4. Gluten
The gluten-free trend swept though the population a few years ago, with doctors frustrated by the flood of patients in their offices, claiming to be gluten intolerant without any of the symptoms that come with it (bloating, diarrhea or constipation, gas).
However, whether or not you are able to process gluten, it does have an inflammatory effect on the body because it irritates gut microbes and thus delicate tissues in your digestive system.
Gluten consumption has been linked to depression due to this inflammatory response, so it might be worth cutting it out for awhile to see if your mood improves.