Babies who continue to breastfeed even after they begin eating solid foods reap immune system benefits.
Almost one third of the beneficial bacteria in a baby’s gut comes directly from mother’s milk and a further 10pc comes from the skin on the mother’s breast.
These bacteria colonise the baby’s intestine and train the immune system to recognise good and bad bugs.
Breastfeeding helps the development of a healthy gut microbiome which in turn protects the baby against allergies, asthma and inflammatory bowel disease throughout life.
“We’re appreciating more and more how these bacterial communities, particularly in the intestine, help guard against the bad guys,” said Dr Grace Aldrovandi, professor of paediatrics and chief of infectious diseases at UCLA Mattel Children’s Hospital.
“We know from animal model systems that if you get good bacteria in your gut early in life, you’re more likely to be healthy.”
Throughout the babies’ first year of life, researchers collected samples of breast milk and infant stool, and swabs from the skin around the nipple.
They analyzed the samples to assess which bacteria were shared between mothers and infants, and calculated the relative abundance of the bacteria.
“Breast milk is this amazing liquid that, through millions of years of evolution, has evolved to make babies healthy, particularly their immune systems,” added Dr Aldrovandi.
“Our research identifies a new mechanism that contributes to building stronger, healthier babies,” she stressed.
Details of the study are published in JAMA Pediatrics