Original Article J. Clin. Biochem. Nutr., 42, 133–137, March 2008 AtjJ01KOchCo098rybeu.18iBno3grS202tnN1i-on0a605,cal040iJlo8/e08ajAtf0c96py1bCrat9fniloci.2nrle0iFc0ra8ele0B1Ri9oacdthiceaml ssociation be w eiRstersyeanrTcdhNoJuaptaraitnlionAntioxidant en t Capacity in Breast and Postnatal Age in Days in Premature Infants Milk Shoichi Ezaki*, Tomoo Ito, Keiji Suzuki, and Masanori Tamura Division of Neonatal Medicine, Center for Maternal, Fetal and Neonatal Medicine, Saitama Medical Center, Saitama Medical University, 1981 Kamoda-Tujido, Kawagoe, Saitama 350-8550, Japan ;?3241R?203aec037cc8eeivpetedd350..170.2.2000077 Received 30 July, 2007; Accepted 5 October, 2007 CopySriugmhtm©a2r0y08TJChBisNstudy aimed to consider the significance of breast milk in preventing oxidative stress by comparing total antioxidant capacity (TAC) in breast milk and formula milk for premature infants, demonstrating the relationship between TAC in breast milk and postnatal age in days. We used the biological anti-oxidant potential test, a new method to measure TAC in breast milk. Breast milk for premature infants were stored at −20°C and thawed within 48 h of collection. We measured TAC in two types of formula milk in the same way. TAC was clearly higher in breast milk than formula milk. Although a negative correlation was observed between TAC in breast milk and age when collected, TAC was always higher than the average TAC in formula milk. TAC in breast milk is higher than TAC in formula milk. We suggest the importance of breast milk for preventing oxidative stress and starting breastfeeding early. Key Words: breast milk, total antioxidant capacity, premature infant Introduction Oxidative stress tends to occur during the neonatal period because the younger the gestational age, the lower the antioxidant capacity (AC) and a lower AC tends to result in an increase in free radicals (FR) and reactive oxygen species (ROS) [1]. Cell damage due to oxidative stress during the neonatal period has been associated with disease [2]. For example, oxidative stress has been reported in association with necrotizing enterocolitis (NEC) if the site of the damage is in the digestive tract [3], with chronic lung disease (CLD) if in the lungs [4], retinopathy of prematurity (ROP) if in the eyes [5], and periventricular leukomalacia (PVL) and intraventricular hemorrhage (IVH) if in the brain [6, 7]. Determining how to avoid oxidative stress is an important factor for improving prognosis. Broadly, there are two ways *To whom correspondence should be addressed. Tel: +81-49-228-3727 Fax: +81-49-226-2325 E-mail: s_ezaki@saitama-med.ac.jp 133 to prevent oxidative stress. One is to avoid factors that trigger the production of FR and ROS. The other is to strengthen AC, which protects the body from cell damage by scavenging FR and ROS when they increase. One study of preventing factors that trigger the production of FR and ROS reported that using 21% oxygen instead of 100% oxygen during resuscitation can keep oxidative stress low, since oxygen causes an increase in FR and ROS [8]. A number of studies of strengthening AC have investi- gated the oral administration of antioxidants (vitamins A, E, and D), but the studies have not reached a consensus of opinion [9–12]. Breast milk is a food that includes antioxidants. Although based on short-term studies, it is known that breast milk has greater AC than formula milk [13, 14]. Breastfeeding has been reported to be clinically significant when compared with formula feeding. For example, compared to formula feeding cohorts, breastfeeding cohorts have been reported to show a 1/10 decrease in risk for development of NEC [15], better neurodevelopment [16], and a decrease in the development of ROP [17]. These results strongly suggest that AC is higher in breast milk than formula milk. The