Wild Blueberries Increase Fat Oxidation Rate During Moderate Intensity Exercise

Abstract

Fruits high in anthocyanins, such as wild blueberries (WBs), have been documented to decrease oxidative stress in active and sedentary populations and has more recently demonstrated the ability to influence lipolytic enzymes and increase the rate of fatty acid oxidation (FA-ox) during rest. To date, changes in FA-ox during exercise has only been examined with blackcurrants. PURPOSE: To examine the effect of freeze dried WBs on the rate of FA-ox and lipid peroxidation during moderate intensity exercise. METHODS: 11 healthy, aerobically trained males (26.6 ± 7.9 yrs, 74.7 ± 8.2 kg, 10.2 ± 3.4% BF) completed an incremental cycle test to determine VO2peak (54.4 ± 7.9 ml/kg/min) followed by a 2-wk washout avoiding foods high in anthocyanins. Participants completed a control (C) exercise protocol of cycling at 65% of VO2peak for 40 min. Urinary F2-isoprostanes (~ 50 mL) and capillary blood FA, glycerol, creatinine and free/total carnitine (~ 250 μL) were collected pre and post sessions. Ventilation, RER, lactate, HR, power output, RPM and RPE were collected before and at 10 min increments. Next, participants consumed 12.5 g freeze dried WB powder, 2x/day (25 g total) for 2-wks, then repeated the exercise protocol. Repeated measures ANOVAs were used to determine differences between conditions. RESULTS: WBs reduced lactate at 20 (C: 3.0 ± 1.1 mmol vs WB: 2.6 ± 1.0 mmol; p=0.005), 30 (C: 2.9 ± 1.0 mmol vs WB: 2.2 ± 0.9 mmol; p=0.005) and 40 min (C: 2.5 mmol ± 0.9 vs WB: 1.9 ± 0.8 mmol; p=0.013) and carbohydrate oxidation by 10.1% at 20 (C: 2.17 ± 0.46 g/min vs WB: 1.95 ± 0.42 g/min; p=0.024), 19.2% at 30 (C: 2.24 ± 0.52 g/min vs WB: 1.82 ± 0.48 g/min; p=0.014) and 14.8% at 40 min (C: 2.10 ± 0.54 g/min vs WB: 1.79 ± 0.45 g/min; p=0.045) while resulting in higher FA-ox by 19.7% at 20 (C: 0.45 ± 0.16 g/min vs WB: 0.53 ± 0.13 g/min; p=0.049), 43.2% at 30 (C: 0.41 ± 0.14 g/min vs WB: 0.58 ± 0.15 g/min; p=0.010) and 31.1% at 40 min (C: 0.45 ± 0.17 g/min vs WB: 0.59 ± 0.13 g/min; p=0.012). No differences were found between C and WB trials for all other variables. CONCLUSION: Results indicate that WBs may increase the rate of FA-ox during moderate intensity activity in healthy, active males. Potential complications with blood sample preparation may have led to unreliable results. Further, the exercise intensity may have been too low to see significant changes in urinary F2-isoprostanes.