There's strong evidence to support the hypothesis presented here. Scientists are very reluctant to say " X causes Y" in something from just one study, but this is a great starting point. Now, other people can test the idea in their own labs and see if the hypothesis continues to hold true. If other people get the same results, then there may be a scientific consensus that everybody can agree to and we can agree that "X causes Y"

They discovered a new species of bacteria that contributes to arthritis. It would be a separate research project entirely to learn what sort of foods and diets contribute to people acquiring the bacteria.

Understanding how the disease begins is the first step to treating it, and ultimately preventing it. There is nothing sinister here, this is the incremental progress that needs to happen in medicine.