I was recently asked the following question:
Is it important to properly combine food due to how our
systems break down these different foods at different rates using
different enzymes, acids and alkalines? Is it true improper food
combining are what cause digestive illness, obesity, and a host of
other ailments?
Is is true our bodies are born with a set amount of digestive enzymes
and if we are not careful and overuse our supply that essentially we
can perish from our lack of enzymes at an early age?
Should I be supplementing my diet with dietary enzymes?

This is the answer I sent:
It makes almost no difference when we eat and how we combine our foods. The enzymes we need to digest most foods are present at all times in our intestines.
The different acidities are all provided for in different parts of our stomach and small intestines.
This is covered pretty well in my book Evolution Rx in the chapter on the stone age diet.
Back then people ate whatever was at hand, when it was available and didn’t know or care what they combined with what. We are the same.
Digestive illnesses have a lot of different causes but food combinations are not one of them. Obesity has only one cause: Eating too much.
We do not use up enzymes. We produce them all on a daily basis in our intestinal cells. The main reason why we would not be able to make an enzyme (a kind of protein) is if we are starving. If our diets are particularly high in certain chemicals, like lactose in milk, then we can make more of some enzymes like lactase to digest it.
We can overeat such that we don’t have enough of an enzyme. We can eat so much of one food, like sugars, that our normal amount of enzymes can’t keep up. Then the partially digested food, in this case carbs, pass on to the next part of our intestine. When too much carbohydrate appears in the large intestine, the colon, the bacteria there go to work on it, break it down and can produce a lot of gas (CO2). This is an uncomfortable condition but not really a disease.
The answer is not to take more enzymes, but to eat fewer carbs.

We can poison our liver and pancreas, with alcohol or hepatitis, to a sufficient degree that some of the liver and pancreatic enzymes aren’t present in great enough amounts. This is when digestive enzymes can be useful.
Unless you have done a lot of harm to your body you should never need to take these supplements.