Invisible dangers lurk around every corner: on every doorknob, in each innocent handshake. Bacteria and pathogens are an inescapable fact of life. Sometimes, though, the enemy comes from within. Sometimes, to avoid the pitfalls of illness and disease, we must simply seek a better balance. The health of our immune systems is in large part predicated on the presence of key nutrients and helpful bacteria in ideal proportions within our digestive tracts as well as our blood streams.