B vitamins are water soluble, but you can still take too much; if you are already taking a multivitamin this might not be necessary. 50mg B3, 10g B5, 300mg B6 and 1000mg B9 or folate/ folic acid may lead to adverse health effects (Shaffer, 2016). Avoid highly fortified and processed foods with extra folic acid. Deficiency in B12 can make extra folate or folate supplementation harmful (Moore et al., 2014; Morris et al., 2007). B12 tends to be the B vitamin people get the least of in their diet. B-vitamins' importance in cognitive function and performance can't be overstated.