The scores
Blue Buffalo Life Protection Formula Senior Chicken & Brown Rice: B (78/100) — Good. Deboned chicken first, brown rice and oatmeal as whole-grain carbs, glucosamine and chondroitin for joint support, turmeric for anti-inflammatory effect, and the LifeSource Bits antioxidant blend.
Iams ProActive Health Healthy Aging Adult 7+ Chicken & Whole Grains: C (64/100) — Okay. Whole chicken first, then chicken by-product meal and three grains (barley, corn, sorghum). Marine microalgae and L-carnitine for cognitive and muscle support at budget pricing.
How the ingredients compare
The top five ingredients:
Blue Buffalo Senior: Deboned Chicken, Brown Rice, Oatmeal, Barley, Chicken Meal
Iams Senior: Chicken, Chicken By-Product Meal, Ground Barley, Ground Whole Grain Corn, Ground Whole Grain Sorghum
The 14-point gap is rooted in the second ingredient slot. Blue Buffalo uses brown rice — a whole-grain carbohydrate. Iams uses chicken by-product meal — a protein-dense ingredient under AAFCO definition, but one that includes organ, ground bone, and other rendered tissue at variable quality. By-product meal isn’t inherently harmful, but the rubric penalizes it relative to named chicken meal because the sourcing is less transparent. Chicken meal at BB’s position five is the cleaner version.
Beyond the top five, the formulas diverge further. Blue Buffalo Senior adds miscanthus grass (fiber), tomato pomace, flaxseed (plant omega-3), fish oil (marine omega-3), glucosamine hydrochloride and chondroitin sulfate at meaningful inclusion levels, and the proprietary LifeSource Bits — cold-formed antioxidant kibble pieces with turmeric, kelp, parsley, and cranberry. Iams Senior adds soybean meal, beet pulp, marine microalgae (DHA), L-carnitine (for muscle metabolism), caramel color, and standard vitamin-mineral premix. Iams includes L-carnitine — a real functional addition for senior muscle preservation — but also includes caramel color purely for cosmetic appearance.
Glucosamine and chondroitin matter for senior dogs. Joint cartilage thins with age, and dietary glucosamine provides precursors the body uses to rebuild synovial fluid and cushion joint surfaces. BB includes both at meaningful positions in the formula. Iams does not. For dogs entering their 7+ years, that’s a material feeding-plan difference.
Where Blue Buffalo Senior pulls ahead
No chicken by-product meal, no corn. Two of the most-cited ingredient-label avoidances in premium dog food. BB Senior skips both. The whole chicken plus brown rice plus oatmeal top is a textbook premium senior formulation, scored accordingly.
Glucosamine and chondroitin for joint support. Senior dogs — especially medium and large breeds — benefit from dietary joint precursors. BB Senior delivers both glucosamine hydrochloride and chondroitin sulfate at meaningful inclusion levels. Iams Senior does not carry either in the listed ingredient panel. For dogs already showing mobility stiffness, this is a functional differentiator.
Anti-inflammatory inclusions. Turmeric, blueberries, cranberries, kelp, and barley grass in the LifeSource Bits blend deliver phytonutrients that function as antioxidants. Not a miracle cure, but a real step above the budget senior formulas that skip these entirely. The cold-formed Bits preserve heat-sensitive compounds that standard extrusion destroys. Shop on Amazon →
Where Iams Senior holds its own
Roughly one-third the price per pound. Iams Healthy Aging 7+ runs about $1.70 per pound at Walmart and Amazon. BB Senior runs about $2.80 per pound. Over a year of daily feeding for a 60-lb senior dog, that’s a meaningful difference. For owners on fixed incomes supporting a senior dog, price is not a small factor.
L-carnitine for muscle preservation. Senior dogs lose lean muscle mass with age, and L-carnitine supports fatty-acid transport into the mitochondria — the cellular mechanism for energy production. Iams includes it explicitly; BB Senior relies on the broader formulation. For dogs losing muscle mass noticeably, the Iams inclusion is a purposeful signal.
Marine microalgae for cognitive support. Iams Senior includes marine microalgae at position eleven — a plant-based DHA source that bypasses the conversion inefficiency of flaxseed. DHA supports cognitive function in aging dogs, which is a meaningful functional ingredient at the budget price point. Shop on Amazon →
The bottom line
If you can afford the per-pound premium and your senior dog benefits from joint support and anti-inflammatory inclusions, Blue Buffalo Life Protection Senior is the clear winner at B/78. If price is the constraint and you’re upgrading from a D- or F-tier senior food, Iams Healthy Aging 7+ at C/64 is a meaningful step up — but know that it’s not a premium formula by our rubric. For A-tier senior options, see our best senior dog food guide.