A new Tufts University study finds that not getting enough vitamin K may harm brain health as people get older.
The research, published in The Journal of Nutrition and conducted by scientists at the Jean Mayer USDA Human Nutrition Research Center on Aging, reveals that a deficiency in vitamin K impairs memory, reduces the brain’s ability to generate new neurons, and increases inflammation.
While earlier research hinted at this connection, the new findings offer some of the first experimental evidence showing how vitamin K may directly influence cognitive decline.
Researchers fed middle-aged mice either a low-vitamin K diet or a diet with sufficient levels of the nutrient over a six-month period. The mice with insufficient vitamin K performed worse in memory tests, had trouble learning new tasks, and showed signs of brain inflammation — particularly in the hippocampus, the region essential for learning and memory.
Brain scans revealed fewer newly formed neurons in vitamin K-deficient mice. This reduced neurogenesis, combined with increased activity of microglia — the immune cells of the brain — indicated a surge in neuroinflammation. Overactive microglia are believed to contribute to age-related cognitive decline and are often seen in neurodegenerative diseases such as Alzheimer’s.
Menaquinone-4, the primary form of vitamin K in the brain, was found in lower concentrations in the brains of the vitamin K-deficient mice. Male mice appeared particularly vulnerable, showing even lower vitamin K levels in brain and liver tissues and suffering higher mortality rates compared to females.
While these findings come from animal models, they align with observational studies in humans. Data from the Rush Memory and Aging Project has shown that individuals with higher levels of vitamin K in brain tissue experienced better cognitive function and fewer signs of dementia before death.
“Vitamin K seems to have a protective effect,” said Tong Zheng, lead author of the study. “Our research is trying to understand the underlying mechanism for that effect, so that we might one day be able to target those mechanisms specifically.”
Though vitamin K is well-known for aiding blood clotting, it also plays a lesser-known but vital role in maintaining brain structure, protecting against oxidative damage, and regulating sphingolipids — key components of cell membranes in the brain.
The study’s authors emphasize that vitamin K deficiency is common in the U.S., particularly among older adults who may not consume enough green vegetables like spinach, kale, Brussels sprouts, and broccoli.
According to Sarah Booth, senior author of the study and director of the HNRCA, the solution isn’t supplements — it’s dietary change.
“People need to eat a healthy diet,” Booth said. “They need to eat their vegetables.”
With the number of Americans over age 65 expected to exceed those under 18 in the coming decade, identifying accessible ways to preserve cognitive health is more urgent than ever. This research suggests that simply adding more vitamin K-rich foods to the plate may be one step toward protecting memory and reducing brain inflammation as we age.