While you’re adding foods to your diet to help block UV rays, you might want to use extra sunblock if you’re a fan of the following foods, which may have the opposite effect:

Citrus Juice

While citrus fruit and juice are fantastic sources of vitamin C, an essential antioxidant, a 2015 study by the department of dermatology at Brown University found that white people who consumed large quantities of citrus products were more likely to develop melanoma. Citrus fruits, including lemons, limes, oranges, and grapefruit, are rich in naturally occurring chemicals called psoralens and furocoumarins, which have been linked to skin cancers. Researchers interviewed subjects over a 25-year span and found that white people who ate grapefruit three times per week or more were at increased risk. Regular orange juice consumption posed less risk, though not insignificant.

Celery Juice

This may be less common in the average diet, but multiple studies over the last two decades show a link between high consumption of psoralen, a compound found in some fruits and vegetables, and skin cancer. A study published in The Journal of Investigative Dermatology found that “substantial exposure to psoralen [and] ultraviolet A dramatically increases the risk of nonmelanoma skin cancer.”

Celery is especially rich in psoralen, though eating the vegetable itself doesn’t present enough of it to be a problem, says Katta. She recommends avoiding celery juice, though, because it can become a concentrated source of psoralen. “I always recommend whole foods over juicing,” she says.