First Class: Teaching the Immune System with Omega-3

Abstract: The immune system is complex, yet naïve in newborns, which is particularly susceptible to the conditions whilst inside the womb and the early external environment. Omega-3 has been shown to positively modulate the immune system against favouring an allergic situation where inflammatory conditions such as asthma, eczema and atopy may develop. Studies suggest that supplementation of omega-3 during pregnancy and lactation can reduce the occurrence of these conditions in newborns.

The role of omega-3 within the body for cardiovascular and brain health has revealed substantial benefits however, omega-3 also has a major role in modulating the immune system. The interaction of omega-3 on inflammatory mediators is central to the recent observations on immune function by reducing some inflammatory conditions such as asthma in children.

Immune Development

During development, the naïve immune system is significantly influenced in the early days by the external environment. There exists a balance between early childhood infections such as the common coughs and colds, and allergic responses in infants. Although both are required for sensitisation to the external environment in an appropriate fashion and to develop immunity against particular pathogens, the balance needs to be within certain limits.

In the modern world where disinfectants and infection control dominate in the efforts to protect kids from getting sick, another phenomenon has risen to the surface. When children are withdrawn or protected against contracting infections from other kids and the environment, the body’s response to allergies becomes amplified [1]. T-cells are the cells of the immune system that responds directly to the environment and mediate what kind of response will be initiated. Allergies are inappropriate inflammatory responses initiated by T-cells, which can result in conditions such as asthma. This is where omega-3 can help.

How Omega-3 Helps

Presently, the complex immune system within children can be quite sensitive to nutritional intake from the mother during pregnancy and breastfeeding. Omega-3 fats are a group of polyunsaturated fatty acids that are taken up by the body through nutrition to reach the blood. Within the blood, omega-3 alters the profile of inflammatory mediates circulating the body. Omega-3 favours the production of anti-inflammatory rather than pro-inflammatory mediators [2], which has long reaching effects on the rest of the body.

The effects of omega-3 on T-cell regulation affects the way the body responds to infections and allergies. Two types of T-cells exist, T-helper Th1 and Th2, corresponding to infection and allergy response respectively. Proinflammatory prostaglandin PGE2 favours expression of cytokines interleukins IL-4 and IL-5 stimulating an allergic response mediated by Th2 [3]. This pathway is lessened with omega-3 supplementation supporting a balance between T-cell responses to infections and allergens [4]. This effect has also been confirmed with dietary levels of omega-3 [5].

Another avenue that omega-3 exerts its benefits is via the regulation of key genes involved in the inflammatory response. Omega-3 reduces gene expression of NF-ĸB, which plays a role in activating other inflammatory process. Furthermore, omega-3 also reduces the expression of other genes that attract inflammatory cells such as neutrophils [2]. Therefore, omega-3 suppresses the inflammatory response via inhibiting central inflammatory gene expression.

So what are the Outcomes for Immune Health?

The importance of omega-3 for proper immune development is indicated by studies investigating the effects of omega-3 on the early years of development. An increased prevalence of asthma in children mirrors that of the change in the fat consumption of the Western diet [6]. Observational studies show that omega-3 is associated with early childhood asthma and atopy. Breast milk low in omega-3 has been associated with increased risk of atopy in breastfed children [7]. In another study, children of mothers with a history of asthma were less likely to develop asthma when mothers ate oily fish than those who did not [8].

Interventional trials have shown that omega-3 supplementation during pregnancy and lactation can reduce the incidence of childhood allergies [9] and also have long lasting effects on health. A study conducted in children with bronchial asthma showed that omega-3 may also decrease symptoms of asthma [10]. As mentioned above, it is thought that this effect is due to the interaction with T-cells, inflammatory gene expression and production. Therefore, supplementation with omega-3 during pregnancy and lactation is important for proper immune development.

In Summary…

The incidence of early childhood allergies can be modulated by supplementing omega-3 during pregnancy and lactation. As the naïve immune system is developing, the balance between fighting infections and responding to allergens must be kept even. If allowed to dominate, the Th2-mediated response to allergies may become overbearing and produce allergic conditions such as asthma, atopy and eczema. Omega-3 is an important nutrient during immune development as it allows for a more balanced and appropriate immune response, decreasing the risk of developing these harmful childhood conditions.

1. Herz, U. and B. Petschow, Perinatal events affecting the onset of allergic diseases. Curr Drug Targets Inflamm Allergy, 2005. 4(5): p. 523-9.
2. Grimm, H., et al., Regulatory potential of n-3 fatty acids in immunological and inflammatory processes. Br J Nutr, 2002. 87 Suppl 1: p. S59-67.
3. Miles, E.A., L. Aston, and P.C. Calder, In vitro effects of eicosanoids derived from different 20-carbon fatty acids on T helper type 1 and T helper type 2 cytokine production in human whole-blood cultures. Clin Exp Allergy, 2003. 33(5): p. 624-32.
4. Gottrand, F., Long-chain polyunsaturated fatty acids influence the immune system of infants. J Nutr, 2008. 138(9): p. 1807S-1812S.
5. Mizota, T., et al., Effect of dietary fatty acid composition on Th1/Th2 polarization in lymphocytes. JPEN J Parenter Enteral Nutr, 2009. 33(4): p. 390-6.
6. Calder, P.C., n-3 polyunsaturated fatty acids, inflammation, and inflammatory diseases. Am J Clin Nutr, 2006. 83(6 Suppl): p. 1505S-1519S.
7. Duchen, K., G. Yu, and B. Bjorksten, Atopic sensitization during the first year of life in relation to long chain polyunsaturated fatty acid levels in human milk. Pediatr Res, 1998. 44(4): p. 478-84.
8. Salam, M.T., et al., Maternal fish consumption during pregnancy and risk of early childhood asthma. J Asthma, 2005. 42(6): p. 513-8.
9. Furuhjelm, C., et al., Fish oil supplementation in pregnancy and lactation may decrease the risk of infant allergy. Acta Paediatr, 2009. 98(9): p. 1461-7.
10. Nagakura, T., et al., Dietary supplementation with fish oil rich in omega-3 polyunsaturated fatty acids in children with bronchial asthma. Eur Respir J, 2000. 16(5): p. 861-5.