How Vitamin D Status May Shape Dementia Risk
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Vitamin D is converted into a hormone that signals through the vitamin D receptor and helps regulate gene activity. The body can make vitamin D3 in skin exposed to UVB light, but synthesis varies with season, latitude, time of day, skin pigmentation, sunscreen use, and age. Serum 25-hydroxyvitamin D is the standard marker used to assess vitamin D status. [1]
Low vitamin D status has been associated with later dementia in prospective cohorts. In 1,334 dementia-free adults with a mean age of 84, levels below 25 nanomoles per liter were associated with a 91 percent higher rate of all-cause dementia and a 128 percent higher rate of Alzheimer's dementia over seven years. These adjusted associations identify risk but do not prove that low vitamin D caused the diagnoses. [2]
Supplement studies provide additional context. In a prospective cohort of 12,388 dementia-free older adults, recorded vitamin D supplement exposure was associated with 40 percent lower dementia incidence over 10 years. A 12-month randomized trial in 210 adults with Alzheimer's disease found improvements in selected cognitive scores and amyloid-related blood markers with 800 IU daily. Together, these findings support measuring status and correcting deficiency with individualized guidance rather than assuming one dose fits everyone. [3] [4]
This clip is excerpted, with permission, from Dr. Rhonda Patrick's appearance on The Diary of a CEO. Thank you to The Diary of a CEO for allowing us to share it.
- ^ 10.4161/derm.24494
- ^ 10.3390/nu15010061
- ^ Chen, Hung-Yu; Creese, Byron; Ghahremani, Maryam; Goodarzi, Zahra; Ismail, Zahinoor; Smith, Eric E. (2023). Vitamin D Supplementation And Incident Dementia: Effects Of Sex, APOE, And Baseline Cognitive Status Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring 15, 1.
- ^ Jia J; Hu J; Huo X; Miao R; Zhang Y; Ma F (2019). Effects of vitamin D supplementation on cognitive function and blood Aβ-related biomarkers in older adults with Alzheimer's disease: a randomised, double-blind, placebo-controlled trial. J Neurol Neurosurg Psychiatry 90, 12.
Steven Bartlett: Vitamin D. You talked about dementia. What is going to help prevent dementia?
Dr. Rhonda Patrick: Vitamin D is actually more than a vitamin. It gets converted into a steroid hormone. A steroid hormone goes into the nucleus of a cell, where the DNA is, and activates and deactivates genes. Vitamin D affects more than 5 percent of the genome.
Why is that important? Seventy percent of the US population has insufficient vitamin D levels. Vitamin D3 is made in the skin through UVB radiation from the sun. If you are not outside, you are not making much vitamin D3 in your skin. Vitamin D3 is then converted into a steroid hormone that regulates many processes.
In modern society, we are inside working much of the time. Even if you are outside, many other factors affect vitamin D production. Anything that blocks UVB radiation reduces your body's ability to make vitamin D3. That includes sunscreen and melanin, the darker skin pigment that acts as a natural sunscreen. Latitude also matters. In more northern places such as England, Wales, Chicago, or Sweden, UVB radiation does not reach the atmosphere for several months of the year. Combine that with sunscreen or melanin and you can have a problem.
One University of Chicago study looked at African Americans and Caucasians and their ability to make vitamin D3 from UVB radiation.
Steven Bartlett: White people.
Dr. Rhonda Patrick: Yes, exactly. As I mentioned, melanin is a natural sunscreen. People whose ancestry is African, South American, or Southeast Asian often have more melanin because their ancestors lived closer to the equator. It is an adaptation that helps prevent burning from the sun's UV rays.
The University of Chicago study found that African Americans had to stay in the sun six to 10 times longer than people with fair skin to make the same amount of vitamin D3. If you take someone with more melanin, like yourself
Steven Bartlett: I am mixed.
Dr. Rhonda Patrick: You have a little more melanin. But let's say you take someone like your mom.
Steven Bartlett: She is Nigerian.
Dr. Rhonda Patrick: Okay. Let's say your mom moves to Chicago.
Steven Bartlett: She moved to bloody England.
Dr. Rhonda Patrick: Or she moved to England. Exactly. Then you are talking about a recipe for a vitamin D problem. You cannot make much vitamin D for perhaps four or five months of the year because UVB radiation is not reaching you, and you also have this natural sunscreen.
Steven Bartlett: What are the consequences in terms of symptoms?
Dr. Rhonda Patrick: It is not usually an acute thing that you can identify by looking in the mirror.
Steven Bartlett: What is the consequence, then?
Dr. Rhonda Patrick: People think of vitamin C deficiency and scurvy, where you can look in the mirror and see your gums falling apart. Vitamin D deficiency or insufficiency is more insidious. Damage can accumulate over time. It may not be noticeable. You may feel lethargic or low in energy without knowing why.
Severe vitamin D deficiency can cause rickets and bone malformations, especially early in life. We now know that vitamin D deficiency or insufficiency can be associated with an 80 percent increase in dementia risk, and that has been shown in multiple studies.
The converse has also been reported. People who supplement with vitamin D3 have had a 40 percent lower risk of dementia. They may be avoiding a common deficiency, and avoiding that deficiency may reduce dementia risk. Studies have also given vitamin D or placebo to people with dementia or Alzheimer's disease. People given vitamin D had improved cognition and lower markers related to amyloid plaques. Vitamin D is regulating a large part of the protein-coding human genome.
Steven Bartlett: If I want to increase my probability of getting dementia, then I need to stay out of the sun, avoid vitamin D, drink alcohol, smoke, be sedentary, and sleep badly.
Dr. Rhonda Patrick: Yes, and eat a lot of refined sugar.
Steven Bartlett: Yeah.
Dr. Rhonda Patrick: Yes, exactly.
Steven Bartlett: Okay.
Dr. Rhonda Patrick: Exactly. You might ask how much vitamin D to take. I am talking about deficiency and insufficiency, and you really want a blood test to know your level.
More than 30 studies have looked at vitamin D levels and all-cause mortality, meaning death from causes such as cardiovascular disease, respiratory disease, and cancer. People with vitamin D levels between 40 and 60, and perhaps up to 80, nanograms per milliliter have had the lowest all-cause mortality. These people are not deficient or insufficient. Insufficiency starts below about 30 nanograms per milliliter, and deficiency at 20 nanograms per milliliter or below.
Studies of the aging brain and vitamin D have found that for every 10-nanomole-per-liter decrease in vitamin D blood levels, there is an increase in white-matter hyperintensities. These are areas of damage in the brain's white matter. White matter includes myelin, which helps electrical signals move so that you can think, talk, and do other things.
Steven Bartlett: I had not had one today, so I feel like you have persuaded me.
Dr. Rhonda Patrick: Many people who are deficient can raise their blood levels into a sufficient range with about 4,000 IU of vitamin D per day. Multiple studies have shown that. It is not hard to take, and vitamin D is probably one of the least expensive supplements. It can cost about 10 cents per pill.
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