Previous RCTs have suggested that prenatal omega-3 supplementation might protect against allergic sensitisation and allergic disease symptoms in early childhood.
Researchers at the South Australian Health and Medical Research Institute and University of Adelaide hence conducted a similar study involving 706 children with a familial risk of allergy, whose mothers had participated in the DHA to Optimise Mother-Infant Outcome (DOMInO) trial (part of the Australian New Zealand Clinical Trials Registry).
Prenatal and postnatal findings
Women with a singleton pregnancy who had not reached 21 weeks' gestation were randomly assigned to either an intervention or a control group. They were asked to consume capsules containing either fish oil concentrate (800mg of DHA and 100mg of EPA daily), or control capsules containing a mixture of three non-genetically modified oils — rapeseed, sunflower, and palm oils.
All capsules looked the same, and neither the women nor researchers knew which capsules the participants were taking.
The supplementation period lasted from enrolment to delivery, after which the researchers obtained data on the participants' children at one, three and six years post-birth, and any allergic disease symptoms were reported by parents via the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire.
The researchers used a skin prick test to determine sensitisation to age-specific common allergen extracts. They reported that changes over time in the symptoms of allergic disease with sensitisation "did not differ between the groups".
Additionally, when averaged across the follow-up period, prenatal omega-3 supplementation had no noticeable impact on allergic disease symptoms, or sensitisation.
The researchers also wrote that the children's sensitisation patterns in relation to common allergens "were consistent with the atopic march — the natural progression of allergic diseases that often start in early life — with sensitisation to eggs at one year old strongly linked to house dust mite sensitisation at six years old.
They did say, however, that the ISAAC questionnaire may not have been suitable for the diagnosis of allergic disease symptoms in children aged one to six, as it had been validated only for children between the ages of six and seven, and teenagers aged 13 to 14.
There were also discrepancies between the overall prevalence of allergic disease as reported by the parents, and the physician's assessment.
The researchers concluded: "Although there is some evidence to suggest that maternal supplementation with 900 mg ω-3 LCPUFA has a protective effect on early symptoms of allergic disease and sensitisation, we did not observe any differences in the progression of disease over time in this longitudinal analysis.
"Further investigation into patterns of sensitisation, classification of atopy phenotypes and harmonisation of clinical symptom recording are essential to progress in this field.
"Long term follow-up of offspring (in adolescence and adulthood) following prenatal interventions are essential to determine true effects on the trajectory of disease, and to confirm whether prenatal ω-3 LCPUFA supplementation may be of benefit as a primary prevention strategy."
Source: World Allergy Organization Journal
"Prenatal omega-3 LCPUFA and symptoms of allergic disease and sensitization throughout early childhood – a longitudinal analysis of long-term follow-up of a randomized controlled trial"
Authors: KP Best, et al.