Vitamins C and E for asthma and exercise-induced bronchoconstriction

Abstract

It is not possible to draw firm conclusions from this review with respect to the comparison of vitamin C and E supplementation versus placebo in the management of asthma or exercise-induced bronchoconstriction. We found only one study relevant to exercise-induced bronchoconstriction; most included participants came from studies designed to assess the effect of vitamin supplementation on the impact of atmospheric pollutants (such as ozone). Evidence is lacking on the comparison of vitamin C and E supplementation versus placebo for asthma with respect to outcomes such as HRQL and exacerbations, which were not addressed by any of the included studies.When compared with lung function tests alone, HRQL scores and exacerbation frequency are better indicators of the severity of asthma, its impact on daily activities and its response to treatment in a patient population. These end points are well recognised in good quality studies of asthma management. However, clinical studies of vitamins C and E in the management of asthma using these important end points of exacerbations and effects on quality of life are not available, and evidence is insufficient to support robust conclusions on the role of vitamin C and E supplementation in asthma and exercise-induced breathlessness.

Asthma and dietary intake: an overview of systematic reviews

“…These results further support to the notion that actual intake of sources of antioxidants might have a beneficial effect against asthma. So far, the evidence from RCTs on dietary antioxidants (single or combined) has provided no justification to use nutritional supplements in the prevention or improvement of asthma management in adults and children (4)(5)(6).…”

“…To date, epidemiological evidence from observational studies is suggestive of a possible protective effect of intake of fresh foods (mainly vegetables and fruits) (3). Welldesigned randomized controlled trails (RCTs) have been carried out to test the effect of antioxidant supplements on asthma risk (4,5) and asthma severity (6) but results have so far been disappointing. More recently, evidence from dietary interventions using increased net intake of dietary sources of antioxidants in asthmatic adults shows some moderate but promising results in improved lung function and markers of inflammation in asthmatic adults (7).…”

Is there sufficient evidence to support the use of vitamin supplements in the asthmatic patient?

“…None of them reported the efficacy of this treatment on health-related quality of life and asthma exacerbations. No significant improvement in asthma symptoms or lung function was observed [14]. These studies provided no data on health-related quality of life of the participants and asthma exacerbations [14].…”

“…Some hypothesized that vitamin E not only may synergize the antioxidant activity of vitamin C but also increase its absorption; therefore, the coadministration of these two vitamins may be of more benefit in the treatment of asthma [13]. The most recent Cochrane systematic review on the efficacy of combination treatment with vitamin C and E supplementation in adult patients with asthma found only three RCTs with 46 participants with different severities of asthma and one RCT on patients with exercise-induced asthma with only eight participants [14]. The dosage of combination treatments varied from 0.5 to 2 g vitamin C and 0.267 to 0.5 g once daily for 5-12 weeks [14].…”

“…The most recent Cochrane systematic review on the efficacy of combination treatment with vitamin C and E supplementation in adult patients with asthma found only three RCTs with 46 participants with different severities of asthma and one RCT on patients with exercise-induced asthma with only eight participants [14]. The dosage of combination treatments varied from 0.5 to 2 g vitamin C and 0.267 to 0.5 g once daily for 5-12 weeks [14]. None of them reported the efficacy of this treatment on health-related quality of life and asthma exacerbations.…”