16 Does supplementation with a fruit-, vegetable-, and berry-concentrate affect post exercise IL-6 concentration?

Abstract

Introduction: Inflammatory cytokines like IL-6 show increased levels after strenuous bouts of exercise [1]. IL-6 induces activation of specific signal transduction mechanisms like the Janus kinasesignal transducer and activation of transcription (JAK-STAT) signaling pathway [2]. This JAK-STAT pathway stimulates gene expression and positive adaptation to physical exercise training via muscle and mitochondria growth or insulin sensitivity. Thus, the inhibition of the inflammatory IL-6 increase post exercise might prevent the adaptive and beneficial effects to skeletal muscle function induced by the exercise bouts [2,3]. We hypothesized that supplementation with an antioxidant fruit-, vegetable-, and berry-concentrate may affect these beneficial inflammatory responses to physical exercise. Methods: 21 trained men (30 40 yr) performed strenuous endurance exercise tests over 40 min at 80% of VO2max on a bicycle ergometer. In this randomized doubleblinded study 11 subjects received 6 capsules/d of the fruit-, vegetable-, and berry-concentrate (Juice Plus+®, Memphis, USA), and the other 10 men received a placebo. The verum provided 7.5mg b-carotene, 200mg vitamin C, 60mg vitamin E and 600mg folate. Blood was collected before exercise, immediately post exercise, 30 min post exercise and 30 h post exercise. The testing and blood drawing protocol were repeated after 4, 16 and 28 wk of supplementation/placebo treatment. Results: IL-6 increased significantly immediately and 30min post exercise at each strenuous endurance exercise test, recovering to pre exercise concentrations 30 h post exercise (p 0.05). Conclusion: The encapsulated fruit-, vegetable-, and berry-powder supplement does not influence plasma IL-6 concentration whose exercise induced increase is regarded to influence beneficially adaptation of strength and endurance performance.