Can bacteria we are born with affect our personality?

It was only recently that it was discovered that babies were born with bacteria in their guts, and weren’t born sterile.  It was thought that babies collected their first gut bacteria at birth from their surroundings.  Now we know that babies develop complex bacterial communities in their gut before they are born.

Research carried out at the University of Valencia in Spain, found two different types of bacteria were typically found in babies at birth:  bacteria that produce lactic acid and enteric bacteria.  They found different environments caused differing dominance of bacteria.  Lactic acid producing bacteria tended to be dominant in mothers who were university-educated or who ate organic food, whereas enteric bacteria were dominant in mothers who had had no secondary education or who smoked.  Even more remarkable was what they found these bacterial strains to cause:  Lactic acid producing bacteria dominance was correlated to asthma related symptoms, whereas enteric bacteria dominance was correlated to a higher chance of developing eczema.

Research shows that gut bacteria may also affect our personality.  A Canadian research team has shown that mice bred in sterile conditions behave unusually and have impaired learning abilities.  In another study they tried switching the gut bacteria of two different strains of mice.  One strain tended to be very aggressive and violent and the other was gentler and more passive.  The results were that their personalities changed.  The passive mice became aggressive and the aggressive mice became friendly.  The researchers found that the gut bacteria produced effects in the brain, which changed the mood of the mice.

It is still not known how bacteria transfer to the fetus from the mother but some have suggested that the bacteria may travel through the placenta.  Also it is thought that the initial micro biome in the gut has an effect on other bacteria developing in the gut.  James Kinross, a surgeon at Imperial College says his view is that “the first bacteria are very likely to influence the development of an infant’s gut and immune system”.  Abnormal micro biomes can cause various problems in later life including altering the risk of obesity.  Could doctors one day administer probiotics to create the ultimate micro biome?