whenever there are so many studies linking the beneficial effects to one particular thing in our diet that they are too numerous to count, there’s probably a “There there”.
Such is the case with naturally fermented dairy and pickled vegetables. We refer to them as probiotics. But what are probiotics exactly? The NIH has an excellent article explaining, in general terms, what they are and how they affect us. It can be found here

Here is another NIH article that discusses how these beneficial microorganisms from fermentation can improve our general health.

In this article, Lactobacillus plantarum was found to be effective in fighting off a biological toxin in an in-vitro study.

A strain of Lactobacillus gasseri was tested in overweight subjects and found to be effective for losing a small amount of weight in a double-blind study. That article can be found here.

bifidobacterium may have beneficial effects as well. Preliminary studies have shown that this bacteria may decrease the number of cancer cells in the colon. That article can be found here.