A Study of High-dose Vitamin D Supplement 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 Hongzheng Zhang at hzzhang@ucdavis.edu or call (916) 900-0150
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. Are you between the ages of 65-90 years old?
  2. *2. Are you able to undergo Brain Magnetic Resonance Imaging (MRI)?
  3. *3. What city are you located in?
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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: 65-90
Healthy Volunteers: Yes
Keywords: vitamin d, vitamin d deficiency, brain health, memory problems, MCI, Alzheimer's disease, forgetfulness, aging, brain
Type: Dietary Supplement study, Phase 2
180 Participants
The UC Davis Alzheimer's Disease Center - East Bay invites you to take part in this study if you are between the ages of 65 and 90 and 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 visit (i.e., months 12, 24, 36 & 42). An additional $50 will be paid for each completed MRI. You will also receive a $10 meal voucher and travel reimbursement (at 40 cents per mile up to $50) for each clinic visit and each trip to the UC Davis Imaging Research Center in Sacramento.
Study duration and period
Participants can expect to be in this research study for about 3.5 years.
Recruitment period
From Oct. 1, 2019
UC Davis Alzheimer's Disease Center - East Bay
100 North Wiget Lane
Suite 150
Walnut Creek, CA 94598
Hongzheng Zhang
Research Topic
  • Must be able to have a Magnetic Resonance Imagining (MRI) scan

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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