I too am just beginning my fast (just completed day 2). I take many vitamins. i have to because I have hormonal imbalances that need to be regularized through vitamins and also fibromyalgia, herniated discs, pcos, pleurisy, so I take my vitamins! I take Niacin, Sam-E, Vitamin C, Calcium, Magnesium, Omega 3 Fatty Acids, and many others. I know that these are good for anyone, especially an ill person. I can't immagine they would have any adverse effects on your fast. On the contrary, all the nutrients will help to replenish your body of minerals, etc. you will be losing. Good luck! Keep taking the vitamins.