Omega-3 is essential for growing brains. In evolutionary terms, the growth in brain size in humans and their more recent ancestors led to a greater capacity for enhanced cognition, more complex behaviour, thought and processing. Research such as that by Dr Michael Crawford at the Institute of Brain Chemistry and Human Nutrition in London suggests that access to large quantities of DHA from fish was responsible for this growth; and even that DHA is responsible for the existence of nervous systems in the first place. The human brain is around 60% fat, and DHA is found predominantly in the grey matter, which includes areas of the brain responsible for sensory perception and intelligence.
How does DHA benefit baby and infant development?
As we have seen, DHA is required for neurological tissue – especially for the development and maintenance of the central nervous system and brain, including the growth of nerve cells and the myelin sheath that insulates the nerves. It is also required for vascular tissue (blood vessels) and for the development of the eye in the foetus and infants and for visual function throughout life. Countless scientific studies have been done on the roles of DHA in babies, infants and children. Here are some interesting findings from just a few of them:
- An American study showed that mothers who were advised to eat less oily fish (due to fears of mercury toxicity) produced children who scored lower on IQ, verbal and motor and social skill tests.
- One study found that mothers given fish oil supplementation went onto produce children who scored higher on hand and eye co-ordination tests than those whose mothers were just supplemented with olive oil.
- The British Journal of Nutrition reported that low birth weight babies supplemented with a higher dose of DHA had significantly greater growth rate of their head than those babies supplemented with a normal dose of DHA. They went onto say that in their research experience, this head size growth is associated with increase in mental development.
- A review published in Nature scientific journal reported two studies that showed neurodevelopment scores were better in babies whose mothers ate good levels of oily fish.
- Other research has shown that “Infants in the placebo group were at increased risk of lower language development assessed as words understood”. Infants in the placebo group were from mothers who were not supplemented extra DHA oil in their diet.
- The Food Science & Nutrition journal published that “cognitive development among breast-fed full-term infants, or in full-term or preterm infants given supplemental DHA, is described as being superior to that in infants consuming formula diets that lack DHA”.
- Researchers found that infants born to mothers with higher blood levels of DHA at delivery had advanced levels of attention spans well into their second year of life. During the first six months of life, these infants were two months ahead of those babies whose mothers had lower DHA levels.
Where can we get DHA, and how do we make sure we’re getting enough?
To answer that, we first need to understand some differences between types of essential fatty acids, and also the different omega-3 fats.
Essential fatty acids encompass omega-3 and omega-6 fats. In the standard Western diet, we tend to get much more omega-6 than omega-3, as omega-6 is found in vegetable oils such as sunflower oil and corn oil that may be used for cooking (although this is not a healthy option!) and that are often found in processed foods and ‘junk’ foods. This means that, for most people, increasing intake of omega-3 fatty acids is beneficial to redress the balance.
There are also different types and sources of omega-3 fats. In fish, we find EPA (eicosapentaenoic acid) and DHA. Adults need both these forms: in some cases, EPA is said to be more beneficial, but new research is also coming to light that adults will at times need also good supplies of DHA. The foetus, young infant and growing child needs both omega-3 just like their parents, but requires a larger supply of DHA, as well as good levels of omega-6.
The other main source of omega-3 is seeds and nuts – particularly flaxseeds and chia seeds. But here, we find another type of omega-3 called alpha linolenic acid (ALA). It is not used in the same way as EPA and DHA, and has to be converted to these other forms by the body, through several steps. If we imagine this like a road system, consuming fish oil gives a direct route to EPA and DHA, like a nice fly-over on a motorway to get to your destination; but consuming ALA in nuts and seeds or their oils means lots of work is needed by the body, like coping with diversions, indirect routes and annoying roundabouts. This process can be completed effectively by the body, but in some cases – and especially in the foetus, infants and young children – only a very small amount of ALA is actually converted to EPA and DHA (some studies say less than 1%). Conversion of EPA to DHA can also be quite limited, and may not happen at all in the foetus.
Therefore, the foetus and young child needs DHA in its ‘ready’ form. It will get this from the mother during pregnancy and through the breast milk during lactation, but supplies will be much better if the mother consumes DHA from fish or fish oil throughout this time. Unfortunately there is also the issue of mercury contamination in fish, and the Food Standards Agency advises that pregnant women – and indeed, any women of childbearing age – should only consume up to two portions of oily fish per week, with a maximum of one portion of swordfish, shark or merlin. I absolutely agree.
Good quality fish oil supplements, on the other hand, are purified to remove all heavy metals and contaminants and absolutely safe to use every day. I advise mothers to supplement with either a DHA-dominant fish oil or a fish oil that has good levels of EPA as well as DHA. (Note that some fish oil supplements are deliberately higher in EPA – these are not ideal during pregnancy and breastfeeding unless an extra DHA supplement is added into the daily regime.)
With vegetarian and vegan mothers I often gently suggest that, for the duration of pregnancy and breastfeeding, they take a DHA-dominant fish oil supplement. I also recommend all expecting mothers to eat foods rich in a variety of healthy fats – fish, flax and chia oil, other nuts and seeds, avocados and coconut oil. The mother will need a good supply of all the essential fatty acids for her own health, as well as taking in good levels of DHA for the baby.
The last trimester
The last trimester of pregnancy (week 28 onwards) is a particularly important time for the foetus’s brain – it grows by an astonishing 260% in this trimester. For this reason, it is particularly important for the mother to be taking in adequate DHA during this time. This also raises another issue: what if the baby is premature? The best thing a mother can do is to breastfeed her infant (if possible) and take in plenty of DHA herself so that the baby receives it through her milk.
The growing child
After the baby is born, the brain continues to grow very quickly. In the first year of life, it grows by another 175%, and in the second year of life, by another 18%. After age 2, changes and growth occur throughout childhood but the total size of the brain only increases by another 21%. This shows that keeping up DHA intake is particularly important for the infant in the first two years of life.
There are countless studies to show that infant development is improved from intake of optimum levels of DHA. Therefore, new babies through infancy and into childhood should have access to DHA through food and potentially supplements, as a key component of developmental ‘brain’ nutrition.
What if the baby is not breastfed?
We have already seen that the baby continues to receive DHA through the mother’s breast milk, and so breastfeeding mothers should keep up their intake. If breastfeeding is not preferred or possible, then the baby should be getting adequate essential fatty acids via milk formula and later on from diet and in some cases, supplementation for kids.
Mother should continue taking omega-3 DHA after pregnancy
Mothers are advised to keep up a good intake of essential fatty acids including EPA and DHA after pregnancy, even if they do not breastfeed. Essential fatty acids are important for many aspects of health – and remember that they are called ‘essential’ because the body cannot make them, we must get them from food and supplementation. DHA continues to be important for the health of the mother’s brain and nervous system and to replace what the growing baby has taken from her during the pregnancy.
For those women who plan to – or may – become pregnant again, it is particularly important to top up stores of DHA between pregnancies, in order to have adequate supplies for the next baby.
In my experience, many women do very well religiously focusing on good essential fat intake during pregnancy, but with the flurry of a new baby, often these routines lose their way. Partners, family and friends can help her stay on track – for example by asking if she would like salmon for supper, checking she took her fish oil this morning or offering to re-order fish oil once the bottle has run out.
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About the Author
Lorna Driver-Davies, BA (Hons), HD, DHNP, CNHC, mNNA
Lorna is a nutritional therapist and herbal medicine dispenser, with a particular passion for women’s health (including fertility and pregnancy) and supporting adrenal gland and thyroid health in both men and women.
For more top tips, check out our omega-3 fish oil pregnancy guide.
