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Does a junk food diet lower children’s IQ?

A new study found that a predominantly processed food diet at the age of three was associated with a lower IQ at the age of 8.5.

Image: PA/PA Archive/Press Association Images

DOES A JUNK food diet lower a child’s IQ?

According to a new study by researchers at the University of Bristol, a diet, high in fats sugars, and processed foods in early childhood may lower IQ, while a diet packed full of vitamins and nutrients may do the opposite.

The results of the population-based cohort study was published online in the Journal of Epidemiology and Community Health.

The authors base their findings on participants in the Avon Longitudinal Study of Parents and Children (ALSPAC), which is tracking the long term health and wellbeing of around 14,000 children born in 1991 and 1992.

Parents completed questionnaires, detailing the types and frequency of the food and drink their children consumed when they were 3, 4, 7 and 8.5 years old.

Three dietary patterns were identified:

  • Processed: high in fats and sugar intake
  • Traditional: high in meat and vegetable intake
  • Health conscious: high in salad, fruit and vegetables, rice and pasta.

Scores were calculated for each pattern for each child.

IQ

The children had their IQ measured using a validated test when they were 8.5 years old.

The results showed that after taking account of potentially influential factors, a predominantly processed food diet at the age of three was associated with a lower IQ at the age of 8.5, irrespective of whether the diet improved after that age.

On the other hand, a healthy diet was associated with a higher IQ at the age of 8.5. The study found that dietary patterns between the ages of 4 and 7 had no impact on IQ.

Nutrition

The authors say that these findings, “although modest, are in line with previous ALSPAC research showing an association between early childhood diet and later behaviour and school performance”.

This suggests that any cognitive/behavioural effects relating to eating habits in early childhood may well persist into later childhood, despite any subsequent changes (including improvements) to dietary intake.

The brain grows at its fastest rate during the first three years of life, say the authors, adding that other research has indicated that head growth at this time is linked to intellectual ability.

They suggest that it is possible that good nutrition during this period may encourage optimal brain growth, and advocate further research on the subject.

Read: Smoking cannabis as a teenager lowers IQ – study>

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Comments (45 Comments)

  • Maybe people who feed their children a diet of fast foods don’t have a high IQ themselves, so maybe it’s inevitable.

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    • When you consider that Irish students rank the lowest in the EU, even below Portugal and Greece with respect to IQ, you must wonder if there is a correlation as we eat more junk food per capita than almost every country in the WORLD, except Scotland! What makes matters more disturbing is that in testing our 5 and 6 year olds, the evidence of low IQ’s is already present!!

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    • where are you getting that information from?

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    • JayK 04/10/12 #

      It was published in a peer reviewed journal so that kind of thing would have been considered, as it says in the article, “(t)he results showed that after taking account of potentially influential factors…”. Removing biases like that is a fundamental step in any experimental design so I’m sure they covered it.

      Reply
    • JayK 04/10/12 #

      My reply was to Pierce’s original comment, not to Matthew’s reply. Just so its clear.

      Reply
    • also we have the highest levels of floride in our drinking water, which effects brain development.

      http://articles.mercola.com/sites/articles/archive/2011/08/12/fluoride-and-the-brain-no-margin-of-safety.aspx

      Reply
    • Seems more likely that it’s not parental IQ, but how much the parents know about nutrition that counts.
      I mean, we’re a nation where a book that tells you how to cook the most basic of foods like spag bol can make it onto the bestseller list and be hailed on national radio as a fantastic must-read.
      If parents can’t even make food that’s that simple and straightforward, what are the odds they’ll be able to make baby food from scratch or food for infants?
      Instead, out comes the bag of oven chips and the sausages, or the takeaway menu, on a daily basis.

      Want to fix it? Make learning basic cookery a mandatory subject that you have to pass to get your leaving cert. Things like mathematics, good literacy, the sciences; these are vital for jobs in the STEM fields and I’m not suggesting they be deemphasised in any way (they need to be pushed more if anything), but if someone can’t even cook their own dinner (and that includes knowing what nutrients the dinner has to provide and how many calories are required and so forth), then there’s a serious hole in their basic education…

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    • @Aoife. when you say “Even below Portugal and Greece ” is there something about the IQ of Portuguese and Greeks that you know but are not sharing. ???

