Antioxidants reduce the frequency and severity of asthma attacks. They combat the exacerbation of lung disorders induced by inhalation of pollutants and irritants, and lessen respiratory distress and permanent lung injury caused by inhaling damaging substances. Asthmatics tend to have reduced blood levels of antioxidants, especially vitamins A, C and E, and selenium. Severe, persistent asthma is associated with below-RDA intakes of magnesium and antioxidants. Antioxidants play crucial roles in respiratory immunity. In children and the elderly, antioxidant supplementation has been shown to reduce respiratory infection incidence.
Vitamin C is the primary antioxidant in the lungs, and is a powerful antihistamine. It enhances immunity and reduces the severity of allergic responses. Glutathione is second in importance after vitamin C and they're synergistic. Working together, glutathione and C normalize leukotriene activity and proliferation, helping to prevent "runaway" inflammation. Lung function and immune response are severely compromised if these antioxidants are below optimal levels. The benefits of supplementing NAC orally prior to the development of lung disorders cannot be overemphasized:
- NAC is one of only a few supplements proven to help control chronic obstructive pulmonary disease (doses 400-1,200 mg/day).
- Mustard gas inhalation causes lung tissue injury, resulting in respiratory distress syndrome. Guinea pigs inhaling 2-chloroethyl ethyl sulfide (mustard gas analouge) had severe lung injury in one hour. Lung edema, congestion, hemorrhaging, and inflammation increased progressively over the following 21days. A single dose of NAC (0.5 g) fed just before 2-chlorethyl ethyl sulfide exposure was ineffective at counteracting these effects. However, guinea pigs given NAC in drinking water for three or 30 days (two groups) prior to exposure had a 69-76 percent reduction in lung injury.
- ROM are formed in response to influenza infection, and increase the pathogenicity of the virus. Mice were infected with influenza, then given NAC (1 g/kg/day) or nothing. They all developed disease symptoms, and many died, but a higher percentage of the NAC group recovered. NAC increased synthesis of glutathione, which probaly counteracted the ROM effects.
- Oxidative stress is involved in asthma and chronic inhalant allergies. Allergically sensitized rats were given NAC (3 mmol/kg/day) for one week, then were exposed to allergens. Nac didn't affect the immediate bronchial spasm reaction to allergen exposure. This later hyperactivity is largely stimulated by leukotrienes and ROM - which are reduced in activity by glutathione.
- Rats were exposed to the smoke of cigarettes/hour/day for four weeks and fed a low protein diet. Liver and lung glutathione levels were reduced from both diet and smoke, and ROM levels were increased. However, there was no reduction in lung glutathione when the diet was supplemented with NAC.
- Oxidants are implicated in lung inflammation caused by air pollution. Rats were exposed to aerosol dust for five hours. One group was given 50 mg/kg NAC one hour prior to exposure. Rats breathing aerosol dust showed significant oxidative stress and slight lung edema, but NAC-treatment prevented these alterations.
