The world today is obsessed with disinfecting everything. Even the organic produce usually comes to us after being thoroughly scrubbed. We rarely spend our days walking barefoot, gardening or munching on produce pulled fresh from the earth. And all of this is affecting our health badly. Most of us think of soil as being utterly irrelevant.But we couldn’t be more wrong. The science is finally catching up with what cultures around the world have known for generations: Dirt is a superfood.
1. It strengthens immunity: One teaspoon of organic soil holds billions of living organisms. Some of them are good and some are bad. With gradual exposure, we develop immunity to the pathogenic organisms, which results in better overall immunity and fewer allergies.
2. It has mood-boosting effects: When we get dirty in nature, some of its micro organisms reach into our bodies and brains through nasal tract or small cuts in the skin. If you feel good when you’re gardening or trekking, it may be in part because Mycobacterium vaccae, a soil microbe enters your body and boosts serotonin levels. This is similar to the way in which most antidepressant medications work. Source 
3. Hardy Probiotics: Unlike usual probiotics we get in market, most of the beneficial bacterial strains found in soil are extraordinarily hardy. They can survive stomach acid, heat, shock, and most importantly they thrive in the environment that makes up the gut.
Its best to get SBO’s (soil based organisms) straight from a garden/farm, but until you have a farm, you can take them in supplement form. I suggest Prescript Assist, which you can purchase here.
Prescript-Assist® is a next-generation combination of 29 probiotic microflora “Soil-Based-Organisms (SBOs)” uniquely combined with a humic/fulvic acid prebiotic that enhances SBO proliferation.
Researchers have found that irritable bowel syndrome patients who took a Prescript Assist probiotic, experienced a significant reduction in symptoms after two weeks. The benefits continued even 1 year after discontinuing Prescript Assist, presumably because the beneficial bacteria stays in the gut and continues to function. Source [1, 2]