Effect of Cherry Juice on Fat Oxidation and Cardio-metabolic Markers

Aims: (1) Examine whether tart cherry juice supplementation with cycling exercise augments fat oxidation rate and therefore plays a role in weight management in healthy active human participants. (2) To extrapolate findings from this study to future biomedical health and disease research.

Methods: Random counterbalanced, within-group, double-blind study design. Participants were randomly allocated into consuming either cherry juice first or placebo. Eleven recreationally active male and female participants were recruited. Participants consumed 30ml Montmorency tart cherry juice concentrate mixed with 100ml water, twice daily for 20 days. Participants underwent a 14 day washout period between trials. All participants were instructed to keep to their habitual intake of polyphenols and anthocyanins. Twenty-four hours before each exercise testing session, participants consumed similar meals at the same times. Diet adherence was monitored through food diaries.

Participants attended each testing session following an overnight fast, with the testing being completed at the same time in the morning to avoid circadian variation. Preliminary testing was conducted to ascertain VO2max and individual FATMAX, 4 days before the one hour pre-supplementation exercise test. VO2max was re-assessed 4 days before the one hour post-supplementation exercise test to determine if any changes in training status affected results.

Testing will occur at baseline, 10 days after the onset of supplementation and after 20 days supplementation. Exercise protocol consisted of 60min cycling at pre-determined individual FATMAX. Continuous gas analysis and heart rate were monitored throughout. Substrate oxidation rates and energy expenditure were calculated using stoichiometric equations (Jeukendrup and Wallis, 2005). During each testing session blood pressure and body composition (impedance) measurements were taken at baseline and pre-exercise during all testing sessions. Resting metabolic rate (indirect calorimetry) was assessed at baseline and pre-exercise during all testing sessions.

Serum blood samples were obtained from participants at the following time points: baseline, pre-exercise and post-exercise for one hour submaximal exercise tests, in both trials. The following markers were analysed: Glucose, Lactate, Triglycerides, HDL, Total Cholesterol and Total Antioxidant Status.

Inclusion criteria

• Aged 18-45
• Male and Female
• Non-smokers
• Recreationally active (minimum 150 minutes physical activity per week)
• Injury free at all times of testing.

Exclusion criteria

• Aged <18 years old, >45 years old
• Current or previous history of gastrointestinal, cardiovascular or renal disease
• Current or previous history of injury that may be exacerbated with the exercise protocol used
• Allergy to maltodextrin or specific fruit products (especially cherries) and those currently taking medication (such as steroids, NSAIDs, antibiotics) or currently using any nutritional supplement.