Changes to the microbiome may predispose children to obesity.

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A study looked at the gut flora of over 700 infants to see if it was linked to obesity risk. Photo: Getty Images

Canadian researchers have found a link between household cleaners and overweight children — a relationship that could be connected to gut bacteria.

A study, published in the Sept. 17 Canadian Medical Association Journal, analyzed the gut flora of 757 infants at 3 to 4 months, and their weight at ages 1 and 3 years. The researchers looked at exposure to disinfectants, detergents, and eco-friendly products used in the home.

They found that frequent use of household disinfectants like multi-surface cleaners was linked to lower levels of Haemophilus and Clostridium bacteria, but higher levels of Lachnospiraceae in the gut flora of babies 3 to 4 months old. Significantly, their body mass index (BMI) was higher at age 3.

Yet these same associations were not found with eco-friendly cleaners.

“Very surprising indeed,” said Dr. S. Daniel Ganjian, a pediatrician at Providence Saint John’s Health Center in California. “While it has been shown that gut flora can affect obesity, no study has made such a strong connection with frequency of cleaning and types of product used with development of overweight/obesity.”

Dr. Gina Posner, a pediatrician at MemorialCare Orange Coast Medical Center in California was less surprised.

“There have been recent studies showing the importance of gut bacteria on weight,” said Posner. “If you are using lots of chemicals that then kill that bacteria, it only makes sense that this could lead to problems with weight.”

Ganjian said the study strongly impacts the direction of future research.

“We need to know which chemicals specifically are the problem — since this study did not look at individual ingredients — and how much of an effect it has on BMI,” he said. “The study shows that there is a statistically significant effect on BMI, but that does not mean that it is clinically significant.”

For example, he said, if increased use of cleaning products leads to an increase in BMI by only .5 units, then that does not mean much. He added that if a child’s BMI is 30 and it should be closer to 20, then .5 units is not relatively much, even though it is statistically significant.

But even with the need for more specific research, there are some things the public can take away from the study.

“Hopefully, people will realize that it is not always good to keep things that clean,” said Posner. “Also, it does seem like, although the eco-friendly products did seem to alter the gut microbiome, they didn’t lead to being overweight. I think this will end up booming the eco-friendly industry even more.”

Posner said it’s a good idea not to worry about dirt so much. Use regular soap over the antibacterial soap, generally speaking. Her advice: Let your child get dirty.

“Don’t obsess about your child getting sick and touching ‘dirty’ surfaces,” Posner said. “It is good for your future health to be exposed to different bacteria and viruses. Obviously, we still want to emphasize handwashing, but over-cleaning can lead to problems as well.”

Ganjian suggests a more moderate approach can also make a difference.

“As the hygiene hypothesis has shown, the cleaner a people we are, the more allergies, autoimmune diseases, and obesity can develop,” said Ganjian. “Don’t wash [hands] too much or too little. Try to be like Goldilocks and stay right in the middle. Stay away from the extremes.”

The hygiene hypothesis is the theory that an extremely clean environment can affect a child’s immune system, putting them at increased risk for certain conditions such as asthma and allergies.

Of course, this doesn’t mean it’s time to throw caution to the wind and never handwash again.

“The study also showed that increased washing has led to a decrease in Haemophilus and Clostridium, which themselves can cause debilitating infections, such as ear infections, meningitis, and bloody diarrhea,” Ganjian said. “We have to make sure that before we recommend less washing, that we won’t start seeing an increase in the rate of these infections.”

Ganjian said it’s also important to remember that there’s no magic answer to weight gain.

“Don’t think that now you can eat all the junk food you want, and as long as you don’t clean your house often, you won’t gain weight,” he said. “As a pediatric obesity specialist, I still recommend to people that the best prevention and treatment of obesity at this time is eating healthy and exercising.”

A study found that frequent use of household disinfectants like multi-surface cleaners was linked to lower levels of certain bacteria, like Haemophilus and Clostridium bacteria, but higher levels of Lachnospiraceae in the gut flora of babies 3 to 4 months old.

By age 3, the children with affected bacteria levels were more likely to be obese. The same link was not seen with eco-friendly cleaners.