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Impact of a vitamin D supplementation initiative in an NHS prison healthcare service during the COVID-19 pandemic

Lookup NU author(s): Dr Iain McKinnonORCiD, Joe Tully

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

Purpose Vitamin D deficiency is a global concern, disproportionately affecting vulnerable populations, including people in prison. Vitamin D was found to be protective against Covid-19 during the pandemic. As a response, Nottinghamshire Healthcare NHS Foundation Trust implemented a vitamin D supplementation policy across three prison healthcare settings in the UK. Design/methodology/approach This pragmatic cross-sectional study retrospectively evaluated the impact of this policy on supplementation uptake and deficiency rates. Vitamin D deficiency was defined as less than 50nmol/L. Cross-sectional data (n=768) were collected from 768 prisoners for periods of two years before and two years after introduction of the policy. Findings There was an overall reduction in vitamin D deficiency from 71% to 55% after policy introduction (χ2 = 12.3, df = 1, p < 0.001). Mean vitamin D levels increased from 41.3nmol/L to 50.3nmol/L. In a small subsample (n=23) in whom Vitamin D levels were available before and after the policy, paired sample analysis showed significant mean vitamin D level increase (p < 0.001). Overall supplementation rates were lower after the policy introduction (43%, n = 330 versus 35%, n = 270) with statistical significance (McNemar’s χ2, p = 0.004). However, there was increased uptake among previously untreated individuals - 40% (n = 175) of those previously untreated (n = 438) received supplementation after policy implementation. An exploratory analysis using binary logistic regression suggested both the specific prison location and a pre-existing vitamin D deficiency as significant predictors of deficiency post-policy. Originality Our findings highlight the potential effectiveness of a simple, population-wide supplementation strategy in reducing vitamin D deficiency within prisons. Future research should employ prospective designs and explore factors influencing supplementation adherence and long-term health outcomes, towards developing the most effective strategies.

Publication metadata

Author(s): Dima A, McKinnon I, Whiting D, Tully J

Publication type: Article

Publication status: Published

Journal: International Journal of Prison Health

Year: 2026

Pages: Epub ahead of print

Online publication date: 19/01/2026

Acceptance date: 04/11/2025

Date deposited: 21/01/2026

ISSN (print): 1744-9200

ISSN (electronic): 1744-9219

Publisher: Emerald Publishing Limited

URL: https://doi.org/10.1108/IJOPH-06-2025-0045

DOI: 10.1108/IJOPH-06-2025-0045

ePrints DOI: 10.57711/fmwa-h610

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