METABOLISM 581 



The above data indicate that potatoes, oranges, raisins, apples, 

 bananas and cantaloups are important base-forming foods. Among 

 the most important acid-forming foods are found rice, whole wheat 

 bread, oatmeal, meats and eggs. Certain fruits, e.g., cranberries, 1 prunes 

 and plums yield a basic ash but are acid-forming foods. 



This is due to the fact that they contain benzoic acid which is 

 synthesized with glycocoll in the body to produce hippuric acid (see 

 page 585). It is worthy of note that some plant foods are base-formers 

 and others are acid-formers. It is also an important fact that acid 

 fruits yield a basic ash (see page 580). 



The normal diet should contain sufficient base-forming elements to 

 neutralize the acids formed. If these acids are not neutralized by 

 the basic elements in the diet they will be neutralized by the fixed 

 bases of the tissues of the body and a seriously deranged metabolism 

 may result. (See experiment on "salt-free diet," page 576.) Organic 

 salts of the alkalis (e.g., sodium bicarbonate or sodium acetate) are often 

 given therapeutically. They reduce the H ion concentration of the 

 urine: the same result so far as urine reaction is concerned may be 

 secured by feeding properly selected base-forming foods. The ingestion 

 of sodium dihydrogen phosphate (NaH^PO^ will increase the acidity 

 of the urine: a like result may be produced by feeding properly selected 

 acid-forming foods. Anything which produces an increase in the H ion 

 concentration of the urine will produce an increase in the ammonia 

 output. 



On a mixed diet the H ion concentration of the urine 2 has been 

 found to be 6 o.i. 3 In nephritis the H ion concentration of the 

 urine may be increased to 5.33 or higher. Alkalis have been used with 

 apparent success in the treatment of nephritis. 4 It is evident that base- 

 forming foods properly selected should be suitable dietary articles for 

 nephritics. 1 For a detailed discussion of acid-forming and base-forming 

 foods see article by Blatherwick. 5 



Experiment. Ingest a uniform diet consisting of milk, crackers, butter, pea- 

 nut butter, and water in desired quantities for a period of three days. Follow this 

 by a period of six days during the first three of which considerable quantities of 

 acid-forming foods (see table page 580) are added to the diet. During the second 



1 Radin reports this berry to contain 0.06 per cent benzoic acid (Blatherwick: Arch, 

 Int. Med., 14, 409, 1914). 



2 Henderson and Palmer: Jour. Biol. Chem., 14, 81, 1913. 



3 H ion concentration may be expressed as gram of ionized H per liter of water. A neu- 

 tral solution has a H ion concentration of iXio~ 7 , or 0.000,000,1 gram per liter. It is 

 often customary to express the H ion concentration according to Sorensen's logarithmic 

 notation. For example instead of expressing the H ion concentration of a neutral solution 

 as i Xio~ 7 he expresses it as 7.00. An increasing H ion concentration decreases this value 

 and an increasing OH ion concentration* increases the value. 



4 Fisher: Nephritis, New York, 1912. 



5 Blatherwick: Arch. Int. Med., 14, 409, 1914. 



