Even on days I have no appetite, I force myself to eat more veg and more soup.
Doc only gave me folic acid, no vitamins whatsoever. When I asked her about it, she told me that she rather give it to me much later, as those vitamins and such usually contain synthetics which she rather not give.
Just make sure you take good take of yourself and dont't fall sick. More vitamins is better than falling sick in my opinion. my aunt got a cough during her 3rd pregnancy, and somehow the meds that the doc had prescribed affected her baby somehow, and my cousin was born with some gum and teething problems.