In the past few years, research has revealed that the root cause of several important diseases - such as bowel disease and cancer - lies in the microbes that reside in the human gut.

While microbes are generally perceived as being responsible for a plethora of serious and often life-threatening conditions, a series of recent experiments demonstrate just how beneficial the gut microbiome is. These microbes are highly metabolically active and their composition varies greatly with an individual’s dietary habits and age.

Previous studies have shown that the ingestion of probiotic-rich food products such as fresh yogurt and kimchi, may have beneficial impacts by helping to replenish the resident microbes in the gut.

Risk of allergies and asthma varies based on microbiome composition

Recently, research at the University of California-San Francisco has revealed that the precise constitution of gut flora impacts susceptibility to allergies and asthma. They found a particular pattern of microbes in the guts of one-month-old infants that is linked to a threefold higher risk of developing allergic reactions by the time they are two years old and asthma by four years of age.

Homer Boushey, a researcher involved in the study stated that, “Asthma has doubled in prevalence in modern westernised societies about every 20 years for the past 60 or 70 years, so an effective strategy for prevention is becoming an urgent need for public health.”

Previous research has shown that the microbiomes present in the lung and gut can affect activity of certain immune cell subtypes such as the Helper-T cells, which facilitate B-cell activation and killing of virally infected cells. This suggests that the microbes in the gut have a direct link to our intrinsic immunity and ability to withstand foreign antigens and agents.

"We have been working for over a decade, trying to figure out why some children get asthma and allergies, and some don't. It seems that the microbial communities within the body could be the keystone to understanding this and a number of different immune diseases,” said Christine Cole Johnson, chair of public health sciences in the Henry Ford Health System and co-senior author of the study.

The increased risk of allergies and asthma can in part be attributed to children staying in excessively sterile environments with minimal exposure to microorganisms. As the immune system is not challenged by foreign antigens, it remains relatively vulnerable to allergic stimuli during the later years.

A report investigating the global burden of asthma suggested that approximately 334 million may be suffering from asthma worldwide. With such staggering estimates, it may be judicious to turn greater attention to the microbiome as a potential target to reduce risk of the condition.

Antibiotics can elevate risk for development of allergies

Separately, a recent finding has disclosed that antibiotic exposure in the early stages of life can enhance an individual’s proclivity for allergies. The study investigated hay fever and eczema as plausible disease outcomes.

It was found that usage of antibiotics in children caused a considerable increase in the risk of both outcomes. A total of 22 studies (including 394,517 patients) were selected to study the risk of eczema and the increased risk due to early life use of antibiotics varied from 15% to 41%. This risk was further elevated with an increase in the dosage of antibiotics.

Antibiotics are an especially important group of pharmaceuticals, not only because of the rate at which microorganisms become resistant to them, but also for the devastating impact they have on the naturally occurring microbiome in human bodies. Prolonged exposure to antibiotics not only leads to heightened risk of certain diseases, but it also alters the types of flora found within the gut by causing development of resistant strains of bacteria.

Breastfeeding may reduce risk of respiratory symptoms for asthma-prone infants

While the causation of asthma is multifactorial and a lot remains to be discovered about the condition, a different experiment recently demonstrated that infants who were genetically predisposed to asthma had a reduced risk of developing respiratory symptoms if they were breastfed.

They looked at 368 infants from the Basel-Bern Infant Lung Development birth cohort in Switzerland and found that those carrying the asthma risk genotypes had a 27% lower relative risk of developing respiratory symptoms during the time they were being breastfed, compared to those who were not breastfed.

This finding validates the fact that external environmental factors may in fact play a role in modulating genetic predisposition for certain conditions. MIMS

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