Prevalence of vitamin D deficiency during the summer and its relationship with sun exposure and skin phototype in elderly men living in the tropics

Marcelo Azevedo Cabral,¹ Carla Núbia Borges,¹ Juliana Maria Coelho Maia,¹ Caio Augusto Martins Aires,² Francisco Bandeira<sup>3

1</sup>Department of Clinical Medicine, University of Pernambuco Medical School, ²Department of Biomedicine, University of Pernambuco Medical School, ³Division of Endocrinology, University of Pernambuco Medical School, Recife, Brazil

Objective: The aim of the study reported here was to determine the prevalence of vitamin D deficiency among elderly men and its association with sun exposure and skin phototypes.
Subjects and methods: This was an analytical cross-sectional study, which involved 284 men aged 60 years or over, randomly recruited from a basic care unit in the city of Recife (Brazil).
Measurements: Serum levels of 25 hydroxyvitamin D (25(OH)D), sun index, and skin phototypes were evaluated.
Results: The prevalence of vitamin D deficiency was 31.5% and 66.7% when cut points of less than 20 and 30 ng/mL, respectively, were used. Mean serum 25(OH)D was 27.86 ± 13.52 standard deviation (SD) ng/mL. There was no difference (P = 0.113) in 25(OH)D (23.98 ± 14.66 SD vs 29.88 ± 13.78 SD) between individuals in the lowest quartile (Q) of the sun index (Q1: 1.96) compared with those in the highest (Q4: 7.86). When considering a cutoff of 20 ng/mL, the sun index was different in the two groups (P = 0.006), but there was no difference when cutoffs of 25 and 30 ng/mL were used. After adjustment, sun index and body mass index were associated positively and negatively, respectively with serum 25(OH)D independently. Most subjects (66.7%) had Fitzpatrick’s skin phototypes IV, V, and VI. Low calcium intake was observed in 72%. There was no difference in serum 25(OH)D levels between patients with low intake and those with intermediate and high intakes. Only 2.5% were taking a vitamin supplement.
Conclusion: We found a high prevalence of vitamin D deficiency among elderly men despite their high sun exposure during the summer months.

Keywords: sun index, serum 25(OH)D levels, body mass index, Brazil