Busy times as Dave B and myself (Dan T) are getting ready to launch our PODCAST, not to mention the usual business that goes with working, and fathering 2 kids under the age of 3! Needless to say, it will be a quick post today on an interesting article out of Santa Barbara, California. Given the (much improving) momentum in the healthcare realm today which is (once again) promoting breastfeeding for a minimum of 6 months and ideally for 2 years or beyond, as per the World Health Organization (WHO). Furthermore, prior studies have shown a positive relationship between breastfeeding (at all) and duration with childhood cognition. See one prior study here.
So, keeping in line with that, a recent study was published in the journal PLEFA, you can link to the study abstract here (full text requires subscription).
In this study the authors examined several countries including Canada & the US. Specifically, they looked at dietary intakes as well as human maternal milk content of fatty acids (FA) including the n-3 FA docashexanoic acid (DHA), the n-6 FA linoleic acid (LA) and examined relationships between these and average children’s test scores on the program for international student assessment (PISA) tests. Furthermore, LA/AA ratio was strongly negatively associated with test scores.
They found that DHA levels were positively associated with test scores in all three areas including math, reading and science, as well (obviously) the 3-test average, while LA was actually inversely associated with these test score outcomes and together they explained 46% of test score variability. The authors suggest that the opposing relationship between DHA and LA could mean that the two FAs are in competition with one another for availability to the developing young brain. They suggest the following possible mechanisms: a) competitive interference with the conversion of n-3 FA into DHA; b) inhibition of desaturase enzymes necessary necessary for the synthesis of all long-chain FA; 3) competition with DHA for incorporation into plasma phospholipids; and d) competition for inclusion in brain phospholipids between DHA and LA’s elongation product, n-6 docosapentanoic acid (DPA6). In fact, they present evidence that all
mechanisms could be happening, which would explain why some studies have shown weaker effects of dietary or supplementary DHA on cognition in children (i.e. higher LA prevents usage of the supplemental DHA).
As with most nutritional research, there are limitations to this study. Specifically, limitations included: a) data source – ecological analysis, therefore the observations in this study should be considered preliminary and the basis for planning future studies; b) 28 countries is relatively a small sample size; c) average length of breastfeeding was NOT controlled for & this has been shown to have cognitive advantages itself. I’ve left out a few that were too technical, but would add a couple of my own: 1) correlation does NOT equal causation – let me clarify, the authors did NOT overstate their findings in any way, but I know that the media & likely others who review the study will; 2) the associations observed were NOT in the same individuals – specifically, the breast milk samples were from a specific time window & the test scores were from a similar window, so it is NOT possible that the test scores were from the offspring who were being fed the sampled breast milk, but rather the sampled breast milk is to represent the FA content of that country around the time of the test scores. The problem with that in my view is that the composition could have changed since the time frame when the children being academically tested were breast fed.
Overall, the study was relatively well done with some obvious logistical challenges. The point is well taken that we need to make sure we’re getting & especially our children are getting enough DHA in their diets in order to give them the best start in life. Furthermore, although amniotic fluid (AF) was NOT examined, I would suggest that if it were done, we might see higher levels of DHA in that medium as well, which could suggest that the higher brain development started in utero & continued neonatally.
In case you’re curious, Canada and the US were in the lower part of the middle of the sampled country levels of DHA in maternal breast milk. This could suggest a reason (& a possible fix to) why our students routinely test so poorly compared to the rest of the world! Simply put, there is less DHA & more LA which results in a delayed brain development compared to populations with more DHA and much less LA in their breast milk.
Interestingly, many of the Asian countries were towards the top of the test scores & DHA levels in Breast milk & if we examine what kind of foods are introduced first to those children in those cultures we often see fatty/oily fish, egg yolks & fermented foods (i.e. kimchi in Korea) all being given as soon as they start eating. These provide higher levels of DHA & in the case of the fermented foods could also help to preserve the integrity of the gut lining which would permit the child to better absorb nutrition from their food, unlike starting by giving a child grain based cereals which could potentially damage the gut lining & decrease absorption & supply of key nutrients.
Well, that’s my take on this. Please sign up today for regular updates & be sure to download the podcast & give us your reviews. Initially, we might not be on Itunes, but hope to be there soon.
Have a great rest of your week everyone!
for Canadian Minds on Health