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    • It would be exceptionall rare in a peer reviewed journal to assert causality, that is usually the media’s job. So Pierce you are right, but the investigators probably never made the assertion.

      They would have said something along the lines of there is a statistically significant correlation between junk food consumption and lowered IQ. This does not infer that one causes the other both could be caused by an unrelated factor, they are however likely to happen together. That is good science, proving causality is near impossible with such a broad study, so it is unlikely they did.

      some funny examples of this – poor dental hygiene is directly correlatable to murder rate in the US… doesn’t for one minute suggest stop brushing your teeth and you will become a murdering lunatic

      The further from the norm the spelling of childrens names are in a given locality can be a statistical indicator of poverty, again not suggesting spell your name wrong and you wont make money!

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    • Just wondering why Mat’s comment gets a load of red .your teeth contain Calcium Fluoride what they put in you’re water is Sodium Fluoride which was first used by the Nazi’s as population pacifying trial in the late 30′s ,and has long been proven to have a major affect on IQ especially in the young.It’s kind of odd that basic proven chemistry gets ignored Calcium fluoride good for teeth ,Sodium Fluoride is a poison simple’s .Just look the 2 chemicals up before you hit the red number please.

      Reply
    • Fluoride is regulated and safe. Ask the EPA, the HSA, the HSE, etc. It’s all about dose: too much salt will kill you but if you don’t have any you’ll die too: it’s a fine line: that why it’s controlled.
      I grew up drinking well water and had ongoing issues with cavities, bad teeth etc. I haven’t had a filling since I moved to an area with fluoridated water. Ask any good dentist they can tell what kids are drinking un-fluoridated water just by looking at their teeth.
      If fluoride was that bad then why aren’t we dropping like flies? There’s bigger issues to worry about: economy, environment, education.

      Reply
  • Surely to goodness there is also a correlation between the IQ of parents and what they feed their three year olds? I’d hazard a guess that the lower the parental IQ, the more junk given to the kids. So is the link actually just genetics, or caused by the burger?

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  • Maria 04/10/12 #

    I wonder is it more to do with the possibility that parents who feed their children a healthy diet are more likely to be educated and have a stronger focus on their kids’ learning and development? Think of it another way, a parent who regularly feeds their kids junk food cannot be too bright themselves. Perhaps the study took these factors into account though.

    Reply
  • Too much telly & playstation, combined with junk food, lowers a child’s IQ. More outdoor activity, is good for a child’s IQ. This also applies to adults.

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  • mike 04/10/12 #

    If a parent is constantly feeding their child junk food the parents IQ must be low to start with. The child might be just inheriting their idiot parents low IQ. .

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  • Lot of guff being thrown about here about diet and genetics. You’d want to be very, very careful before you go linking race, nationality or genetic background to intelligence. There is a word for that kind of thing and it is not a nice one.

    It is equally likely that the underlying reasons are sociological. If you come form a comfortable middle class background, chances are you are growing up in an environment where you are being fed a balanced diet, where your parents are taking an active interest in your development and early education. Admittedly, that’s a broad statement and definitely not absolute. If you are from a disadvantaged background or on a low income there are so many societal pressures negatively impacting on your life that food is only one of a number of factors that could be affecting your IQ or academic performance. But it’s interesting that people often seem to want to ascribe a genetic or dietary reason for these problems. If it’s genetics it implies that the problem is fixed and immovable so, feck it, why change anything to try and improve the situation. If it’s diet, well, these people bring it on themselves and their children by eating crap. Not like me, no no, I made the right choice in my dietary habits, will live to eighty seven and produce children that are less of a drain on the nation unlike those plebs sucking down chips. There’s very good chapter in Ben Goldacre’s book, ‘Bad Science’ describing a so-called ‘study’ into the effects of fish oil supplements on exam scores in schoolchildren. I’d recommend reading it.

