1. Help protect the body from pathogens that would otherwise enter through the digestive system.  Many pathogenic bacteria, such as E.  coli and H. pylori THRIVE in an alkaline environment.  This is why E. coli lives in the alkaline environment of the intestines and H.  pylori secretes ammonia to neutralize stomach acid to protect itself.  Reducing stomach acid just makes it that much easier for these pathogens to set up shop in the body where they DO NOT belong. 

 2. To allow for the absorption of minerals as non-chelated minerals are reacted with the acid to convert them in to absorbable salts.  

3. Reduction of acid reflux, which results from the lack of stomach acid.  A lack of stomach acid leads to fermentation by yeast overgrowth in the stomach and by fermentation of foods not being digested properly.  The resultant gas formation builds up in the stomach and is eventually rapidly released up the esophagus carrying traces of acid with it.  

4. To allow for the proper digestion of proteins.  The digestive enzyme pepsin cannot work without sufficient levels of hydrochloric acid (stomach acid).  When  proteins are not broken down properly the intact proteins can enter the bloodstream forming antigens.  This in turn can lead to serious and even life threatening allergic reactions.

 5. Absorption of vitamins.  The B vitamins B₆, B₁₂ and folate in particular are dependent on sufficient stomach acid for absorption.  Stomach acid levels decline though with age naturally.  This is why deficiencies of B₆, B₁₂ and folate are so common in the elderly.  

6. Conversion of silica to orthosilicic acid for use by the body.  Silica is essential for the formation of collagen, elastin, and chondroitin.  Without sufficient silica we develop numerous conditions including osteoporosis, osteoarthritis, heart disease, emphysema, diverticulitis, etc.  Even wrinkles and cellulite can result from a loss of silica leading to a reduction of the structural proteins collagen and elastin.  In order for silica to be absorbed and utilized it must first be converted in to orthosilicic acid.  This occurs from a reaction between silica and water, but the process is greatly enhanced by the presence of an acid.  The primary acid for this conversion is stomach acid. 

As I mentioned before stomach acid DECLINES with age.  This leads to a drop in the conversion of silica in to orthosilicic acid, and therefore a loss of collagen, elastin, and chondroitin production as we age.  Now go back and look at the symptoms that develop from the loss of these structural proteins.  Notice how these are not seen in younger people but are common in the elderly?  So why do we see this in the elderly?  Because the lack of stomach acid interferes with the absorption of nutrients needed for the production of structural proteins.  These nutrients include silica, zinc, copper and amino acids. 

As we can see if you want to speed up the production of "age-related disorders" a simple way is to do this is to neutralize your stomach acid.

It should be noted that most of the nutrients needed to form stomach acid are acid dependant for absorption.  Therefore the lack of stomach acid leads to further declines in stomach acid, leading to less absorption of stomach acid forming nutrients, leading to less stomach acid formation.........   It is a vicious cycle downhill once started.  Therefore I recommend avoiding antacids, acid blockers also known as proton pump inhibitors, alkaline waters, calcium carbonate (coral, oyster shell, dolomite), calcium oxide/hydroxide (lime) and magnesium oxide/hydroxide.