Research appearing in the International Journal of Tuberculosis and Lung Diseases (2007; 11(1): 103-9) looked at fish consumption, and the relative consumption of omega-6 and omega-3 fatty acids in 1,002 pregnant Japanese women. Increased fish consumption and consuming more omega-3 fatty acids (in relation to omega-6 fatty acids) reduced the chance of having a child with asthma.
Another study that appeared in Clinical and Experimental Allergy (2007; 37(11): 1616-23) looked at the dietary habits of 16,187 subjects between the ages of 23 and 54 years. It found that a small amount of fish in the diet reduced the chances for developing asthma. The subjects who never ate fish during childhood had an increased risk of developing asthma at an early age.
Pregnant women, who had an increased risk for having a child with asthma were involved in research that appeared in Pediatric Allergy and Immunology (2004;15:517-522). The 616 women were instructed to give the newborn either 500 mg/day of fish oil or a placebo. Breast-fed infants were not given a supplement until the age of six months (there is a high concentration of omega-3 fatty acids in breast milk). The children were evaluated a 18 months of age (376 of the original group participated in the evaluation). Omega-3 fatty acid levels were measured and it was found that asthma symptoms, nocturnal coughing and doctor visits (for asthma), were reduced in those with high levels of omega-3 fatty acid in the blood.
According to research published in the European Journal of Clinical Nutrition (2005; 59(12): 1335-46). It found that omega-3 fatty acids were especially helpful for preventing exercise induced bronchospasm. This was supported by a review article appearing in the Australian New Zealand Journal of Medicine (1994;24:727), which found that a diet low in omega-3 fatty acids and high in omega-6 fatty acids, and the increased use of margarine may be part of the reason that asthma is on the rise. The article notes that asthma is low in Scandinavia and in Mediterranean countries where there is less omega-6 consumption and more consumption of omega-3 and olive oil.