About Green Kiwifruit Powder (Actazin, Zyactinase)
Freeze-dried green kiwifruit powder standardized to the protease actinidin, plus fibre and polyphenols, marketed under Actazin, Zyactinase (Phloe/Kivia) and Livaux (gold). Whole green kiwifruit (2–3 fruit/day) has reasonably consistent RCT evidence for constipation (Chan 2007; Gearry 2023 vs psyllium and prunes). Powder capsules are less convincing: Ansell 2015 (randomized double-blind placebo-controlled, healthy adults) found Actazin 600/2,400 mg increased stool frequency modestly; Blatchford 2017 (n≈45, functionally constipated) showed microbiome shifts (Faecalibacterium prausnitzii) with 2,400 mg but was not powered for symptoms; Weir 2018 (Zyactinase, randomized double-blind placebo-controlled) reported increased defecation frequency and improved stool scores; but Kindleysides 2015 (1 g/day freeze-dried extract, 3 weeks) found NO difference vs placebo on any bowel outcome. Most positive trials come from the New Zealand producers or Plant & Food Research. Well tolerated; kiwifruit allergy is a contraindication (cross-reacts with latex/birch pollen). Doses of ~500 mg in protein or collagen blends are below the lowest studied dose.
What Green Kiwifruit Powder (Actazin, Zyactinase) supports
- May increase stool frequency (small mixed RCTs)
- Shifts gut microbiome toward F. prausnitzii (one trial)
How much Green Kiwifruit Powder (Actazin, Zyactinase) to take
The RDA prevents deficiency. The effective range is what clinical trials used to actually move the outcome.
Effective
600–2400
mg
Actazin trials used 600 and 2,400 mg/day (Ansell 2015; Blatchford 2017); Zyactinase RCTs used ~1,500 mg/day; a 1 g/day freeze-dried extract RCT was null (Kindleysides 2015). Whole-fruit constipation trials use 2–3 green kiwifruit/day (~150–200 g), far above any capsule dose.
Clinical evidence
Limited clinical evidence. Several small producer-funded RCTs of 600–2,400 mg/day powder with modest stool-frequency gains, one null 1 g/day RCT; whole-fruit evidence is stronger but not transferable to capsules
NIH Fact Sheet