What are the digestive juices?

Gastric Juice. The colorless, watery juice. I have no idea where to buy it, maybe at any store, dunno. But I hope that helps you. Gastric Juice help SO much to digest in your digestive system.
Gastric juiice will always be made within you unless you dead. Getting back to the pancrease and the isle of langerhorn - might have a lot to do with it - I don't know - somehow our bodies create enough acid not to destroy our stomach but instead destroy not only our own food but even toxins ie poisons at times! wow

There is also a crayola brand juice that has no sugar, no aspertame, no calories. That is good.