Purine nucleotide, nucleoside, base, and uric acid determination in infant formula and breast milk in Japan

• Published in: Gout and Uric & Nucleic Acids Vol. 47; no. 1; pp. 19 - 27
• Main Authors: Fukuuchi, Tomoko, Koguchi, Rio, Saigusa, Daisuke, Kaneko, Kiyoko, Yamaoka, Noriko
• Format: Journal Article
• Language: Japanese
• Published: Japanese Society of Gout and Uric & Nucleic Acids 25.07.2023
• Subjects: breast milk; infant formula; purine content; uric acid
• ISSN: 2435-0095
• DOI: 10.14867/gnamtsunyo.47.1_19

Infant formula contains all the nutrients necessary for the healthy growth of infants. There are some differences between breastfeeding and artificial feedings, such as regarding the immune function and intestinal flora, mainly attributed to the type and amount of physiologically active factors in breast milk and infant formula. It has been reported that milk contains purines, including nucleic acids, nucleotides, nucleosides, and uric acid. In particular, human milk contains more free nucleotides than cow's milk, and nucleotides in human milk are semiessential nutrients that activate immune cells in the digestive tract. The addition of 5'-mononucleotides to infant formula is recommended. However, no physiological function of uric acid in the intestinal tract was found, although it has been reported that mammalian milk contains xanthine oxidase and a large amount of uric acid. Uric acid causes changes in intestinal microbiota in the intestinal tract. This study aimed to quantify uric acid and its precursors, purines (nucleotides, nucleosides, and bases) in breast milk and infant formula. Infant formula and breast milk contained more uric acid than other purines. Additionally, breast milk contained significantly higher levels of uric acid than infant formula. Nucleotides were the second most abundant molecular species, being more abundant in infant formula than breast milk. Some differences in the content and composition of infant formula among different sales companies or product forms were observed. We need to consider the role of uric acid, the most abundant purine molecular species ingested during infancy.