Inter‐individual variability in redox and performance responses after antioxidant supplementation: A randomized double blind crossover study

Abstract

Aim We aimed to investigate the inter‐individual variability in redox and physiological responses of antioxidant‐deficient subjects after antioxidant supplementation. Methods Two hundred individuals were sorted by plasma vitamin C levels. A low vitamin C group (n = 22) and a control group (n = 22) were compared in terms of oxidative stress and performance. Subsequently, the low vitamin C group received for 30 days vitamin C (1 g) or placebo, in randomized, double‐blind, crossover fashion, and the effects were examined through a mixed‐effects model, while individual responses were calculated. Results The low vitamin C group exhibited lower vitamin C (−25 μmol/L; 95%CI[−31.7, −18.3]; p < 0.001), higher F2‐isoprostanes (+17.1 pg/mL; 95%CI[6.5, 27.7]; p = 0.002), impaired VO2max (−8.2 mL/kg/min; 95%CI[−12.8, −3.6]; p < 0.001) and lower isometric peak torque (−41.5 Nm; 95%CI[−61.8, −21.2]; p < 0.001) compared to the control group. Regarding antioxidant supplementation, a significant treatment effect was found in vitamin C (+11.6 μmol/L; 95%CI[6.8, 17.1], p < 0.001), F2‐isoprostanes (−13.7 pg/mL; 95%CI[−18.9, −8.4], p < 0.001), VO2max (+5.4 mL/kg/min; 95%CI[2.7, 8.2], p = 0.001) and isometric peak torque (+18.7; 95%CI[11.8, 25.7 Nm], p < 0.001). The standard deviation for individual responses (SDir) was greater than the smallest worthwhile change (SWC) for all variables indicating meaningful inter‐individual variability. When a minimal clinically important difference (MCID) was set, inter‐individual variability remained for VO2max, but not for isometric peak torque. Conclusion The proportion of response was generally high after supplementation (82.9%–95.3%); however, a few participants did not benefit from the treatment. This underlines the potential need for personalized nutritional interventions in an exercise physiology context.

Effects of CurraNZ, a New Zealand Blackcurrant Extract during 1 Hour of Treadmill Running in Female and Male Marathon des Sables Athletes in Hot Conditions: Two Case Studies

“…This less-than-optimal adaptation would allow anthocyanin-induced metabolites to affect one or more of the many events involved in exercise-induced fat oxidation. However, case studies with a focus on physiological and metabolic responses to the intake of New Zealand blackcurrant extract or any other dietary supplementation can easily provide a non-response, as is common in cohort studies that examine the effects of supplementation (e.g., Margaritelis et al [ 28 ]). Therefore, the effectiveness of the intake in the present study for the male Marathon des Sables athlete during exertional heat stress will require confirmation in a cohort study of male athletes and with an adequate sample size [ 29 ] to confirm generalizability.…”

Nutritional health

“…16 The global dietary supplement markets are growing at almost obscene rates with an increased consumer demand for preventive healthcare and aging populations in developed countries able to afford these products. While for many commercially available supplements meaningful data are, at best, incomplete, examples of promising preventive approaches by nutrient supplementation may potentially be assumed for antioxidants, 17,18 bioactive collagen peptides, 19 and nitrates. 20 In summary, the intricate interplay between nutrition and physiology underscores the critical importance of dietary choices in maintaining optimal health.…”

Ten “Cheat Codes” for Measuring Oxidative Stress in Humans

“…HPLC-based methods can measure the concentration of low molecular weight antioxidants, like vitamin C (Margaritelis et al, 2023). EPR spectrometry can measure the vitamin C and E radicals to provide information on their redox activity in human samples (Bailey et al, 2022).…”

“…ELISA kits can measure some lipid peroxidation products (Halliwell and Lee, 2010), notably F2-isoprostanes. While they can be insufficiently specific in some cases (Nikolaidis et al, 2011), they have illuminated individual responses to exercise in humans (Margaritelis et al, 2014; N.V. Margaritelis et al, 2018Margaritelis et al, , 2023.…”