Abstract
BackgroundAsthma is the most prevalent chronic disease to complicate pregnancies worldwide, affecting around 12% of pregnant women in Australia. Oxidative stress and inflammation manifest during pregnancy; however asthma in pregnancies further intensifies oxidative stress. Consumption of antioxidant-rich foods has been shown to be beneficial for asthma control in non-pregnant asthmatic adults. It has not been investigated whether antioxidant-rich foods can improve the elevated oxidative stress that occurs with asthma in pregnancy, thereby improving asthma control. The primary aim of this study is to determine whether increased consumption of antioxidant-rich foods for 12 weeks will improve maternal asthma control, compared to standard dietary intake during pregnancy.Methods/designA 12 week, parallel randomized controlled trial will be conducted. One hundred and sixty eight pregnant women with mild, moderate, or severe asthma, currently using inhaled corticosteroids, and with poor diet quality, will be recruited at approximately12 weeks gestation. Following a 4 week run-in period, women will be randomized to either a 12 week antioxidant intervention (increased consumption of antioxidant-rich foods (≥5 servings/day vegetables, ≥2 servings/day fruit, ≥8 ½ servings/day grains (mostly wholegrains), 3–4 serving/week lean meat) or standard pregnancy care. The primary outcome is asthma control score (decrease of 0.5, the minimally clinically significant change). Secondary outcomes include plasma antioxidants, markers of oxidative stress, and time to, and number of, exacerbations. With two-tailed t-tests at 80% power, a sample size of 52 completions per group is required. Allowing for a 78% retention including a 20% removal of women from the analysis due to non-compliance, we will recruit 168 women.DiscussionIt is expected that this 12 week study will improve asthma control. This is significant because asthma is the most prevalent condition to complicate pregnancies and contributes to poor maternal, neonatal and infant health outcomes. Our research will provide the first evidence to show that, in pregnancy, consumption of antioxidant-rich foods is a key modifier of clinical asthma status. This research is crucial for contributing to the evidence base to inform future guidelines given existing clinical and research gaps.Trial registrationACTRN12613000301763
Highlights
Asthma is the most prevalent chronic disease to complicate pregnancies worldwide, affecting around 12% of pregnant women in Australia
Our research will provide the first evidence to show that, in pregnancy, consumption of antioxidant-rich foods is a key modifier of clinical asthma status
The lungs have endogenous antioxidant mechanisms to combat the damaging effects of reactive oxygen species; levels of antioxidants in the lungs as well as in circulation are reduced in asthmatic patients [4,5,6]
Summary
Asthma is the most prevalent chronic disease to complicate pregnancies worldwide, affecting around 12% of pregnant women in Australia. Consumption of antioxidant-rich foods has been shown to be beneficial for asthma control in non-pregnant asthmatic adults. The primary aim of this study is to determine whether increased consumption of antioxidant-rich foods for 12 weeks will improve maternal asthma control, compared to standard dietary intake during pregnancy. Other human mechanistic studies have shown that the airway epithelium in asthmatic adults is more susceptible to oxidants than in non-asthmatic adults [8], and Zalewski et al identified lower labile sputum zinc levels that were associated with increased frequency of wheeze, asthma severity and reduced lung function [9]. Asthmatic subjects who withdrew antioxidant-rich foods from their diet for 10 days, including limiting fruit (≤1 serving/d) and vegetable (≤2 servings/d) intake (n = 22), had reduced plasma carotenoids, increased sputum neutrophils and poorer lung function and asthma control [10]. Dietary modification through whole foods appears a valuable strategy for improving outcomes associated with asthma
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