The nucleic acid content of different foods is expressed generally in terms of purine equivalents, with the data derived from the hydrolysis of nucleic acids and free nucleotides to the constituent bases. Careful analysis by Robert McCance, Elsie Widdow-son, and colleagues since the 1930s forms the basis of tables of the composition of foodstuffs.
Foods may be classified into three groups: high, low, or essentially purine free (Table 1). As a general rule, growing organisms such as yeast, or rapidly metabolizing tissues such as liver, will be rich in both DNA and RNA. Seeds, grain, and fish eggs are good sources of the genetic material, DNA. Muscle tissue is an excellent source of nucleotides, such as the energy source ATP. Extracts of meat and yeast have very high purine contents but are usually eaten in small quantities. Some vegetables may provoke gout attacks by virtue of their oxalic acid content rather than that of purines, but legumes, fast-growing parts of brassicas, and asparagus tips may also have significant nucleic acid content. Fats, white flour, sugar, and fruit juices have been separated from the 'living' part of the food and so they are poor sources of nucleic acids.
Table 2 provides data for specific foodstuffs, obtained from the Documenta Geigy Chemical Composition of Foodstuffs tables. The ideal diet for subjects at risk of gout or of uric acid lithiasis is no more than one meat meal per day, using only the low-purine meat and vegetables indicated.
See also: Ascorbic Acid: Physiology, Dietary Sources and Requirements. Choline and Phosphatidylcholine. Gout.
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