Photodynamic therapy is a widely used treatment for actinic keratoses—rough, scaly patches on the skin that may develop into cancer if not treated. Typically, complete skin healing after photodynamic therapy takes between five and ten days, but a recent study found that healing rates differ markedly between vegans and omnivores.

The study involved 60 patients (30 omnivores and 30 vegans) who were treated with photodynamic therapy for actinic keratosis. Researchers compared side effects using a local skin response score at three intervals: three days, seven days, and 30 days post-treatment. They also noted the time required for complete skin healing in both groups.

They found that vegans experienced higher total local skin response scores at each interval, indicating they had more severe side effects. On day three, vegans had considerably more swelling and blistering than omnivores. By day seven, they had more redness, peeling, swelling, and blistering. At thirty days, redness and peeling were still more noticeable in vegans. The time required for complete skin healing was notably longer for the vegan group.

These findings suggest that diet influences healing time following photodynamic therapy, with vegans being more prone to prolonged side effects and slower healing.

Photodynamic therapy involves the use of a photosensitizing agent (a drug that becomes activated by light) and a specific wavelength of light. When the photosensitizer is exposed to this light, it produces reactive oxygen species that can destroy targeted cells. It differs from photobiomodulation—often called red-light therapy—which uses low-intensity light to stimulate cellular processes and promote healing and pain relief. Learn more about photobiomodulation in our overview article.