New York, Feb 22 (IANS): In six separate studies, US researchers have revealed that breastfeeding and other factors influence a baby's immune system development and susceptibility to allergies and asthma by what's in their gut.

"The findings further advance the so-called 'hygiene hypothesis' theory that early childhood exposure to microorganisms affects the immune system's development and onset of allergies," said Christine Cole Johnson, chair of Henry Ford Hospital's department of public health sciences and principal research investigator.

The gut microbiome is the collection of microorganisms in the gastrointestinal (GI) tract and the human body has billions of these microbes.

The GI tract contains what scientists often call a bacterial ecosystem.

The gut microbiome is known to play an important role in immune system development and is thought to contribute to a host of diseases like obesity, autoimmune diseases, circulating disorders and pediatric allergies and infection.

Exposure to these microorganisms or bacteria in the first few months after birth actually help stimulate the immune system.

"The research is telling us that exposure to a higher and more diverse burden of environmental bacteria and specific patterns of gut bacteria appear to boost the immune system's protection against allergies and asthma," Johnson said.

The studies were presented at the annual meeting of the American Academy of Allergy, Asthma and Immunology in Houston recently.