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.