Here's something I'm reading which I'm personally experiencing as well recently:

The Surprising Healing Qualities ... of Dirt

A doctor discovers exposure to healthy farm soil holds keys to healthy bodies

http://www.yesmagazine.org/issues/how-to-eat-like-our-lives-depend-on-it/how-dirt-heals-us?utm_source=YTW&utm_medium=Email&utm_campaign=20131206

Some excerpts:
"While soil scientists are busy documenting these soil-to-food links, immunologists and allergists in Europe are working above ground to uncover another intriguing soil-health connection, the so-called "farm effect." Why is it that children raised on ecologically managed farms in Central Europe have much lower rates of allergy and asthma than urban children or those raised on industrialized farms? Once again, almost everything points to microbes—in manure, in unpasteurized milk, in stable dust, on unwashed food and, yes, in the soil. In one study, researchers cultured farm children's mattresses and found a potpourri of bacteria—most of which are typically found in soil."
....
"But what if our own immune cells are simply a backup mechanism to a more sophisticated first line of defense—our resident microbes?
And what if a healthy and diverse soil microbiome can foster a more diverse and protective human microbiome?"
....
"A group of French microbiologists were among the first to document this game of pass-the-gene when they identified the exact same sequence of DNA in two different Bacteroidetes bacteria species, one living on seaweed and the other in the intestines of Japanese people. They concluded that the marine bacteria had hitchhiked their way into the human gut via sushi and other seaweed dishes and passed their seaweed-digesting DNA on to resident microbes of the human host. The end result of this exchange is that many Japanese—and possibly people from other seaweed-eating cultures—have acquired a greater ability than the rest of us to extract valuable nutrients from their nori."
....
"Thinking of a healthy body as an extension of a healthy farm, and vice versa, is a paradigm shift for many of us. But when we consider that all of our cells get their building blocks from plants and soil then, suddenly, it all makes sense. In fact, it is not too much of a stretch to say: We are soil."