against cancer. The researchers are left between a rock and a hard place to make recommendations involving a group of fruits beneficial for treating a type of cancer (colon) that results in the second highest cancer-related deaths and increase prevalence of a type of another dangerous form of cancer (melanoma).