Dietary antioxidants and asthma in adults

Thorax. 2006 May;61(5):388-93. doi: 10.1136/thx.2004.024935. Epub 2006 Feb 7.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Antioxidants / administration & dosage*
  • Ascorbic Acid / blood
  • Asthma / blood
  • Asthma / etiology*
  • Case-Control Studies
  • Cohort Studies
  • Diet / standards*
  • Energy Intake
  • Female
  • Humans
  • Male
  • Middle Aged
  • Risk Factors

Substances

  • Antioxidants
  • Ascorbic Acid