The enzymes produced in the stomach digest protein only in the very acid conditions of the stomach. Carbohydrate digesting enzymes are produced by the salivary glands and mix with food in the mouth and by the pancreas from where they mix with food in the duodenum. They work best in neutral conditions. There are also a couple of protein digesting enzymes made in the pancreas. Poor absorption of nutrients is usually due to food moving too quickly along the guts. This is easily controlled by a high fibre intake coming entirely from plant cell walls. No animal product has fibre and the high levels of fat associated with most meats simply grease the progress along the gut.