Vitamin D is best known for helping the body build and maintain strong bones. People get it from sunlight, certain foods such as oily fish and fortified dairy products, and dietary supplements.
In recent years, scientists have also become interested in whether vitamin D can help keep the brain healthy as people grow older.
As we age, memory and thinking skills can gradually decline, increasing the risk of conditions such as dementia. Researchers are searching for simple ways to protect brain function, and vitamin D has become one possible candidate. However, experts still do not know exactly how much vitamin D is best for brain health.
A new study from Rutgers University explored this question by following women between 50 and 70 years of age who were overweight or obese. Excess body fat can affect how vitamin D is stored and used, making this group especially important to study. The research also encouraged all participants to lose weight during the one-year trial.
The women were divided into three groups. One group took the recommended daily amount of 600 international units (IU) of vitamin D, another took 2,000 IU, and the third took 4,000 IU each day. The researchers then measured memory, learning ability, and reaction time before and after the study.
The results brought both encouraging and unexpected findings. Women taking 2,000 IU each day showed better memory and improved learning compared with those taking the standard dose. This suggests that a moderate increase in vitamin D may support certain aspects of brain function.
At the same time, the study found a possible drawback. Women taking 2,000 IU, and especially those taking 4,000 IU, had slower reaction times. In everyday life, slower reactions could make it harder to avoid obstacles, respond quickly while walking, or recover from losing balance.
This finding is important because falls are a major cause of injury in older adults. Previous research has also suggested that people taking high doses of vitamin D, particularly 2,000 IU or more each day, may experience more falls. Although scientists do not yet know exactly why, slower reaction times could be one possible explanation.
The study raises several important questions. Researchers still need to determine the ideal amount of vitamin D for different people and whether the effects are the same in men and women. They also want to better understand whether slower reaction times directly increase the risk of falls.
The research was led by Sue Shapses at Rutgers University and published in The Journals of Gerontology: Series A. The findings show that vitamin D may influence the brain in more than one way, providing possible benefits for memory while also affecting how quickly people react. More studies are needed before doctors change current recommendations.
Vitamin D is only one part of maintaining a healthy brain as we age. Eating a balanced diet rich in vegetables, fruits, whole grains, healthy fats, fiber, B vitamins, and antioxidants, staying physically active, and following medical advice all support long-term brain health.
This study reminds us that when it comes to supplements, more is not always better, and finding the right amount may be the key to gaining benefits while avoiding unwanted effects.
If you care about health, please read studies about how Mediterranean diet could protect your brain health, and the best time to take vitamins to prevent heart disease.
For more health information, please see recent studies about plant nutrients that could help reduce high blood pressure, and these antioxidants could help reduce dementia risk.
Copyright © 2026 Knowridge Science Report. All rights reserved.
