LPG is the best bio supermarket in berlin i guess. u have to become a member to pay a bit less than no-members. membership is about 12 to 20 euros per month and u can quit if u go or leave berlin for more months without problems.
in this supermarket at kollwitzplatz, which is quite huge, u can find nearly everything u need.
the bistro offers good food and coffee and also theres a bakery. u can get best bread - all u need. glutenfree, vegan etc.