Thursday, December 18, 2014
Many people enjoy the post-exercise flush in the skin, but not many feel the same about post- exercise breathlessness. New research has found that vitamin C may help reduce bronchoconstriction and other respiratory symptoms caused by exercise.
Published in the Allergy, Asthma & Clinical Immunology journal, the study found that besides attenuating exercise-induced increases in oxidative stress markers, vitamin C also helps in the metabolism of histamine, prostaglandins, and cysteinyl leukotrienes, which are mediators in the pathogenesis of exercise-induced bronchoconstriction.
The researchers conducted a meta-analysis using respiratory function markers like FEV1 and FEF25-75. FEV1 is the standard pulmonary function outcome for evaluating exercise-induced bronchoconstriction in the large-airways, whereas FEF25-75 measures small-airway obstruction.
Results from the meta-analysis revealed that vitamin C halved post-exercise FEV1 decline and incidence of respiratory symptoms in participants who experience exercise-induced broncho-constriction. Another trial reported that vitamin C halved the duration of the respiratory symptoms in male adolescent competitive swimmers.
In addition to the meta-analysis, the researchers conducted a secondary analysis of a study involving 12 participants with an average age of 26 years. These participants had asthma and suffered from exercise-induced bronchoconstriction. The FEV1 and FEF60 levels before and after exercise were analysed in the vitamin C and placebo groups. In 5 out of the 12 participants, exercise caused a decline greater than 60% in FEF60. However, when vitamin C was administered, the FEF60 levels increased by between 50% to 150%. This is a novel finding because it indicates that vitamin C may have substantial effects on the small airways.
“Given the safety and low cost of vitamin C, it seems reasonable for physically active people to test whether vitamin C is beneficial on an individual basis, if they have documented exercise-induced bronchoconstriction or suffer from respiratory symptoms such as cough or sore throat after taking vigorous exercise,” concluded the researchers.
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