INHIBITION OF BETA-GLUCURONIDASE BY CASEIN HYDROLYSATE FORMULA

Background: A casein hydrolysate infant formula has been shown to be a ssociated with lower levels of neonatal jaundice than are standard inf ant formulas. Because beta-glucuronidase is related to neonatal jaundi ce, this study examined the effect of a casein hydrolysate formula on beta-glucuronidase. Methods: beta-glucuronidase activity was measured with or without added dietary components. The beta-glucuronidase sourc es used were meconium, breast milk, and the purified bovine liver enzy me. The dietary components assayed for their effect on beta-glucuronid ase activity included casein hydrolysate formula (Nutramigen), whey-pr edominant formula (Enfamil), breast milk, enzymatically hydrolyzed cas ein, and other constituents of the casein hydrolysate formula. Stool s amples of 6-day-old infants, who were exclusively fed one of the two f ormulas or breast milk, were also assayed for inhibition of beta-glucu ronidase. Results: Only Nutramigen, enzymatically hydrolyzed casein, a nd stool from Nutramigen-fed infants consistently demonstrated signifi cant inhibition of beta-glucuronidase activity, ranging from 45% to 85 % of that in controls. The inhibition of beta-glucuronidase in purifie d bovine liver demonstrates a dose response in a pH range from 4 to 7. 3. Conclusions: Hydrolyzed casein contains a beta-glucuronidase inhibi tor that, in casein hydrolysate-fed infants, persists after passage th rough the digestive tract. These data are consistent with the possibil ity that inhibition of beta-glucuronidase is a mechanism by which infa nts fed casein hydrolysate have lower jaundice levels than infants fed routine formulas or breast milk. Further study of this mechanism is n eeded. (C) 1997 Lippincott-Raven Publishers.