Prevalence of vitamin D deficiency during the summer and its relationship with sun exposure and skin phototype in elderly men living in the tropics
Clinical Interventions in Aging Volume 2013:8 Pages 1347 - 1351, DOI: http://dx.doi.org/10.2147/CIA.S47058
Marcelo Azevedo Cabral,1 Carla Núbia Borges,1 Juliana Maria Coelho Maia,1 Caio Augusto Martins Aires,2 Francisco Bandeira3
1Department 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.
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Note: The sun index in this study seems to ignore the time of day.
Seniors could have gotten just as high sun index at 7 AM as at 1 PM.
When visiting Singapore (which is also close to the equator) in 2011, I noticed that elderly were outside exercising at 7 AM and had gone indoors by 9 AM, so as to avoid the hot sun.
See also VitaminDWiki
- Overview Middle East and vitamin D
- Vitamin D levels in the Middle East: very low, especially in summer – June 2012
- Review of Vitamin D Deficiencies in developing countries - Oct 2011
- Seniors getting noon sun had 88 percent chance of having at least 30 ng of vitamin D – Dec 2012
- Overview Seniors and Vitamin D seniors get about 1/4 as much vitamin D from same time in the sun as do the youth
- Vitamin D levels in healthy populations around the globe – Aug 2012 a database, which includes Brazil