Sunday, August 25, 2013

Does Soda Rot Your Brains Along With Your Teeth?

This study made big news last week, but I was in the midst of AHS13 in Atlanta, and besides the normal conference exhausting insanity, I also had either food poisoning or some sort of gastroenteritis. Only now I'm recovered enough to unbury myself (more or less) from the usual home and work chores.

U2 Some Days Are Better Than Others

I'll do a companion post on AHS13 and my talk there in a bit, but I did want to do a quick review of the horrifying study tracking soda consumption in 5 year-olds. The study was part of a Fragile Families and Child Wellbeing cohort of about 3000 urban US children and their mothers from 20 different cities. The sample is 51% African American, 28% Hispanic, and unmarried mothers outnumber the married ones 3:1. In this cohort,  43% of the 5 year old children consumed at least one soda per day, and 8.2% drank three or more servings a day. Those who did drink 4 or more sodas daily were over twice as likely to destroy things belonging to others, get into fights, and physically attack people, and violence across the cohort linearly correlated with the amount of soda consumed. We've seen a similar pattern in a previous study of adolescents. No one has measured it in young children before.

Covariates included violence in the home, fruit juice and candy consumption, obesity, maternal education, and hours of TV watching, and when the statisticians took these confounders out, the correlations between violence and soda consumption still held. Perhaps the most interesting bit of the study is that fruit juice consumption was correlated with less aggression and candy with mildly increased aggression, so sugar itself is clearly not the whole story here. The authors had all sorts of guesses as to what might be going on, but with the observational nature of the study they are only hypotheses. The main theory is the magical combo of preservatives, caramel coloring, caffeine, and sugar is a quick ticket to aggression and wild swings of blood sugar (though blood sugar wasn't measured). Since soda consumption is also correlated with depression in adults, and depression in parents is correlated to behavioral problems in offspring, high soda-drinking moms might be depressed with high soda-drinking aggressive kids.

Regardless of the whys and wherefores, one doesn't have to go too far out on a limb to say that giving kids soda is a lousy idea, and that the sugar alone is not the problem or only a piece of it (despite my fondness for the fructose malabsorption theory).

Times have changed… (from Gene Simmons Twitter feed) via Mark D. White


  1. The ad was a joke, I think:

  2. I can't believe anyone's taking this study seriously. I'll just quote Dr. Allen's blog post:

    Probable intervening variable: Mothers who don't limit their children's food choices or amounts thereof are also very likely poor administrators of other necessary forms of discipline, which in turn creates the aggression, attention problems and withdrawn behavior in the kids.

    1. Oh I completely agree there are many weaknesses in this study. But ORs >2 and the lack of correlation with fruit juice/candy makes it interesting IMO. And aggression in the home and education were also accounted for, though we could all think of another million confounders. Combinations of sugar and caffeine (and or alcohol, which will also accentuate a hypoglycemic effect along with the impulsivity) have been linked violent behavior in those who are predisposed for decades, but never studied in children this young before.

    2. Emily - nice writeup, and I agree that it's interesting. I probably lean a little bit toward Psycritic's point of view, not just because there are too many confounders to count, but mostly because we, as a society, have generally been led to believe that fruit juice is a healthy beverage for our children. To me, it's largely the same reason that epidemiological studies that don't account for any healthy user bias find that vegetarians are healthier.

      I know you know all of this, of course. I just don't find the fact that fruit juice had a mild negative correlation with violence very telling.

  3. Hmmm, now I wonder why this could be:

    Obesity and IQ | JayMan's Blog

    Seriously, one day the medical – and the social science community – may stop relying on inherently bad science:

  4. It's possible that rotting teeth and gums are themselves enough cause of bad behaviour, through irritation, inflammation, and discomfort.
    As a wise counsellor once told me, to get me to go to the dentist, your mouth is where you live.
    If you can't rest happily amongst the flavours and sensations there, you'll never settle down.


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