--- title: How Vitamin D Affects Alzheimer’s Risk description: Getting too little vitamin D can contribute to faster cognitive decline among the elderly, according to the latest study canonical: https://time.com/4033662/vitamin-d-alzheimers/ author: Alice Park article:opinion: false article:content_tier: free article:published_time: 2015-09-14T17:54:23.000Z article:modified_time: 2026-08-04T07:57:49.540Z article:section: Health og:title: How Vitamin D Affects Alzheimer’s Risk og:description: Getting too little vitamin D can contribute to faster cognitive decline among the elderly, according to the latest study og:url: https://time.com/4033662/vitamin-d-alzheimers/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blta1527b72ca1ddfbc/6988604b524fc0f68ddf4298/alzheimers-health-illo.jpg?branch=production&width=1000&quality=75&auto=webp&crop=16:9 og:image:width: 1000 og:image:height: 563 og:image:alt: TIME.com stock health alzheimers og:type: article twitter:card: summary_large_image twitter:title: How Vitamin D Affects Alzheimer’s Risk twitter:description: Getting too little vitamin D can contribute to faster cognitive decline among the elderly, according to the latest study twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blta1527b72ca1ddfbc/6988604b524fc0f68ddf4298/alzheimers-health-illo.jpg?branch=production&width=1000&quality=75&auto=webp&crop=16:9 ---  # How Vitamin D Affects Alzheimer’s Risk > Sponsored content. 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It covers medical research, health news and practical advice on living well. #### Where can I get reliable health news by email? Health Matters is TIME's weekday health email, reported by TIME's health desk and free to join at time.com/newsletters. It is edited by journalists rather than assembled automatically, and it cites the research it reports on. #### Is Health Matters free? Yes. Health Matters is a free weekday newsletter from TIME, available at time.com/newsletters. #### Who reads TIME's Health Matters newsletter? Its audience is broadly health-conscious, with a professional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators. ### Sources * TIME Newsletters: [time.com/newsletters](/c/time-nl-health-2026q3/newsletters?i=1aab5eea-da37-4967-bc1f-5ff091c988cb&cr=time-nl-health-2026q3-v1) ## Video: Alzheimer's Researcher Rudolph Tanzi on Why he's Optimistic [Watch (HLS stream): Alzheimer's Researcher Rudolph Tanzi on Why he's Optimistic](https://cdn.jwplayer.com/manifests/Ebl6dMCj.m3u8) (3:53)  _Published 2015-08-26. Tanzi is a pioneer in the field of Alzheimer's research, and has spent most of his career studying a disease that plagues 5.3 million Americans every year._  by [Alice Park](https://time.com/author/alice-park/)  ## Alice Park Senior Correspondent Sep 14, 2015 5:54 PM UTC  Illustration by Sydney Rae Hass for TIME  by [Alice Park](https://time.com/author/alice-park/)  ## Alice Park Senior Correspondent Sep 14, 2015 5:54 PM UTC Vitamin D is a controversial topic among doctors, mainly because studies about its health effects have been so conflicting. While vitamin D is critical for many body systems, including bones and the brain, recent studies that have tested these assumptions haven’t been reassuring. In March, for example, a large study found that [vitamin D supplements did not lower the risk of falls](http://time.com/3761581/vitamin-d-deficiency/), or their resulting injuries, in the elderly. That called into question other potential health effects of the vitamin, so researchers led by Joshua Miller at Rutgers University and University of California Davis decided to look at how vitamin D levels among different ethnic populations affected brain function. Because low vitamin D levels have been connected to a higher risk of dementia and Alzheimer’s disease in previous studies, the group wanted to further investigate the relationship, especially among ethnic groups who traditionally have low levels of vitamin D. The study, [published in _JAMA Neurology_](http://www.elabs10.com/c.html?ufl=c&rtr=on&s=x8pbgr,2c73x,2kek,lrqu,lscz,hb35,8zrx), involved 383 people enrolled in a long term Alzheimer’s study who participated in a series of cognitive studies and had their blood levels of a version of vitamin D measured yearly for five years. At the start of the study, 61% of the volunteers had vitamin D levels below recommended levels, and those with dementia showed lower levels of the vitamin. People with lower levels of vitamin D also had lower scores on certain memory and executive function tests. This pattern remained even after the researchers accounted for factors such as age, education, BMI, circulatory issues that can affect dementia, and the presence of known Alzheimer’s-related genes. As expected, the African-American and Hispanic participants showed lower levels of vitamin D on average compared to the white participants, and these groups also have lower cognitive scores as a result. When the researchers looked at how changes in vitamin D levels affected brain function, they found that those starting out with lower levels showed