Fermented foods are foods that have been through a process of lactofermentation in which natural bacteria feed on the sugar and starch in the food creating lactic acid. This process preserves the food, and creates beneficial enzymes, b-vitamins, Omega-3 fatty acids, and various strains of probiotics.
Natural fermentation of foods has also been shown to preserve nutrients in food and break the food down to a more digestible form. This, along with the bevy of substances which stimulate the growth of microorganism created during the fermentation process, could explain the link between consumption of fermented foods and improved digestion.
Ethiopian and other cultures around the world have been eating fermented foods for years, Studies have even shown the link between probiotic rich foods and overall health. Sadly, with the advances in technology and food preparation, these time-honored traditional foods have been largely lost in our society.