Comparison of powdered versus oily vitamin D3 in adults with vitamin D deficiency
Official title: The Effects of Eight Weeks of Supplementation With Two Vitamin D₃ Formulations in Adults With Subclinical and Clinical Vitamin D Deficiency: A Randomized Controlled Superiority Pilot Trial
Run by Center for Health Sciences, Serbia · NCT07317830 · Data updated 2026-11-12
This study will test whether a powdered or an oily vitamin D3 supplement better raises blood vitamin D levels in adults with vitamin D deficiency over eight weeks.
Quick facts
| Study type | Interventional |
|---|---|
| Ages | 18 Years to 80 Years |
| Sex | All |
| Enrollment | 20 (estimated) |
| Sponsor | Center for Health Sciences, Serbia Academic / other |
| Locations | 1 site (Belgrade) |
| Status | Recruiting |
| Started | December 15, 2025 |
| Main results expected | May 31, 2026 |
| Study ends | June 15, 2026 |
| Registry record updated | January 5, 2026 |
| Trial ID | NCT07317830 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Adults aged 18 and older with serum 25(OH)D below 75 nmol/L, BMI 18.5–29.9 kg/m2, no major acute or severe chronic disease, willing to avoid other vitamin D supplements and to attend study visits are ideal candidates.
✕Probably not a fit
People who are pregnant or breastfeeding, underweight or obese, recent users of dietary supplements, on medications that alter vitamin D or calcium balance, or with abnormal clinical labs are unlikely to benefit from participation.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This is a randomized, controlled, superiority pilot trial comparing two oral vitamin D3 formulations (powdered and oily) given for eight weeks to adults with subclinical or clinical vitamin D deficiency. Participants meeting BMI and health criteria will be randomized to one of the two formulations and monitored with serial serum 25-hydroxyvitamin D measurements to compare magnitude and speed of response and the proportion achieving sufficiency. The trial excludes pregnancy, recent supplement users, and people on medications that materially alter vitamin D or calcium metabolism. Results will provide preliminary comparative bioavailability data to inform formulation choice and design of larger confirmatory trials.
Why it matters
Potential benefit: If successful, the trial could identify which formulation more quickly and effectively restores vitamin D levels, helping clinicians choose formulations and dosing strategies to correct deficiency.
How similar studies have gone: Previous comparative studies have shown mixed results, with some evidence that oil-based vitamin D can raise serum 25(OH)D more rapidly but findings are inconsistent, so direct head-to-head pilot data remain useful.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: * Adults aged 18 years and over * Serum 25(OH)D \< 75 nmol/L * BMI 18.5 - 29.9 kg/m2 * Free of clinically significant acute disorders and severe chronic diseases * No planned travel to high-UV destinations or tanning bed use during the trial * Willing to avoid non-study vitamin D supplements * Able to give written informed consent and comply with study visits * Submitted informed consent Exclusion Criteria: * Pregnancy of breast feeding * Underweight or obesity * History of any dietary supplement use within 8 weeks before screening * Medications that materially alter vitamin D metabolism or calcium balance * Subjects with a history of medicine or alcohol abuse * Abnormal values for lab clinical chemistry (\> 2 SD) * Unwillingness to return for follow-up analysis * Participation in other clinical trials within 60 days prior to screening
Where it's running
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Center for Health Sciences
Belgrade, Serbia Recruiting
Study contacts
- Study coordinator: Sergej Ostojic, MD, PhD
- Email: sergej.ostojic@chess.edu.rs
- Phone: +381112643242
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.