Not everyone digests foods optimally. A common digestive problem is insufficient production of HCI, which can result in diminished ability to absorb vitamins B6, B12 and folic acid. HCI can be affected by the overuse of antacids or ulcer medications that buffer it or reduce its total output. Fresh foods, which contain enzymes, are often easier for the body to digest, negating the body's need to produce more of its own digestive enzymes. However, in some people raw foods can inhibit enzyme production or cause too little or too much HCI production, resulting in poor digestion.
Enzyme activity is sped up by heat and slowed by cold.
Temperatures over 120' F such as used in normal cooking destroy enzymes. The best sources of enzymes are fresh foods eaten raw or lightly steamed. Most juice is pasteurized, a process that destroys enzyme activity, making juices last longer and killing contaminants such as E. coli bacteria. The standard American diet often falls short in providing sufficient natural food borne enzymes. Food processing often removes vitamins and minerals that help form enzymes.