Vitamin d pills might tweak hormones in healthy young women
NCT ID NCT06610968
First seen Jun 27, 2026 · Last updated Jun 27, 2026
Summary
This pilot study tests whether taking 5,000 IU of vitamin D daily for three weeks changes testosterone and other hormone levels in young, healthy women aged 18 to 35. Twenty participants will be randomly assigned to receive either vitamin D or a placebo pill. The goal is to see if vitamin D supplementation has any short-term effect on the hormone profile.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- Vitamin D (cholecalciferol) supplement
- What this could lead to
- If it works, this could point toward a role for vitamin D in hormone regulation in healthy women.
- What could go wrong
- This is a very small pilot study with only 20 participants, so results may not be reliable or apply to others. It only looks at short-term effects.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Not a phased trial
Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.
- Participants
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About 20 people
The number the study aims to enrol. It can still change while the study runs.
- Started
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Jul 2025
- Expected to finish
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Sep 2026
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 to 35 years
- Sex
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Female participants only
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * Assigned female at birth * 18 to 35 years of age * No chronic diseases affecting the uptake of Vitamin D or causing Vitamin D sensitivity (e.g., sarcoidosis, tuberculosis, Wegener's granulomatosis, other forms of vasculitis, inflammatory bowel diseases, etc.) \[21\] * Completion and signature of the informed consent document * Non-pregnant or trying to become pregnant * No supplementation with Vitamin D within three months of enrollment * No documented gynecological disease (e.g., PCOS, endometriosis, etc.) * Weight greater than or equal to 110 lbs Exclusion Criteria: * Pregnant * Supplementation with Vitamin D within three months of enrollment * Taking exogenous hormones * Documented gynecological disease (e.g., PCOS, endometriosis, etc.) * Suffering from chronic diseases affecting the uptake of Vitamin D or causing Vitamin D sensitivity (e.g., sarcoidosis, tuberculosis, Wegener's granulomatosis, other forms of vasculitis, inflammatory bowel diseases, etc.) \[21\] * Weight less than 110 lbs
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As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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University of Southern California Health Sciences Campus Center for Health Professions
Los Angeles, California, 90033, United States