Effect of omega-6 and 3 imbalance on childhood allergy and respiratory disease.
In developed countries, there has been a fall in the consumption of saturated fat and an increase in the consumption of polyunsaturated fat, particularly linoleic acid (omega-6), over the last few decades. In the USA between 1935 and 1939, linoleic acid accounted for only 9% of fatty acids in the food supply. By 1984, linoleic acid consumptionn had risen to 15%. These changes are largely due to a decrease in the use of butter and lard and an increase in the use of margarine and vegetable oils[1].
The changed pattern of LA (omega-6) consumption has resulted in a marked increase in the ratio of omega-6 to omega-3 PUFAs in the diet, with the current ratio being between 5 and 20 in most Western populations. The increased intake of the omega-6 PUFA linoleic acid has been claimed to be causally related to increased prevalence and incidence of atopic diseases in children.
Maternal fish intake during pregnancy has been consistently demonstrated to have protective effects on atopic or allergic diseases in infants and children: maternal fish intake was inversely associated with eczema (adjusted odds ratio (OR): 0.75; 95% confidence interval (CI): 0.57, 0.98), asthma (OR: 0.20; 95% CI: 0.06, 0.65), and sensitization to food and dust mites.
This is not the case for the effects of fish intake during infancy or childhood on atopic outcomes, (namely, eczema, hay fever, and asthma). The effects have been inconsistent, although the majority of the studies reported protective effects [2].
There are benefits of omega-3 PUFAs supplementation in reducing the incidence of infectious respiratory diseases. In a US study, children aged 18-36 months were provided 237-ml formula with 0, 43, or 130 mg DHA per day for 60 days. Toddlers consuming the formula with 130 mg DHA per day have fewer adverse events (p=0.007) and a lower incidence of respiratory illness (p=0.024), compared to the formula without DHA [3].
References:
[1] Black PN, Sharpe S: Dietary fat and asthma: is there a connection? Eur Respir J 1997;10:6-12. For abstract, go to the following link:
http://www.ncbi.nlm.nih.gov/pubmed?term=%22The+European+respiratory+journal+%3A+official+journal+of+the+European+Society+for+Clinical+Respiratory+Physiology%22%5BJour%5D+AND+10%5Bvolume%5D+AND+6%5Bpage%5D+AND+1997%5Bpdat%5D&cmd=detailssearch
[2] Shek LP, Chong MF, Lim JY, et al.: Role of Dietary Long-Chain Polyunsaturated Fatty Acids in Infant Allergies and Respiratory Diseases. Clin Dev Immunol. Published online 2012 August 28. doi: 10.1155/2012/730568: go to the following link for full text:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3461300/
[3] Minns LM, Kerling EH, Neely MR, et al.: Toddler formula supplemented with docosahexaenoic acid (DHA) improves DHA status and respiratory health in a randomized, double-blind, controlled trial of US children less than 3 years of age. Prostaglandins Leukot Essent Fatty Acids. 2010;82:287-93.
For abstract, go to the following link:
http://www.ncbi.nlm.nih.gov/pubmed?term=%22Prostaglandins%2C+leukotrienes%2C+and+essential+fatty+acids%22%5BJour%5D+AND+82%5Bvolume%5D+AND+287%5Bpage%5D+AND+2010%5Bpdat%5D&cmd=detailssearch
The changed pattern of LA (omega-6) consumption has resulted in a marked increase in the ratio of omega-6 to omega-3 PUFAs in the diet, with the current ratio being between 5 and 20 in most Western populations. The increased intake of the omega-6 PUFA linoleic acid has been claimed to be causally related to increased prevalence and incidence of atopic diseases in children.
Maternal fish intake during pregnancy has been consistently demonstrated to have protective effects on atopic or allergic diseases in infants and children: maternal fish intake was inversely associated with eczema (adjusted odds ratio (OR): 0.75; 95% confidence interval (CI): 0.57, 0.98), asthma (OR: 0.20; 95% CI: 0.06, 0.65), and sensitization to food and dust mites.
This is not the case for the effects of fish intake during infancy or childhood on atopic outcomes, (namely, eczema, hay fever, and asthma). The effects have been inconsistent, although the majority of the studies reported protective effects [2].
There are benefits of omega-3 PUFAs supplementation in reducing the incidence of infectious respiratory diseases. In a US study, children aged 18-36 months were provided 237-ml formula with 0, 43, or 130 mg DHA per day for 60 days. Toddlers consuming the formula with 130 mg DHA per day have fewer adverse events (p=0.007) and a lower incidence of respiratory illness (p=0.024), compared to the formula without DHA [3].
References:
[1] Black PN, Sharpe S: Dietary fat and asthma: is there a connection? Eur Respir J 1997;10:6-12. For abstract, go to the following link:
http://www.ncbi.nlm.nih.gov/pubmed?term=%22The+European+respiratory+journal+%3A+official+journal+of+the+European+Society+for+Clinical+Respiratory+Physiology%22%5BJour%5D+AND+10%5Bvolume%5D+AND+6%5Bpage%5D+AND+1997%5Bpdat%5D&cmd=detailssearch
[2] Shek LP, Chong MF, Lim JY, et al.: Role of Dietary Long-Chain Polyunsaturated Fatty Acids in Infant Allergies and Respiratory Diseases. Clin Dev Immunol. Published online 2012 August 28. doi: 10.1155/2012/730568: go to the following link for full text:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3461300/
[3] Minns LM, Kerling EH, Neely MR, et al.: Toddler formula supplemented with docosahexaenoic acid (DHA) improves DHA status and respiratory health in a randomized, double-blind, controlled trial of US children less than 3 years of age. Prostaglandins Leukot Essent Fatty Acids. 2010;82:287-93.
For abstract, go to the following link:
http://www.ncbi.nlm.nih.gov/pubmed?term=%22Prostaglandins%2C+leukotrienes%2C+and+essential+fatty+acids%22%5BJour%5D+AND+82%5Bvolume%5D+AND+287%5Bpage%5D+AND+2010%5Bpdat%5D&cmd=detailssearch