Serum Vitamin C Levels and Use of Health Care Resources for Wheezing Episodes

Mainous, Arch G.; Hueston, William J.; Connor, Margaret K.

doi:10.1001/archfami.9.3.241

Cited by 7 publications

(6 citation statements)

References 14 publications

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“…Twenty-three of these assessed asthma as an outcome,13 – 35 9 assessed wheeze,36 – 44 5 assessed both asthma and wheeze,45 – 49 2 assessed airway reactivity50 51 and 1 assessed both asthma and airway reactivity 52. Twenty-six of the papers studied the effects of measures of dietary intake;16–19 23 25 27 29 31 32 34–38 40–45 47 49 – 52 23 studied biochemical levels in serum or plasma13–15 17 18 20 21 23 24 26–28 30 31 33 34 36 37 39 42 46 48 50 and 1 assessed the effects of antioxidant levels in sputum 22. Further information about the individual studies is presented in the online supplement.…”

Section: Resultsmentioning

confidence: 99%

Association between antioxidant vitamins and asthma outcome measures: systematic review and meta-analysis

Allen

Britton

Leonardi‐Bee

2009

Thorax

176

134

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Background: Epidemiological studies suggest that dietary intake of vitamins A, C and E may be associated with the occurrence of asthma. A systematic review and metaanalysis was conducted in accordance with MOOSE guidelines to determine whether vitamins A, C and E, measured as dietary intakes or serum levels, are associated with asthma. Methods: MEDLINE, EMBASE, CINAHL, CAB abstracts and AMED (up to November 2007), conference proceedings and bibliographies of papers were searched to identify studies of asthma, wheeze or airway responsiveness in relation to intakes and serum concentrations of vitamins A, C and E. Pooled odds ratios (OR) or mean differences (MD) with 95% confidence intervals (CI) were estimated using random effects models. Results: A total of 40 studies were included. Dietary vitamin A intake was significantly lower in people with asthma than in those without asthma (MD 2182 mg/day, 95% CI 2288 to 275; 3 studies) and in people with severe asthma than in those with mild asthma (MD 2344 mg/day; 2 studies). Lower quantile dietary intakes (OR 1.12, 95% CI 1.04 to 1.21; 9 studies) and serum levels of vitamin C were also associated with an increased odds of asthma. Vitamin E intake was generally unrelated to asthma status but was significantly lower in severe asthma than in mild asthma (MD 21.20 mg/day, 95% CI 22.3 to 20.1; 2 studies). Conclusions: Relatively low dietary intakes of vitamins A and C are associated with statistically significant increased odds of asthma and wheeze. Vitamin E intake does not appear to be related to asthma status.Diet has been widely implicated in the aetiology of cardiovascular disease 1 2 and other disorders, but the role of diet in the aetiology of respiratory diseases is less clearly defined. Over the past 15 years many observational epidemiological studies have reported associations between diet and asthma, and particularly for the antioxidant vitamins A, C and E. However, randomised controlled trials of vitamin supplementation in asthma thus far have been inconclusive. [3][4][5][6] In view of this apparent inconsistency between the observational and experimental data, 7 we have attempted to determine the magnitude of the overall associations of these vitamins estimated by the observational studies by carrying out a systematic review and meta-analysis to provide pooled quantitative estimates of the likely magnitude of the effect of dietary intake and blood levels of antioxidant vitamins on a range of measures of asthma and asthma severity. METHODS Systematic review methodsA comprehensive search of the MEDLINE (1950 to November 2007), EMBASE (1980( to November 2007, CINAHL (1982( to November 2007 and AMED (1985( to November 2007 was conducted to identify all published comparative epidemiological studies assessing the relation between antioxidant vitamins and asthma status. Search terms were selected under guidance from the Centre for Reviews and Dissemination and the Airways Group Specialist search terms.8 Reference lists from identified relevant studies and...

