This group of water-soluble vitamins incorporates thiamine (B1) and riboflavin (B2), pyridoxine (B6), folate (B9) and cobalamin (B12). The Bs play various roles in body functioning, but many, especially B6, B9 and B12, are crucial in the production of neurotransmitters, which aid cognitive function and help regulate your moods (or not). They’re also necessary for energy production and blood formation (you know, that stuff on your tampon each month). Because the Bs aren’t stored in your body (they’re water-soluble, remember?), supplements are generally helpful as a safety net.