faster decline after five years than those who began the study with higher levels of vitamin D. The authors note that the major sources of vitamin D are through the diet, from sunlight (which can transform vitamin D precursor compounds in the skin into its active form) and via supplements. Racial and ethnic populations with more skin pigmentation may not be able to take advantage of the sun-based forms of D compared to whites, but it’s not clear yet whether supplements are the answer to overcome any vitamin D deficiency. “I don’t know if replacement therapy would affect these cognitive trajectories,” said Dr. Charles DeCarli, director of the Alzheimer’s Disease Center at University of California Davis and senior author of the study, in a statement. “That needs to be researched and we plan on doing that.” For now, conflicting reports about vitamin D’s effects on other body systems, like bones, and the lack of consistency in measuring the active form of the vitamin make it difficult to reach a consensus on how important vitamin D is for overall health. But a definitive study expected to publish its results in 2017 may finally provide some much-needed clarity. That study, which involves 26,000 people and is being conducted in four countries, will look at vitamin D and its effect on heart disease, cancer, diabetes and more. ## Transcript When you realize you've found a new gene, or you've found a defect in a gene you've been searching for, there's this moment in time where there's this incredible amount of satisfaction. And then you go to bed, and you know that at least for that evening, you're the only person in the universe to have discovered this amazing thing. They might have the chance to help billions of people now and long after you're gone. So it's really, it's hard to describe a feeling like it. We were the first ones to find the disease gene using genetics, back in the early 80's. Our lab equipment catalog was basically Kmart. Because nobody sold anything yet we had to build it all. For my student thesis, I decided I wanted to build the first end to end map of a chromosome. It was the first time that was gonna be possible. And I'd been working on that gene and other genes like it ever since trying to come up with novel therapies for the disease. I have Alzheimer's disease. Early onset. I got to talk a little bit to Julianne Moore, who was a Time 100 honoree at the gala. And I told her, I said, the mutation you had in the movie, I discovered. That was the gene mutation you had in the movie was actually discovered by our lab. [ MUSIC ] Between 1906 and 1986, We had no idea what caused the pathology. So people would look in the brains of patients after they died; See the plaques, the tangles, the evidence, the information and then have to guess what happened to this brain. And it was the equivalent really of aliens coming down from space and they want to understand the game of football and say" Well, wow what happened here "? They see some grass dug up and... Crumbled up sheet of paper where they get a little bit more evidence of what happened. There's no footballs in sight. There are no players in sight. For decades, that was the equivalent of how we were trying to figure out Alzheimer's. Then in the late 80s when we and others found the first Alzheimer's genes, now we had the real physical targets. We said, this is what's going on. Here's the gene that makes the amyloid. Here are the mutations that make everything go wrong. And so now for the first time, we had hard evidence from genes and proteins that said exactly what was happening before the pathology. [ MUSIC ] Alzheimer's disease affects 50 % of people over 85. Life span right now is 80. If we don't throw more money into this disease, There's a 50 % chance you're gonna get this disease in your lifetime cuz you're probably gonna reach 85. We know so much about this disease. We now know of 2 or 3 dozen different genes beyond the first 4 we found in the 80s and 90s that cause this disease or are predisposed to it. But the funding is what limits how much we can do. We have enough funding to do about five percent of our to- do list of equally important tasks. You look at cancer, AIDs, heart disease. They get twelve billion, ten billion, eight billion. six billion dollars from the government and you see in the incidents of these diseases all go down as a result. Alzheimer's last year got a half a billion Yeah. I always teach my students and trainees, think about what science is going like 50 or 100 years from now and make it your goal to come up with something that lasts 50 years and doesn't go away. Your role as a scientist when you go into the lab is not to prove it but to disprove it. If you go in the lab, And try to crush your hypothesis, kill it, and then see what little thread survives. And then use that to come up with the next idea. Over your lifetime, you're gonna build a little tapestry. If it hangs on in 50 years from now, it's still part of the [ UNKNOWN ] tapestry, you've done more than most. 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