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Section: Resultsmentioning

confidence: 99%

Association between antioxidant vitamins and asthma outcome measures: systematic review and meta-analysis

Allen

Britton

Leonardi‐Bee

2009

Thorax

176

134

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“…Seven publications examined the association between dietary intake of vitamin C and the risk of having asthma 11,13,14,28–31 and three of these reported a protective effect of vitamin C 13,14,31 . There was statistically significant heterogeneity among the relative risks reported by the included studies ( Q ‐test: P = 0.02; H = 1.61; I 2 = 0.61).…”

Section: Resultsmentioning

confidence: 99%

“…[25][26][27][28] Two randomized clinical trials were not included because the limited number of participants was not suitable for an independent meta-analysis. 15 The remaining studies were retrieved and reviewed in detail: 10 articles met the inclusion criteria 13,15,16,[29][30][31][32][33][34][35] ( Fig. 1).…”

Section: Characteristics Of Studies Included In the Meta-analysismentioning

confidence: 99%

“…Seven publications examined the association between dietary intake of vitamin C and the risk of having asthma 11,13,14,[28][29][30][31] and three of these reported a protective effect of vitamin C. 13,14,31 There was statistically significant heterogeneity among the relative risks reported by the included studies (Q-test: P = 0.02; H = 1.61; I 2 = 0.61). The overall pooled relative risk of asthma was 1.06 (95% CI: 0.79-1.43) for subjects in the highest dietary intake category compared with those in the lowest category.…”

Section: Effect Of Antioxidant Intake On Overall Asthmamentioning

confidence: 99%

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Observational studies on the effect of dietary antioxidants on asthma: A meta‐analysis

Gao

et al. 2008

Respirology

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“…Only among participants who were not using vitamin or mineral supplements did we find that participants with either current or former asthma had lower serum vitamin C concentrations than did those who did not have asthma. In a previous analysis of NHANES III data, serum vitamin C concentrations also were not found to be associated with having a physician diagnosis of asthma (52). Whether circulating concentrations of antioxidants are a useful indicator of antioxidant status and its association with asthma is unclear.…”

Section: Studies Of Circulating Concentrations Of Antioxidantsmentioning

confidence: 87%

Serum Antioxidant Concentrations Among U.S. Adults with Self‐Reported Asthma

2004

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Antioxidants may protect the lungs of people with asthma against oxidative stress. Among participants aged > or = 20 years from the Third National Health and Nutrition Examination Survey (1988-1994), we examined serum antioxidant concentrations of 771 persons with current asthma, 352 persons with former asthma, and 15,418 persons without asthma. After adjustment for age, participants with current asthma had similar mean concentrations of vitamin A, retinyl esters, vitamin C, vitamin E, vitamin E/cholesterol ratio, vitamin E/triglyceride ratio, alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin, lycopene, and selenium as participants without asthma. We repeated these analyses among participants who did not use vitamin or mineral supplements. After age adjustment, participants with current asthma had lower vitamin C and beta-cryptoxanthin concentrations and a lower mean vitamin E/triglyceride ratio than participants without asthma. In multiple linear regression models that included age, sex, race or ethnicity, education, smoking status, nonhigh-density lipoprotein cholesterol concentration, high-density lipoprotein cholesterol concentration, body mass index, physical activity, and alcohol use, asthma status was not significantly associated with any of the antioxidant concentrations. However, lower vitamin C concentrations were observed among people with current or former asthma than among people who never had asthma (p = 0.014). In the United States, people with asthma do not have manifest antioxidant deficiencies.

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Serum Vitamin C Levels and Use of Health Care Resources for Wheezing Episodes

Abstract: Serum vitamin C levels do not appear to be a marker for use of health care services for wheezing. Future investigations of the role of antioxidants in managing respiratory conditions should focus on the clinically important outcomes of health care use.

Cited by 7 publications

References 14 publications

Association between antioxidant vitamins and asthma outcome measures: systematic review and meta-analysis

Association between antioxidant vitamins and asthma outcome measures: systematic review and meta-analysis

Observational studies on the effect of dietary antioxidants on asthma: A meta‐analysis

Serum Antioxidant Concentrations Among U.S. Adults with Self‐Reported Asthma

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