Ingredient file // Other
Blue 2
Blue color for buyers, nothing for nutrition
Blue 2 is a synthetic dye, also called indigo carmine, added to give kibble a blue tint. It supplies no meaningful nutrition or flavor. The color helps sell a consistent look to owners; evidence does not show that dogs prefer it.
- What it is
- A certified synthetic blue dye added in small amounts to change the appearance of dog food.
- Made from
- Synthetic indigo treated with sulfuric acid
- Main job
- Colors kibble blue
- Typical amount
- Proposed use: 10 to 200 mg/kg of feed
- Watch for
- The label does not disclose its dose
- Not the same as
- Blue 1
Our read // In our catalog
In 1 of every 94 foods we track
Share of foods that list it
1%
27 of the 2,533 foods with an ingredient list on file, from 3 brands. All dry dog food.
Each square is 1% of the catalog
Where it sits on the label
Median position 25. In the top five of 0 foods, so it is usually a minor ingredient.
Above the salt
Usually listed after the salt, which caps it at roughly 1% of the recipe in 100% of foods.
Price per lb
Median of the cheapest bag price across 26 priced foods, 72% below the catalog. The price is the food's, not the ingredient's.
Who leans on it
52%
of the foods that list it are from Pedigree. 3 brands use it in total.
What it is
How it is made
Chemical manufacturers make Blue 2 deliberately for coloring food. They produce synthetic indigo, alter it so it dissolves in water, then purify the resulting dye before it reaches a pet food plant.1,5,6
- 01 // Source Synthetic indigo A chemical process starting with aniline and formaldehyde produces indigo, which is purified before further processing.
- 02 // Process Sulfonated Heating indigo with sulfuric acid changes it into the water-soluble blue dye called indigo carmine.
- 03 // Process Purified and certified The dye is isolated and purified; FDA checks batches against identity and impurity specifications.
- 04 // Output Blue powder The finished coloring reaches food manufacturers as a dark blue powder or granules.
What is in it
Composition, as fed
86-97
% color
Total coloring matter measured across batches of the dye powder. This describes the additive itself, not the amount in a bag of kibble.
These measured components overlap: the related blue compounds contribute to total coloring matter. The published batch results give no separate moisture figures, so an honest dry matter conversion is unavailable.1
Why it is in the bag
What the manufacturer gets
-
01
Tints the kibble
Blue 2 dissolves in water and adds blue color to the food. It is a visual ingredient, with no nutritional or flavoring job.1,5
-
02
Keeps color consistent
Pet food color suppliers say manufacturers use added color to cover differences between batches. That gives repeat buyers a familiar-looking product.7
-
03
Colors at small doses
An applicant proposed 10 to 200 mg/kg of feed for dogs and cats. A small dose spreads the coloring cost across a large amount of food.1,7
How much An applicant proposed 10 to 200 mg/kg of feed; EFSA assessed up to 250 mg/kg of complete dog food as safe.1
Our read // The claims
What the evidence supports
Strong: controlled studies in dogs agree. Some: small or mixed dog data. Thin: mechanism or lab work only. None: nothing, or the evidence points the other way.
-
Brands say
Blue 2 is safe at ordinary dog food levels
Evidence
- Strong
- Some
- Thin
- None
EFSA assessed indigo carmine as safe up to 250 mg/kg of complete dog food. An older beagle feeding study found no dye-attributed lesions, but viral deaths limited that study. The assessment applies to dye meeting purity specifications.1,4
-
Brands say
Blue 2 makes kibble more appealing to buyers
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
Owners judging 8 commercial dog foods cared strongly about appearance and color. That study did not isolate Blue 2 or show that this particular shade improves sales. The claim is plausible, but dye-specific proof is missing.3,7
-
Brands say
Dogs prefer kibble colored blue
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
A color-vision study tested 3 dogs and showed they distinguish colors. The 8-food appearance study tested owners, not dogs eating blue kibble. Seeing a color does not demonstrate a preference for Blue 2.2,3
-
Owners say
Blue 2 causes cancer in dogs
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
A rat experiment produced injection-site tumors in 14 of 80 injected animals; injection does not model eating kibble. A 2-year beagle feeding study reported no dye-attributed lesions, although viral deaths weakened its conclusion.4
-
Owners say
Blue 2 makes dogs hyperactive
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
EFSA reviewed toxicity studies but reported no controlled dog behavior test of Blue 2. The older dog feeding study recorded clinical signs and pathology rather than hyperactivity. There is no direct evidence for this claim.1,4
Straight answers
What owners ask
-
Q01
Is it just filler?
NoIt has a job: coloring the kibble. It adds no meaningful protein, fat or fiber, so it does nothing for the food's nutritional value. Treat it as a cosmetic ingredient.1,5
-
Q02
Can dogs see blue kibble?
YesDogs can distinguish blue from some other colors. That does not mean blue kibble tastes better to them or makes them eat more; the appearance research here measured owners' reactions.2,3
-
Q03
Is Blue 2 banned?
NoFDA lists Blue 2 for coloring food and requires certification of its batches. Its presence on a US dog food label is not, by itself, evidence of an unsafe product.5,6
-
Q04
Can I tell how much is added?
NoThe ingredient list names a certified dye but does not state its dose. Its place near the end tells you it weighs less than ingredients above it, not its concentration in milligrams.6
Who uses it
Brands, best sellers and the company it keeps
Top brands, by foods that list it
Amazon best sellers that list it
- #12 Pedigree Adult Grilled Steak & Vegetable Flavor Dry Dog Food
- #22 Cesar Filet Mignon Flavor & Spring Vegetables Garnish Dry Dog Food
- #41 Pedigree Small Dog Grilled Steak and Vegetable Flavor Dry Dog Food
- #73 Pedigree Puppy Chicken & Vegetable Flavor Dry Dog Food
Rank on Amazon's dog food best seller list, checked October 2026.
Usually listed with, share of the foods that list it
- Soybean Meal 100%
- Meat and Bone Meal 78%
- Corn Gluten Meal 78%
- Natural Flavor 74%
- Animal Fat 67%
- Chicken By-Product Meal 63%
- Whole Grain Ground Corn 48%
- Salt 44%
- Whole Grain Corn 37%
- Brewers Rice 37%
- Ground Whole Grain Wheat 37%
- Dried Plain Beet Pulp 33%
Our read // On the bag
Judge the food beyond its blue pieces
Blue 2 near the end of an ingredient list tells you the maker chose a colored look. It tells you nothing useful about protein quality or whether your dog likes the food. Read the main ingredients and nutritional analysis first. If you want food without cosmetic dye, choose one without Blue 2 on the label.
Sources
What we read
Checked October 1, 2026.
- 1 Safety of a feed additive consisting of indigo carmine for cats, dogs and ornamental fish (Sensient Colors Europe GmbH)
- 2 Color vision in the dog
- 3 Consumer Acceptance of Dry Dog Food Variations
- 4 145. Indigotine (FAO Nutrition Meetings Report Series 46a)
- 5 21 CFR 74.102: FD&C Blue No. 2
- 6 GFI #223 Small Entity Compliance Guide Declaring Color Additives In Animal Foods
- 7 Visual purchasing: how to use color to appeal to pets and owners