These are new to me. Prebiotics are fiber food for probiotics, though they are indigestible to us. I have been looking at reviews of Now's Inulin (the major prebiotic) and see lots of people mentioning it helped with candida as well as digestion issues. Since I had no clue I had candida, I suspect others are clueless too. Anyway, prebiotics seem just generally great for our health. Another source is buckwheat/kasha & some other foods.
You have to start slowly on prebiotics, maybe just 1/16th of a tsp or less to start. Build up as you are able. Until your body gets some of its benefits it can cause gas and bloating. After you get used to it, which takes maybe a month or so, if you ever had any problems with regularity, they are history most likely. I personally now take 1 tsp a day.