Written by Susan Sweeny Johnson, PhD, Biochem. Decreasing the dietary ratio of omega-6 to omega-3 fatty acids in 52 mothers during pregnancy and breast-feeding, significantly reduced the incidence of infant food allergy by 13% and infant eczema by 16%.
Childhood food allergies, often manifested as asthma and eczema, are on the rise (1). At Children’s Hospital Boston, the number of new patients seen in the allergy and immunology clinics for food allergy has increased 10-fold since 1991 (2). The cause of these allergic reactions is unclear, although environmental pollution and diet choices are thought to play a role. Some studies have suggested that the type of polyunsaturated fatty acids consumed by the mother during pregnancy and by the infant in early life affect the onset of asthma, eczema, and food allergies.
Initiation of allergy is associated with an inflammatory response upon exposure to an antigen. Decreasing inflammation through diet modification may reduce initiation of allergy. Recent studies suggest that omega-6 fatty acids such as linoleic acid are converted to arachidonic acid, which is in turn often converted to a prostaglandin that promotes inflammation and allergy. Omega-3 fatty acids, EPA (eicosopentanoic) acid and DHA (docosahexanoic acid), on the other hand, compete with arachadonic acid which reduces the production of inflammatory prostaglandins. (3,4)
Earlier studies indicated a positive effect of fish oil supplementation in pregnant mothers on early immunity in their children (5,6). Now a new study has examined the effect of lowering the ratio of omega-6 fatty acids to omega-3 fatty acids in the blood of pregnant mothers and their infants. The maternal diets were randomly supplemented with either fish oil containing 1.1 gm EPA and 1.6 gm DHA or a placebo containing soy oil with 2.5 gm of linoleic acid and 0.28gm of linolenic acid. The ratio of omega-6 to omega-3 in the first group was less than 0.1 while in the placebo group the ratio was 9.
The occurrence of food allergies in infants born to mothers or fathers who had food allergies was observed with or without fish oil supplementation in the diets of the pregnant and nursing mothers (from 25 weeks gestation to the 3rd or 4th month of infant life). Fifty-two mothers were in the fish oil group and 63 were in the placebo group.
Allergies were determined by assessing the children at 3, 6 and 12 months for allergic reactions (such as eczema, wheezing or hives) arising from ingestion of either milk, eggs or wheat, in the presence of IgE antibodies, and/or a reaction to a skin prick test using the aforementioned foods. Presence of an allergy was determined only after repeated reaction to exposure of the offending food AND and a positive IgE or skin prick test.
The most dramatic specific reduction in food allergy was found in egg allergy, determined by skin prick test from 0 -12 months. Six out of 52 infants in the high omega-3 group tested positive for allergy but 18 out of 63 in the placebo group were positive (p* for the trend is 0.02). Overall, the prevalence of food allergy was lower in the high omega-3 group (1 ⁄ 52,or 2%) compared to the placebo group (10 ⁄ 65, or 15%, p* less than 0.05 for the trend) as well as the incidence of IgE-associated eczema (high omega-3 group: 4 ⁄ 52, or 8%; placebo group: 15 ⁄ 63, or 24%, p less than 0.05 for the trend).
In conclusion, decreasing the dietary ratio of omega-6 to omega-3 fatty acids in the mother during pregnancy and lactation may reduce the incidence of infant food allergy.
The CDC reports:
- In 2007, approximately 3 million children under age 18 years (3.9%) were reported to have a food or digestive allergy in the previous 12 months.
- From 1997 to 2007, the prevalence of reported food allergy increased 18% among children under age 18 years.
- Children with food allergy are two to four times more likely to have other related conditions such as asthma and other allergies, compared with children without food allergies. (7)
Food allergy accounts for about 35–50 percent of emergency room visits for anaphylaxis (severe allergic reaction) and causes about 30,000 episodes of anaphylaxis and 100–200 deaths per year in the United States (8).
* p is a measure of the significance of the result – the lower the value, the more significant the difference is.
Source: Furuhjelm, Catrin, et al. “Fish oil supplementation in pregnancy and lactation may decrease the risk of infant allergy.” Acta paediatrica 98.9 (2009): 1461-1467.
© 2009 The Author(s)/Journal Compilation ª2009 Foundation Acta Pædiatrica/Acta Pædiatrica 2009
Posted August 26, 2009.
REFERENCES:
- Asher MI, Montefort S, Bjo¨ rkste´n B, Lai CKW, Strachan DP, Weiland SK, et al. Worldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjuctivitis, and eczema in childhood: ISAAC phase one and three repeat multicountry cross-sectional surveys. Lancet 2006; 368: 733–43.
- See the Food Allergy Research and Education website.
- Calder PC, Miles EA. Fatty acids and atopic disease. Pediatr Allergy Immunol 2000; 11(Suppl 13):29–36.
- Serhan CN. Novel eicosanoid and docosanoid mediators: resolvins, docosatrienes, and neuroprotectins. Curr Opin Clin Nutr Metab Care 2005; 8: 115–21.
- Dunstan JA, Mori TA, Barden A, Beilin LJ, Taylor AL, Holt PG, et al. Fish oil supplementation in pregnancy modifies neonatal allergen-specific immune responses and clinical outcomes in infants at high risk of atopy: a randomized, controlled trial. J Allergy Clin Immunol 2003; 112: 1178–84.
- Olsen SF, Osterdal ML, Salvig JD, Mortensen LM, Rytter D, Secher NJ, et al. Fish oil intake compared with olive oil intake in late pregnancy and asthma in the offspring: 16 y of registry-based follow-up from a randomized controlled trial. Am J Clin Nutr 2008; 88: 167–75.
- http://www.cdc.gov/nchs/data/databriefs/db10.htm
- http://www3.niaid.nih.gov/topics/foodAllergy/PDF/FoodAllergyExpertReport.pdf
