I would recommend the following as a guide to preserving the enzyme potential and placing less of a burden on the digestive system as well as the rest of the body.
Do not eat more than you need to. Eating too much puts a huge burden on the digestive resources.
Eat less high calorie foods containing sugar and fat. Eat less refined foods and man made foods. Increase intake of raw fruits and vegetables.
Avoid foods which you like but you know don't agree with your digestive system.
Look at the principles behind food combining, where concentrated starches and protein are separated. This eases the digestive burden.
Make sure you drink enough water. A good amount is half a pint about thirty minutes before meals. The digestive process requires water. The metabolic enzymes function more efficiently with water.
By taking all these measures, enzymes will be preserved, the digestive system will have a great load taken off it, and every cell in the body will have its burden eased.
About the Author
The author manages an holistic medicine website for London, England. It includes london osteopathy and london psychotherapy plus a number of other therapies as well as articles on nutrition.