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(OR02-02-26) The Effect of Vitamin D Supplementation on the Status, Mental Health, and Bone Health, of Adult Male Prisoners in the United Kingdom: An Open Controlled Trial

Saturday, July 25, 2026
8:42 AM - 8:54 AM ET
Location: Maryland Ballroom A

    Presenting Author(s)

  • Jonathan Tammam, PhD

    Professor of Nutrition and Dietetics
    Oxford Brookes University
    Oxford, England, United Kingdom

    Disclosure(s): No relevant financial relationship(s) with ineligible companies to disclose.

    • Co-Author(s)

  • MP

    Matthew Poulter, PhD

    Oxford Brookes University
    Oxford, England, United Kingdom

  • BL

    Bethan Leach

    Oxford Brookes University
    Oxford, England, United Kingdom

  • CG

    Catherine Graham, PhD

    Lake Lucerne Institute, Switzerland

  • SC

    Shelly Coe, PhD

    Oxford Brookes University
    Oxford, England, United Kingdom

Disclosure(s):
Jonathan Tammam, PhD: No relevant financial relationship(s) with ineligible companies to disclose.
Objectives: Prisoner diets are identified as failing to meet many micronutrient requirements, including vitamin D (VD). Prisoners, experience a higher burden of poor mental health and wellbeing compared to general populations. This study aimed to examine whether daily vitamin D3 supplementation is associated with changes in serum 25-hydroxyvitamin D (25(OH)D), depressive symptoms, wellbeing, anxiety, aggression, and bone health in adult male prisoners.

Methods: An open-label controlled trial was conducted for 12 weeks with 84 adult male prisoners (active n=53; control n=31), resident for the study period, with no medical conditions. Mean age was 37±10 years (active) and 40±9 years (control). The active group received 25 µg (1000 IU) vitamin D3 daily. Primary outcomes were serum 25(OH)D and wellbeing (Warwick-Edinburgh Mental Wellbeing Scale). Secondary outcomes included depression (PHQ-9), anxiety (GAD-7), aggression (BPAQ), and calcaneal bone indices. Between-group differences at follow-up were analysed using ANCOVA adjusting for baseline values.

Results: N=63 completed the trial. Baseline dietary VD intake was 2–4 µg/day in both groups. At 12 weeks, adjusted mean serum 25(OH)D was higher (p < 0.001) in the supplementation group (81.3 vs. 48.4 nmol/L), with a large effect size (Cohen’s d=1.49). Depressive symptom scores were lower (p=0.04) in the supplementation group (adjusted mean difference −2.19 points; η²=0.12). No significant differences between groups were observed for wellbeing, anxiety, aggression, or bone indices.

Conclusions: Daily VD supplementation was effective in significantly increasing serum 25(OH)D concentrations and improving depressive symptom scores in adult male prisoners. This is important for people in prison with limited exposure to sunlight. No associations were observed for wellbeing, anxiety, aggression, or bone health.

Funding Sources: Nigel Groome Scholarship