Association of sunlight exposure with 25-hydroxyvitamin D levels among working urban adult Filipinos

OBJECTIVES: To determine the association of different levels of sunlight exposure, measured using the Filipino sunlight exposure questionnaire (SEQ) with 25-hydroxyvitamin D (25-OHD) levels among working urban adult Filipinos. METHODS: Seventy-five adult participants, living and working in Metro Manila, for at least 1 year, were grouped according to their perceived sunlight exposure pattern: low sunlight exposure (mostly indoor work); moderate sunlight exposure (both indoor and outdoor work); and high sunlight exposure (mostly outdoor work). After completion of the self-administered Filipino SEQ, they underwent serum 25-OHD level determination. Strength of correlation between the SEQ scores and 25-OHD levels was computed. RESULTS: Serum 25-OHD levels generally increased with increasing sunlight exposure levels. The overall Pearson’s correlation between the SEQ scores and 25-OHD levels of the participants was 0.396 (P = 0.001). The correlation for the individual domains was 0.342 for intensity of sunlight exposure (P = 0.003), 0.321 for factors affecting sunlight exposure (P = 0.005), and 0.256 for sun protection practices (P = 0.027). CONCLUSIONS: The sunlight exposure of working urban adult Filipinos, as measured by the Filipino SEQ, has an overall significant, direct and moderate association with serum 25-OHD levels. This Filipino SEQ can serve as a valuable clinical tool for sunlight exposure assessment to identify individuals at risk for vitamin D deficiency.