I thought this was interesting, it was announced this morning. [But again, as I've said before, one study does not mean it's true--keep that in mind when you read this.] A new study from Indiana University has found that large doses of vitamin C can stem the cycle of inflammation that contributes to exercise-induced asthma (EIA), a wheezing and tightness of the chest that can occur after rigorous exercise.

The study, involving asthma sufferers who have EIA, found that participants who had taken 1,500 mg of ascorbic acid for two weeks showed improved post-exercise lung function and a decreased concentration of biomarkers in their urine related to airway inflammation. This included the infamous leukotrienes, which play a key role in the inflammation that can lead to EIA.

The findings, appearing in the online issue of Respiratory Medicine, could provide asthma suffers a nutrition-based tool for controlling their EIA symptoms, even if it means continuing with their daily maintenance medications.

"Ascorbic acid supplementation could offer asthmatics better control even if it means no change in their medication status," said lead author Sandra Tecklenburg, a doctoral candidate in IU Bloomington's Department of Kinesiology and an assistant coach for IU women's track and cross country teams.

"They could have more symptom-free days or just feel better. For me, that's important because I'd like to see the asthmatic athletes I'm coaching be able to finish a workout or not have to drop out of a race, or just perform better in general."

About the placebo-controlled study:

* The double-blind, randomized, crossover study involved eight asthmatics who have EIA, also called exercise-induced bronchoconstriction. In turn, they received 1,500 mg of vitamin C daily for two weeks and ran on a treadmill. Their urine was examined for a variety of inflammation biomarkers related to lung function, making this the first study involving vitamin C to examine such biomarkers.

* Post-exercise lung function dropped by an average 6.4 percent for study participants receiving vitamin C supplementation, compared to drops of 14.3 percent and 12.9 percent for participants on a normal diet or receiving a placebo respectively. A drop of less than 10 percent is no longer considered EIA. The ascorbic acid diet reduced the maximum post-exercise fall in forced expiratory volume in 1-sec (FEV1) by about 56 percent compared to the usual diet.

* The concentration of the airway inflammatory biomarkers (e.g., leukotrienes and prostaglandins) in the urine decreased substantially following exercise on the ascorbic acid diet compared to the usual and placebo diets. Tecklenburg said this is particularly notable concerning the involvement of these biomarkers in the pathogenesis of EIA.

Vitamin C is an antioxidant. Tecklenburg said the study found it helped reduce the oxidative stress that can lead to EIA by disrupting the cycle caused when free radicals trigger an immune response in the body, which then produces more free radicals. Ascorbic acid is water soluble so it does not become toxic in large quantities. Tecklenburg said none of the study subjects reported adverse side effects from the dosage, which is more than 10 times the recommended daily allowance for adults.

Co-authors of the study are Timothy Mickleborough, an associate professor in the Department of Kinesiology; Alyce Fly, associate professor in the Department of Applied Health Science; Yeon Bai, doctoral candidate in the department of Applied Health Science; and Joel Stager, professor in the Department of Kinesiology.

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