{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T22:34:40Z","timestamp":1790030080843,"version":"4.0.1"},"reference-count":23,"publisher":"FapUNIFESP (SciELO)","issue":"10","license":[{"start":{"date-parts":[[2020,10,1]],"date-time":"2020-10-01T00:00:00Z","timestamp":1601510400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"},{"start":{"date-parts":[[2020,10,1]],"date-time":"2020-10-01T00:00:00Z","timestamp":1601510400000},"content-version":"am","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"},{"start":{"date-parts":[[2020,10,1]],"date-time":"2020-10-01T00:00:00Z","timestamp":1601510400000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Rev. Assoc. Med. Bras."],"abstract":"<jats:p>SUMMARY  OBJECTIVE: To evaluate seasonal variation of 25(OH)vitamin D [25(OH)D3] levels, and factors associated with it, in healthy adult men, who exercised outdoors for 50 min., at least twice a week, from 10AM to 4PM, in a Brazilian semitropical region.  METHODS: Blood samples were collected at the end of each season for 25(OH)D3, measured by liquid chromatography with tandem mass spectrometry. Ultraviolet irradiation was estimated by radiometer, calculating the daily photobiological response to vitamin D synthesis in human skin (D-VitD). The prevalence of 25(OH)D3 &lt;20ng\/mL changed with the seasons (p=0.000): 8.7% (n=6\/69), 1.5% (n=1\/66), 0 (n=0\/64), and 21.7% (n=13\/60), respectively, at the end of winter, spring, summer, and autumn. The prevalence, adjusted for multiple comparisons, was higher in winter than summer (p=0.026), and in autumn than spring (p=0.001) and summer (p=0.000). There were no associations of 25(OH) D3 levels with BMI (p=0.207), body fat (p=0.064), and phototype (p=0.485), in univariate analysis. It was associated with D-VitD in the 30 days before blood sampling (p=0.000), after adjustment to body fat. The prevalence of 25(OH)D3 &lt;30ng\/mL varied seasonally (p=0.000): 69.6% (n=48\/69), 68.2% (n=45\/66), 43.8% (n=28\/64), and 88.4% (n=53\/60), respectively, in winter, spring, summer, and autumn.  CONCLUSIONS: In a Brazilian subtropical region, a seasonal variation in 25(OH)D3 was observed in healthy adult males, although they spent at least 50 min outdoors twice a week, wearing shorts and T-shirts. 25(OH)D3 &lt;20ng\/mL was 21.7% in autumn; D-vitD 30 days prior to blood sampling was the only factor independently associated with 25(OH)D3 levels.<\/jats:p>","DOI":"10.1590\/1806-9282.66.10.1431","type":"journal-article","created":{"date-parts":[[2020,11,6]],"date-time":"2020-11-06T19:30:31Z","timestamp":1604691031000},"page":"1431-1436","source":"Crossref","is-referenced-by-count":9,"title":["Seasonal variation of vitamin D among healthy adult men in a subtropical region"],"prefix":"10.1590","volume":"66","author":[{"given":"Tiago Oselame","family":"Fontanive","sequence":"first","affiliation":[{"name":"Universidade Federal do Rio Grande do Sul,  Brasil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nidea Rita Michels","family":"Dick","sequence":"additional","affiliation":[{"name":"Instituto de Pesquisa da Brigada Militar de Porto Alegre,  Brasil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mariana Costa Silva","family":"Valente","sequence":"additional","affiliation":[{"name":"Universidade Federal do Rio Grande do Sul,  Brasil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vani dos Santos","family":"Laranjeira","sequence":"additional","affiliation":[{"name":"Universidade Federal do Rio Grande do Sul,  Brasil; Hospital de Cl\u00ednicas de Porto Alegre,  Brasil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marina Venzon","family":"Antunes","sequence":"additional","affiliation":[{"name":"Universidade Feevale,  Brasil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marcelo de Paula","family":"Corr\u00eaa","sequence":"additional","affiliation":[{"name":"Universidade Federal de Itajub\u00e1,  Brasil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rita de C\u00e1ssia Marques","family":"Alves","sequence":"additional","affiliation":[{"name":"Universidade Federal do Rio Grande do Sul,  Brasil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rafael","family":"Linden","sequence":"additional","affiliation":[{"name":"Universidade Feevale,  Brasil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8300-2073","authenticated-orcid":false,"given":"Tania Weber","family":"Furlanetto","sequence":"additional","affiliation":[{"name":"Universidade Federal do Rio Grande do Sul,  Brasil"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"530","published-online":{"date-parts":[[2020,10]]},"reference":[{"issue":"3","key":"ref1","doi-asserted-by":"crossref","first-page":"383","DOI":"10.3390\/ijerph16030383","article-title":"Vitamin D status and mortality: a systematic review of observational 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