A Vitamin Deficiency May Increase Dementia Risk For Those With Hearing Or Vision Loss
Hearing and vision loss are extremely common as we age. Globally, at least 2.2 billion people1 have some form of vision impairment (the majority over age 50) and hearing loss affects more than a quarter of adults older than 60.
While there are genetic and environmental components at play here, nutrition can also play a role. A new study published in Frontiers in Nutrition found that adults with vision or hearing impairment who were vitamin D deficient had a significantly higher risk of developing dementia2. Here's what you need to know.
About the study
The goal of this study was to explore whether low vitamin D levels were linked to a higher risk of dementia in adults with vision and/or hearing impairment—two conditions already known to raise the risk of cognitive decline.
Researchers analyzed already collected health data from a large global database to identify adults ages 50 and older with sensory impairment who had their vitamin D levels measured through a blood test.
Participants were then grouped based on their vitamin D status (deficient vs. sufficient), and the researchers followed their health records for up to 10 years to track new cases of dementia, including Alzheimer’s disease and vascular dementia. To make the comparison as fair as possible, they used statistical matching techniques to ensure the two groups were similar in factors like age, health history, and other baseline characteristics.
The link between vitamin D deficiency and dementia
After analyzing the data, researchers found a clear pattern. Compared to those with sufficient vitamin D levels, the deficient group had:
- 55% higher risk of developing dementia overall
- 70% higher risk of vascular dementia
- 48% higher risk of Alzheimer's disease
- 40% higher risk of cognitive impairment
Even vitamin D insufficiency (levels between 20–29 ng/mL) was associated with a 39% higher dementia risk, suggesting a graded effect where lower levels correlate with greater risk.
Sensory impairment & cognitive decline (where vitamin D may fit in)
Vision and hearing impairment have long been recognized as modifiable risk factors for cognitive decline and dementia.
Large population studies have shown that when the brain receives less sensory input (like sounds or visual cues) it may have to work harder to interpret information, which can increase cognitive load. And in some cases, reduced sensory stimulation may also contribute to social isolation, lower physical activity, and changes in brain structure, all of which are associated with faster cognitive decline.
In addition, untreated hearing loss has been linked to faster brain atrophy and a higher risk of dementia, while vision impairment can make it harder to stay socially engaged, read, or participate in cognitively stimulating activities. Because of these connections, maintaining hearing and vision health is increasingly viewed as an important part of protecting long-term brain health.
Vitamin D enters the picture because people with sensory impairment may be more likely to have low vitamin D levels. Individuals with vision or hearing challenges may spend less time outdoors or have reduced mobility, which can limit sunlight exposure, the body’s primary source of vitamin D.
That makes vitamin D deficiency more common in this population and raises the question of whether correcting low vitamin D levels could help address one piece of the broader dementia risk puzzle.
Vitamin D may have neuroprotective properties. As vitamin D receptors exist throughout the brain, this vitamin may help protect the brain through several mechanisms—including amyloid-beta clearance (the protein that accumulates in Alzheimer's), neurotrophin regulation, and anti-inflammatory pathways.
How to increase vitamin D status
Fatty fish, egg yolks, UV-exposed mushrooms, and fortified foods all provide some vitamin D, and your body produces it when UVB rays hit your skin. However, it's notoriously difficult to achieve optimal vitamin D levels (especially from a deficient state) through food and sunshine alone.
Therefore, adding a high-quality supplement is going to be your best bet. Vitamin D3 (cholecalciferol) is generally preferred over D2 because it's more effective at raising blood levels.
If you're looking for a high-quality product, check out this expert-vetted and comprehensive guide of top vitamin D supplements.
The takeaway
This research adds to growing evidence that vitamin D deficiency may be a modifiable contributor to dementia risk, particularly for adults with vision or hearing impairment. Getting your levels tested is simple, and optimizing through supplementation is an actionable step you can take today.
