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Exercise-induced endotoxemia: the effect of ascorbic acid supplementation.
Tony Ashton1, Ian S Young, Gareth W Davison
1Department of Sport Science, De Montfort University, Lansdowne Road, Bedford, England, UK. tashton@dmu.ac.uk
Free Radical Biology & Medicine
|July 30, 2003
Summary
Strenuous exercise increases endotoxemia (lipopolysaccharide). Antioxidant ascorbic acid supplementation prevented this increase, suggesting a free radical process, but limited its use as an oxidative stress marker.
Area of Science:
- Exercise Physiology
- Biochemistry
- Immunology
Background:
- Strenuous, long-duration aerobic exercise can cause endotoxemia, characterized by increased plasma lipopolysaccharide (LPS) levels.
- This endotoxemia is linked to cytokine release, oxidative stress, and altered gastrointestinal function.
- The impact of short-term strenuous aerobic exercise and antioxidant supplementation on exercise-induced endotoxemia remains unclear.
Purpose of the Study:
- To investigate the effects of short-term strenuous aerobic exercise on endotoxemia and oxidative stress markers.
- To determine if oral ascorbic acid (vitamin C) supplementation can mitigate exercise-induced endotoxemia and associated oxidative stress.
Main Methods:
- Healthy volunteers underwent maximal acute aerobic exercise.
- Plasma levels of lipopolysaccharide (LPS), nitrite, and ascorbate free radical were measured pre- and post-exercise.
- Participants received oral ascorbic acid supplementation (1000 mg) or a placebo.
- Changes in biochemical markers were analyzed with and without ascorbic acid supplementation.
Main Results:
- Maximal aerobic exercise significantly increased plasma LPS concentrations (endotoxemia) and nitrite levels.
- Ascorbate free radical levels also increased post-exercise.
- Oral ascorbic acid supplementation significantly increased plasma ascorbic acid levels.
- Supplementation with ascorbic acid abolished the exercise-induced increases in plasma LPS and nitrite.
- Ascorbic acid supplementation led to a significant increase in plasma ascorbate free radical levels both before and after exercise.
Conclusions:
- Short-term strenuous aerobic exercise induces significant endotoxemia and increases markers of oxidative stress.
- Ascorbic acid supplementation effectively prevents the rise in LPS and nitrite associated with exercise.
- The amelioration of exercise-induced endotoxemia by antioxidants suggests a free radical-mediated mechanism.
- The utility of the ascorbate radical as an oxidative stress marker is limited in individuals supplemented with ascorbic acid.