Vitamin B6 can also influence serotonin and dopamine levels, which can impact your sleep if taken too late, Keatley says.

B-complex vitamin supplements usually contain all eight ... D supplements because it contains 2,000 IU of vitamin D3 — the active form of vitamin D, also known as calcitriol.

The researchers drilled down on the data to focus on a biologically active component of vitamin B12, which indicates the amount of B12 the body can actually use. They found that participants with ...