A perfect example of functional food is sauerkraut. Apart from the high nutritional value of the cabbage itself, fermentation creates loads of beneficial compounds such as enzymes, amino acids, vit B12, and vit K2 (so great for vegans). Lactic acid bacteria produce bacteriocins (natural pathogenic bacteria hunters), and in a proper 6 week ferment, become so diverse and numerous, that 2 tbsp of kraut pack as much probiotic punch as a whole bottle of store-bought probiotic capsules. Add to this the fact that the anti-inflammatory, antioxidant, and anti-cancer properties of the cabbage are enhanced by fermentation, and it’s easy to see why sauerkraut (and non-European cabbage ferments like suan cai or kimchi) has a long and continuous tradition in human nutrition.