The effects of fruit vegetable concentrate upon oxidative stress and buffering capacity in vivo

Turner, Mark Christopher

Abstract

Western diets are high in protein and insufficient in fruit and vegetable consumption. This can result in low-grade acidosis, which is linked with various metabolic diseases and can also impact exercise performance. Supplementing with fruit vegetable concentrate (FVC) could potentially attenuate the effects of low-grade acidosis and provide protection against the effects of oxidative stress due to the high antioxidant potential within these nutritional supplements.

The first study investigated the dose response of acute FVC supplementation upon blood acid-base levels during resting conditions. Eight physically active males (age: 23 ± 2 yr; height 180.1 ± 6.2 cm; weight 76.9 ± 7.2 Kg) consumed either a manufacturer recommended dose (9 g) of energised greens (FVC), an equal dose placebo (PLC), or a known acid-base regulator (NaHCO₃) in a single blind, randomised crossover design. Capillary blood samples were taken every 15 minutes to measure changes in blood pH, bicarbonate (HCO₃-) and base-excess (BE). A visual analogue scale (VAS) was used to analyse potential changes in gastrointestinal discomfort. Blood pH rose in all trials but was only significantly elevated in the NaHCO3 trial (P<0.001) compared to FVC and PLC trials. Similarly, HCO₃- only rose following NaHCO₃ ingestion (P<0.001) with no significant increases in the FVC or PLC trials (P>0.05). BE significantly increased during the NaHCO₃ trial (P<0.001) with no changes following FVC or PLC ingestion.

The second study investigated the effects of acute FVC supplementation upon markers of oxidative stress during an acute bout of intermittent exercise. Seven physically active males (age: 25 ± 6 yr; height 179.0 ± 6.7 cm; weight 73.2 ± 9.1 kg, 54.7 ± 7.3 VO₂max) consumed either a manufacturer recommended dose of FVC (9 g) or a placebo with 750 ml of water after an overnight fast. One-hour post ingestion subjects completed an acute bout of intermittent exercise consisting of eight 2-minute intervals at 85% Wmax interspersed with seven 2-minute intervals at 50% Wmax of the subject’s pre-determined maximal wattage (Wmax). Heart rate and RPE were measured at the end of each interval. Venous blood samples were drawn pre, post ingestion, immediately post, one and two hours post exercise for changes in Thiobarbituric Acid Reactive Substances (TBARS), Total Antioxidant Capacity (TAC), and Total Glutathione (TGSH). Body mass, urine osmolality and urine pH was measured pre and post ingestion and immediately post exercise. There were no significant main for condition (P=0.80) or time (P=0.56) or interaction effects (P=0.17) for changes in TGSH concentrations. There was no significant main effect for condition (P=0.47), or time (P=0.62) respectively for changes TAC concentrations, nor were any interaction effects observed (p=0.39). However there were no main (P=0.53), or interaction effects (P=0.97), TBARS concentrations were lower following FVC supplementation but were not significantly different. Furthermore there was no significant differences as a result of PLC supplementation (P=0.37). There were no effects for time (P=0.99) or conditions (P=0.92) for changes in body mass, noir where significant differences observed for changes in urine pH between conditions (P=0.84) or at any time point (P=0.47). Urine osmolality declined post-ingestion with no differences between conditions (P>0.05) however, were significantly different between pre-ingestion and post-exercise concentrations (P<0.05).

The results from the current thesis show that acute FVC supplementation does not have an effect upon blood acid base levels at rest and therefore it is unlikely to attenuate changes in acid-base balance as a result of exercise. Furthermore, despite containing a high abundance of antioxidant compounds, acute supplementation with FVC does not attenuate the effects of exercise induced oxidative stress in healthy males during intermittent exercise. Further research is required as to the effects of acute and chronic supplementation upon acid-base regulation and antioxidant capacity as a result of FVC supplementation, as well as the effects of such supplementation upon populations with poor diets that lack fruit and vegetables.

Citation

Turner, M. C. (2012). The effects of fruit vegetable concentrate upon oxidative stress and buffering capacity in vivo. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4215943

• Thesis Type: Thesis
• Deposit Date: Jul 28, 2014
• Publicly Available Date: Feb 23, 2023
• Keywords: Sports sciences
• Public URL: https://hull-repository.worktribe.com/output/4215943
• Additional Information: Department of Sport, Health and Exercise Science, The University of Hull
• Award Date: Feb 1, 2012