Asthma and oxidant stress: nutritional, environmental, and genetic risk factors.

Abstract

A considerable body of evidence suggests that oxidant stress results in inflammation and tissue damage in the respiratory system, and later in immune damage, and that individuals with lowered cellular reducing capacity are at increased risk to develop asthma. Reducing capacity in the erythrocyte is generated through the pentose phosphate pathway and this pathway also generates a major portion of the reducing capacity in all cells of the body. Therefore, dietary, environmental, and genetic factors which diminish cellular reducing capacity will increase tissue vulnerability to oxidant stress and are likely to increase asthma risk. Dietary selenium deficiency lowers red cell glutathione peroxidase activity and is associated with an increased risk for asthma, and low dietary intakes of vitamins C and E also appear to increase asthma risk. High body iron stores increase free radical production and may also elevate asthma risk. Environmental lead exposure depresses the activities of a several enzyme systems that influence cellular reducing capacity (glucose-6-phosphate dehydrogenase, NAD synthetase, glutathione peroxidase, superoxide dismutase, catalase) and consequently may increase asthma risk. Genetically-determined low activity of glucose-6-phosphate dehydrogenase lowers cellular reducing capacity and may also heighten asthma risk. Simple dietary and environmental interventions may significantly reduce oxidant stress and prevent or minimize the development of asthmatic symptoms and should prove to be a cost effective approach to asthma management in addition to current pharmacological strategies.

Vitamins and respiratory disease: antioxidant micronutrients in pulmonary health and disease

“…The initial proposal of Seaton et al (1994) has been examined in a case-control study (Soutar et al 1997) in which it was found that those individuals with the lowest intakes of vitamin C and Mn are associated with a > 5-fold increased risk of bronchial reactivity (Table 3). The various nutrients that have been shown in subsequent casecontrol or cross-sectional studies to be associated with a reduced risk of asthma are vitamins A, C and E, flavones and flavonoids, Mg, Ca, Na, K, Se, Cu, Zn and fatty acids (Schwartz & Weiss, 1990;Greene, 1995;Bodner et al 1999;Smit et al 1999;Fogarty & Britton, 2000;Grievink et al 2000a;Hijazi et al 2000;Romieu & Trenga, 2001;Smit, 2001). However, longitudinal studies have shown that only vitamin E has a protective effect (Troisi et al 1995).…”

Amelioration of asthmatic inflammation by an aqueous extract of Spinacia oleracea Linn

“…In bronchial asthma, various mediators induce the infiltration of mast cells, eosinophils and Th2 lymphocytes into lesions with downstream mediators, resulting in classical asthmatic phenotypes, such as mucous over-production, airway hyper-responsiveness, and submucosal thickness (4).…”

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“…The imbalance between ROS and antioxidant defenses is defined as oxidative stress, and is involved in relevant processes such as ageing and several degenerative diseases 26 . Free radicals can damage DNA, proteins and lipid membranes.…”