Background: Polyphenols in fruits and vegetables provide anti-oxidant, anti-inflammatory and anti-atherosclerotic effects. Reduced risk for cardiovascular disease is likely associated with the effects by polyphenols on blood pressure and arterial stiffness. Studies with 7-day intake of New Zealand blackcurrant extract showed changes during supine rest for cardiovascular parameters. We examined the effects of an acute intake of New Zealand blackcurrant extract on cardiovascular function during supine rest in healthy males.

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 visited the laboratory for resting measurements at baseline (no supplementation) and 2 hours after intake of two capsules with New Zealand blackcurrant extract (600 mg containing 210 mg of anthocyanins). Capsules were taken one hour after breakfast of one slice of bread and water and 2 hours before testing. After being seated in a chair for 10 min, participants were asked to lie horizontally on a massage table for resting measurements. Whole body 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 volume measured. Cardiovascular observations during the 10 min with the lowest minute ventilation were analysed.

Results: At supine rest, there was no effect on heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure and stroke volume. However, 10 out of 15 participants had lower systolic and diastolic blood pressure values with acute intake of New Zealand blackcurrant extract. There was a trend for cardiac output to be higher by 5% (baseline: 5.68±0.71, NZBC: 5.99±0.98 L·min-1, P=0.09, d=0.36). Total peripheral resistance was reduced by 7% (baseline: 15.67±2.85, NZBC: 14.45±3.04 mmHg·min·L-1, P<0.05, d= -0.41).

Conclusions: In previous work, we observed with 7- and 14-day intake of New Zealand blackcurrant extract larger changes in cardiac output and total peripheral resistance than in the present study. Our observations indicate only a moderate effect on cardiovascular function at rest with acute intake. Future studies need to address whether an acute intake of New Zealand blackcurrant extract is effective in people with hypertension or peripheral arterial disease.

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).