Purpose To determine if 7d of New Zealand blackcurrant (NZBC) extract alters the heat shock, infammatory and apoptotic response during prolonged exertional-heat stress. Methods Ten men (Age: 29±2 years, Stature: 1.82±0.02 m, Mass: 80.3±2.7 kg, V̇O2max: 56±2 mL·kg−1·min−1) ingested two capsules of CurraNZ™ (NZBC extract: 210 mg anthocyanins·day−1) or PLACEBO for 7d prior to 1 h treadmill run (65% V̇O2max) in hot ambient conditions (34 °C/40% RH). Blood samples were collected before (Pre), immediately after (Post), 1 h after (1-Post), and 4 h after (4-Post) exercise. Heat shock proteins (HSP90, HSP70, HSP32) were measured in plasma. HSP and protein markers of infammatory capacity (TLR4, NF-κB) and apoptosis (BAX/BCL-2, Caspase 9) were measured in peripheral blood mononuclear cells (PBMC). Results eHSP32 was elevated at baseline in NZBC(+31%; p<0.001). In PLACEBO HSP32 content in PBMC was elevated at 4-Post(+98%; p=0.002), whereas in NZBC it fell at Post(− 45%; p=0.030) and 1-Post(− 48%; p=0.026). eHSP70 was
increased at Post in PLACEBO(+55.6%, p=0.001) and NZBC (+50.7%, p=0.010). eHSP90 was increased at Post(+77.9%, p<0.001) and 1-Post(+73.2%, p<0.001) in PLACEBO, with similar increases being shown in NZBC (+49.0%, p=0.006 and+66.2%, p=0.001; respectively). TLR4 and NF-κB were both elevated in NZBC at PRE(+54%, p=0.003 and+57%, p=0.004; respectively). Main efects of study condition were also shown for BAX/BCL-2(p=0.025) and Caspase 9 (p=0.043); both were higher in NZBC. Conclusion 7d of NZBC extract supplementation increased eHSP32 and PBMC HSP32 content. It also increased infammatory and apoptotic markers in PBMC, suggesting that NZBC supports the putative infammatory response that accompanies exertional-heat stress.