AusSMC: New research from Europe suggests eating three or more burgers a week may boost a child’s risk of asthma and wheeze – at least in developed nations. Conversely, a Mediterranean diet, rich in fruit, vegetables, and fish seems to stave off the risk, the research shows.
The research team base their findings on data collected between 1995 and 2005 on 50,000 children between the ages of 8 and 12 from 20 rich and poor countries around the world including New Zealand*. Their parents were asked about their children’s normal diet and whether they had ever been diagnosed with asthma and/or have had wheeze. Just under 30,000 of the children were tested for allergic reactions, to see if diet also influenced their chances of developing allergies. Diet did not seem to be associated with becoming sensitised to common allergens, such as grass and tree pollen.
But it did seem to influence the prevalence of asthma and wheeze. High fruit intake was associated with a low rate of wheeze among children from rich and poor countries. Similarly, a diet high in fish protected children in rich countries, while a diet rich in and cooked green vegetables protected children against wheeze in poor countries. Overall, a Mediterranean diet, high in fruit, vegetables, and fish was associated with a lower lifetime prevalence of asthma and wheeze.
But eating three or more burgers a week was associated with a higher lifetime prevalence of asthma and wheeze, particularly among children with no allergies in rich countries. A heavy meat diet, however, had no bearing on the prevalence of asthma or wheeze. The authors say that fruit and vegetables are rich in antioxidant vitamins and biologically active agents, while the omega 3 polyunsaturated fatty acids found in fish have anti-inflammatory properties, so there are biologically plausible links for the findings. Burger consumption could be a proxy for other lifestyle factors, they add, particularly as the increased asthma risk associated with it was not found in poor countries.
*The Phase 2 research was undertaken by a European team of scientists as part of the International Study on Allergies and Asthma in Childhood which is based at the University of Auckland and headed by Professor Innes Asher.
Comments from the AusSMC
Professor Philip Thompson is the National President of the Thoracic Society of Australia and New Zealand.
“There is widely published data on the relationship between obesity and asthma, and the health benefits of antioxidants in diet and compelling evidence on the harm of poor diets on conditions such as heart disease and diabetes.
“Increasingly, it is becoming clear that poor diet is also linked to the prevalence of asthma and wheeze, and that healthy food choices – particularly fresh fruit, vegetables and fish – help to protect against the risk of these conditions.
“Diet is only one factor potentially influencing asthma prevalence. Other factors include:
• childhood exposure to tobacco smoke;
• air pollution;
• widespread use of antibiotics affecting natural resistance to infections and allergens; and
• modern home design with tightly sealed rooms restricting the inflow of fresh air and the “flushing out” of allergens and air pollutants.”
Dr Peter Smith, an allergy specialist who runs a private clinic in Queensland, comments:
“We are what we eat. Fresh fruit and vegetables are high in anti-oxidants that help combat the fatty acids and inflammatory compounds that can be in junk food.
“Omega 3 fatty acids are better oils to have.There are also genetic factors that influence how we cope with oxidant stresses. Oxidants can come from diet and environmental pollutants. the vulnerable – suffer the most.”
Comments from the UK SMC
Dr Keith Prowse, British Lung Foundation spokesperson, said:
“This is an interesting study showing an association between diet and the severity levels of asthma among children. Whether this is a direct result of diet or a reflection of other aspects of lifestyle is uncertain and further investigation would be needed for more conclusive evidence. The British Lung Foundation (BLF), the only charity working to support everyone affected by lung disease, would like to reinforce the need for children to have a balanced diet and healthy lifestyle.”
* Nagel et al. (2010) Effect of diet on asthma and allergic sensitisation in the International Study on Allergies and Asthma in Childhood (ISAAC) Phase Two, Thorax, 65: 516-522