Key word: bacteria. We are all covered from head to toe with them. And increasingly, scientists are convinced that these microorganisms are central to understanding why allergies are becoming more common among children, especially in the developed world.
The bacteria that coat our skin, settle in our mouths, and live in our intestines not only outnumber our own cells by a ratio of ten to one, but play a crucial role in training our immune systems.
And changes in lifestyle, ranging from the increase in cesarean deliveries to the excessive use of antibiotics and a sedentary lifestyle, are contributing to the reduction of these «friendly» microorganisms, resulting in an increase in allergies.
In the UK alone, one in three people suffers from some type of allergy.
To see if the decline in bacteria might be a factor, the BBC’s Horizon program ended the lives of two British families affected by the problem.
under the microscope
In one family, eight-year-old Joe suffers from severe asthma, hay fever, eczema, allergies to nuts, pets, and dust mites.
In the other, four-year-old Morgan has an endless list of allergies. In addition to severe eczema and hay fever, she is allergic to dairy, nuts, soy, kiwi, avocado, banana, latex, as well as cats, dogs, and horses.
Both families agreed to provide bacterial samples from their skin and intestines, and even from their homes, in the hope of getting clues as to the reason for the allergies.
The results were incredible. Like many in Western countries, these families featured fewer varieties of bacteria compared to traditional tribes in parts of the developing world. And the experiment found that a hunting community not only had more diversity of bacteria, but only one of its 15,000 members suffered from any type of allergy.
Caesarean section and breastfeeding
The lifestyle in the West seems to be changing our bacteria and our susceptibility to allergies.
There are many elements responsible for this, but a big factor could be how children grow.
In the UK, 25% of babies are delivered by caesarean section, a figure that is significant when you take into account that a study in Norway found that babies born by caesarean section are 52% more likely to suffer from asthma than those born by caesarean section. born by vaginal delivery.
The data is even more relevant for Latin America which, according to a Unicef study, had a 30% rate of cesarean sections in 2013.
Scientists consider that the bacteria babies are exposed to as they pass through the birth canal protect them from allergies and it is possible that the increase in cesarean deliveries is making children more prone to allergies.
But apparently the attack on batteries continues as babies grow. Breast milk is now known to contain up to 900 species of bacteria, offering a possible explanation for why breastfed babies are less likely to suffer from allergies.
Meanwhile, one of the biggest threats to the bacteria that protects us from allergies is from antibiotics. These medicines often reduce our «friendly» bacteria.
A study involving several medical institutions in England and Scotland found that the use of antibiotics in the first years of life could increase the risk of eczema by 40%.
For another pate, Horizon followed two families for 24 hours and found that they spend an average of 91% of their lives indoors, a pattern that was mirrored across the UK. As existence becomes more sedentary, contact is lost with a variety of microorganisms that are normally found in gardens and in the outdoor air.
One study even found that if you have more plants and flowers around the house, you’re likely to have more bacteria on your skin and suffer from fewer allergies.
Professor Graham Rook of University College London calls these bacteria our «old friends» and is in no doubt about their importance to our health.
«In a way,» he says, «realizing that humans are actually ecosystems and that we are so dependent on these microorganisms is probably the most important advance in medicine in the last 100 years,» he said.