Exposing babies to excessive amounts of household cleaners and disinfectants can disrupt the normal bacteria of the gut and lead to children becoming overweight, found a study released this week in the Canadian Medical Association Journal. A Canadian national on-going study of children and their development showed fairly conclusively that a mother's reports of using cleaning products such as general household liquid cleaners was closely associated with a child being overweight at age 3.
Why does this matter? Each human being has more microorganisms in their gut – estimates vary with some over 40 trillion – then they have human cells in the rest of their body. We already know that the variation in "gut flora" from one person to another determines how we absorb nutrients and even whether we get disease. For example, there are genes that make individuals more or less likely to develop a very serious chronic gastrointestinal disease called Crohn's syndrome, but that environmental factors such as a person's gut flora determines whether one child in a family develops the syndrome and another with the same genes does not develop it.
We also know that the gut microflora of rodents determine whether they get overweight or not. In fact, you can take the stools of a fat rat and place it in the bowels of a thin rat and make the thin rat fat and vice versa.
We also know that whether a child is breast or bottle fed, delivered vaginally or by caesarean section, or treated with antibiotics in the first year of life can markedly change his or her gut microflora. In this study, Canadian researchers showed that in the 757 children whose gut microflora was tested through stool samples and independently of the three factors just cited, there was a significant difference in which bacteria were found in the gut of children raised in the households using a lot of cleaning products versus the gut of children from households that used less of these products. The children in the houses that used a lot of these universal cleaning products were also more likely to be overweight.
The association of being overweight and the heavy use of general cleaning products is in line with previous studies showing higher levels of the now restricted cleaning agent triclosan (which I have written about in the past) in obese adolescents. These kinds of cleaning agents are also strongly associated with the development of wheezing in children.
We do not know if this study will be duplicated in the future, but it is in line with the similar studies mentioned above. The study also found the use of "ecologically friendly" cleaning agents seemed not to be associated with either obesity or wheezing, but unfortunately, the definition of "ecologically friendly" is rather vague.