Vitamin B9 and How Folic Acid Affects Dementia

Vitamin B9 is also known as folic acid or folate. Technically, folate is the term for the vitamin B9 that is found naturally in foods, while folic acid is the name for the synthetic supplement that is added to foods and vitamins.

Adequate amounts of folic acid have commonly been recommended to prevent birth defects such as spina bifida. But, did you know that getting enough folate has also been associated with a reduced risk of developing dementia?​

A spinach and orange salad on a plate
Natasa Mandic / Stocksy United

The Research

One study conducted involved 166 people: 47 of whom were diagnosed with Alzheimer's, 41 with vascular dementia, and 36 with a mixed dementia diagnosis. Additionally, 42 people who did not have cognitive impairment were also included in the study.

Researchers measured each participants' levels of folate and after reviewing the results, they found that people with dementia had significantly lower levels of folic acid as compared to those without dementia. The results were similar for each of the three types of dementia included in this study.

A second study reviewed multiple research studies and concluded that low folic acid levels clearly were associated with the presence of both mild cognitive impairment and dementia.

A third study which focused solely on women found that lower levels of folic acid were associated with a higher risk of mild cognitive impairment.

Does Adding Folic Acid to Your Diet Help?

Possibly, although the results are not conclusive thus far. One study involving 900 older adults who lived in their own homes found that long-term supplementation with vitamin B12 and folate improved memory.

Another study which involved administering folic acid to rats found that both short-term and long-term memory improved. (Whether this would translate to humans is unknown.)

However, other studies did not find a significant difference in the cognition of people whose diets were supplemented with folic acid. Clearly, more research is needed on this topic.


People with adequate levels of folate generally have a lower risk of dementia. Although it's unclear if folic acid supplementation will decrease the risk, a healthy diet (including leafy green vegetables which are naturally high in folate) has repeatedly been correlated with a reduced risk of dementia.

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