Doctors claim beneficial effects for neural development of the child. Does science back that up?
DHA pills. Source
Some are beneficial, many are scam. This is the first post of my new mini-series on food supplements.
Our personal story
When my wife got pregnant, the doctor sat down with us and gave us a list of vitamins, trace elements and other stuff that she should take from now on. Of course, he wanted us to buy all of it straight from him. But I – who was already doing research in food toxicology at that time – new that most marketed food supplements are basically scam (if you want prove, follow this blog series).
I mean I know of the importance of folic acid, but that’s basically it, right? Also, pregnant couples are the perfect victims for scams, as you would do ANYTHING to protect and help the little invisible miracle inside the womb.
One of the doctor’s claims sounded especially questionable to me: the intake of a supplement called DHA would benefit the development of the foetal nervous system – including the brain. “DHA-Children” would be smarter and more relaxed.
I took all of this with more than just a bit of my usual scepticism, and I had a hard time convincing my wife not to buy right away, but rather to do some research first.
And research I did.
So later that day, at home, in front of my laptop, Pubmed-articles opened on 20 tabs, I was - to my, but not my wife’s surprise - proven wrong. And DHA ended up as one of two supplements we really bought.
But let’s start from the beginning:
What is DHA and where can you find it?
DHA is the abbreviation for docosahexaenoic acid, and it is a so-called “omega-3-fatty acid” (Ω-3-FA). Even though there are other Ω-3-FAs around, DHA is sometimes used synonymously with the latter term, as it’s the most relevant compound of this group in both occurrence and bioactivity – let’s call it the “signature Ω-3-FA”.
The chemical structure of DHA. Ω-3 refers to the appearance of the first double bond at position 3 (counted from the "back" of the molecule, which was the ancient way of doing it). Source
Ω-3-FAs are essential to us humans (and to other mammals), that means we need them, but we cannot produce them ourselves. Luckily for us, fish can. They – and other sea food – are the richest nutritional source of DHA and other Ω-3-FAs.
What is the function of DHA?
DHA accumulates in nerve cells of our eyes and our brain (or more accurately in their cell membranes) where it plays an important role in the biosynthesis of neuroprotectins, a class of compounds whose main job is to protect those cells.
Now it gets interesting: The evolution of early men coincides with the increased settling at sea shores – and thus with the inclusion of sea food in the diet.
This has led some researchers to believe DHA might have played a role as co-factor in the evolution of the human brain – and that high intake of Ω-3-FAs could be beneficial for nerve development and function.
So numerous researchers performed experiments on animals, and demonstrated that the administration of a DHA-enriched diet indeed leads to an enhancement of visual and cognitive abilities. One of these rats later even featured in a TV series...
Ok, the last one was not entirely true, I apologize. But the rest is, and it’s pretty amazing stuff.
Scientists went one step further and investigated the situation for humans.
In adults, they found nice anti-inflammatory effects (fish-loving Japanese get significantly less inflammations than the average Western meathead) and of course protective effects against Alzheimer’s disease. So eating enough fish is unquestionably beneficial for adults.
Effects of DHA during pregnancy and early childhood
But the real important finding was that sufficient supply with Ω-3-FAs was crucial for brain development of unborn and young children. Sloppily said: if the brain grows fast, it needs high amounts of DHA to incorporate it into the cell membranes. This seems to happen especially in the last trimester of a pregnancy. Without sufficient DHA, cells are prone to oxidative stress and are not proliferating and differentiating in optimal speed.
Children whose mothers took up a DHA-rich diet during pregnancy and lactation have slightly increased cognitive functions (precisely: in average, an additional 3.3 IQ points by the age of 9) as compared to those whose mothers consumed a regular diet. For premature babies, this effect is most likely even stronger.
However, there are also other effects: with a DHA-rich diet, you have:
- a significantly reduced risk for inflammations, one of the most common reasons for pregnancy complications.
- a reduced risk for premature birth
- most likely, an improved development of visual acuity of the child, as the retina is the second important tissue that uses DHA
In overall, the positive effects of DHA during pregnancy, but also early childhood for both mother and child are surpisingly well established (surprising because science on food constituents is often somewhat vague and sometimes contradictory - here it isn't).
But why do we have to supplement DHA?
When humans started to plant crops and to domesticate animals, the intake of sea food - and thus Ω-3-FAs - decreased in many cultures (apart from island populations like Japan). Especially in today’s standard Western diet there is a shortage of those compounds. We simply don’t consume enough, and especially pregnant women with their increased demand aren’t.
Still, we don’t have to supplement, we can just eat more sea food or products containing fish oil. The US authority for food, the FDA, doesn’t advise supplementation, but an “intake of 2 two seafood meals (8-12 oz) per week”.
However, pregnant women will often not feel comfortable with that, since today’s sea food contains high levels of toxic pollutants, in particular heavy metals and sea food can be of dubious quality if you live far from a shore. You want neither heavy metals nor food-poisoning microbes near your unborn, even if the problem is only hypothetic.
So many feel more comfortable with a clean product – i.e. a supplement pill.
Conclusion and the “one-case-study”
Whether you like it more natural (sea food) or safe (supplement), if you’re pregnant, consume enough DHA. It is scientifically proven that your child will benefit in terms of cognitive and visual abilities.
Of course, our doctor’s claims (“smarter and more relaxed”) were quite an overstatement nevertheless.
Still, my personal human study with an n=1 (a.k.a. my son) was quite a success.: He is incredibly smart (ok, every single father will say this, maybe I’m too biased for this kind of study). Relaxed, not that much. But again, I am living with him, I might be biased.
Disclaimer: In my blog, I'm stating my honest opinion as a researcher, not less and not more. Sometimes I make errors. Discuss and disagree with me - if you are bringing the better arguments, I might rethink.