Do you think alien life forms on distant worlds would be a suitable food for humans?

There is a gap in our knowledge of evolution, i.e. how life got going in its earliest replicating form. So presumably there could be other chemical triggers for life switching on. Is an alien world with a different carrier of genetic information possible? If so, would such life be a source of food for humans? Or, would it more likely be deadly poisonous? After all, some life on Earth with similar DNA is poisonous to humans.