A Study of High-dose Vitamin D Supplements in Older Adults

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Please answer a few questions to see if you may qualify.
Have questions? Please contact the study coordinator Madeleine S. Marroquin-Serrano at msmarroquin@ucdavis.edu or call (916) 579-7044
By clicking "Next", you're consenting to participate in this questionnaire. There are no right or wrong answers and everything you enter is confidential.
  1. *1. What is your age?
  2. *2. Do you have any of the following?
  3. *3. How much Vitamin D (in IU) are you taking, if any? Enter "0" if you are not taking any Vitamin D.
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"There is evidence that low vitamin D levels are linked with increased risk of dementia and Alzheimer's disease (AD)."
Age: 65 to 90 years old
Healthy Volunteers: Yes
Keywords: vitamin d, vitamin d deficiency, cognitive decline, dementia, alzheimer's, cognitive health
Type: Dietary Supplement study, Phase 2
180 Participants
We invite you to take part in this study because you are between the ages of 65 and 90, and you may be deficient in Vitamin D.

The purpose of this study is to test if supplementing high dose vitamin D will correct severely low vitamin D levels. Results will be compared to treatment with standard dose vitamin D.
This study requires

You will be randomly assigned by a computer program to one of the following treatment groups: High dose Vitamin D (4,000 IU daily) or Standard dose Vitamin D (600 IU daily)

The Vitamin D supplements will be provided by the study team, at no cost to participants.

The study includes the procedures described below. If you agree to participate, the following procedures will occur:

  • A blood draw to check your Vitamin D levels and other blood tests

  • Collection of a urine sample to look for signs of infection or bleeding

  • Review of your medical records and medication history

Who can participate

Inclusion criteria:

  1. 65-90 years old.
  2. Low Vitamin D on blood test (level ≤ 20 at screening visit).
  3. Able to undergo a Brain Magnetic Resonance Imaging (MRI).
  4. Normal Cognition, Mild Cognitive Impairment or Mild Alzheimer's Disease.

Exclusion criteria:

  1. Normal Vitamin D levels on blood test.
  2. History of >1 kidney stone episode.
Benefits and risks of participating

We cannot promise any benefits to you as a result of taking part in this research study.


The study doctor will discuss the risks associated with taking part in this research study.
If you agree to take part in this research study, we will compensate you $50 for study entry, plus $50 per annual follow-up visits (months 12, 24, 36 & 42). An additional $50 will be paid for each completed MRI. You will also receive meal vouchers and travel cost reimbursement. This is a $10 meal voucher per clinic visit, 40 cents per mile up to a maximum of $50 for providing your own transportation to and from the clinic or Imaging Research Center.
Study duration and period
We expect that you will be in this research study for about 3.5 years.
Recruitment period
From March 20, 2019
UC Davis Medical Center
4860 Y Street
Suite 3900
Sacramento, CA 95817
Madeleine S. Marroquin-Serrano
Research Topic
  • Vitamin D Deficiency
  • Cognitive Decline

Have any questions or want to learn more? Leave your contact details below and the research team will reach out to you.


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