Improved definition (EN only): Food consumed as part of the usual diet which fulfills a specific physiological function, providing health effects that go beyond traditional nutritional effects.

food that is taken as part of the usual diet and has beneficial effects that go beyond traditional nutritional effects

European Commission, Joint Research Centre, "Functional food in the European Union", http://bookshop.europa.eu/en/functional-food-in-the-european-union-pbLFNA23380/ [13/06/2016]

functional food