Most medical conditions related to immune system dysfunction, such as asthma, allergies, and even autoimmune diseases, can be traced in the first few months after birth. And the mechanisms associated with immune system development are not poorly understood.

Now, a new study, published in the journal Cell, has shown a link between breast milk, intestinal (gut) bacteria, and the development of the immune system.

Researchers at Karolinska Institutet, Sweden, found the connection and said the first few months of the birth is decisive in determining the diseases related to the immune system.

The study’s last author Dr. Petter Brodin said, “A possible application of our results is a preventative method for reducing the risk of allergies, asthma, and autoimmune disease later in life by helping the immune system to establish its regulatory mechanisms.”

“We also believe that certain mechanisms that the study identifies can eventually lead to other types of treatment for such diseases, not just a prophylactic,” added Dr. Brodin, who is a pediatrician and researcher at the Department of Women’s and Children’s Health, Karolinska Institutet.

The incidence of autoimmune diseases, such as asthma, allergies, type 1 diabetes, and Crohn’s disease, is increasing in children and teenagers globally.

Breast milk is rich in human milk oligosaccharides (HMOs), which babies are unable to metabolize on their own. The production of HMOs is associated with the evolutionary advantage of nourishing specific gut bacteria that play an important part in their immune system, according to Science Daily. And bifidobacteria are one such bacterial class.

Previous studies have shown that bifidobacteria are common in breastfed babies in countries that have a low incidence of autoimmune diseases.

Dr. Brodin explained, “We found that babies whose intestinal flora can break down HMOs have less inflammation in the blood and gut. This is probably because of the uniquely good ability of the bifidobacteria to break down HMOs, to expand in nursing babies, and to have a beneficial effect on the developing immune system early in life.”

The researchers are now planning to follow the babies for a longer time to see which ones develop asthma, allergies, and atopic eczema.

“We’re planning a new experiment using bacterial substitution to see if we can help all babies have a healthier immunological start in life,” Dr. Brodin said.

“We’re also working with other researchers to compare the development of the immune system in Swedish babies with babies who grow up in rural sub-Saharan Africa,” he added, “where the incidence of allergies is much lower.” The article first appeared in Science Daily.