Feb 08 2011

Processed Foods and IQ

A new epidemiological study finds a correlation with eating a highly processed diet at age 3 and later slightly lower IQ (by a few points). The study compared diets of children from ages 3 to 8 – the diets fell into three categories: high in processed food, traditional (meat and potatoes) and “health conscious” (lots of salads and fish). They found a difference only in the high in processed food diet with the lower IQ.

From one point of view, the lesson to be drawn from this study is obvious – growing kids have a high metabolic and nutritional demand, the brain is particularly demanding, and therefore suboptimal nutrition can be a drag on development. This effect is clear in children who are undernourished. It remains unclear if there are significant difference in children who are well-fed but who have diets which are not considered healthful. This study suggests there is a small difference.

But I must point out that this is an epidemiological, not experimental, study. So the children were not randomized to different diets. The researchers controlled for the obvious confounding factors, like socio-economic group and breast feeding, but there are potentially many other confounding factors that were not controlled for. For example – parents who rely on processed food might do so because they have little time to cook or prepare better meals. These same parent may spend less quality time with their children. Or parents who allow their kids to eat mainly processed foods may be more permissive in general. I wonder, for example,  if they controlled for television watching or video-game playing.

Given the small size of the effect in this study and the observational, rather than experimental, design of the study I don’t think we can draw any firm conclusions from the results. At best the results are interesting and require further study.

I do think we need to examine the processed food industry, on many levels – salt content, calorie content, and overall nutritional content. I do not see any reason why processed food cannot be as healthful as whole food. It seems to me that many people assume this is not the case, based upon nothing but the naturalistic fallacy. It should only depend on what is put into the processed food. Manufacturers are under marketing pressure to make their products affordable and tasty, and so they manipulate the content to have good mouth feel (which usually means fat) and good taste (fat, sugar, and salt) and a long shelf life (salt).

Processed food is not necessarily lacking in vitamins, minerals, or quality proteins or fats as building blocks. It depends on the specific product.

We should resist the urge to make processed food into an automatic villain. Rather we should demand from the industry transparency in what is in their products, and demand more healthful products with less salt, fewer calories, and more complete nutrition. There has been some shift in this direction, but it’s not clear if it has had any significant impact. It seems that manufacturers use whatever the latest health food fad is for marketing. If people want low fat, then they will have low fat products with tons of sugar. If they want low carbs, then they up the fat. Probably some combination of regulation and savvy consumers will be necessary to reform the industry.

20 responses so far

20 Responses to “Processed Foods and IQ”

  1. CWon 08 Feb 2011 at 8:38 am

    I have to admit that I wasn’t exactly sure what “processed food” entailed, so I googled it.

    On nutrition.about.com (http://nutrition.about.com/od/askyournutritionist/f/processedfoods.htm), it echoed your comments about sodium, calorie, nutrition, etc.

    It also stated at the bottom that “Processed meats might be some of the worst of these foods. Eating these meats may increase your risk of colorectal, kidney and stomach cancer. Processed meats include hot dogs, bologna, sausage, ham and other packaged lunch meats.” It references three meta-analyses, of which only the one seemed to make a conclusive remark linking cancer with meat (all meat, not just processed).

    I’m guessing that this means “processed food” must be full of those nasty “toxins” that I need to cleanse?

  2. geraldguildon 08 Feb 2011 at 9:17 am

    Your skepticism is justified. We know that SES alone has substantial impact on IQ scores. SES must be controlled for. I have no data to substantiate the notion that lower SES children consume a higher proportion of processed foods, but, this claim is prevalent. And the small difference of a “few IQ points,” given the standard error of estimates of most IQ tests, is just as likely to be error.

    That doesn’t take away the inherent nutritional problems with processed foods. Transparency – YES! Consumer Savvy – YES! But economical and accessible options seem to be slim for a significant proportion of our children.

  3. ccbowerson 08 Feb 2011 at 11:50 am

    I assume that the arrow of causation being inferred is backwards

  4. ccbowerson 08 Feb 2011 at 11:56 am

    I’m partially kidding of course, but these are the studies in which the news stories get all wrong. My mother will likely tell me this “fact” when she reads it in the next Prevention magazine article.

  5. Smedon 08 Feb 2011 at 12:16 pm

    What is the purpose of a study like this when it has such an obvious flaw from the outset? Can any conclusions be drawn from it?

  6. hippiehunteron 08 Feb 2011 at 6:30 pm

    At the risk of pointing out the bloody obvious, parents who feed their children a diet high in Mcdonalds are probably not very smart themselves nor are they the sort of parents I can easily picture spending regular time reading with their kids.

    Next amazing study will be “children fed a diet high in tofu, mung beans and organic vegetables more likely to beleive in homeopathy, reiki and acupuncture”

  7. sonicon 08 Feb 2011 at 11:24 pm

    the researchers did control for SES. (From the article linked to)-
    “The researchers found a link between IQ and diet, even after taking into account other factors such as the mother’s level of education, social class and duration of breast feeding.”

