Vitamin D is well known for helping keep bones strong and healthy. Many people, especially older adults, take vitamin D supplements to prevent bone loss and stay active as they age.
However, scientists are now discovering that vitamin D may also affect the brain, including memory, learning, and how quickly a person can react.
A recent study from Rutgers University explored this idea in more detail. The research focused on how different amounts of vitamin D influence brain function in older adults. The findings were published in The Journals of Gerontology: Series A.
Vitamin D comes from several sources. The body can produce it when the skin is exposed to sunlight. It can also be found in certain foods, such as fatty fish and fortified milk, and in dietary supplements. Because many older adults do not get enough sunlight or dietary vitamin D, supplements are commonly used.
In this study, researchers looked at overweight and obese women between the ages of 50 and 70. This group was chosen because both aging and excess body weight can affect brain health. The study lasted for one year, giving researchers enough time to observe meaningful changes.
The participants were divided into three groups based on how much vitamin D they took each day. One group took 600 international units, which is the standard recommended daily amount. Another group took 2,000 units, and the third group took 4,000 units.
All the women were also encouraged to lose weight during the study, as weight loss can improve both physical and mental health.
At the end of the study, the researchers found that vitamin D had both positive and negative effects, depending on the dose. Women who took 2,000 units per day showed better memory and learning ability compared to those who took only 600 units. This suggests that a moderate increase in vitamin D may help support brain function.
However, the study also found something unexpected. Women who took 2,000 units had slightly slower reaction times. Reaction time refers to how quickly a person can respond to a situation, such as catching themselves when they trip or reacting to changes in their environment.
The effect was even stronger in the group that took 4,000 units per day. These women experienced more noticeable delays in their reaction times. This finding is important because slower reactions can increase the risk of falls, which are a major concern for older adults.
Falls can lead to serious injuries such as broken bones or head injuries. Previous research has suggested that taking more than 2,000 units of vitamin D daily may increase the risk of falling. This new study supports that concern and suggests that higher doses, like 4,000 units, may be especially risky.
Although the study provides useful information, it does not answer all questions. For example, it is still unclear whether the slower reaction times directly lead to more falls. More research will be needed to confirm this link.
The study also focused only on women, so it is not yet clear whether men would experience the same effects. Future studies may help determine how vitamin D affects different groups of people and what the safest dosage might be.
The lead researcher, Sue Shapses, emphasized that while vitamin D can offer benefits, more is not always better. Finding the right balance is important. A dose that improves memory may not be the same as a dose that keeps reaction time sharp.
In addition to vitamin D, there are many other ways to support brain health as people age. A balanced diet, such as the Mediterranean diet, which includes fruits, vegetables, whole grains, and healthy fats, has been linked to better brain function. Nutrients like B vitamins, fiber, and antioxidants found in foods like berries and nuts may also help protect the brain.
Overall, this study highlights the complex role of vitamin D in brain health. It shows that while moderate amounts may improve memory and learning, higher doses could slow reaction time and increase risks in daily life.
For anyone taking vitamin D supplements, it may be wise to speak with a doctor to find the most suitable dose. The goal is to gain the benefits while avoiding potential risks, especially as we grow older and maintaining both mental sharpness and physical safety becomes more important.
If you care about nutrition, please read studies about a breakfast linked to better blood vessel health, and drinking too much coffee could harm people with high blood pressure.
For more information about health, please see recent studies about unhealthy habits that may increase high blood pressure risk, and results showing plant-based protein foods may help reverse diabetes.
Copyright © 2026 Knowridge Science Report. All rights reserved.
