For the study, the researchers analysed the gut flora of 757 infants from the general population at age 3-4 months and weight at ages 1 and 3 years, looking at exposure to disinfectants, detergents and eco-friendly products used in the home. In contrast eco-friendly cleaning products didn't increase the likelihood of children becoming overweight.
"We found that infants living in households where disinfectants were used at least weekly were twice as likely to have higher levels of the bacteria called Lachnospiraceae at three to four months of age", said Anita Kozyrskyj, a U of A pediatrics professor and lead on the investigation into how adjustment of infant gut microbiome impact health.
"At three years of age, those same children had a higher body mass index (BMI) than children who were not exposed to frequent home use of disinfectants as infants". And while the researchers are not advocating that we all stop using our disinfectants, Dr. Kozyrskyj does suggest that they should not be overused. And in previously published studies researchers have found that disruptions in the natural development of the infant gut bacteria - due to a cesarean delivery, prenatal and postnatal antibiotics, or formula feeding - have been associated with a higher risk of childhood obesity, they said.
The researcher said it was important to distinguish detergents from disinfectants since the usage of both is highly connected.
USA cleaning products representatives said the study made "sensational claims". "Indeed, concerns over the potential for antibacterial products to be too effective or even toxic has motivated use of "green" or eco-friendly alternatives", the authors continue. "There were notable limitations in the research, as reported by the "Journal's" editors, along with a study design that ignored all interventions in the children's lives between 3 months and 3 years of age and it did not account for 'the timing of food introduction and child diet'". "The different kinds of species increase, some even decrease".
Based on the study, the researchers argue eliminating disinfectant agents in your home can help protect your infant's gut microbiome and reduce the risk of weight gain and obesity. Fecal samples were collected and parents were asked how often cleaning products were used in the home. In contrast with disinfectant use, there was an inverse dose-response between frequency of use of eco-friendly products and the abundance of Enterobacteriaceae in the infants' fecal samples. More than 80 per cent of households use multi-surface cleaners with disinfectants at least once a week and infant exposure likely occurs through contact with aerosols or cleansed surfaces, Kozyrskyj said.
"However, we found no evidence that these gut microbiome changes caused the reduced obesity risk", Kozyrskyj said. As she notes in the podcast, "Our analyses were controlled for other well-known factors that affect microbiota", so it wasn't those factors that explained any of the realists we obtained. "Because this is a first study, confirmatory research in other cohorts is required", Dr. Kozyrskyj acknowledges.
"I would be comfortable in saying the high use of disinfectants had a contributory role".
They call for further studies "to explore the intriguing possibility that use of household disinfectants might contribute to the complex causes of obesity through microbially mediated mechanisms".
There are many findings that point to a possible causative role for disinfectants in altering gut flora and subsequently leading to a higher childhood BMI, said Kozyrskyj, noting that in studies of mice, Lachnospiraceae has been shown to cause insulin resistance and increased fat storage. They used World Health Organization growth charts for BMI scores.