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01-04-2013 | Immunology | Article

Diet linked to severe asthma

Abstract

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medwireNews: Individuals with severe persistent asthma consume more fat and less fiber than healthy individuals, and this is associated with reduced lung function and increased airway inflammation, show study results.

"The relationships between dietary intake and asthma outcomes highlight the potential role for nutritional counselling in asthma management and suggest that dietary fibre and fat may be important nutrients to target," suggest Lisa Wood, from Hunter Medical Research Institute in Newcastle, Australia, and colleagues.

The team reports that patients with severe asthma had an average fiber intake that was 5 g/day lower than that reported by healthy controls in food-frequency questionnaires. Severe asthmatics also had a higher sodium intake and a lower potassium intake.

Patients with severe asthma had a higher total fat intake than healthy controls, at a mean difference of 5 g/day. Furthermore, for each additional 10 g of fat consumed, the likelihood for severe persistent asthma increased by 48%.

Dietary fiber intake was positively and significantly associated with forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1/FVC. Fat intake was positively associated and fiber intake and negatively associated with airway eosinophil percentage, while saturated fat intake was positively linked to sputum eosinophil percentage.

"This study suggests that fibre has a protective role in asthma, a finding supported by recent work in chronic obstructive pulmonary disease where lower fibre intakes were associated with risk of chronic obstructive pulmonary disease diagnosis in women," say Wood et al.

The researchers included 137 patients with stable asthma in their study, of whom 64 had severe persistent asthma, and 65 healthy controls. Dietary differences were evident between controls and patients with severe asthma, but not between controls and those with mild or moderate asthma.

Inhaled corticosteroid dosage and oral corticosteroid usage in the past 12 months did not appear to explain the dietary differences in patients with severe asthma, the researchers note in Respirology.

However, all asthmatics had significantly higher leptin levels than controls and leptin levels were positively linked to body mass index, which the team says "may indicate a link between appetite, leptin and corticosteroid use in asthma."

By medwireNews Reporters

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