Oxidative stress and antioxidant deficiencies in asthma: potential modification by diet

Abstract

The lungs of asthmatic patients are exposed to oxidative stress due to the generation of reactive oxygen and nitrogen species as a consequence of chronic airway inflammation. Increased concentrations of NO*, H2O2 and 8-isoprostane have been measured in exhaled breath and induced sputum of asthmatic patients. O2*-, NO*, and halides interact to form highly reactive species such as peroxynitrite and HOBr, which in turn cause nitration and bromination of protein tyrosine residues. Oxidative stress may also reduce glutathione levels and cause inactivation of antioxidant enzymes such as superoxide dismutase, with a consequent increase in apoptosis, shedding of airway epithelial cells and airway remodelling. The oxidant/antioxidant equilibrium in asthmatic patients may be further perturbed by low dietary intakes of the antioxidant vitamins C and E, selenium and flavonoids, with a consequent lowering of the concentrations of these and other non-dietary antioxidants such as bilirubin and albumin in plasma and airway epithelial lining fluid. Although supplementation with vitamins C and E appears to offer protection against the adverse effects of ozone, recent randomised, placebo-controlled trials of vitamin C or E supplements for patients with mild asthma have not shown significant benefits over standard therapy. However, genetic variation in glutathione S-transferase may influence the susceptibility of asthmatic individuals to oxidative stress and the extent to which they are likely to benefit from antioxidant supplementation. Long-term prospective trials are required to determine whether modification of dietary intake will benefit asthma patients and reduce the socio-economic burden of asthma in the community.

Selenium biochemistry and its role for human health

“…Negative correlations were observed between serum Se level and rheumatoid arthritis, asthma, and immune activation (through soluble interleukin-2 receptor and erythrocyte sedimentation rate) in Crohn's disease. [207][208][209] Plasma Se and SelP concentration is lower in patients with sepsis at different levels of seriousness or sepsis-like illness. 210 Blood, plasma or erythrocytes Se level is generally lower in patients with psoriasis, a chronic immune-mediated skin lesion.…”

Obesity, Nutrition, and Asthma in Children

“…Importantly, TLR can also be activated by some dietary fatty acids. It should not be surprising that elevated dietary saturated fatty acids have been associated with asthma risk 57,58 and asthma severity. 59 Low antioxidant intake and serum levels have been associated with asthma risk and severity.…”

Air pollution, oxidative stress and dietary supplementation: a review

“…Recent research has identified oxidative stress as one potential feature underlying the toxic effect of air pollutants, which trigger a number of redox sensitive signalling pathways, such as those of inflammatory response and cytokine production [2][3][4][5]. Toxicity may arise from an imbalance of biological pro-oxidant and antioxidant processes [6] linked to increased exposure to oxidants or the presence of impaired antioxidant defences [7,8]. This imbalance has long been recognised in investigations of ozone (O 3 ) [9], one of the most potent oxidants, and more recent studies have focused on this particular mechanistic hypothesis [10].…”