The scores
Blue Buffalo Indoor Health: B (76/100)
Purina Pro Plan Cat: C (56/100)
That's a 20-point gap that spans an entire letter grade. Blue Buffalo lands in B territory alongside other premium cat foods, while Purina Pro Plan sits in the lower half of C grade — adequate but unremarkable.
How the ingredients compare
Here are the first five ingredients side by side:
Blue Buffalo: Deboned Chicken, Chicken Meal, Brown Rice, Barley, Oatmeal
Purina Pro Plan: Chicken, Brewers Rice, Corn Gluten Meal, Poultry By-Product Meal, Wheat Flour
Both start with chicken, which is good. But the similarity ends there. Blue Buffalo follows with chicken meal (concentrated animal protein), then three wholesome grains. Purina Pro Plan follows chicken with brewers rice (a processed grain by-product), corn gluten meal at number three (a cheap plant protein), poultry by-product meal (unnamed poultry parts), and wheat flour (a filler). The gap in quality is clear from ingredients two through five.
Where Blue Buffalo pulls ahead
No corn, wheat, or soy. Blue Buffalo's formula is completely free of the three most common filler grains in commercial cat food. Purina Pro Plan has corn gluten meal at position three and wheat flour at position five — two ingredients that inflate protein numbers cheaply without delivering the animal-based amino acids cats need as obligate carnivores.
Omega-3 sources. Blue Buffalo includes both flaxseed and fish oil, providing plant-based and marine omega-3 fatty acids. These support skin health, coat quality, and overall inflammation management. Purina Pro Plan's omega-3 profile relies more heavily on added supplements rather than whole-food sources.
Named protein sources. Blue Buffalo uses deboned chicken and chicken meal — both named, identifiable animal proteins. Purina Pro Plan uses "poultry by-product meal" at position four, which is an unnamed source. You don't know if it's chicken, turkey, or a mix. Named proteins mean transparency about what your cat is eating.
Fruits and vegetables. Blue Buffalo includes cranberries, blueberries, and other whole-food ingredients that contribute natural antioxidants. These are small amounts, but they reflect a more thoughtful formulation philosophy than Purina Pro Plan's filler-heavy approach. Shop on Amazon →
Where Purina Pro Plan holds its own
Veterinary recommendations. Purina Pro Plan is one of the most commonly recommended brands by veterinarians. This carries weight — vets see clinical outcomes across thousands of cats, and feeding trials matter. However, vet recommendations are influenced by multiple factors including company feeding studies and clinic partnerships, not just ingredient quality.
Research backing. Purina invests heavily in nutritional research and conducts extensive feeding trials. Their formulas are developed by a large team of pet nutritionists with decades of data. Blue Buffalo also conducts research, but Purina's scale and history in this area are hard to match.
Price. Purina Pro Plan typically costs less than Blue Buffalo per pound. For multi-cat households, the price difference adds up. That said, you're paying less for demonstrably lower-quality ingredients. Shop on Amazon →
The bottom line
Blue Buffalo Indoor Health is the clear winner here, scoring 20 points higher with a noticeably cleaner ingredient list. No corn, no wheat, no soy, no unnamed proteins — just named meats and wholesome grains. Purina Pro Plan's reputation with vets is real, but when you look at what's actually in the bag, the ingredient quality doesn't match the premium positioning. If your cat is currently on Purina Pro Plan and you're considering an upgrade, Blue Buffalo is a strong step up.
Read our full reviews of Blue Buffalo and Purina Pro Plan for the complete ingredient breakdowns.