I am ordering some sublingual methyl B12 on iherb.com, and I've noticed that some of the brands include folic acid and B6 in them, along with the methyl B12. This made me wonder if those two B vitamins are considered important for the absorption of B12? Or are they simply there for the convienence of getting more than one vitamin in one pill? Because I'd rather not muddy the waters by including more than one vitamin in a pill (harder to tell what helps), but by the same token, do I need those other two for best absorption? Thanks!