Very Low Levels of DHA Found in Human Donor Milk for Premature Infants
Valentine, C. J. et al., Nutrients, 9: in press, 2017
Division of Obstetrics and Gynecology, University of Cincinnati, Cincinnati, Ohio, USA
Pasteurized human milk and/or infant formula containing DHA omega-3 fatty acid is used for feeding preterm infants with a preference for the former when possible. In view of the fundamental importance of DHA for supporting optimal cognitive performance and visual acuity in infants along with other health benefits, the present study evaluated the levels of key nutrients (amino acids and essential fatty acids) in mothers’ milk as collected from donor milk banks in five US states. Milk samples from 15-16 mothers per bank were analyzed. The fatty acid compositions (with an emphasis on DHA) were determined by gas-liquid chromatographic analyses.
The average DHA concentrations across the five regional banks ranged from 6.09 to 8.20 mgs of DHA per 100 ml milk. A very wide variation in the measured levels was found – ranging from 2.22 mgs per 100 ml (0.08 mol % of total fatty acids) and up to 20.20 mgs per 100 ml (0.67 mol % of total fatty acids). The authors point out that that the normal accretion rate of DHA in the infant within the womb during the last trimester of pregnancy is approximately 50-75 mgs/kg body weight/day; however, such accumulation of DHA in the bodies of infants born before the last trimester is missed. Based on breast milk intakes of 150 ml/kg body weight/day, the authors estimated that at least 0.8 mol % of total fatty acids in the donor milk would need to be present as DHA in order to approach the normal accretion rates. Overall, the DHA levels as measured in the human donor breast milk from the various donor milk banks were found to be much below target intakes as needed for the premature infant to support normal/ideal accretion rates.
The present study raises serious public health concerns regarding the insufficient supply of DHA via donor breast milk for the premature infant. In order to reach target DHA levels in donor breast milk to support adequate DHA accretion rates, much higher intakes of DHA than are typically consumed during lactation are required. Direct supplementation of the pasteurized human donor milk with DHA is another option if necessary. Higher target DHA levels in breast milk for the premature infant are needed than for the term infant. Previous research has indicated that donor supplementation at a daily intake of approx. one gram DHA/day can result in milk DHA levels approaching targets of 0.8 mol % of total fatty acids (Valentine et al., Breastfeed. Med., 8: 86-91 (2013). Major surveys of the DHA status in human breast milk collected worldwide have shown dramatic differences which reflect wide variations in dietary DHA intakes. These DHA levels have ranged from 0.06 % to 1.40 % of total fatty acids in milk fat. As expected, regions with higher intakes of fish/seafood tended to exhibit considerably higher levels of DHA available from breast milk. These worldwide surveys have found the average (mean) level of DHA to be 0.32-0.37 % of total fatty acids (Brenna et al., Am. J. Clinical Nutr., 85: 1457-1464 (2007); Fu et al., Public Health Nutr., 19: 2675-2687 (2016). There is considerable evidence as published to indicate even higher levels of DHA approaching 1.0 to as high as 1.5 % of milk fat should be considered as optimal for many ELBW (extremely low birth weight) infants. Thus, it is important that health care professionals have access to and provide the necessary information on increasing DHA intakes from appropriate fish/seafood sources, functional foods, or supplements as needed for mothers donating milk for various sub-groups of preterm infants to ensure sufficient DHA levels in the donor milk supply.