Metamucil doesn't contain any probiotics so it doesn't really help in rebuilding healthy flora.
The flavors vary, but if you combined them all the list of ingredients would be:
psyllium hydrophilic mucilloid citric acid ,
D&C Yellow #10,
FD&C Yellow #6,
sucrose citric acid
You can find plain psyllium without all the additional gunk. To rebuild flora, you'd be better off looking into kefir, organic yogurt, or a good refrigerated probiotic formula.