What is the ruling on consuming foods available in European markets that contain ingredients of unknown origin, such as mollusks or the fatty substance E471, when it is not clear whether they are permissible (halal) or forbidden (haram)?

The basic principle concerning beneficial things is permissibility, unless there is evidence to prove their prohibition, based on the Almighty's saying: "It is He who created for you all of that which is on the earth." Accordingly, there is no harm in eating from these things unless one is certain or predominantly believes that they contain something unlawful. Foods whose permissibility is doubted remain permissible according to their original status, unless it is proven that they contain something unlawful.