Imbalances in the microbiome are associated with a host of metabolic and immune system dysfunctions. These include eczema, asthma, allergies and food intolerances; weight issues such as obesity or an inability to put on weight; emotional issues such as stress, anxiety and depression; inflammatory responses such as irritable bowel syndrome and arthritis; auto-immune responses involving chronic inflammation or demyelination; even cognitive dysfunctions such as poor short-term memory and disorders such as autism.
Much of the damage to our population of friendly microbes is caused by modern diets. Our ancestors ate a huge variety of natural foods which supported the multitude of different microbial populations which are the hallmark of a healthy gut. Now we eat a much narrower range of foods and many of those are processed or laced with chemicals which kill off many of the communities in our gut that we rely on for healthy functioning. In a recent experiment, just ten days on an exclusive junk food diet was found to wipe out 1,300 species of bacteria, more than a third of the normal gut population.