Wheat, Rice, and Children's Brains

There is another post-worthy probiotics paper on the hopper, but before that I wanted to cover an article called Breakfast Staple Types Affect Brain Gray Matter Volume and Cognitive Function in Healthy Children (freely available on PLoS one).  I like some parts of this paper, though it is observational in nature, so keep that in mind.

As we all know, our big old brains develop not only prenatally, but also throughout childhood and adolescence.  In children, several studies have been done showing nourishing breakfasts help cognitive performance compared to skipping breakfast - especially the "high quality" breakfasts, with one study showing that a breakfast of low glycemic index foods having an immediate positive effect on attention throughout the morning (1).

In other introductory information, many studies in children have been able to correlate the amount of brain gray matter (vs. white matter) and IQ, especially gray matter in the prefrontal and orbitofrontal cortex and the cingulate gyrus.  Therefore, since breakfast types affect cognitive function, and brain structure can correlate with IQ, does breakfast type correlate with brain structure and IQ?  I don't know.  Let's find out.

These Japanese researchers (funded by a national Young Scientists' grant) studied 290 healthy children ages 5-18 years.  In Japan, apparently boiled white rice or white bread make up a typical breakfast.  (I remember eating a lot of this cereal plus sugar in skim milk when I was a kid. Kapow!)  The scientists were able to split the children into groups of habitual rice-eaters, habitual white bread eaters, and those who consumed both regularly.  Then they tested the IQs (using standard measures for kids <16 and a separate standard test for 16 and older), scanned the kids in a MRI, and collected their data.  Questionnaires were filled out by the kids or their parents with respect to morning eating habits, health, wealth, etc.

Using varying statistical techniques and a couple varieties of imaging data collection, the researchers found that the gray matter ratios (gray matter volume divided by intracranial volume) were significantly higher among the rice eaters vs. the white bread eaters, even after adjusting for age, gender, wealth, average weekly frequency of eating breakfast, and number of breakfast side dishes.  The Verbal IQ in the rice group averaged 104.7, in the bread group 100.3.  The Performance IQ was 102.1 in the rice group and 97.9 in the bread group.  This difference was non-significant.

As the kids became older, the differences in gray matter ratio increased between bread and rice groups.  Overall, calories consumed among rice eaters were slightly lower than those who habitually ate bread.

Now the researchers spend a lot of time talking about how all of these findings can be explained by the lower glycemic index of rice compared to white bread.  They feel that low GI foods provide steadier blood glucose levels, and "stable and efficient glucose supply is important for neurons."  It is notable that "cerebral metabolic rates of glucose utilization are approximately two times higher in children compared with adults." (Could be why children seem to have so much more of a natural "sweet tooth" than most adults).  The researchers also felt that since white bread has more fat than white rice, that the increased fat content might be a problem for the brains of white bread eaters (they suggest fat decreases neuronal plasticity).  I rather strongly disagree with them here and will have to pull their supporting paper when I have a minute… right now I have to finish up and dash off to work.

So all told, this study is only an observation, and causal factors cannot be determined with this dataset.  And I think the whole high GI/low GI chase is probably a red herring.  These Japanese kids were all likely relatively low-fat and high carb compared to say, American kids of the same age, and I do tend to think that healthy, low-toxicity carbs and fruit are fine for kids, who are not as likely to have leptin resistance as their adult counterparts.  As for the fat issue - I think a common sense way to think about this issue is to look at neonates.  They are the extreme version of the child, after all, and everyone can agree about the best food for them (human breast milk).  Neonates need a diet high in sugar (though lactose does not contain fructose) and 50% fat with lots of saturated fat.  I don't see how fat can be vital for the baby brain but somehow becomes toxic for the growing child brain.  I wish someone could explain that to me in a way that makes any physiologic sense, because it seems to be taken for truth by so many medical professionals and scientists.   If you can explain exactly when and how fat becomes toxic (somewhere presumably between the ages of 3 and 5, which is when ancestral humans were weaned?) drop me a comment.  "Lipotoxicity" doesn't count without more information as to the specific mechanism - neither do studies poisoning animals and/or humans with large amounts of corn oil or trans fats.

I'm perfectly willing to accept that the bread, derived from wheat, has toxic factors that cause inflammation or hurts the microbiota or interfere with absorption of minerals or whatever, and theoretically could be a casual factor as part of the differences seen in the children's brains in this paper.  My kids get rice and potatoes and fruit and milk as carb staples, in addition to meat, fish, nuts, and vegetables.  All in all, I believe metabolic flexibility and low-toxicity and premium quality food for premium micronutrients are the most important things for a healthy diet and a healthy brain.

End note - thanks to Jamie for the paper!!!  Also, Blogger comments were acting up for a few days.  If you asked me a question in the last few posts, I've been meaning to chime in when I get a moment.  Don't despair.