{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T20:06:58Z","timestamp":1791662818593,"version":"4.3.4"},"reference-count":51,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2026,5,22]],"date-time":"2026-05-22T00:00:00Z","timestamp":1779408000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Background: Vitamin D deficiency is a common global health problem and remains highly prevalent in T\u00fcrkiye, where limited food fortification and heterogeneous clinical practices contribute to variability in testing and supplementation strategies. Aims: To provide T\u00fcrkiye-specific best practice recommendations for defining clinically relevant serum 25-hydroxyvitamin D [25(OH)D] thresholds, identifying adult risk groups for targeted testing, and recommending evidence-based prevention, treatment, and monitoring approaches while minimizing under-treatment and inappropriate high-dose use. Methods: This national expert consensus document was developed by endocrinologists from across T\u00fcrkiye using a structured, modified Delphi methodology. Draft statements informed by systematic literature reviews were rated via online surveys using a 9-point Likert scale, followed by two Delphi rounds and a face-to-face consensus meeting in \u0130stanbul in October 2025. Results: Recommendations addressed sun exposure, laboratory assessment, screening, supplementation, treatment, and follow-up. Serum 25(OH)D &lt;20 ng\/mL was defined as deficiency and &lt;12 ng\/mL as severe deficiency, with a target range of 20\u201350 ng\/mL. Routine population-wide screening was not recommended; instead, targeted testing in high-risk adults and symptom-driven biochemical evaluation were endorsed. Empiric supplementation was recommended for selected high-risk groups, with cholecalciferol as the preferred agent. Higher individualized doses were suggested in obesity or malabsorption, while loading regimens were reserved for specific clinical indications, such as severe deficiency or certain medical conditions that impair vitamin D metabolism. Reassessment of 25(OH)D at 8\u201312 weeks was recommended. Conclusion: These consensus-based recommendations provide a practical, context-specific framework for assessing, preventing, treating, and monitoring vitamin D deficiency in adults in T\u00fcrkiye.<\/jats:p>","DOI":"10.3390\/nu18111665","type":"journal-article","created":{"date-parts":[[2026,5,22]],"date-time":"2026-05-22T16:06:08Z","timestamp":1779465968000},"page":"1665","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Best Practice Recommendations for the Assessment, Prevention and Treatment of Vitamin D Deficiency in T\u00fcrkiye: A 2026 Update in a Setting with Limited Mandatory Food Fortification"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0075-6313","authenticated-orcid":false,"given":"Dilek","family":"Gogas Yavuz","sequence":"first","affiliation":[{"name":"Department of Endocrinology and Metabolism, Marmara University School of Medicine, \u0130stanbul 34710, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u00d6mercan","family":"Topalo\u011flu","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Zonguldak B\u00fclent Ecevit University Medical Faculty, Zonguldak 67100, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9756-2285","authenticated-orcid":false,"given":"Mutlu","family":"G\u00fcne\u015f","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Health Sciences University Bursa Y\u00fcksek \u0130htisas Training and Research Hospital, Bursa 16310, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alper","family":"G\u00fcrlek","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Hacettepe University Faculty of Medicine, Ankara 06100, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0478-1193","authenticated-orcid":false,"given":"Ay\u015fe","family":"Kubat \u00dcz\u00fcm","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, \u0130stanbul School of Medicine, \u0130stanbul University, \u0130stanbul 34093, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zafer","family":"Pekkolay","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Dicle University School of Medicine, Diyarbak\u0131r 21280, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zeynep","family":"Cant\u00fcrk","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Kocaeli University Faculty of Medicine, Kocaeli 41380, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zeliha","family":"Hekimsoy","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Manisa Celal Bayar University Faculty of Medicine, Manisa 45010, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u00d6zen","family":"\u00d6z G\u00fcl","sequence":"additional","affiliation":[{"name":"Department of Endocrinology and Metabolism, Bursa Uluda\u011f University Medical School, Bursa 16059, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1636-1444","authenticated-orcid":false,"given":"Refik","family":"Tanakol","sequence":"additional","affiliation":[{"name":"American Hospitals in \u0130stanbul, \u0130stanbul, 34365, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1056\/NEJMra070553","article-title":"Vitamin D deficiency","volume":"357","author":"Holick","year":"2007","journal-title":"N. 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