Journal of Clinical Oncology
June 29, 2015
A prospective study of more than 100,000 Americans suggests that consuming citrus fruit, specifically whole grapefruit and orange juice, frequently may increase one’s chance of developing melanoma. However, experts stress more research is needed and caution against making any dietary changes based on this study at this time.
Over a 25-year period, people who consumed these forms of citrus at least 1.6 times daily were 36% more likely to develop melanoma compared to those who consumed it less than twice a week. Citrus was not associated with increased risk of any other non-skin cancer.
Eating whole grapefruit had the strongest effect on melanoma risk, followed by drinking orange juice. Conversely, consuming either grapefruit juice or whole oranges was not associated with melanoma risk, and neither were other fruits and vegetables.
The researchers believe that the apparent link between melanoma and citrus may be due to high levels of substances called furocoumarins found in citrus fruits. Prior research showed that furocoumarins make the skin more sensitive to sunlight, including melanoma-causing ultraviolet (UV) rays.
What This Means for Patients
Knowing about risk factors may help people make more informed lifestyle and healthy choices. These new findings suggest that eating whole grapefruit and drinking orange juice may increase the risk of melanoma, in combination with excessive sun exposure.
However, this single observational study is not sufficient to warrant a decrease in citrus intake, particularly given all proven health benefits of this food group. In the meantime, people who consume large amounts of citrus may consider taking extra caution to avoid prolonged sun exposure.