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A Clean Connection to Childhood Obesity?

Perhaps your mother told you cleanliness is next to godliness. That concept found its way into a 1778 sermon by John Wesley. But it’s even older than that. Ancient Babylonian and Hebrew religious texts have the earliest references. Now, CMAJ wants to put cleanliness next to obesity. Could there be a clean connection?

An Association with Using Household Disinfectants

Researchers from the University of Alberta found an association between weekly use of household disinfectants and excess weight in 3-year-old toddlers.  On top of that, they found a possible explanation. They found more of a particular bug – Lachnospiraceae – in the feces of these infants when they were three months old. Mon Tun and colleagues published their findings in the CMAJ this week.

Their suspicion is that these disinfectants are not just cleaning up all the surfaces in a household. They think the disinfectants are also changing the bugs that live in a baby’s gut. Conveniently, the researchers also found that using eco-friendly cleaners didn’t have those same bad associations. It’s vindication for parents with an environmental conscience!

Not So Fast

Do we have to say it? Correlation is not causation. Despite a slick press release and a podcast to hype the study, all we really have here is an interesting correlation. Using lots of disinfectants can be a flag for many other behaviors. The same goes for opting into “eco-friendly” cleaners.

Thus, residual confounding is an important limitation of the study. The authors didn’t mention that in their paper. Didn’t make it into the press release either. However, in a commentary alongside this paper, Moira Differding and Noel Mueller made that point clear. This study tells us something about plausibility, but nothing about causality.

It’s also worth noting that the data on using disinfectants comes entirely from self-reports. That could be a significant source for errors.

“An Intriguing Possibility”

Differding and Mueller leave us with an appropriate caution. This study gives us an intriguing possibility to explore. Nothing more. Unfortunately, the media hype tells a different story.

Click here for the study and here for the commentary. For a sample of media coverage, click here.

Texize Pine Oil Disinfectant, photograph © Brandon Reese / flickr

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September 21, 2018

One Response to “A Clean Connection to Childhood Obesity?”

  1. September 21, 2018 at 12:05 pm, Tricia said:

    Thanks for consistently adding discerning and well-founded critical reviews of the latest health research hitting the web and journals. Your level-headed, pointed and sometimes even humorous perspective helps to balance the information clamoring for media attention.