Human Breast Milk Ingredient Adjusts to Optimize for Beneficial Gut Bacteria Over Time
A new study, led by Sharon Donovan of the University of Illinois, shows that human milk oligosaccharides, or HMO, produce short-chain fatty acids that feed a beneficial microbial population in the infant gut.
Not only that, the bacterial composition adjusts as the baby grows older and its needs change.
Even though HMO are a major component of human milk, present in higher concentration than protein, many of their actions in the infant are not well understood. HMO are virtually absent from infant formula.
For the first time, scientists have shown that a complex mixture of HMO and a single HMO component produce patterns of short-chain fatty acids that change as the infant gets older.
A healthy microbiome* has both short- and long-term effects on an infant's health. In the short term, beneficial bacteria protect the infant from infection by harmful bacteria. In the long term, beneficial bacteria strengthen the immune system so that it can fend off chronic health problems like food allergies and asthma.
In the study, breast milk was obtained from mothers of preterm infants at Chicago's Rush University Medical Center, and the HMO were isolated and analyzed. The scientists tested bacteria from 9- and 17-day-old sow-reared and formula-fed piglets. Because piglets grow so rapidly, these ages reflect approximately three- and six-month-old human infants.
The colon bacteria were added to test tubes containing HMO and two prebiotics commonly used in infant formulas. These mixtures were allowed to ferment and then sampled to see how the bacterial population was changing over time and what products were being produced by the bacteria.
When the HMOs were introduced, the bacteria produced short-chain fatty acids, at some cases at higher levels than other prebiotics now used in infant formula. The short-chain fatty acids can be used as a fuel source for beneficial bacteria and also affect gastrointestinal development and pH in the gut, which reduces the number of disease-causing pathogens.
Further, different HMOs produced different patterns of short-chain fatty acids, and the composition of bacteria in the gut changed over time. "It was distinctly different at 9 vs. 17 days, making it likely that the functions of HMO change as the human infant gets older," Dr. Donovan said. "There's evidence that these compounds can bind to receptors on immune cells and, to our knowledge, no current prebiotic ingredient can do that," she said.
The above story is based on the May. 14, 2012 news release by University of Illinois College of Agricultural, Consumer and Environmental Sciences. The study was published in the April issue of the Journal of Nutrition: M. Li, L. L. Bauer, X. Chen, M. Wang, T. B. Kuhlenschmidt, M. S. Kuhlenschmidt, G. C. Fahey, S. M. Donovan. Microbial Composition and In Vitro Fermentation Patterns of Human Milk Oligosaccharides and Prebiotics Differ between Formula-Fed and Sow-Reared Piglets. J Nutr, 2012; 142 (4): 681 DOI: 10.3945/jn.111.154427
* a microbiome is the totality of microbes, their genetic elements (genomes), and environmental interactions in a particular environment.
The World Alliance for Breastfeeding Action (WABA) is a global network of individuals & organisations concerned with the protection, promotion & support of breastfeeding worldwide. WABA action is based on the Innocenti Declaration, the Ten Links for Nurturing the Future and the Global Strategy for Infant & Young Child Feeding. WABA is in consultative status with UNICEF & an NGO in Special Consultative Status with the Economic and Social Council of the United Nations (ECOSOC).