Early childhood is a good time to manipulate babies' gut bacteria ,as the bacteria respond better to alterations in diet at this age.
Researchers led by Ruth Ley at Cornell University in Ithaca, New York, have found that microbes in a baby's body grew more numerous and diverse with age, but profound shifts occur as he samples new foods, reports New Scientist.
The scientists reached the above conclusion after analysing the bacteria in stool samples from a baby boy from birth to the age of 2 and a half- the first time this has been done while the baby's diet was recorded.
Besides a course of antibiotics to treat an ear infection, it was the introduction of peas and formula milk that caused the greatest upheavals, said Ley.
While the baby was breastfeeding, the bacteria in his stomach contained numerous genes useful for breaking down milk sugars.
When he moved to a diet of solid foods, there were more bacteria with genes that influence starch digestion.
The study has been published in the Proceedings of the National Academy of Sciences.