Anthocyanin-rich New Zealand blackcurrant extract reduces treadmill running-induced gastrointestinal symptoms in the heat: pilot observations.

We examined the effect of anthocyanin-rich New Zealand blackcurrant (NZBC) extract on running-induced gastrointestinal symptoms in the heat. Recreationally active men (n = 12, age: 28 ± 6 yr, BMI: 24.5 ± 1.8 kg·m^-2, $\dot{V}$O_2max: 56 ± 6 mL·kg^-1·min^-1) volunteered. Participants dosed with 7 days of NZBC extract (CurraNZ®) (210 mg anthocyanins) or placebo. Exercise consisted of treadmill running for one hr at 65%$\dot{V}$O_2max (34.1 ± 0.1°C, 40.8 ± 0.2% relative humidity) with the recording of gastrointestinal symptoms during and at 60 min following recovery in normal conditions. With placebo, 11 participants (92%) reported gastrointestinal symptoms (e.g. belching, stitch), and this was reduced to four participants (25%) with NZBC extract. Using a modified visual analog scale, the accumulated score of gastrointestinal symptoms was lower with 7-day intake of NZBC extract (placebo: 112, NZBC extract: 54, p = 0.04). The prevalence of upper, lower and other gastrointestinal symptoms was reduced (upper, placebo: 75%, NZBC extract: 25%; lower: placebo: 25%, NZBC extract: 17%; other, placebo: 50%, NZBC extract: 25%). With placebo, only two participants reported severe symptoms (one participant for dizziness and nausea with that participant still reporting those in the NZBC extract condition). Seven-day intake of New Zealand blackcurrant extract reduced the incidence of gastrointestinal symptoms during 1-h of running in hot environmental conditions. Future research should examine the efficacy of NZBC extract on exercise-associated gastrointestinal symptoms in conditions in which gastrointestinal symptoms can be expected to be severe.