The growth of obesity has to do with the antibiotics we give to children.
The world is of microbes. They have been here for more than 3,700 million years and have had time to colonize every corner of the planet.
Although they are invisible, they represent the bulk of the Earth’s biomass.
In our interior, we harbor almost a kilo and a half of bacteria from thousands of different species. Without them, we could not exist.
However, since Louis Pasteur showed that most of the diseases had their origin in microscopic pathogens, viruses and bacteria became enemies to beat for medicine.
This began to be achieved in the first half of the 20th century, with the appearance of the first antibiotics.
Infections that previously killed millions of people became minor illnesses thanks to drugs such as penicillin, one of the great triumphs of humanity.
However, success was not free, although that has only begun to be understood in recent years.
According to Martin Blaser, director of the Center for Advanced Biotechnology and Medicine at Rutgers University, antibiotics have changed the ecosystem of the bacteria that inhabit us and have encouraged the development of bacteria immune to any treatment.
Blaser has written a book about the negative aspects of using antibiotics, whose consequences go beyond making the bacteria resistant.
The microbiome is part of the story, although it is not the whole story. He conducted an experiment with mice to see what was the relative importance of antibiotics and caloric intake in obesity.
“What we saw was that if we gave the mice a high-calorie diet, they got fat. If we gave them antibiotics they got fat too, but if we gave them everything together, they gained much more weight.”
Life is like that, things are not necessarily exclusive, we can see that in this case where both things contribute.
How do antibiotics make us fat?
Antibiotics are very important. They are not the only factor that is affecting our microbiome, but mainly, the growth of obesity has to do with the antibiotics we give to children.
Obesity has spread throughout the world. First, it started in developed countries, but now, children in India or China and throughout the developing world are getting fatter.
In fact, if you look at children under five, 80% with overweight and obesity are in developing countries and in a few years, they will be 90%.
That means that right now there are 50 million children in the world below five who are obese or overweight. And it is estimated that by 2020 it will be 100 million.
Obesity is not just an epidemic, it is a global pandemic.
“What we have discovered is that developing countries are experiencing what we had seen in developed countries thirty years ago. It is happening, and very fast.”
Now, it turns out that in many developing countries the use of antibiotics in children is greater than in the US or Europe.
Children under one year of age are receiving up to ten batches of antibiotics a year because their mothers worry that they are sick and the pharmacist gives them antibiotics for everything from a fever to a headache, and antibiotics are out of control.
There are individual factors that are changing our microbiome, and the effects are cumulative.
Cesarean sections have negative effects, antibiotics have negative effects and giving formula instead of breast milk, too. It all adds up.
In Europe, for example, there is tremendous variation between the north and the south, with the north using cesareans and antibiotics much less than the south, although there is no higher rate of serious infections.
That also happens in the US. In the South, they use 50% more antibiotics than in the western states. This reflects the medical culture and the wishes of the patients.
“For this reason, I wrote the book, to tell people why you should not ask your doctor for antibiotics and you should ask if you are sure you need to take antibiotics,” emphasizes Blaser.
People should know that taking antibiotics or having a cesarean section has hidden costs.
“Everyone is trying to divide the world in black and white and is almost always gray,” says Blaser.
For example, Helicobacter is bad for us and is good too.
“As scientists, we need to better understand the relationship we have with the bacteria, to understand what people we would have to eradicate it from and who we have to maintain or recover it from. We do not know the answers to these questions and we are trying to give everyone a shoe of the same size. It is not correct.”
Blaser explains that he has seen that If an organism disappears, it could cause the disappearance of others. “It is exactly what we have seen for the last 20 years. We are losing ecological diversity.”
According to researcher María Gloria Domínguez-Bello, we have already lost 50% of our diversity. Our ecosystem is running out.
The consequences are serious. Two scenarios are foreseen:
1. The expansion of diseases that we are already seeing grow. More obesity, more asthma, more food allergies, more autism, more irritable bowel, more diseases of the esophagus.
2. Winter of antibiotic; or the invasion of microbes. Those invasions have existed before and killed many people.
One of the best defenses against these invaders is a normal microbiome and to maintain this normal microbiome we should stop using broad-spectrum antibiotics as we do now and look for ways to know which specific infection we suffer from and then treat it with a more specific antibiotic.
The US government has developed a national plan to control antibiotic resistance. “We are working to create narrow-spectrum antibiotics and improve the diagnosis so that doctors, nurses and dentists use antibiotics better and we believe will yield less resistance,” says Blaser.
Because we are facing an ecological change, one aspect of that change is resistance to antibiotics. Another aspect is obesity.
Many studies have been done in mice because they have microbiomes similar to ours and in many aspects with an immune system with parallelisms.
“We have a type of mouse that develops type 1 diabetes spontaneously, and with them, we have shown that antibiotics can accelerate diabetes, which they develop earlier and more frequently.”
He is studying the mechanisms by which antibiotics have that effect. We know that antibiotics change the microbiome and microbiome products.
They change the interaction of the microbiome with the intestine, how the genes are expressed in the intestine and how the immune system is regulated.
“We think it’s a very good model to see what causes this worsening of diabetes and how we can reverse it.”