Babies who breast feed longer have been found to have healthier levels of lactic acid bacteria in their gut compared to infants who are fed formulate or switched to food earlier, according to a recent study. These results strongly support the argument that breast feeding is healthier for newborns, a claim that has been recently called into question by scientists.

Many mothers and health professionals alike have argued that breast feeding can lead to a healthier mind, body, and even weight of a child. However, a study published earlier this year in the peer-reviewed journal Social Science and Media disputed those claims, showing that they are grossly overstated.

In one of the largest sample-size studies ever conducted on the subject, researchers found that while breastfed children did indeed see small health benefits, these improvements were so small they were almost insubstantial. In a comparative assessment where one child in a pair of siblings was fed formula while the other was breastfed, the researchers found that there was barely any difference between their health.

Now however, researchers from the National Food Institute at the Technical University of Denmark in Søborg are adding a new item to the list of breast feeding benefits that might just prove a little more impactful.

Health professionals have long understood that the natural balance of bacteria in a person's gut is crucial to maintaining a well-functioning immune system. Microbial population in the intestines have also been known to keep one another in check, limiting the chances of a full-blown colonization of any one bacteria type - thus preventing infection.

This is why it's so important for newborns to develop gut bacterial variety as soon as possible.

Taking samples of gut bacteria from 330 Danish children for the first three years of their life, researchers analyzed the DNA signatures of these samples, observing the development of bacterial composition as each child grew older.

According to the results of this analysis, longer breast feeding (nine to 13 months) encouraged "friendly" lactic acid bacteria to flourish in baby guts for longer, increasing the overall bacteria variety before children were weaned off breast feeding and introduced to foods.

The researchers also found that baby gut bacteria wildly changes right up the age of 3, regardless of when the child is swapped over to food.

Authors of the study wrote that children may be more susceptible to dangerous external factors right up to turning 3-years-old. Having a greater and more stable bacterial count during this time could prove hugely beneficial, but further research would be needed to verify this theory.

The first study was published in Social Science and Media on January 29.

The second study was published in the May issue of Applied and Environmental Microbiology.