A study published in the Journal of Clinical Oncology on Monday has found a surprising link between high citrus consumption and risk of melanoma, which according to experts is the most severe form of skin cancer. The study that analyzed dietary patterns of over 100,000 Americans identified orange and grapefruit juice as the biggest culprits.
The study had more than 40,000 men and more than 60,000 women as participants. While the men participated in the Health Professionals Follow-UP Study, the women were part of the Nurses’ Health Study.
This means the researchers carried out the study only on individuals associated with the healthcare industry. This pattern of the study has allowed some experts to complain that the studied individuals are not representatives of the general population.
The research team found that melanoma risk was extremely low among the participants. Less than 2% of them ended up having melanoma during a period of 25 years. To be more precise, only 1,840 participants developed melanoma during this period. However, the chances of getting the condition were clearly much higher among people consuming citrus fruits or juices in high quantity.
The researchers found that individuals who consumed citrus juice or fruit 1.6 times per day had 36% greater risk of getting the cancer than individuals who consumed such items less than two times in a week. The researchers defined a serving as one orange, half a grapefruit or 1 glass or 6 ounce citrus juice.
According to the study authors, the link between citrus consumption and risk of melanoma might stem from high levels of furocoumarins found in citrus fruits. Plants produce these organic chemical compounds for protecting themselves against a wide variety of predators including mammals and insects.
Furocoumarins are photoactive, which means their toxicity increases when then come in contact with ultraviolet radiation. These organic compounds are known for increasing our skin’s sensitivity to sunlight.
During this study, the researchers didn’t take age, alcohol intake, cigarette smoking and several other lifestyle factors that we normally link with cancer into consideration. According to the study’s lead author Shaowei Wu, the findings of this study suggest that individuals who consume orange and/or grapefruit juice in high quantity should try to avoid extended sun exposure. Wu represents the Warren Alpert Medical School of Brown University as a postdoctoral research fellow.
The findings have been described as “intriguing” even by the American Society of Clinical Oncology. However, experts at the organization have said that it’s not yet the right time to introduce any change in the dietary recommendations involving oranges and grapefruits.