Breast milk helps protect the infant from gut infections, but can its constituents be included in foods to protect adults? A Teagasc team may have the answer, writes Áine Bird
THE BENEFITS OF breastfeeding are widely known, strengthening the child's immune system and enhancing the child's intestinal health.
What are the properties of human milk that account for these effects? And perhaps more importantly, is there any way that the adult immune system can enjoy similar benefits?
Teagasc researchers have recently developed a technique which may allow these properties to be incorporated into adult beverages.
Oligosaccharide concentration is thought to be one of the key factors in the health-promoting properties of human milk. "Our interest in the oligosaccharides arose from the fact that there are very high concentrations of these substances in human milk," explains Dr Raj Mehra, Principal Research Officer in the Teagasc Moorepark Food Research Centre.
"Oligosaccharides are just carbohydrates made up of chains of three to 10 monosaccharides. Human milk is known to provide protection for infants. The oligosaccharides promote growth of bacteria such as Lactobacillus and Bifidobacterium in the colon, which lead to good gut health. They also prevent adhesion of pathogens to the gut wall," he explains.
Mehra and his team have developed a method for the extraction and enrichment of oligosaccharides from whey-based streams of cows' milk. While the levels of oligosaccharides in cows milk are much lower than those in human milk they are structurally similar.
"We've been looking at enrichment of bovine whey streams. Whey is made up of lactose, salts, protein and the oligosaccharides. We take out the protein and then the lactose. Removing the lactose concentrates the levels of oligosaccharides," he says.
The process is carried out using a membrane filtration system. "This is the cheapest method but it is hard to find the best membrane, it's a difficult process. We tried different membranes and this resulted in a number of oligosaccharide fractions," says Mehra.
Now that the oligosaccharides have been concentrated the next step in the process is to investigate the effects in "model beverages" and develop a method of adding the oligosaccharides to these beverages.
"In the next six months we will be developing large-scale processes to produce ingredients to add to infant formula and adult beverages. We have a beverage company and a dairy company who we will work with. Infant formula companies are also interested."
It is presently unknown whether all of the benefits experienced by infants will also be seen in adults. "The jury is still out on this. The bacterial species involved may be different in adults and children but the oligosaccharides will still prevent the adhesion of pathogens to the gut wall so that is promising," says Mehra.
Tests are being conducted to establish what the effect of the increased oligosaccharide concentration would be on the human gut. "We're feeding oligosaccharides to a pig model, which is the nearest to the human gut model, to see if bacterial growth is enhanced in the gut with increased oligosaccharides."
The team in Moorepark is also collaborating with a research group at the University of California Davis, the leading university in studies of the structural and biological characterisation of milk oligosaccharides.
The Teagasc researchers are currently at the end of their second year of a project funded by the Food Institutional Research Measure (Firm), of the Department of Agriculture and Food, and the Dairy Levy.