Scientists from Xuanwu Hospital and several other institutions have found that vitamin B supplementation may slow cognitive decline.
High levels of homocysteine (Hcy) are a major risk factor for dementia, and previous research has shown that B vitamins can help reduce homocysteine levels.
However, whether taking B vitamins can directly protect cognitive function has been unclear.
In this new study, researchers reviewed evidence from 95 studies involving 46,175 participants to evaluate whether B vitamin supplementation reduces the risk of cognitive decline and dementia.
The results showed strong evidence that B vitamins benefit cognitive function. The effect was especially clear in studies where the placebo groups showed measurable cognitive decline, suggesting that B vitamins help slow this process.
When the intervention lasted more than 12 months, participants taking B vitamins experienced significantly less cognitive decline compared with those taking a placebo. In contrast, shorter intervention periods did not show this benefit.
The researchers also found that among people without dementia, B vitamin supplementation slowed cognitive decline, while this effect was not seen in people already diagnosed with dementia.
In addition, lower folate levels—and not low B12 or B6—were strongly linked to a higher risk of dementia and cognitive decline. Among adults aged 50 and older without dementia, higher dietary folate intake was associated with a substantially reduced risk of developing dementia. However, higher intake of vitamins B12 or B6 did not show the same protective effect.
Based on these findings, the team suggests that B vitamins—particularly folate—may help slow cognitive decline, especially when used early and over long periods. They also highlight the importance of ensuring that people at high risk for dementia have access to adequate vitamin B supplementation.
The study was published in Nutrition Reviews and conducted by Zhibin Wang and colleagues.
