What to do with doubtful food received from non-Muslims?

I often receive chocolates or cakes or other foods stuff from colleagues/friends or neighbors. We take special care about ingredients and if we are not sure, we don't consume it, in fact usually we don't consume.

Can we give such things, we are not sure of, to non-Muslims, such as homeless people, or even non-Muslim neighbours? Or should we throw the food in the dust bin?