Asthma Research Today is a free monthly online journal that collates and summarizes the latest research about Asthma, including details on symptoms, diagnosis, treatment, causes, medications.

Dietary antioxidants and asthma in adults.

Patel BD, Welch AA, Bingham SA, Luben RN, Day NE, Khaw KT, Lomas DA, Wareham NJ

Department of Public Health and Primary Care, Institute of Public Health, Cambridge, UK.

BACKGROUND: Several antioxidant nutrients have been reported to be inversely associated with asthma. A study was undertaken to assess the independent associations of these nutrients with asthma in adults. METHODS: A nested case-control study was performed in 515 adults with physician diagnosed asthma and 515 matched controls using dietary data obtained from 7 day food diaries. The main outcome measures were physician diagnosed asthma and current symptomatic asthma (diagnosed asthma and self-reported wheeze within the previous 12 months). RESULTS: Cases were similar to controls in age, sex, social class, and daily energy intake but had a lower median intake of fruit (132.1 v 149.1 g/day, p< or =0.05). 51.5% of the population reported zero consumption of citrus fruit; relative to these individuals, people who consumed >46.3 g/day had a reduced risk of diagnosed and symptomatic asthma (OR adjusted for potential confounders 0.59 (95% CI 0.43 to 0.82) and 0.51 (95% CI 0.33 to 0.79), respectively). In nutrient analysis, dietary vitamin C and manganese were inversely and independently associated with symptomatic asthma (adjusted OR per quintile increase 0.88 (95% CI 0.77 to 1.00) for vitamin C and 0.85 (95% CI 0.74 to 0.98) for manganese), but only manganese was independently associated with diagnosed asthma (OR 0.86 (95% CI 0.77 to 0.95)). Adjusted plasma levels of vitamin C were significantly lower in symptomatic cases than in controls (54.3 v 58.2 micromol/l, p = 0.003). CONCLUSIONS: Symptomatic asthma in adults is associated with a low dietary intake of fruit, the antioxidant nutrients vitamin C and manganese, and low plasma vitamin C levels. These findings suggest that diet may be a potentially modifiable risk factor for the development of asthma.

Published 1 May 2006 in Thorax, 61(5): 388-93.
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