Low fish consupmtion seems to be a common factor among many of those suffering from asthma and allergies. There are also indications that a mother's consumption of oily fish during pregnancy can reduce a child's likelihood of developing asthma.
Asthma is reported to be increasing in industrialised societies and fish oils have been clearly linked with reductions in its effects. For example, Dr Bipen Patel, a clinical epidemiologist at Cambridge University in the UK, reported to the British Thoracic Society meeting in December 2002 on an investigation of the links between oily fish consumption and asthma-related symptoms. In 770 people, 333 of whom had a history of asthma, there was a clear correlation in that the asthma group had far fewer fish consumers. Dr Patel noted that asthma has become more common in the UK over the past 30 years and that the amount of oily fish in the diet had declined over the same period.
In another example, fish oil supplementation was demonstrated in a joint UK American trial to reduce exercise-induced bronchorestriction (EIB) in elite athletes. EIB is a condition suffered by some athletes after intense exercise and not by others. Ten from each group participated in a randomised, double-blind crossover study in which half received fish oil capsules containing 3.2g EPA and 2.2g DHA daily for three weeks. The authors concluded that dietary fish oil supplementation had a markedly protective effect in suppressing EIB.
Asthma is more common in children. A six-country survey of nutrition and respiratory health of children in central and eastern European countries has shown a clear link with the consumption of fish. A total of 20,271 children aged from seven to eleven years were surveyed on respiratory health and food intake. The authors concluded that low fish intake, less than once a month, was the most consistent predictor of poor respiratory health.
In 2007, Spanish researchers reported a study that followed 460 children from birth to age 6. Allergies were least common among those that ate the most fish.
The respiratory benefits for children of oily fish consumption probably begin even before birth. Frank Gilliland, professor of preventive medicine at the University of Southern California, reported to the American Thoracic Society in May 2004 on analyses of data drawn from the Children’s Health Study, coupled with further research on maternal diets. Researchers selected 300 asthmatic children and 400 non-asthmatics. The results indicated children born to asthmatic women who had eaten oily fish “at least a few times a month” during pregnancy were 71% less likely to develop asthma by their fifth birthday than those born to similar women who consumed no fish.