Taking fish oil in pregnancy may prevent childhood asthma

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Asthma - a condition that leads to narrowing of the airways - is a common health concern in children.

In fact, according to the National Asthma Council of Australia, one in nine or 10 children have asthma.

Children are more likely to develop asthma if their mother smoked during pregnancy, if they're born prematurely, or if there is someone in the family with the condition, among other causes.

Now new research, published in the New England Journal of Medicine in December 2016, sheds fresh light on the topic.

It found that women who took omega-3 fatty acid supplements (fish oil supplements) in pregnancy reduced the risk of their children developing asthma by almost one third.

Author Professor Hans Bisgaard says they've "long suspected" there was a link between the low intake of omega-3 fatty acids in Western diets, and the rising rates of childhood asthma.

"This study proves that they are definitively and significantly related."

The study involved over 700 pregnant women in their third trimester. The women either took either fish oil supplements or a placebo.

The researchers found that the mums who took fish oil supplements in pregnancy reduced their children's risk of asthma by 31 per cent.

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"Asthma and wheezing disorders have more than doubled in Western countries in recent decades," said Professor Bisgaard. "We now have a preventative measure to help bring those numbers down."

Obstetrician Dr Joseph Sgroi from the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) agrees this study seems "encouraging".

But he cites a larger study from 2015 that found "very little evidence" that fish oil can reduce the risk of diseases such as asthma, and said that he believes more research into this area is needed.

Dr Bastian Seidel from the Royal Australian College of General Practitioners (RACGP) agrees. As a Director of the National Asthma Council, he says it's too soon to put these findings into practice.

Currently, Dr Seidel says the World Health Organization (WHO) recommends women consume at least 2.6 grams of omega-3 fatty acids daily, with the aim of consuming 100-300mg of DHA (a key component of fatty acids).

Dr Seidel says that popular pregnancy supplements ensure you fulfill those requirements for DHA.

But if you're not planning to take fish oil supplements in pregnancy, should you change your mind based on this study?

Dr Sgroi doesn't think so.

He says if you're eating the recommended amount of fish per week, you should be getting enough omega-3 fatty acids currently needed for proper development.

That said, he adds there is "no harm" in taking fish oil supplements if you want to. What can be harmful is taking more than the recommended amount.

You also need to be careful about which fish oil supplements you choose.

Dr Seidel says some supplements made from fish liver (such as cod liver oil) may contain excessive amounts of retinol, which should be avoided in pregnancy.        

You also shouldn't you increase your intake of fish beyond the recommended amount, either.

Instead, stick to Food Standards Australia and New Zealand guidelines, which advise pregnant women not to consume more than 2-3 serves of fish per week. Eating more than that amount can result in increased consumption of pollutants, such as mercury, which can be harmful to a developing baby's brain.

Also remember that the larger the fish, the more mercury it may contain, says Dr Sgroi. For this reason, pregnant women are advised to limit their intake of larger fish (such as shark, swordfish and king mackerel) to only one serve a fortnight.

If you are worried about the chances of your baby developing asthma, Dr Seidel says the best thing you can do is seek advice from your GP.

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