Study finds vitamin C boosts brain health in older adults

Levels of the nutrient in the blood are linked with brain connectivity in older people, suggests the study.

The research, involving more than 2,000 Japanese people over the age of 64, found that those with lower vitamin C levels in their blood plasma tended to have a lower volume of gray matter in their brains.

They also had lower connectivity among a collection of brain regions known as the default mode network (DMN), according to the study published in the journal PLOS One.

Researchers say their findings suggest optimal vitamin C levels could aid brain health.

Vitamin C, also known as ascorbic acid, is an essential nutrient that the human body cannot produce on its own.

Studies show it is crucial for building and repairing tissues, supporting a healthy immune system, and acting as an antioxidant to protect cells from free radical damage.

But, because it can't be stored in the body, it must be consumed daily.

Sources include citrus fruits, such as oranges and lemons, bell peppers and chili peppers, strawberries, broccoli, Brussels sprouts and tomatoes.

Previous research has discovered links between diets higher in vitamin C and lower risk of cognitive impairment in older adults.

But few studies had looked directly at vitamin C levels in blood plasma and any potential associations with brain structure and connectivity within brain networks.

For the new research, scientists at Hirosaki University in Japan analyzed MRI scans and plasma vitamin C levels of 2,044 Japanese adults over the age of 64.

They measured the volume of each participant’s gray and white brain matter, accounting for individual differences in total brain volume between participants.

They also evaluated connectivity within the default mode network, which is associated with numerous cognitive functions, such as attention and autobiographical memory.

After accounting for other factors that could affect brain structure and connectivity — including age and education levels — the researchers found that participants with lower plasma vitamin C levels tended to have lower gray matter volume, as well as lower connectivity within the default mode network.

Study co-author Dr. Haruka Nagaya said: "These findings suggest the possibility that optimal levels of vitamin C in blood plasma could potentially support cognitive function and counteract cognitive decline.

"However, the findings do not confirm any such cause-effect relationship between vitamin C levels and brain health, and further research is needed to explore the biological mechanisms behind the observed statistical associations."

The team said future research could build on the findings by taking repeated plasma vitamin C measurements over time, accounting for additional lifestyle and nutritional factors, and including participants of different ethnicities and socioeconomic levels.

Co-author Dr. Tomohiro Shintaku said: “Our study demonstrates that higher plasma vitamin C levels are associated with better preserved structural connectivity of the default mode network, a key brain network involved in cognitive function.

"This finding generates the exciting hypothesis that a diet rich in vitamin C might play a supportive role in maintaining brain health and mitigating age-related cognitive decline in older adults.”

He added: “What I found most fascinating about this research is that we were able to detect these subtle but significant associations between a single nutritional factor and large-scale brain networks by utilizing a robust, community-based cohort of over 2,000 older adults.

"It truly highlights the potential impact of our everyday dietary habits on our brain structures.”