Does omega fatty acids help brain development of premature babies?
The results from a Norwegian study show no sure long-term effects of omega-3 and omega-6 supplements.
Infants born before the 37th week of pregnancy are defined as premature. They can face extra challenges immediately or later in life.
Of course, their weights at birth are less than for babies born after the normal nine months. Much of foetal growth occurs in the third trimester, including a doubling of brain weight.
The fatty acids omega-3 and omega-6 are vital for development of the central nervous system. In the womb, babies get these through the placenta. This source is cut off when they are born prematurely.
In a new study involving collaboration between the University of Oslo’s Department of Nutrition and the Akershus University Hospital, researchers investigated the long-term effects of giving premature infants omega-3 and omega-6 supplements. The children were followed up for eight years and measurements were made of their brain volumes and cognitive skills including thinking, learning and memory.
“The study is the first of its kind with such a long follow-up and it measures brain volume with the help of MRI technology,” says the first author of the study, Astrid Nylander Almaas. She is a paediatrician at Akershus University Hospital.
Eight years
The study included 129 prematurely born children who had all weighed less than 1,500 grams at birth. The children were placed randomly into two groups. One group was given supplements of omega-3 and omega-6 in breast milk from their mothers or donors, whereas the others got a placebo with their breast milk.
A placebo is an inactive substance used to show whether the effect of an intervention can be attributed to an anticipated benefit.
All the children were either given a placebo or the supplement as soon as they were able to digest breast milk.
The omega fatty acids were given in high doses, meaning high in comparison with the amounts found in natural breast milk. The babies were given such supplements or the placebos for nine weeks.
“Some 60 percent of our brains are comprised of fat. In the third trimester, brain volume doubles, and the area of the folds in the cerebral cortex is quadrupled. Building blocks are needed for this, including fat. Premature infants do not get these building blocks through the placenta and all nutrients have to be given to them from elsewhere,” explains Almaas.
She compares the brain of premature babies as hazelnuts which should have been walnuts.
“We wanted to see whether supplements of the building blocks omega-3 and omega-6 could increase the brain volume and cognitive function.”
The babies were examined at ages six months, 20 months and eight years.
At the age of six months the infants’ brain developments were assessed through tests, questionnaires and observations. The researchers were looking in particular for learning and recognition skills. Those who had been given the omega-3 and omega-6 scored higher for attentiveness and recognition than those who were only given regular breastmilk. At the age of 20 months there were indications of better recognition in so-called free-play exercises, in which the toddlers were observed as they played.
After eight years
The children were tested again at age eight. Brain volume was quantified through magnetic resonance imaging (MRI) scans, which essentially took pictures of their brains. Now the researchers no longer found significant effects from the omega-3 and omega-6 supplements. A total of 98 children were subjected to all three tests.
Almaas says she and her colleagues were not really surprised by the results. “Previous studies have shown an effect from omega-3 and omega-6, but just for a short period. We followed these kids up to primary school age, yet the intervention only lasted nine weeks. So it wasn’t likely that the effect would endure for eight years. There are so many factors involved in the development of the brain in the course of these years, such as nutrition and socio-economic status.”
“Individual studies have found an effect of the supplements while they are being given. It would be interesting to try giving the supplement for more than nine weeks, for instance for half a year,” she says.
Almaas stresses that the results are important even though no long-lasting effect was found.
“Although we discovered no significant impact long-term, this is an important contribution to research. Omega-3 and 6 are still vital supplements even if their effects are not detectable eight years later.”
Double-blinded
The study was published in the journal Pediatrics earlier this year. The design used by Almaas and her colleagues was a randomized controlled trial, or RCT, which is often used in serious medical research.
In an RCT the participants are randomly divided into an intervention group and a control group. In this test, the control group was given a placebo. Neither the researchers nor the participants who were feeding the babies knew which ones were receiving the long-chain fatty acids in breast milk and which were not. In other words, the test was double-blinded.
“As this was a randomized, controlled and double-blinded test, the results are reliable. The study had a high follow-up rated and consisted of enough participants to reveal something about the impact of the intervention, even though we would have liked to have had more participants. We would have seen it if there were a large effect from fatty acids even though there were only this many children in the study,” says Almaas.
Praiseworthy
Thomas Halvorsen, a professor at the University of Bergen and paediatrician at Haukeland University Hospital, thinks the study was professional and he would like to see more research conducted in this area.
“This was a well-structured study. Such RCT studies are not performed with prematurely born infants, which makes this all the more commendable.”
“Such studies demand many resources and are often quite costly. Prematurely born babies are often more susceptible to a number of problems in life. This study has used babies weighing less than 1,500 grams, and you needn’t go further back than to the 1970s and ‘80s to see a survival rate far below what we have today.”
“This is why we should do research on long-term effects. It is hard to carry out follow-ups, especially for several decades. There is much we don’t know about the lives of such babies as they grow to adolescence and adulthood,” says Halvorsen.
He points out that the publication in a recognised journal, despite the so-called negative findings – the lack of a long-term effect of the fatty acid supplements – indicates the quality of the research.
“Getting negative findings published can be hard to do. Higher requirements and more criticism are made regarding the study design than would be seen if a significant difference were found between the two groups. But here the authors have clearly done a solid job and the study got published despite negative findings."
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Read the Norwegian version of this article at forskning.no
Translated by: Glenn Ostling
