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NCT Number: NCT07317830

Effects of Different Vitamin D3 Formulations in Vitamin D-Deficient Adults

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.

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Key information

Conditions

Vitamin D Deficiency Avitaminosis Deficiency Diseases Malnutrition Nutrition Disorders Nutritional and Metabolic Diseases

Age range

18 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Center for Health Sciences

Belgrade, 11000, Serbia

Location status: Recruiting

Location contact

Nikola Todorovic, PhD

PRINCIPAL_INVESTIGATOR

Sergej M Ostojic, MD, PhD

CONTACT

[email protected]

+381-11-2643-242

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Experimental 1 (powdered supplement)

Dietary Supplement

Active powdered ingredient (2,000 IU/d)

Experimental 2 (oily supplement)

Dietary Supplement

Active oily ingredient (2,000 IU/d)

Primary outcomes

  1. 25(OH)D

    Time frame: Change from baseline 25(OH)D at 8 weeks

    Serum levels of 25(OH)D

Secondary outcomes

  1. Total calcium

    Time frame: Change from total calcium at 8 weeks

    Serum levels of total calcium

  2. Ionized calcium

    Time frame: Change from ionized calcium at 8 weeks

    Serum levels of ionized calcium

  3. Phosphorus

    Time frame: Change from phosphorus at 8 weeks

    Serum levels of phosphorus

  4. Magnesium

    Time frame: Change from magnesium at 8 weeks

    Serum levels of magnesium

Study contacts

Contact information is provided by the study sponsor or research team.

Sergej Ostojic, MD, PhD

CONTACT

[email protected]

+381112643242

Sponsors and collaborators

Lead sponsor

Center for Health Sciences, Serbia

Other

Registry information

Official study 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

Acronym: AMORPH-D

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Jan 5, 2026
Registry last updated
Jan 5, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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