    I’m also surprised to hear that Irish children score so poorly in terms of IQ. Maybe you already have, but could you post the link to the study? Presumably it is available on PubMed? In my experience, students emerging from the Irish Education system have greater literacy skills and a broader knowledge base than their UK counterparts by the point of entry into university (observation, not a something I can back up with solid data). If our children really reported to be are so far behind in terms of intelligence I would really like to see the data and parameters examined.

    Finally, for those sterling individuals who have gone out of their way to warn us of the dangers of fluoridation….

    http://www.youtube.com/watch?v=Qr2bSL5VQgM

    Reply
  • A lot of its Iazyness of the parents if they don’t care what eat themselves, they won’t care what they feed their children & will just go for what’s easiest & quickest.
    & some parents need to learn to say no to there kids! Wen they demand junk food sweets & fizzy drinks!

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  • No its People with low IQ’s give to their kids

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  • A dumb obedient population is much easier to control. Thats why most of the celebrities people worship today are airheads. Its a culture of stupid we are living in.

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  • It is great to see someone has finally explained what correlation actually means!! I suggest every journalist read Bad Science by Ben Goldacre !! Maybe then we would get stories that actually make sense!!

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  • Matt fluoride occurs naturally in spring water and as far as I’m aware there are no companies in Ireland adding fluoride to bottled water.

    Chemtrails-Geoengineering, vapour trails occur naturally

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  • I would be more concerned about the impact junk food has on their physical health as IQ is predominantly innate, that is, you are born with it and have it for life. It is relatively inflexible over the lifespan. I’m suspicious of any claims about foods which either decrease or increase a child’s IQ. It may have an impact on their concentration and attention when doing the IQ test yes, which would then impact their scores.

    Reply
  • Finipops 04/10/12 #

    Those burgers do look tasty though!

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    • Nothing unhealthy about a homemade hamburger (and it’ll be cheaper and tastier to boot).

      The problem is with the industrially made hamburgers, made from salt, filler, food dyes, mechanically reclaimed meat product and flavorings.

      I’ll take a home-made, charcoal-grilled half-pound burger stuffed with fresh mozzerella and jalapenos with chipotle relish (total cost a little under €8) instead please. NYOM.

      Reply
  • And the fluoride in our water supply

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  • …..keeps the teeth in our gobs.

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  • I was talking to a science student who said the flouride idea is a myth, its a completely chemically different type of flouride than that that goes into water that is toxic.

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  • mmmmm burgers…. oh no my IQ

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  • Feeding kids fast food may or may not reduce there IQ,but parents with high IQs and the same for parents with low IQs that smoke around their kids both need to re-evaluate there IQis :) what next…….

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  • The main reason people feed there kids junk food is because its cheaper. Fresh fruit veg & meat are much better but if you have a tiny budget to feed your kids & pizza is cheaper then what choice to these families have. Their IQ has nothing to do with it.

    Reply
    • mike 04/10/12 #

      healthy food is just as cheap as junk food if you are willing too make the effort. Healthy dinner for 3 kids:
      1 bag carrots tescos 1 euro.
      1 bag baby potatoes 99 cents.
      1 bag frozen peas 89 cents.
      1 pack Jamie Oliver healthy fish fingers 1.99
      Total price for dinner for 3 kids ?4.87

      Reply
    • Gagsy 99 04/10/12 #

      And lets not forget tastier.

      I’ll happily spend a few IQ points on a Big Mac.
      (Sure I’ve loads to spare!)

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    • Healthy food isn’t as cheap as cheap food, it’s cheaper, and the less processed stuff you use, the cheaper it gets.

      eg. Take mike’s recipe, swap out the spuds for pasta, and the processed fish for beef mince and add in an onion and a tin of tomatos and you have enough spag bol to feed three kids for two to three days (depends on the ages and portion sizes, obviously) for €7.50. (And if you can find factory shops and the like to shop at, the cost falls even more).

      Money is not the catch; the catch is that you have to have the time to cook and you have to know how to cook…

      Reply
  • We could be just thick tho??

    Reply

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