Researchers at the Alpert Medical School’s Department of Dermatology found that diets rich in vitamin A are associated with a 17 percent reduced risk of developing the second most common type of skin cancer, cutaneous squamous cell carcinoma.
According to the National Institutes of Health, vitamin A plays an active role in the immune system, healthy vision and cell communication; foods high in vitamin A concentration include mango, liver and carrot.
The research team included a number of faculty in the Department of Dermatology, including the paper’s lead author Eunyoung Cho, associate professor of dermatology and epidemiology, Abrar Qureshi, chief of the department of dermatology at the Rhode Island Hospital and chair of the department at the medical school and Wen-Qing Li, assistant professor of dermatology and epidemiology. The team also included Jongwoo Kim, who was a visiting scholar from Korea at the time of the project, and Min Kyung Park, who was a post-doctoral fellow at the time.
The researchers used data collected by two observational studies done at Harvard: The Nurses’ Health Study — which has been collecting data from female nurses since 1976 — and The Health Professional Follow-Up Study — which has been collecting data from male health professionals since 1986.
Both studies were comprised of a comprehensive questionnaire administered every two years and included questions regarding a participant’s diet and whether they had been diagnosed with skin cancer.
The team began by collecting and extracting data on vitamin A intake and the diagnoses of the second most common type of skin cancer, cutaneous squamous cell carcinoma. If a participant noted that they had been diagnosed with the target skin cancer, Qureshi would collect and analyze medical records and biopsies to confirm the reporting. This step was critical to ascertain that participants reporting positive diagnoses did in fact have the disease.
By adjusting for risk factors such as skin color, UV exposure and where participants live, “this research underscores that a healthy diet may protect against various ailments, in this case, skin cancer,” Qureshi said. “We’re not saying don’t wear sunscreen, but if you are out in the sun anyway then consider taking vitamin A.”
Unlike the design of other epidemiological studies, which are case control studies and as a result tend to be retrospective, this study used a prospective investigation, Cho said. This meant that the researchers collected data on the participants before they developed the skin cancer, leading to a less biased study.
Though other studies testing the relationship between vitamin A intake and skin cancer incidences have shown mixed results, the researchers believe that their experiment was more extensive and used more thorough methodology.
Still, the study did have limitations, Qureshi said. “No study is perfect.”
Since the data used was collected using only health professionals as participants, it may not be representative of the general population. The study also did not have specific data on the times of day the participants were exposed to the sun, which can be connected to skin cancer development.
In the future, the team hopes to expand on this research by incorporating a number of factors, such as whether taking vitamin A supplements may reduce skin cancer incidence.
