FCAAIA Notes: About 4 years ago, I posted an abstract indicating that giving infant’s fish oil did not decrease their incidence of allergic disease (“Fish Oil Does Not Prevent Early Allergies in Infants). In this study, the children of women who took either fish oil or placebo during the second half of pregnancy did not ultimately show any difference in their rates of allergic disease. Children whose mothers took fish oil were less likely to have a positive skin test to dust mites but did not have less allergic disease.
Here’s an important point however: The thymus gland which is essential for the development of white blood cells called T cells and the development of “tolerance” (not having allergy) forms early in gestation and is already formed by 20 weeks. To really answer the question the authors asked, I would like to see this study repeated with fish oil supplements being started as soon as the woman is known to be pregnant.
(Source: http://www.medscape.com/viewarticle/863946?nlid=106008_3821&src=WNL_mdplsfeat_160607_mscpedit_aimm&uac=112079PK&spon=38&impID=1120338&faf=1 May 31, 2016. For Medscape articles: User name: FCAAIA, Password: Allergies)
Taking fish oil supplements during pregnancy has no effect on a child’s IgE-associated allergies, Australia-based researchers report.
“Several observational studies have reported protective associations between increased fish intake in pregnancy and allergic disease symptoms in offspring from infancy to 6 years of age,” write Dr. Karen Best of the Child Nutrition Research Centre, North Adelaide, South Australia and colleagues.
“However, these observational studies are unable to establish causality because of the difficulty in adjusting for complex confounding factors,” they note in Pediatrics, online May 25.
The team aimed to determine whether taking n-3 long-chain polyunsaturated fatty acids (LCPUFA) fish oil during pregnancy would have protective effects on children at six years of age, when respiratory symptoms become more prevalent.
To investigate, they conducted a six-year follow-up study of 706 children with a family history of allergic disease from the Docosahexaenoic Acid to Optimize Mother Infant Outcome (DOMInO) trial. For that study, women were asked to consume capsules containing either 500 mg of fish oil concentrate, providing about 800 mg/day docosahexaenoic acid (DHA) and 100 mg/day eicosapentaenoic acid (EPA), or 500 mg vegetable oil capsules (control group) from 21 weeks’ gestation until delivery.
The Australian team assessed allergic diseases symptoms – including eczema, wheeze, rhinitis and rhino-conjunctivitis – in the six-year-olds via questionnaire and sensitization by skin prick test.
They found no difference in the percentage of children with any IgE-associated allergic disease between the n-3 LCPUFA and control groups (31.5% vs. 31.5%; adjusted relative risk, 1.04; p=0.73).
However, there was a reduction in the percentage of children sensitized to house dust mite Dermatophagoides farinae (13.4% vs. 20.3%; aRR, 0.67; p=0.0495).
Dr. Best told Reuters Health by email, “Observational studies of increased fish intake during pregnancy have shown a reduction in symptoms of allergy in the early school age child. It is perhaps not surprising that our randomized controlled trial did not show such an effect as the exposure period was a defined length of time, whereas offspring born to women in observational studies are most likely exposed to increased n-3 LCPUFAs, via diet, over a lifetime.”
“However, it is interesting to note the protective effects of our intervention on the atopic status of the children,” she says. “The significant reduction in sensitization to house dust mite was unexpected though highly plausible when one considers that this same cohort of children showed a significant reduction in sensitization to hen’s egg at 12 months of age in an earlier study.”
She adds, “It does seem evident that prenatal supplementation of n-3 LCPUFA during pregnancy has some effect on sensitization of the child; however, more research would be needed to determine clinically significant benefits.”
Allergist-immunologist Dr. Amal H. Assa’ad of Cincinnati Children’s Hospital Medical Center, Ohio, was not surprised by the study results.
“Several previous studies have shown the prevention of allergies through interventions during pregnancy. This study had the same outcome, specifically when examining the children after several years of life,” she told Reuters Health by email. “While there was a reduction in sensitization to dust mite, this did not reflect on the overall incidence of allergic diseases.”