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Danish and Finnish studies: Oily fish or fish oil supplements taken during pregnancy boost the baby’s brain and development

Danish and Finnish studies: Oily fish or fish oil supplements taken during pregnancy boost the baby’s brain and developmentA pregnant woman can support the development of her baby’s brain and vision by consuming oily fish regularly, according to a new Finnish study. Meanwhile, a new Danish study shows that fish oil supplements given to pregnant women give their offspring a better start at life because of their content of omega-3 fatty acids. Unfortunately, the consumption of omega-3 has gone down, and pregnant women are discouraged from eating tuna and other good sources of omega-3, as these fish contain mercury. Health authorities should take this dilemma into account and possibly recommend high-quality supplements of purified fish oil to pregnant women and small children – just like they recommend extra folic acid, iron, and vitamin D. Pregnant vegetarians and vegans should pay careful attention and make sure that their child gets enough omega-3.

Fish oil contains a type of long-chained omega-3 fatty acid called DHA (docosahexaenoic acid), which is highly important for proper development of the baby’s brain, nervous system, and eyes. That is why pregnant women or women planning to conceive should make sure to consume sufficient amounts of DHA to give their offspring a better start at life.

Finnish study of oily fish during pregnancy

In the study from Turku University Hospital, Finnish scientists looked closer at how pregnant women can boost the development of their babies’ brain and vision by consuming oily fish regularly during pregnancy. According to Laitinen, a Finnish researcher, the mother’s diet during pregnancy and breastfeeding is determining for how much omega-3 her child gets.
Laitinen and her team of scientists analyzed data from 58 mothers and their offspring, which had been collected from a larger trial. The mothers kept a diary of their eating habits, and adjustments were made for confounding factors such as smoking and whether or not they developed diabetes.
The scientists then measured the content of long-chained omega-3 fatty acids in the mothers’ diets and in their blood. Similarly, blood levels of omega-3 were measured in the babies, as soon as they were one month old. Afterwards, the children’s eyesight was tested at the age of two years. The researchers found that offspring of mothers who had consumed fish three times weekly or more during the last three months of their pregnancy had better vision.
Laitinen claims that this is because oily fish contain the type of long-chained omega-3 fatty acids known as DHA. Also, she points to other essential nutrients such as vitamin D and vitamin E. The study is published in Pediatric Research, and Laitinen argues that the results of this research should be included in future dietary guidelines for pregnant women. However, one should pay attention to the fact that some fish are polluted with mercury. A good alternative could be supplements of high-quality, purified fish oil.

Danish study of fish oil supplementation during pregnancy

The Danish study included 736 women and their children. The women were divided in two groups. One group got 2.4 grams of fish oil daily for the last three months of their pregnancy, while the other group got a matching olive oil placebo. The scientists could see that the children of mothers who had taken fish oil grew faster until the age of six years with no greater risk of overweight. This study supports earlier studies showing that fish oil supplements taken during pregnancy have a positive impact on the child’s development. The Danish study is published in British Medical Journal.

Epidemiological studies show that maternal consumption of oily fish during pregnancy improves the baby’s cognitive development.

Facts about the omega-3 fatty acids, DHA and EPA

  • The human brain contains large quantities of EPA and DHA. DHA is very important for learning skills, memory, and vision
  • DHA supports the cerebral blood flow and keeps the blood-brain-barrier intact, thereby protecting the brain tissue against bacteria and toxins
  • The largest concentration of DHA in the body is found in the retina and is a precondition of visual acuity
  • EPA and DHA prevent postnatal depression
  • EPA has anti-inflammatory properties

Making sure that pregnant women and children get enough omega-3

Health authorities recommend eating fish several times per week. One should ideally consume 350 grams of fish each week, of which 200 grams should come from oily fish that contain the most DHA and EPA. Unfortunately, some types of fish contain mercury, an environmental toxin that can harm the fetus. Fish at the top of the food chain contain the most mercury, which is why pregnant women should try to avoid tuna and other predatory fish. Salmon is considered to be relative safe but stick with free-range salmon from clean waters and try to avoid salmon from the Baltic Sea, as they often contain more mercury and other types of pollution.
Pregnant women who dislike the taste of fish or just don’t eat fish often enough can opt for a high-quality fish oil supplement with purified fish oil. Fish oil based on free fatty acids has the best bioavailability. Make sure to choose a fish oil supplement that is within the official threshold levels for peroxide value and content of environmental toxins.

EFSA: Pregnant women should eat more DHA

The European Food Safety Authority (EFSA) has acknowledged that fish oil supports children’s brain and vision. For that reason, EFSA claims that pregnant women should increase their intake of DHA, especially during the third trimester, where the baby’s brain develops substantially faster than during any other part of the pregnancy. EFSA specifically advises pregnant and breastfeeding women to get at least 100-250 mg of DHA in addition to eating oily fish 1-2 times weekly. Fish is also a good source of iron, zinc, selenium, and vitamin B12. When purchasing fish oil supplements, check the label to see how much DHA is in the product.

Vegetarians should pay careful attention

Vegetable sources contain a form of omega-3 called ALA (alpha-linolenic acid). Many people’s digestive systems have difficulty with handling the enzymatic conversion of this type of omega-3 into DHA and EPA. In addition, there is the fact that, ever since the Stone Age, our main source of omega-3 has been oily fish and shellfish. Pregnant vegetarians should make sure to get plenty of DHA plus iron, zinc, selenium, and vitamins D and B12.


Springer. Fish-rich diets in pregnancy may boost babies´ brain development. ScienceDaily September 20, 2018

Rebecca Kofoed Vinding et al. Effect of fish oil supplements in pregnancy on bone, lean and fat mass at six years: Randomised clinical trial. BMJ 2018

Shulkin M el at. N-3 Fatty Acid Supplementation in Mothers, Preterm Infants, and Term infants and Childhood Psychomotor and Visual Development: A systematic Review and meta-Analysis. The Journal of Nutrition, March 2018

John Protzko el al. How to make a Young Child smarter: Evidence From Database of Rising Intelligence. Perspectives on Psychological Science. 2013

Mayo Clinic. Postpartum depression

Marin Strøm et al. Fish and-long-chain n-3 poly-saturated fatty acid intakes during pregnancy and risk of postpartum depression: a prospective study based on a large national birth cohort. The American Journal of Clinical Nutrition. 2009

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