The recent breastfeeding/IQ study: I've read it, which is more than some journalists have done. Anyone want to hear what the study actually says?

[welliemum]

I'm treading on tamum's toes here a bit - she's a Proper Geneticist and I'm not.

However.. I do have a bit of practice at reading papers.

First of all, here's the abstract. The full article needs subscriber access unfortunately.

Main finding: In the populations they examined, they found 2 versions of a particular section of a gene. For children with the (commoner) C version, breastfed children had significantly higher IQ scores. For children with just the G version, breastfeeding didn't correlate with IQ.

Can we be sure this is a true effect?
The researchers were very careful on this point. They ruled out:

1. confounding by social class
2. confounding by mother's IQ
3. the gene affecting whether a baby breastfeeds
4. whether the mum's genetic profile affected the baby's growth and hence development

... and several other more technical points.

I think it's a very good study. The researchers have been very careful to exclude other explanations for their findings, and are only claiming results that are well-supported by evidence. No wild claims here.

IMO the study is convincing in a number of ways:

1. the gene cluster in question has a strong link to both intelligence and breastfeeding (via fatty acids) - ie biological plausibility
2. the study methods are sound as mentioned above
3. it can explain why previous studies on bf and intelligence have had conflicting findings (the effect would depend on each population's genetic profile and this wasn't measured).
4. the fact that they studied 2 populations half a world apart and found a consistent effect is very significant. (Repeatability is a big pitfall in this type of genetic study)
5. er, and another one which I now can't remember

It's a pity though, that they couldn't measure how long the babies were bf for. If they showed a great effect for longer bf, that would be additionally convincing; and more detail would also be hugely helpful for women unsure how long to bf for.

One of these populations was a birth cohort from NZ in the 70s. Only 57% were bf, and they would have had a very short duration of bf. No 6 month exclusive bf in those days. This suggests to me that even a little bf can have a big effect.

Tamum or anyone - what do you think?

sorry, I should say - very interesting welliemum thanks for posting. I think that the standard of science reporting is truly shocking.

SP, I agree with you that the strongest studies tend to test one clear question, which can seem like a small gain when there are so many other questions unanswered.

But if 90% of the population carry the gene, that's not really a small effect, is it?

And to have shown a strong effect of bf on intelligence is an important step too. All over MN you will see poeple disputing that very thing.

I think testing is a long way off, but for any given baby, it's likely that bf is going to affect their IQ.

Sorry, meant variant not gene - everyone has the gene.

do you think that the potential increase in intelligence is a major factor in helping women to perservere?
that's interesting. that wouldn't have been something I would have thought of, it certainly isn't something I have emphasised or even referred to tbh.

I must say I await with eager joy Ben Goldacre's take on the reporting of this study

hc, when I was struggling to bf dd1 - it was really touch and go - I did think about the neurological development side of things. I wouldn't have said it was a decision factor because I had lots of reasons for wanting to bf. Also, I hoped that whatever happened, dd1 would have the sort of home environment that would compensate well for any shortcomings in early nutrition.

that's interesting wellie, I might approach it differently now this study has been published, because that evidence is pretty convincing.
and of course people will have read it.
I love Ben Goldacre

Yes, in fact I wonder if HVs and MWs and anyone else involved with bf are going to read up about this, because they'd need to understand the basics in case someone asks.

I heart Ben Goldacre.

ohmigod, Ben Goldacre is a FOX!!!

Message withdrawn

oh, I managed to miss the bit about 90% having the gene.

sorry to be flippant, and I do agree that it's quite amazing the found a single genetic variant which affects the degree to which babies benefit from bf. But the more general finding, that genetics can effectively over-ride the benefits of bf is bleeding obvious, and a bit of a bug-bear of mine tbh (like people saying that bf "prevents" asthma. it only reduces the risk very slightly, and saying it does prevent asthma opens up the way for people to dismiss the effects of bf "because my dd was bf and she has asthma" ). but I suppose that gets back to the way these studies are reported and Ben Goldacre territory.

the question about whether they might test for this gene was just a thought really - i wouldn't support such testing. but I bet they do it, and I bet people use it as an excuse not to bf.

Oh, SP, I completely agree about the difference between risk and fate, hence irritating "I ff my genious baby so the study is rubbish" arguments.

As to using genetic results as an "excuse" not to bf... I'm not so sure. I supsect you'd have to look very hard to find a baby with an overall genetic profile such that they had no advantage whatsoever from bf. And if you did find that baby - well, it wouldn't matter if the mum didn't want to bf, would it?

nothing really to do with the study but i don't understand why people so readily accept that giving their 5-year-old fish oils will help them concentrate better in school but they're so ready to dismiss the effect that 'mummy oils' will have on the brain of a newborn. i was talking to someone the other day, a total believer in fish oils for kids who pooh-poohs the importance of bfing...

it's usually called self-justification, aitch.

i speak as a mix then ffer, by the way. whose dd eats a LOT of fish... [justifies self]

Well, those "bf-ers" in the study would virtually all have been mix-feeders aitch, so you're all right.

Welliemum- you would be surprised....I used to take scientific papers, each page in a seperate document wallet to the bath with me when I was a student ...

I'd love to know what you read when you feel like a challenging read, something you can really get your teeth into.....

Then I go from polymorphisms to linkage disequilibrium and haplotype analysis ......

Or chemical synthesis cos that I really don't understand

Am impressed. Linkage analysis and all its friends just make my eyes bleed.

Yum to Ben Goldacre

I forwarded him a really daft press release once (it gave the 'formula' for a 'good night's sleep with a cold' and it ended up as you having to drink lots of Lemsip), and he emailed back to me saying thank you very much, and that he would wipe his arse on any newspaper that printed a story based on it

Bless.

Pruni, not your type

pruni's type well, helloo little lady.