Low vitamin C levels linked to less gray matter in brain

Older adults with lower levels of vitamin C in their blood tend to have less gray matter and weaker connections in a brain network tied to memory and attention, according to a large new study from Japan that adds to growing evidence linking diet to brain aging.

The study, led by Haruka Nagaya of Hirosaki University, analyzed MRI scans and blood plasma samples from 2,044 Japanese adults over age 64, measuring gray and white matter volume as well as connectivity within the default mode network; a set of brain regions involved in memory, self-reflection and attention. After adjusting for age, education and physical activity, they found that participants with lower plasma vitamin C levels consistently showed reduced gray matter volume and weaker connectivity within that network.

Dr. Jessica McCarthy, a New Jersey-based neuropsychologist who specializes in dementia assessment and neurodegenerative disorders, told Newsweek the most notable part of the study is not simply that a link exists, but where it was found.

“We have historically thought about Alzheimer’s in the context of brain localization—meaning that change occurs in the brain because specific regions of the brain are impacted, like the hippocampus, which is responsible for converting short-term memory into long-term storage, and the frontal lobe, which is responsible for the executive functions,” McCarthy said. “However, the researchers found associations instead with greater gray matter volume—which can be thought of as the ‘meat and potatoes’ of the brain—and stronger connectivity within the default mode network.

“Increasingly, we’re recognizing that many neurodegenerative diseases are disorders of brain networks, not just isolated structures.”

Gray matter contains the neuron cell bodies responsible for memory, attention, language and decision-making. Some loss or decline is a normal part of aging, but faster-than-expected loss has been linked to mild cognitive impairment, Alzheimer’s disease and other types of dementia.

The default mode network, meanwhile, is one of the brain’s major communication systems and is among the earliest networks disrupted in Alzheimer’s.

“While this study cannot tell us whether vitamin C preserves gray matter, it raises an intriguing possibility that lifestyle choices such as consumption of foods rich in vitamin C may help,” McCarthy said.

Few studies had so far examined whether vitamin C levels measured directly in the blood correspond to physical changes in the brain. The new findings help fill that gap, though the authors caution that the study is observational and cannot prove that vitamin C directly causes the brain differences observed.

Future research, they say, should track vitamin C levels over time and include participants from more diverse backgrounds.

McCarthy said the findings fit into a broader pattern connecting nutrition, sleep and physical activity to brain resilience over the course of a lifetime.

“Those of us in medical and mental health care should be having these conversations with people in their 20s, 30s and 40s, not just in older age, because we also know that brain changes occur in Alzheimer’s before an observable symptom even presents itself,” she said. “Rather than asking whether one nutrient prevents Alzheimer’s disease, the more meaningful question may be how these lifestyle factors work together to help the brain maintain healthy networks and preserve cognitive reserve as we age.”

Newsweek reached out to Hirosaki University for more information via email.

Contact Newsweek editors on this story: Kara Dolman and Emma Lee-Sang.