By Roberta Attanasio
“Breastfeeding is the normal way of providing young infants with the nutrients they need for healthy growth and development. Virtually all mothers can breastfeed, provided they have accurate information, and the support of their family, the health care system and society at large. Colostrum, the yellowish, sticky breast milk produced at the end of pregnancy, is recommended by World Health Organization as the perfect food for the newborn, and feeding should be initiated within the first hour after birth.”
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.
Now, results from a new study published on line (February 3, 2014) in the Proceedings of the National Academy of Sciences (Secretory antibodies in breast milk promote long-term intestinal homeostasis by regulating the gut microbiota and host gene expression) show that the beneficial effects of maternal secretory IgA persist after weaning.
In newborn mice and humans, secretory IgA derives almost entirely from breast milk. However, both mice and humans start producing their own secretory IgA as the immune system matures. The researchers used mice that either did or did not receive maternal secretory IgA in breast milk and found that early exposure of newborn mice to secretory IgA in breast milk led to increased protection against potentially harmful microbes. In addition, these mice had a different composition of the gut microbioma and, later in life, exhibited an altered pattern of expression of certain genes — genes that, in humans, are associated with intestinal inflammatory diseases.
Thus, the researchers suggest that exposure to secretory IgA derived from maternal milk in the neonatal period helps in protecting against intestinal inflammation later in life.