Oxidation and free-radical damage are terms used to describe injury to cells caused by highly reactive chemical particles. A free radical is a molecule that readily gives up an electron—almost like firing a tiny chemical “bullet.” This process is referred to as oxidation, oxidative stress, or free-radical damage. Certain nutrients, including vitamins C and E, help protect cells from this damage by neutralizing free radicals. In this sense, antioxidants act like microscopic “bullet-proof vests” for our tissues.
In asthma, two primary processes contribute to symptoms: irritation and inflammation of the airways, largely driven by oxidative stress, and spasm of the airway muscles. From a physiologic standpoint, therapies that protect the lining of the airways or help relax bronchial smooth muscle would be expected to benefit people with asthma. Supporting this idea, research published in the New England Journal of Medicine demonstrated increased markers of free-radical activity in patients with asthma, suggesting that oxidative stress plays a role in the disease process.
A growing body of research supports the value of antioxidants in asthma. A review published in the American Journal of Clinical Nutrition found that a diet low in vitamin C is a risk factor for asthma. The review examined 11 studies conducted between 1973 and 1995 that evaluated vitamin C supplementation in asthmatic patients. Seven of these studies reported improvements in pulmonary function tests with vitamin C doses ranging from 1 to 2 grams per day. Exposure to oxidants was also shown to worsen asthma symptoms.
Additional research has shown that low plasma levels of antioxidant nutrients are associated with greater asthma severity. A study published in the European Respiratory Journal found that patients with severe asthma had significantly lower concentrations of both dietary and non-dietary antioxidants. Similarly, research in Thorax reported that individuals with asthma consumed fewer vitamin C–rich foods compared with healthy controls.
Vegetables are among the richest dietary sources of antioxidants, and higher intake appears to be beneficial. Data from the E3N study, published in Thorax, showed that increased consumption of fruits and vegetables was associated with fewer asthma symptoms. Overall, nutrition appears to be a valuable tool in supporting asthma management.
In addition to antioxidant vitamins, other nutrients shown in research to support asthma health include omega-3 fatty acids, selenium, magnesium, coenzyme Q10, and manganese.
