Benefits
Faster 5 km run in one trial, using a different haskap powder
In a randomized, double-blind, placebo-controlled trial in 30 non-smoking male recreational runners aged 18 to 45, 6 g a day of haskap berry powder for 6 days (plus a dose about an hour before testing) beat placebo: the 5 km time trial was about 21 seconds faster (P = 0.016, roughly a 2% improvement) and time to exhaustion was about 20 seconds longer (P = 0.031). Important caveats: this was a parallel-group study, not a crossover; no women were included; and the powder was a commercial Haskapa product, not EnduBerry Nu. The study was co-funded by Haskapa and by Mibelle, the maker of EnduBerry Nu.
Antioxidant rationale is a theory here, not a measured result
Haskap berries are rich in anthocyanins, and one popular idea is that these help the body handle exercise-related oxidative stress and support blood flow. That remains a proposed explanation, not something shown here. The running trial measured only performance, heart rate, oxygen use, blood lactate and perceived effort; it did not measure a single marker of oxidative stress, antioxidant capacity or inflammation.
Background reading: a review of related berries and blood vessels
The only other source on this page is a 2025 review article about blueberry and honeysuckle anthocyanins and blood vessel health. A review summarizes other people's work; it is not a test of this ingredient, and results seen with other dark berries are not evidence for this one.
Mechanism of action
Anthocyanin antioxidant activity
In laboratory testing, cyanidin-based anthocyanins can neutralize reactive molecules, and berry polyphenols may help blood vessels relax. Whether this is what improved running times is unknown: the trial did not measure oxidative stress or antioxidant capacity, so the link to better oxygen delivery is an idea rather than a demonstrated chain of events.
Polyphenol vascular signaling
Berry polyphenols modulate endothelial function and blood flow, a plausible route to improved endurance performance.
Clinical trials
Randomized, double-blind, placebo-controlled trial using two separate groups of people, not a crossover (Nutrients, 2022; PMID 35215430). The product tested was a commercially available Haskapa haskap powder, not EnduBerry Nu.
30 non-smoking male recreational runners aged 18 to 45; no women were studied
The haskap group took 6 g a day of freeze-dried haskap powder (about 150 mg anthocyanins) for 6 days plus a dose about an hour before testing. Against placebo, the 5 km time trial was about 21 seconds faster (P = 0.016, roughly 2%) and time to exhaustion was about 20 seconds longer (P = 0.031), with modest changes in heart rate and oxygen use at easier paces. Limitations: 30 participants in total, men only, separate groups rather than a crossover, and the study was co-funded by Haskapa, whose powder was tested, and by Mibelle, which makes EnduBerry Nu.