Cancer researchers are examining if eating citrus might put people more at risk for developing melanoma since researchers have long known that certain citrus juices on the surface of the skin can make skin so sensitive to light that people can end up with serious burns.
Dr. Abar Qureshi, director of dermatology at Brown University and Rhode Island Hospital, and his team wanted to know if simply eating citrus could also lead a higher risk of sensitivity to light and as a result developing skin cancer.
To do this, researchers, in collaboration with Rhode Island Hospital and Brigham and Women’s Hospital in Boston, examined health and diet data from more than 100,000 participants for up to 26 years. All of those involved were health professionals -- participants of the ongoing Nurses' Health Study and Health Professionals Follow-Up Study.
The researchers found that those who ate the most citrus fruits or juices (about 1.6 servings of citrus per day) had a higher incidence of melanoma, up to 36 percent higher than their peers, according to the study published this week in the Journal of Clinical Oncology.
However, researchers noted there were also inconsistencies that would need further explanation. For example some people who had grapefruits were at a high risk for cancer but those who had grapefruit juice were not.
Qureshi, the senior author of the study, said the study findings were interesting but needed to be replicated before doctors started advising anyone to start changing their diet.
“It’s an early signal. We would never ask people to stop consuming overall healthy fruits and vegetables,” said Qureshi, who advised people to be careful about exposure to sunlight if they are concerned.
"It’s combination of citrus plus sun," that needs investigating, Qureshi said.
Qureshi said he and his team want to know more about how certain chemicals in citrus juice called psoralens and furocoumarins could lead to people being more photosensitive. It’s unclear why some people were more at risk depending on the kind of fruit they ate or how it was prepared, he said.
An editorial published in the same journal found that more study was needed in part because the population, all health professionals, did not accurately represent the general population and some of the findings were at odds with what has previously been determined by past studies.
“This is a potentially important study, given that citrus consumption is widely promulgated as an important dietary constituent and has demonstrated benefit for coronary heart disease, cancer prevention, and overall health effects,” Marianne Berwick, of the Department of Internal Medicine at the University of New Mexico, wrote in her editorial. “At this point in time, a public overreaction leading to avoidance of citrus products is to be avoided.”
Dr. Barney Kenet, a New York-based dermatologist, said those afraid of skin cancer should take care to wear sunscreen, stay out of the sun during the midday and get regular checks from a dermatologist, pointing out those are actions known to decrease risk of skin cancer no matter what someone is eating.
“It’s good for information to be out there. The problem comes when people jump to conclusions prematurely,” said Kenet. “Clearly citrus has a place in a healthy diet. “