{
  "abstract": "Background/Objectives: Whether self-directed supplement use reaches people who are deficient is unclear. We examined vitamin D, iron and vitamin B12 status and supplement use in a screened workforce. Methods: Cross-sectional analysis of 793 employees (75.2% women, aged 18 to 67) in Poland sampled from April to June 2026; 25-hydroxyvitamin D [25(OH)D], ferritin and vitamin B12 were measured by automated immunoassay, and supplement use was ascertained from an open inventory. Deficiency was defined as 25(OH)D < 30 ng/mL, ferritin < 30 µg/L and vitamin B12 < 200 pg/mL. Results: Deficiency was common (vitamin D 53.2%; iron 29.4%, 38.3% of women; vitamin B12 3.0%). Vitamin D users reached the target more often than non-users (77.4% versus 38.5%; adjusted odds ratio 5.5, 95% CI 3.7 to 8.3; 1.8 in a sensitivity scenario that reclassified prompted reports as use); with 22 iron and 17 vitamin B12 users, no association could be characterised. Few deficient participants listed the corresponding supplement (vitamin D 9.0%, iron 2.2%, vitamin B12 0%; 32.1% and 9.1% with a prompted item). Among deficient respondents, 70.2%, 69.2% and 86.4% (vitamin D, iron, vitamin B12) reported neither a prior diagnosis nor a supplement, and routine characteristics discriminated deficiency poorly (C-statistic 0.58 for vitamin D, 0.57 for iron within women). Conclusions: Vitamin D supplement use was associated with better status, but most biochemical deficiency occurred in people who reported neither a diagnosis nor a supplement and could not be identified from routine characteristics.",
  "abstract_shown": true,
  "affiliations": [
    "Faculty of Medicine, Andrzej Frycz Modrzewski Krakow University, 30-705 Kraków, Poland",
    "Housemed S.A., 30-703 Kraków, Poland",
    "Department of Clinical and Experimental Pathology, Wrocław Medical University, 50-368 Wrocław, Poland",
    "Labplus R&D, 50-266 Wrocław, Poland"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Dominik Swadźba"
    },
    {
      "affs": [
        2
      ],
      "name": "Sebastian Makuch"
    },
    {
      "affs": [
        0,
        3
      ],
      "name": "Siddarth Agrawal",
      "orcid": "0000-0003-1118-5090"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/63zxztywshty6.bib",
  "cited_by": 0,
  "doi": "10.3390/nu18213611",
  "fulltext_url": null,
  "id": "63zxztywshty6",
  "issns": [
    "2072-6643"
  ],
  "landing_url": "https://www.mdpi.com/2072-6643/18/21/3611",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [],
  "openalex": null,
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-30",
  "publisher": "MDPI AG",
  "ris": "https://research.draconitic.com/paper/63zxztywshty6.ris",
  "sources": [
    {
      "first_seen": "2026-10-31T00:21:06Z",
      "native_id": "10.3390/nu18213611",
      "source": "crossref",
      "url": "https://www.mdpi.com/2072-6643/18/21/3611"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "issn:2072-6643",
      "subfield": "nutrition"
    }
  ],
  "title": "Vitamin D Supplement Use Is Associated with Better Status, Yet Most Biochemical Vitamin D, Iron and Vitamin B12 Deficiency Is Unrecognised and Unsupplemented: A Cross-Sectional Study of a Screened Corporate Workforce in Poland",
  "title_text": "Vitamin D Supplement Use Is Associated with Better Status, Yet Most Biochemical Vitamin D, Iron and Vitamin B12 Deficiency Is Unrecognised and Unsupplemented: A Cross-Sectional Study of a Screened Corporate Workforce in Poland",
  "type": "peer-reviewed",
  "updated_at": "2026-11-01T00:21:03Z",
  "url": "https://research.draconitic.com/paper/63zxztywshty6",
  "venue": "Nutrients",
  "versions": []
}