By Roberta Attanasio
“Breastfeeding is the normal way of providing young infants with the nutrients they need for healthy growth and development”, the World Health Organization tells us. Breastfeeding confers short-term and long-term benefits on both child and mother, and virtually all mothers can breastfeed, provided they have accurate information, as well as the support of their family, the health care system and society at large.
According to the American Academy of Pediatrics, “Babies are born ready to learn to breastfeed. During pregnancy a woman’s body gains weight and changes to support breastfeeding. Think of the first months of life as the “fourth trimester” where you and your baby get to know each other. Breastfeeding is part of getting to know yourself and your baby on a whole different level.”
One of the benefits of breastfeeding derives from the influence of breast milk on the gut microbiota — the complex ecological community made up of the trillions of microbes that inhabit the gastro-intestinal tract. This community of microbes is extremely diverse and dynamic — it varies between individuals and it fluctuates according to several factors, as for example age, diet and disease. The gut microbiota colonizes babies at birth, and undergoes many changes during early life. It interacts with the immune system and it drives immune development and maturation from birth.
Bruce German, a food scientist (University of California, Davis), told Michael Pollan at the New York Times “Mother’s milk, being the only mammalian food shaped by natural selection, is the Rosetta stone for all food. And what it’s telling us is that when natural selection creates a food, it is concerned not just with feeding the child but the child’s gut bugs too.”
Results from recent studies indicate that early exposure to secretory IgA contained in maternal milk is important for maintaining a healthy gut microbiota. Secretory IgA is one of the different types of antibody and is a first line of defense in the intestine — it protects us from harmful microbes and toxins. It is also produced in the mammary gland by a specific cell type, the so-called plasma cell, and is a major component of breast milk. The beneficial effects of maternal secretory IgA persist even after weaning.
Now, results from a new study (Establishment of Intestinal Microbiota during Early Life: a Longitudinal, Explorative Study of a Large Cohort of Danish Infants) published this month in the journal Applied and Environmental Microbiology, show that breastfeeding promotes the growth of lactic acid bacteria in the baby’s gut flora — these bacteria are beneficial to the development of the child’s immune system.
Tine Rask Licht, one of the researchers involved in the study, said “We have become increasingly aware of how crucially important a healthy gut microbial population is for a well-functioning immune system. Babies are born without bacteria in the gut, and so it is interesting to identify the influence dietary factors have on gut microbiota development in children’s first three years of life.”
The study shows that there are significant changes in the intestinal bacterial composition from nine to 18 months following cessation of breastfeeding and other types of food being introduced. However, a child’s gut microbiota continues to evolve right up to the age of three, as it becomes increasingly complex and also more stable.
“The results help to support the assumption that the gut microbiota is not — as previously thought — stable from the moment a child is a year old. According to our study important changes continue to occur right up to the age of three. This probably means that there is a ‘window’ during those early years, in which intestinal bacteria are more susceptible to external factors than what is seen in adults,” Tine Rask Licht explains.
The new findings could be used to support initiatives to help children develop a type of gut microbiota beneficial for the immune system and for the digestive system.