Popular supplement may have surprising effect on brain health

Scientists at Emory University have found that older adults who took high doses of vitamin D did better on memory and thinking tests. The study focused on people who had both sleep problems and early signs of memory trouble. These two conditions together are known to raise the risk of developing Alzheimer's disease. The findings were recently published in a medical journal called Sleep Medicine.

The researchers studied 54 adults who were 50 years old or older. All of the participants had trouble sleeping and showed signs of mild cognitive impairment, or MCI. MCI is a condition where a person's memory and thinking skills are slightly worse than normal for their age, but not bad enough to be called dementia. Doctors consider it a middle stage between normal aging and more serious memory diseases.

Sleep problems are very common in people with MCI. Nearly half of all MCI patients have trouble sleeping, and poor sleep can make memory problems worse over time. Researchers wanted to know if taking vitamin D supplements might help protect the brain in people dealing with both of these challenges at the same time.

To measure thinking skills, the scientists used a test called the Montreal Cognitive Assessment, or MoCA. This is a well-known tool that doctors use to check a person's memory and reasoning. Participants also answered questions about whether they took vitamin D supplements, how much they took, and what kind.

The researchers found something interesting. People who took 5,000 international units, or IU, of vitamin D each day scored significantly better on the thinking test. Those who took lower doses did not show the same benefit. The difference in scores was large enough for the scientists to take notice.

However, the researchers were careful not to jump to conclusions. The study was observational, which means the scientists watched and recorded what people were already doing rather than setting up a controlled experiment. This type of study cannot prove that vitamin D caused the better test scores. It is possible that people who already had better brain health were also more likely to take supplements.

Lead researcher Victoria Pak, an associate professor at Emory University's Nell Hodgson Woodruff School of Nursing, said the findings are exciting but need more investigation. 'Our findings give us an interesting lead on the relationship between vitamin D supplement intake and cognitive performance, particularly in people with mild cognitive impairment and sleep disturbances,' she told Newsweek. She added that finding something that might be changed or controlled — like taking a supplement — is especially important when memory symptoms are already appearing.

Scientists have some ideas about why vitamin D might help the brain. Research has shown that vitamin D may help control inflammation, which is swelling or irritation inside the body. Poor sleep is also linked to higher inflammation, and inflammation in the brain has been connected to memory decline. These clues suggest that vitamin D might help reduce the kind of brain inflammation caused by poor sleep.

The study also found that it did not matter much whether people took vitamin D2 or vitamin D3, which are two different forms of the supplement. The amount taken appeared to matter more than the type. This is a useful clue for future research.

The next step, Pak said, is to run a randomized clinical trial. In that kind of study, some participants would be given vitamin D and others would not, and researchers would compare the results. That kind of experiment can actually show whether vitamin D causes better brain health, not just whether the two things happen together. Until those results are in, experts say it is too soon to recommend high-dose vitamin D for everyone.

Pak made clear that people should not start taking high doses on their own. 'Whether supplementation is appropriate depends on the individual, so anyone considering it should talk with their healthcare provider about what's right for them,' she said. Larger studies with more participants are still needed before doctors can make any official recommendations about vitamin D and brain health.