Overview
This randomized controlled superiority pilot trial will evaluate the efficacy of two vitamin D3 formulations administered over eight weeks in adults with subclinical or clinical vitamin D deficiency. The study will compare changes in serum 25-hydroxyvitamin D concentrations between formulations, as well as the proportion of participants who will achieve vitamin D sufficiency. Both formulations are expected to improve vitamin D status, with the hypothesis that one formulation will demonstrate superior bioavailability, resulting in greater and faster increases in circulating 25-hydroxyvitamin D. The findings will provide preliminary evidence to inform formulation selection and dosing strategies for correcting vitamin D deficiency and will support the design of larger, confirmatory trials.
Eligibility
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