Time for the second instalment of my “how to spot a dodgy science/health story” series. This one is more well known than Publication By Press Release and is one of the first questions to ask of any article claiming a new discovery kills, cures or otherwise alters your health:
All too often the answer to that question is no. The most notorious examples are probably the “Miracle Drug/Food Cures Cancer” headlines, where it turns out that the cancer being destroyed isn’t in a person, it’s just a bunch of cells in a dish. Certainly killing the contents of a petri dish may be an important first step in discovering a new treatment but the vast majority of stuff that can do that never makes it much further. Lots of things can kill cancer cells in a dish, domestic bleach works well, but I wouldn’t recommend it as a medication.
|Cartoon from the wonderful xkcd|
But even if your new wonder drug does turn out to be safe, that doesn’t mean it’ll work in people. Firstly there is the issue of quantity. Cells can be given huge doses but humans might need to consume impossible amounts for it to do anything. Plus human beings are wonderfully, confusingly, unpredictably complex. Far more so than a single type of cell in a carefully controlled plastic environment. There are an almost infinite number of reasons why something that works “ex-vivo” (in the dish) will be a total flop in a full blown person.
It’s not just cells in dishes that are the problem though. Moving on to whole animals isn’t a guarantee things will work in humans. Fruit flies, Zebra fish and nematode worms are all popular “model organisms” but quite clearly very different to us. Even calling in our mammal cousins can’t tell us everything.
I was reminded of this today when I read this particularly groan worthy story which claims that being born by Cesarean section could affect brain development. It draws this conclusion from a study done in mice and says that those mice born by C section showed increased brain cell death after birth and this may be linked to these mice having a different microbiome to those who got a good dose of mum’s bugs on the way out.
This becomes even more important when the story starts speculating about the involvement of the microbiome (the bacteria that live in and on an individual). Different strains of mice have different microbiomes. Even identical strains raised in different labs will vary thanks to diet, environment and how strictly they are isolated from other germs etc. The microbiome is a fascinating field for study and will probably open up a whole new world of information about our bodies, but at the moment it is very much in it’s infancy. We can’t even accurately identify all the bacteria that are there, never mind how they interact. So it’s a whopping great Olympic triple jump of a leap to suggest that something seen in baby lab mice, which may or may not be linked to their microbiomes, can tell us anything about the affect of differing microbiomes in humans.
1- It’s just a meeting abstract, nothing has been peer reviewed yet (see post on Publication By Press Release!)
2- Even if there is an increase / decrease in brain cell death – how do we know the C section mice are worse off? This doesn’t seem to have been tested, it’s assumed natural is better but it’s theoretically possible that the opposite is true.
3-It’s one single (unpublished) study, many if not most individual papers turn out to be flawed so it should be taken with a big ‘ole pile of salt until it’s repeated by others.
4- The whole microbiome bit just seems to have been chucked in because it’s a bit of a buzzword at the moment, especially with anything related to C sections. I’m amazed they didn’t get epigenetics in there too.
5- The article speculates that brain differences may also be caused by C section babies not getting the “rush of hormones” during normal labour. Which may be true of lab mice having planned C sections but a large number of human c sections happen well after labour began *coughs* sometimes 34 hours after *coughs*
6- Wonderfully, for an article so full of extrapolation, speculation and a few baffling errors, it ends with the phrase: “having the full facts available before a choice is made is important.”
Well yes it is.