Nutritional interventions and the IL-6 response to exercise

IL-6 is a pleiotropic cytokine with a wide range of biologic effects. In response to prolonged exercise, IL-6 is synthesized by contracting skeletal muscle and released into circulation. Circulating IL-6 is thought to maintain energy status during exercise by acting as an energy sensor for contracting muscle and stimulating glucose production. If tissue damage occurs, immune cells infiltrate and secrete cytokines, including IL-6, to repair skeletal muscle damage. With adequate rest and nutrition, the IL-6 response to exercise is attenuated as skeletal muscle adapts to training. However, sustained elevations in IL-6 due to repeated bouts of unaccustomed activities or prolonged exercise with limited rest may result in untoward physiologic effects, such as accelerated muscle proteolysis and diminished nutrient absorption, and may impair normal adaptive responses to training. Recent intervention studies have explored the role of mixed meals or carbohydrate, protein, omega-3 fatty acid, or antioxidant supplementation in mitigating exercise-induced increases in IL-6. Emerging evidence suggests that sufficient energy intake before exercise is an important factor in attenuating exercise-induced IL-6 by maintaining muscle glycogen. We detail various nutritional interventions that may affect the IL-6 response to exercise in healthy human adults and provide recommendations for future research exploring the role of IL-6 in the adaptive response to exercise.