The value of dietary fiber in the adult diet is now recognised as important but in a journal this month researchers suggest that babies may also benefit from the effects on bowel health by adding fiber to milk formula.
In the June issue of the Journal of Nutrition, researchers from the University of Illinois, US report that piglets that consumed formula with moderate levels of fermentable fiber tolerated an induced infection of Salmonella typhimurium much better than those fed a plain control formula or one with a non-fermentable fiber.
The ongoing research is targeting a $2 billion-a-year, sometimes fatal problem of acute diarrhea that, according to the US Centers for Disease Control and Prevention, accounts for about 9 per cent of all hospitalisations of children under age five in the United States annually. While experts encourage mothers to breast feed their infants to stimulate natural protection against a multitude of diseases, the vast majority of infants are fed infant formulas.
"We know that breast milk is important because it sets up microbiota in the colon and fights off infections," said Kelly Tappenden, professor of food science and human nutrition and principal investigator of the research. "Infants are most susceptible to diarrhea diseases compared to other segments of the population. Many such diseases peak in the first year of life. We are interested in trying to prevent diarrhea-related diseases in babies. Our hope is that infant formulas can be enhanced to provide much of the same activity that a mother's milk will do."
Tappenden and colleagues divided 48 two-day-old piglets into four groups fed in equal amounts every 12 hours. The gastrointestinal tract and general development of neonatal piglets are similar to that of human infants born about eight weeks early.
The more rapid growth rate of the piglets allows researchers to observe changes at a rapid pace. A control group received a standard sow-milk replacement formula. A second group got formula supplemented with non-fermentable fiber (methylcellusose). The other two groups, respectively, received formulas containing soy polysaccharide (a moderately fermentable fiber) and fructo-oligosaccharides (a highly fermentable fiber).
The fiber sources are among multiple possibilities and were chosen to test a broad range of levels, Tappenden said. The soy fiber is different than the soy protein that is used in soy-based formulas for babies that are allergic to cow's milk.
After seven days, the piglets were infected with the salmonella strain that commonly occurs in infants. The piglets' activity and signs of illness were monitored for seven more days, after which the piglets' small intestines and colons were evaluated.
"There was no change in body temperature among the piglets, but there was a reduced incidence of diarrhea, and the activity level was maintained for those on the higher fibre diets," Tappenden said. "The control animals and those that were fed the non-fermentable fiber developed severe diarrhea and became very lethargic. What that tells us is that it is not just fiber that is important, but fiber quality is very important and that we need a fermentable fiber."
In the experimental piglets, there were positive changes in the transport of nutrients. However, Tappenden said that her team might have waited too long into the recovery process to do the analysis, preventing an accurate determination of what the changes were and why they occurred.
She said that the team will now look at the first 48 hours after infection. "We know that fermentable fiber is doing something positive, but we still cannot say why. These new tests may help us answer that by looking at the conditions at the peak of infection."
Fibers are fermented in the body into short-chain fatty acids, which are short lipid molecules, thought to be good for the digestive tract by providing increased intestinal structure and function, as well as promoting resistance against invading pathogens.
Tappenden warned that while the pre-clinical results are encouraging, they are far from leading to changes in infant formulas.
"By our results, we could see that adding dietary fiber does not seem to alter the development of a newborn's intestinal tract. It made no difference to the healthy group. The presence of the fiber did help in an infectious state, however. Thus it may be that all newborns could consume the fiber without the worry of negative consequences on their development."
The Illinois Council on Food and Agricultural Research funded the project.