Fish-oil supplements taken during pregnancy might help prevent allergies in babies at high risk for them, preliminary research suggests.
A study in Australia found that babies whose mothers took fish oil had weaker immune reactions to common allergy triggers and, at one year of age, showed signs of being less allergy-prone. It's too soon to recommend the supplements for some pregnant women, but investigators say their findings lay the groundwork for larger, longer-term studies of whether fish oil can reduce childhood allergies.
In general, pregnant women are advised against taking any medication or supplement unless the benefit is known to outweigh any potential risk to the fetus. Pregnant women should always consult their doctor before taking drugs or supplements.
The new study looked at whether fish-oil capsules - rich in healthful omega-3 fatty acids - might help prevent the development of allergies in babies born to women with a history of hay fever or asthma. Children with a family history of allergies are at increased risk of developing them.
The theory is that because omega-3 fatty acids have anti-inflammatory properties, they may affect the developing immune system in a way that makes it less prone to allergic reaction, according to study author Dr. Susan L. Prescott of the University of Western Australia in Perth.
According to the study authors, it's possible that the rise in allergic disease over the past few decades could be related, in part, to a decline in omega-3 fats in the Western diet. Fatty fish like salmon, tuna and sardines are a prime source of omega-3s; the fats are also found in certain vegetable sources, such as canola oil and flaxseed.
In the study, 98 pregnant women took either fish-oil capsules or, for comparison, capsules containing olive oil. The women took four capsules per day from the 20th week of pregnancy until delivery. Analyzing cells taken from the babies' umbilical cord blood, the researchers found greater amounts of omega-3 fats in the cell membranes of newborns whose mothers took fish-oil supplements. In addition, their immune cells tended to have a less allergic response to allergy-producing substances like cat dander, compared with babies in the comparison group.
At the age of 1, infants whose mothers took fish oil were three times less likely to show sensitivity to egg during skin tests used to detect allergies. Babies in the fish-oil group were more likely to develop the allergic skin condition eczema; but among infants with eczema, those in the fish-oil group were much less likely to have a severe case.
Past studies in which fish-oil supplements were given to adults with allergies have yielded mixed results. According to Prescott's team, omega-3 supplementation may have to take place when the immune system is developing in order to have a benefit.
The next step is to do larger studies looking at whether children exposed to fish-oil capsules in the womb actually do develop allergies at a lower rate over time.
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