Processed food linked to increase in asthma
8th April 2014 – A diet with high volumes of processed food, fat and refined sugar could be a contributing factor to an increase in the prevalence of asthma, a new study suggests.
Further research also suggests dietary fat can have an effect on inhalers that contain salbutamol.
In the UK, 1 in every 12 adults and 1 in every 11 children are being treated for asthma – or 5.4 million people. According to Asthma UK, diet is one of several aspects of modern life that may be contributing to a rise in asthma in the last few decades.
Asthma is also a major health concern in Australia, with 1 in 10 Australians having the condition. Based on research presented to the Thoracic Society of Australia and New Zealand annual meeting, evidence suggests that a poor diet with high amounts of processed food, fat and refined sugar could be increasing inflammation in the body and therefore contributing to the prevalence of asthma.
Associate Professor Lisa Wood, who heads the nutrition programme at the Centre for Asthma and Respiratory Diseases at the University of Newcastle in Australia, and her colleagues, used the Dietary Inflammatory Index (DII) to compare 99 people with asthma to 61 healthy people.
The DII, established in the United States in 2009, is an index used to assess the inflammatory potential of individual diets.
All the participants in the study underwent blood tests as well as spirometry, a test to measure lung function. They filled out a food frequency questionnaire, from which their DII was calculated.
Diet, inflammation and asthma
The researchers found several indicators that a pro-inflammatory diet is linked to an increase in asthma:
- Mean DII score was higher for the participants with asthma than those in the healthy control group.
- For every 1 unit increase in the DII score, the odds of having asthma increased by 62%.
- In the third of patients with the highest DII score, their lung function was reduced by about 10% when compared to the third of patients with the lowest DII score.
- Levels of interleukin-6 in the blood (an indicator of inflammation) were also positively associated with DII score.
Associate Professor Wood says in a statement: "The usual diet consumed by asthmatics in this study was pro-inflammatory relative to the diet consumed by the healthy controls, as assessed using the DII score. The DII score was associated with lower lung function and increased systemic inflammation. Hence, consumption of pro-inflammatory foods in the diet may contribute to worse asthma status."
Dietary fat and salbutamol
Along with Dr Mehra Haghi and colleagues at the University of Sydney in Australia, Associate Professor Wood has also studied the effects of dietary fat on the effectiveness of the asthma medicine salbutamol (also known by the trade name Ventolin).