Background: Intake of polyphenols results in plasma bioavailability of metabolites that can last for days. Studies have mostly employed dosing protocols that examined observations following acute or daily prolonged intake. We examined the effects of intermittent and daily intake of New Zealand blackcurrant (NZBC) extract over a 14-day period on cardiovascular function during supine rest.

Methods: Healthy physically active males (n=15, age: 24±6 yr, body mass: 78±16 kg, height 177±7 cm, BMI: 24.7±4.3 kg·m-2 (8 normal weight, 6 overweight, 1 obese), body fat: 15±5%) volunteered. Participants visits included resting measurements at baseline (no supplementation), after 14-day intermittent intake (14-I, i.e. every other day) and 14-day daily intake (14-D) of two NZBC extract capsules (210 mg of anthocyanins for two capsules). Last dose was consumed one hour after breakfast of one slice of bread and water and 2 hours before visiting the laboratory. Cardiovascular measurements were obtained with a beat-to-beat blood pressure monitoring system (Portapres® Model 2, Finapres Medical Systems BV, Enschede, The Netherlands). Expired air was collected for two times for 10 min with Douglas bags and volumes measured. Cardiovascular observations during the 10 min with the lowest minute ventilation were analysed.

Result: During supine rest, there was no effect on heart rate and systolic blood pressure. Lower diastolic blood pressure was recorded and similar for intake conditions [baseline: 70±7, 14-I: 64±5 (P<0.01, d= -0.99), 14-D: 63±9 mmHg (P<0.05, d= -0.87)]. Lower mean arterial pressure was recorded and similar for intake conditions [baseline: 87±7, 14-I: 81±6 (P<0.01, d= -0.92), 14-D: 81±9 mmHg (P=0.03, d= -0.74)]. Higher stroke volume was recorded only for 14-day daily intake [baseline: 94.9±13.4, 14-I: 100.0±14.3, 14-D: 103.1±18.1 mL (P=0.01, d=0.51)]. Cardiac output was higher with a trend for change at 14-day intermittent and a change with 14-day daily intake [baseline: 5.68±0.71, 14-I: 6.15±0.90 (P=0.05, d=0.58), 14-D: 6.14±0.88 L·min-1 (P=0.02, d=0.58)]. Total peripheral resistance was reduced and similar for intake conditions (baseline: 15.67±2.85, 14-I: 13.59±2.50 (P<0.01, d= -0.78), 14-D: 13.43±2.61 mmHg·min·L-1 (P<0.01, d= -0.82)].

Conclusions: Beneficial effects of intake of anthocyanin-rich NZBC extract on resting cardiovascular function can be obtained by intermittent (i.e. every other day) intake of 210 mg of anthocyanins. Future work may want to address the effects of longer intermittent intake than the 2-weeks employed in our study. It would also be of interest to examine plasma bioavailability of anthocyanin-derived metabolites with intermittent intake of NZBC extract.

Acknowledgements: Supplementation was provided by Health Currancy Ltd (United Kingdom) and CurraNZ Ltd (New Zealand). Financial support for conference attendance was obtained from Blackcurrant New Zealand Inc (New Zealand).