It depends on the level of your candida in your small intestine. For people that have more candida than beneficial flora in the small intestine(especially upper small intestine) then the candida has a chance to utilize the vitamins before your body does. I've seen a lot of research on candida being very efficient in utilizing nutrients. So it depends on the level of your candida and how strong your symptoms are. I mostly agree with Dr. Biamonte. For people that have mild candida -- supplementing might do them some good --as long as the body utilizes them before the candida does.
I don't think the vitamins actually feed the candida but it utilizes the nutrients for metabolism, improving cell functions etc..... If you take vitamins and they are making you more lethargic/having a bad reaction with them then this might be sign that its not the right time to be supplementing.
You need to eat less sugar and more fat. Also wear airy under garments and eat plain real cultured yogurt. The no sugar thing suck but the yeast feed on this. Also you can dab an little PLAIN naturally cultured yogurt down there to help combat the yeast. Sounds weird but I am not making that up. Two good varieties are Strauss yogurt and Pavel's Russian yogurt.