A capsule for containing beverage ingredients is designed to be inserted in a beverage production device in order to have water under pressure enter the capsule in order to interact with the ingredients in the capsule. The capsule includes a base body and a foil member closing the base body by being attached to a flange-like rim extending from the side wall of the base body of the capsule. The capsule thereby includes a resiliently deflectable sealing member which is designed to be biased against a sealing surface of a holder of the beverage production device when the capsule is positioned in the beverage production device. The sealing engagement of the sealing member of the capsule and the sealing surface is self-reinforcing when pressurized.