Iams vs Purina One

Two affordable mainstream brands. Iams is WSAVA-aligned (Mars); Purina ONE is the entry tier of Purina (not the WSAVA-aligned Pro Plan line).

Iams

Average score: 73/100. 60 products. WSAVA-aligned. Country: US.

Purina ONE

Average score: 77/100. 86 products. Country: US.

Verdict

Overall scores are close — Iams averages 73/100 vs Purina ONE at 77/100. Iams is WSAVA-aligned (feeding trials, on-staff vet nutritionist, owned manufacturing); Purina ONE is not. Catalog breadth: Purina ONE (86 products) is broader than the smaller line (60).