Effects of Vitamin C Supplementation on C-Reactive Protein, Lactate and Blood Pressure Following Resistance Exercise in Overweight Men

Background and Objectives: Strenuous exercises have been shown to induce inflammation. However, consumption of products rich in antioxidants such as vitamin C may enhance this effect. The purpose of this study was to assess effects of vitamin C supplementation on C-reactive protein, lactate and blood pressure following resistance exercise in overweight men. Materials and Methods: In a randomized, double-blinded placebo-controlled trial, 20 young men (age of 38.8 y ±3.4 and BMI of 28.36 kg/m2 ±1.2) voluntarily participated and were randomly divided into vitamin C supplementation (n = 10) and placebo (n = 10) groups. After two weeks of receiving 500 mg/d of vitamin C or placebo, participants were involved in a session of resistance exercises (three sets of eight repetitions at 80% of one repetition maximum). To assess changes in C-reactive protein and lactate, blood samples were collected after blood pressure measurement at phases of baseline, pre exercise, immediately post resistance exercise and 24 h post exercise. Results: Results using ANOVA with repeated measurement showed that levels of C-reactive protein, lactate and systolic and diastolic blood pressure were not significantly changed in participants after supplementation (p 0.05). Moreover, significant increases were seen in lactate and systolic and diastolic blood pressure immediately after exercise intervention in both groups (p 0.05). However, C-reactive protein levels significantly increased only in placebo group immediately post resistance exercise and 24 h post exercise, compared to those at baseline (p = 0.008 and p = 0.021, respectively) and pre exercise (p = 0.007, and p = 0.019, respectively) times. The unique statistically significant difference between the two groups included a significant increase in level of C-reactive protein in placebo group immediately post resistance exercise (p = 0.031) and 24 h post exercise (p = 0.038) times, compared to supplement group. Conclusions: Results from the present study have demonstrated the beneficial effects of vitamin C supplement on improved blood pressure and lactate tolerance as well as decreased inflammatory responses of C-reactive protein caused by resistance exercises.