Eat Your Carrots
A diet rich in vitamin A is linked to lower skin cancer risk.
BY MOLLIE RAPPE
HEALTH DISCOVERIES l WINTER 2020 5
E
ating foods with lots of vitamin A, like sweet potatoes, carrots,
and leafy greens, may reduce the risk of getting the second-most-
common type of skin cancer, according to dermatologists at Brown.
“Our study provides another reason to eat lots of fruits and
vegetables as part of a healthy diet,” says Eunyoung Cho, ScD, an associate
professor of dermatology.
Cutaneous squamous cell carcinoma (SCC) makes up about 20 percent of
skin cancer cases and is more common among people with fair skin who have
excessive sun exposure or use tanning beds. Researchers have long known
vitamin A is essential for healthy skin cells, but until now haven’t been able to
show it could reduce skin cancer risk.
“Skin cancer, including squamous cell carcinoma, is hard to prevent,” Cho
says, “but this study suggests that eating a healthy diet rich in vitamin A may
be a way to reduce your risk, in addition to wearing sunscreen and reducing
sun exposure.”
The analysis, which was published in the Journal of the American Medical
Association Dermatology, looked at the diets and skin cancer results of
participants in two large, long-term observational studies, which followed
more than 170,000 men and women over several decades. About 123,000
participants were white, and thus had significant risk of developing skin
cancer, but had no prior history; and there were nearly 4,000 reported cases
of SCC.
People who consumed the most vitamin A were 17 percent less likely to get
SCC than those with the lowest intake. Those in the highest category said that
on average they ate the amount of vitamin A in one medium baked sweet
potato or two large carrots each day, while those in the lowest category
reported eating a daily equivalent of one-third cup of sweet potato or one small
carrot—which is still more than US dietary guidelines.
The study subjects got most of their vitamin A from fruits and vegetables
rather than supplements or animal-based foods like milk, certain fish, and
liver.
Because the analysis was based on surveying people about the foods they
ate and observing whether they got skin cancer, it can’t establish cause and
effect. It’s possible that another factor may have led to the differences. So Cho
says she’d like to conduct a clinical trial to see if vitamin A supplements can
prevent SCC.
But running a dietary clinical trial is technically difficult, because
researchers have to ensure that participants actually stick to the diet. “If a
clinical trial cannot be done, then a large-scale prospective study like this is
the best alternative for studying diet,” Cho says.