The best replacement for fos is inulin.

The best alternatives to fos are rated as following:
★★★★★  inulin
  aos

Your alternative for fos is not listed? Suggest!
Speaking about fos, one probably shouldn't forget about probiotics.

Other search terms related to fos and their ratings are:
★★★★★ probiotics
You have in mind a companion for fos and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of fos in all years. Click on graph for more.
fos
inulin
aos