Previous research included another two-year study, published in 2010 in Neurology, that found that vitamin B12, vitamin B6, and folic acid supplements did not improve the mental abilities of men 75 and older. Eight years after the study ended, though, the men had a small decrease in their risk of cognitive impairment, though it was not a significant change.

Certain people taking the supplements in the new long-term study did experience some small positive effects. One analysis of the data found that people with low blood levels of holotranscobalamin, the active form of vitamin B12, improved their thinking speed with the vitamin B12 and folic acid supplements.

 

“This agrees with the entire clinical picture of B12-related to memory trouble,” said Zwerling.

The supplements given to both groups in the new study also included 15 micrograms of vitamin D3, which may improve brain function at high levels. It is possible that vitamin D3 diluted the effects of the other supplements on mental performance, although it could have simply eliminated any vitamin D3 deficiency among the participants.

“Individuals, especially the elderly, differ in their metabolism of vitamin D and susceptibility to vitamin D deficiency,” said Zwerling. “Overall, the use of D3 just ‘evened the playing ground’ in a population known to have high rates of deficiency.”

Although this new study failed to demonstrate the mental benefits of vitamin B12 and folic acid supplements, vitamin B12 remains essential for overall health.