How it works
Polysaccharopeptides from Trametes versicolor that activate natural-killer cells and macrophages. PSK has been used as an adjuvant in Japan since the 1970s.
The evidence
Multiple randomized human trials with consistent, replicated results. In pets the effect is inferred from conserved biology and species-appropriate dosing.
What the evidence supports
Supports the normal function of immune cells (NK cells, macrophages).
The studies behind it
The primary literature for this compound, with what each paper actually found.
Read the research
- Do dog and cat longevity supplements work? A graded audit of the shelf
We went compound by compound through the ingredients sold as pet longevity supplements and graded each on honest evidence — including the ones with a beautiful mechanism and no outcome data. A field guide for the sceptical buyer.
- The longevity compounds, and how strong the evidence really is
An honest, compound-by-compound map of the pet-longevity literature — with a graded evidence badge and primary-source citations for every molecule, including the ones that disappoint.
- Turkey tail: the immune mushroom with a 50-year clinical track record
PSP, PSK, TLR2, and natural-killer cells — why a shelf fungus has a longer clinical track record than most things in the supplement aisle, and where the evidence stops.
- Why one science base serves both dogs and cats
Aging and immune biology are largely conserved across mammals. Here's how we translate human and preclinical evidence into species-safe doses for pets — and where the translation gets careful.
The content on this site is for informational purposes only and is not veterinary advice. These statements have not been evaluated by a food or drug regulatory authority and are not intended to diagnose, treat, cure, or prevent any disease. Always consult a licensed veterinarian about your pet's health.