    The education level of the mothers was controlled for (see above)

    This is kind of study is not generally used to draw conclusions, but similar studies have led to further research of interest- for example, smoking causes certain types of cancer.

    Dr. N-
    There are a number of reasons that some foods do not hold up well to processing- often fruits and vegetables start to degrade as soon as they are picked. (We grow tomatoes because we know of no other way to get them). There are processing methods that are better than others, and it seems the food industry does make some attempt to make nutritious foods available (the recent inclusion of more whole grains would be an example). Consumer demand seems to be the most effective driver here.

  8. ccbowerson 09 Feb 2011 at 12:38 am

    “We grow tomatoes because we know of no other way to get them”

    Here is an example of a food when processed, results in (by some measures such as lycopene) a higher level of nutrition.

    “fruits and vegetables start to degrade as soon as they are picked”

    Frozen foods are more “processed” than the foods in the produce section, but for many vegetables frozen versions are actually superior in flavor and nutrition since they can be picked at a ripened stage. In addition, any worries about degredation appear misguided, when often the alternative is not eating the fruit/vegetable.

  9. elmer mccurdyon 09 Feb 2011 at 1:20 am

    Just reading the post the observation I’d make is that too much fish obviously isn’t good for you. In fact can’t it lower your IQ?

  10. elmer mccurdyon 09 Feb 2011 at 1:26 am

    cause of toxins, of course

  11. eiskrystalon 09 Feb 2011 at 4:01 am

    What amuses me is the title. “Healthy eating boosts IQ”. Doesn’t that imply that healthy eating isn’t then the norm. That’s a telling problem in itself.

    I think we need to put more energy into getting people cooking and knowing their foods well before we worry about tighter regulation of an industry that we don’t technically “need”.

  12. sonicon 09 Feb 2011 at 2:16 pm

    You are correct- it is better to eat something than nothing.
    Your comment about frozen vegetables is correct- the sooner they freeze them the better they are.
    Of course they don’t compare to fresh picked– sorry if you haven’t had the experience.

    I agree- to the extent that people know about the food, we don’t need regulation. I would second the motion that we spend time on educating about food and not so much on the regulation aspect.

  13. eeanon 09 Feb 2011 at 2:53 pm

    @sonic when hippiehunter noted that only the ah “non-smart” would fill their kids with mcdonalds, I don’t think he meant education. You didn’t go to college with any morons? 🙂

    I agree with the general thought of why make such a study when almost any result would turn out to be unclear.

  14. cwfongon 09 Feb 2011 at 3:35 pm

    sonic, regulation is primarily about about safety. A shift from buyer beware to seller beware. What’s in the can should safely match what’s written on the label.

    Then it will be for you to decide of course the extent to which it might lower your IQ. Otherwise we get closer to a slippery slope, where we might have to match labels to IQs. Like writing, “if you can’t read this, you can’t buy this.”

  15. ccbowerson 09 Feb 2011 at 7:18 pm

    “Of course they don’t compare to fresh picked– sorry if you haven’t had the experience.”

    And what percentage of your diet is fresh picked? Eating locally helps, but this also requires limiting your diet to seasonal produce in your area.

  16. Donna B.on 09 Feb 2011 at 8:40 pm

    It seems that some clarification of terms would come in handy in this discussion.

    Highly processed meats (bologna, hot dogs, etc.) seem to me to be code for commercially processed meats. I have a feeling that similar products processed non-commercially would simply be labeled preserved.

    Same thing with the vegetables. My Aunt Mary’s canned tomatoes would be preserved, but Del Monte’s would be highly processed.

    Further, it’s just “cool” to say McDonald’s or fast food chains are somehow serving highly processed foods. A $25 gourmet hamburger is somehow less processed?

  17. sonicon 10 Feb 2011 at 12:37 am

    So you are complaining about a study (the type which lead to the realization that smoking causes cancer) by seconding a comment that has no apparent study to back it? (No, really, I’m being a pain in the ass).

    I agree that regulation might be what you say. However, as my dear friend works for the largest lobbying firm in the state, I can tell you that the fact of regulation is seldom that sane. It seems more likely and more valuable to have informed eaters than to trust a system that I know is not reliable. (I avoided using the word corrupt, but now I can’t– darn!)

    I’m not sure about the percentage, but much of the year most of what I eat is picked right before eating. I’d like it to be even more, but I have more to learn. My main methods come from

  18. cwfongon 10 Feb 2011 at 1:03 am

    sonic, no regulatory system is or ever will be perfect where big money is concerned. But corporations don’t have much use for the honor system either. Nor for the honorable intentions of their customers.

  19. eiskrystalon 10 Feb 2011 at 4:03 am

    Sonic/cwfong exactly. The food industry is already regulated quite heavily.

    There is already food information on all food sold, they even wanted to dumb it down further in England with some kind of traffic light system and more regulation is really just not going to work and further will make us look even more like a mummy state.

  20. Nicolason 10 Feb 2011 at 11:11 am

    Just how long will it take for this to become a piece of scary misinformation at NaturalNews, or mercola.com?

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