However, omega-3 supplementation during infancy did not decrease these risks, Linh BaPhuong Huynh, MD, MSc, School of Nutrition and Health Sciences, Taipei Medical University, Taiwan, and colleagues wrote.
The meta-analysis examined 12 randomized controlled trials published between 2003 and 2018 involving 3,274 mother-infant pairs, with mean doses of omega-3 polyunsaturated fatty acid (PUFA) ranging from 492 mg to 3,700 mg per day for mothers and 184 mg to 390 mg per day for infants.
Maternal omega-3 PUFA consumption while they were pregnant and lactating had significant effects on risks for egg sensitization (RR = 0.58; 95% CI, 0.47-0.73) and peanut sensitization (RR = 0.62; 95% CI, 0.47-0.8), the researchers found, but infant consumption did not have any protective effect on food allergy.
Specifically, the researchers said, the effects that maternal omega-3 supplementation had on the first 3 years of their child’s life (the “early period”) and afterward (the “late period”) were remarkably different.
There was a significant association between maternal omega-3 supplementation during pregnancy and lactation and food allergy (RR = 0.53; 95% CI, 0.33-0.85) during the early period but not during the late period, the researchers said.
Also, the researchers said, the protective effect that maternal omega-3 PUFA intake had on egg sensitization was inconsistent between the two periods, but it was consistent for peanut sensitization. Whereas maternal omega-3 supplementation reduced risks for egg sensitization only for the early period (RR = 0.55; 95% CI, 0.44-0.71), it reduced risks for peanut sensitization for the early (RR = 0.61; 95% CI, 0.4-0.94) and the late period (RR = 0.62; 95% CI, 0.44-0.87).
The five studies (n = 1,072) analyzing cow’s milk only found sensitization with omega-3 supplementation during pregnancy and lactation during the early period, with no differences in the numbers of infants reporting any event between the omega-3 PUFA and comparison groups.
Three studies (n = 1,412) found reductions in risk for cashew nut sensitization (RR = 0.45; 95% CI, 0.26-0.77; I2 = 0%) during the late period with maternal omega-3 supplementation.
Additionally, three studies (n = 1,412) found no significant effect on food allergy status (RR = 0.93; 95% CI, 0.63-1.37; I2 = 0%), egg sensitization (RR = 0.9; 95% CI, 0.65-1.27; I2 = 0%) or peanut sensitization (RR = 0.95; 95% CI, 0.58-1.56; I2 = 0%) with omega-3 PUFA supplementation in infants.
Further analysis found a log-linear dose-response relationship between the daily dose of omega-3 supplementation during pregnancy and incidence of infant egg sensitization during the early period (estimate = –0.0003; standard error = 0.0001; P < .001) with no heterogeneity across the studies (I2 = 0%; Q = 3.34).
With an association between higher doses and lower incidence rates, the researchers said, there was a 3.2% decrease in risk for egg sensitization with every 100 mg per day of standard supplementation during the early period.
Based on these findings, the researchers said that maternal omega-3 supplementation contributes to decreases in risks for infant food allergy, but supplementation directly to infants does not.
The researchers called for additional studies investigating doses and durations of maternal omega-3 PUFA interventions as well as randomized controlled trials exploring the effects of infant supplementation, in addition to studies of how allergic skin inflammation, the gut microbiome and the timing of other food introductions may influence these results.
Theresa Bingemann, MD, FACAAI, FAAAAI
The use and impact of omega-3 fatty acids in allergic disease continues to resurface. Previous studies have looked at prevention and treatment of asthma, allergic rhinitis and atopic dramatis as well. Like in the study here, there have been mixed results. This study does have encouraging results when omega-3 fatty acids are used in pregnancy for reducing food allergy sensitization. Further study is needed.
I am frequently asked about allergy prevention, and I know some moms who take omega-3 fatty acids and often probiotics in pregnancy. In my experience, this is often done after the first child has allergic disease. The results have been mixed. There are many factors that impact the likelihood of food allergy.
Infant atopic dermatitis severity and timing of food introduction are two factors that can have a significant impact on the development of food allergy. It is impossible to tell from the paper what the incidence of atopic dermatitis was in each of the groups. We also do not know if the infants were breastfed and for how long. I would also like to know more about the maternal diet and timing of highly allergenic food introduction.
When the data are not clear and questions remain as to the exact benefit of an intervention, I ask myself, “What is the harm of recommending this?” As long as moms are using a reliable product and they do not have any contraindications to taking these pills, the only downside is cost. If someone is comfortable with that and recognizes that it may not be beneficial, then I would not stop them from using these supplements. As far as eating more fish in pregnancy instead for omega-3 intake, it is important to follow recommendations regarding methylmercury exposure.
A large double-blind randomized control trial of atopic mothers with supplementation in pregnancy is needed, ideally simultaneously in multiple countries. I would like to see issues such as other supplements, atopic dermatitis incidence and severity, duration of breastfeeding and timing of food introduction addressed as well. I would exclude other interventions such as probiotics. Finally, I would want to see a longer duration of follow-up and ideally some food challenge data.