A recent study conducted by researchers at Emory University in the United States has found that vitamin D supplementation may improve cognitive performance in individuals displaying early signs of dementia, such as memory lapses and sleep disturbances. Participants who received 5,000 international units (IU) of vitamin D daily—equivalent to 125 micrograms—performed better on tests measuring memory and thinking skills compared to those with vitamin D deficiencies.

The study, published in the journal Sleep Medicine, reported that those supplemented with vitamin D scored approximately 13% higher than their deficient counterparts. The researchers noted that higher daily doses of vitamin D were linked to overall enhanced cognitive function. This correlation was observed irrespective of the form of vitamin D taken, whether vitamin D2 derived from plant sources like vegetables and mushrooms, or vitamin D3 typically obtained from eggs, fish, or sunlight exposure.

Victoria Pak, a nursing professor at Emory University and lead author of the study, emphasized the importance of addressing modifiable factors such as vitamin D intake during the early stages of cognitive decline. She suggested that this period, marked by mild cognitive impairment and sleep problems, could serve as a critical opportunity to support brain health and potentially delay further deterioration.

This research builds on a growing body of evidence connecting vitamin D levels to cognitive function. Earlier this year, a team including neurologists from Galway University Hospital in Ireland published findings indicating that adequate vitamin D consumption in middle age might slow cognitive decline in later life. Additionally, a 2025 study led by researchers at the University of Delaware highlighted the significance of sufficient maternal vitamin D intake during pregnancy for the cognitive development of offspring.

With Alzheimer’s disease and other forms of dementia on the rise globally, these studies contribute to a broader understanding of preventative strategies focused on accessible nutritional interventions. Further research is needed to establish definitive guidelines, but the current data underline the potential role of vitamin D supplementation in maintaining cognitive health among older adults.