i have a d deficiency! if i don't get enough i get constipated. Funny- i am not iron deficient this time, and i read the d can help that too- but they don't know how! Crazy. I wish i had been on d with dd. i'm on a ton now, so i can function as a human but i hate having to pay attention to bowel movements all the time. Really sucks!!!! and i think the fiber one bars hurt my belly.