There's so much hedgey language in the abstract, the rest of the study is barely worth reading. The short answer is that the study is pointing to some interesting preliminary findings, but there's nothing solid there that suggests any conclusion.
Which is fair. That's how science works. We notice something. We study it. It either does what we thought or it doesn't. We're still in the "noticing something" phase.
That's not stopping people from selling you pre-biotics, though, or you buying them.
Although the latter approach is still in its infancy, some important insights have already been gained about how the microbiota might influence a number of disease processes both within and distant from the gut. These discoveries also lay the groundwork for the development of therapeutic strategies that might modify the microbiota (eg, through the use of probiot-ics). Although this area holds much promise, more high-quality trials...are needed, as well as laboratory investigations of their mechanisms of action.