Ingredient file // Fat or oil
Cod Liver
A strong omega-3 and vitamin organ, used sparingly
Cod liver is the fatty organ cod liver oil comes from, more than half fat by weight. In kibble it adds EPA, DHA and a lot of vitamin D, and that vitamin D is why it only ever goes in as a small ingredient.
- What it is
- The whole liver of the cod, a fat-storage organ, used in dog food as a fish fat and vitamin source.
- Made from
- Livers sorted from gutted cod
- Main job
- Omega-3 fats and vitamins
- Typical amount
- Not published
- Watch for
- Extra vitamin D from supplements added at home
- Not the same as
- Cod liver oil
Our read // In our catalog
In 1 of every 2595 foods we track
Share of foods that list it
0%
1 of the 2,595 foods with an ingredient list on file, from 1 brand. All dry dog food.
Each square is 1% of the catalog
Where it sits on the label
Median position 28. In the top five of 0 foods, so it is usually a minor ingredient.
Above the salt
Almost always listed before the salt, so there is more of it than a pinch.
Who leans on it
100%
of the foods that list it are from Blue. 1 brand use it in total.
What it is
How it is made
Cod is caught for its white fillets. The liver comes out with the guts during gutting, often on deep-sea trawlers. It is the same organ the cod liver oil industry extracts its oil from.1,3,4
- 01 // Source Atlantic cod Cod are caught and headed and gutted, much of it on deep-sea vessels, leaving viscera that include the liver.
- 02 // Process Liver sorted out Livers are separated from the other guts. In cod and related fish the liver is 1.3 to 6.9% of whole weight.
- 03 // Process Chilled Raw livers spoil fast. In tests they kept food-grade quality for up to 2 days at 4°C.
- 04 // Output Cod liver A soft, fatty organ, about 36% water and 59% fat as fed, weighed into the recipe raw.
What is in it
Composition, dry matter
56,000
IU/kg vit D
Vitamin D in dry cod liver, about 19 times AAFCO's top level for a complete adult food. This is why it stays a minor ingredient.
Why it is in the bag
What the manufacturer gets
-
01
Adds EPA and DHA
Raw cod liver carries 4.7 g EPA and 6.2 g DHA per 100 g as fed. It puts marine omega-3s into a recipe as a whole food rather than a bottled oil.1
-
02
Vitamins A and D
Fish livers concentrate both vitamins, so a small amount adds a lot. Feed scientists note that synthetic vitamins A and D usually supply the same need more cheaply.2
-
03
Uses a fishery leftover
Much cod gut residue is lost at sea because it degrades fast. The by-products of one day's fillet production yielded 550 to 1,700 kg of lipid in one study.3,4
How much No recipe amount is published; at its vitamin D level, cod liver at 5% of diet dry matter would supply about 2,800 IU/kg, near AAFCO's 3,000 ceiling.1,7
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
Cod liver is rich in omega-3 fats
Evidence
- Strong
- Some
- Thin
- None
Plain arithmetic. Raw cod liver holds 4.7 g EPA and 6.2 g DHA per 100 g as fed, about 17% of its dry matter. The real question is how much of it the recipe uses.1
-
Brands say
Supplies natural vitamins A and D
Evidence
- Strong
- Some
- Thin
- None
True: about 4,800 µg vitamin A and 90 µg vitamin D per 100 g as fed. The word natural adds nothing, since synthetic vitamins cover the same need more cheaply.1,2
-
Brands say
Fish omega-3s ease arthritis in dogs
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
In a 38-dog trial, 82% on a fish oil diet bore more weight vs 38% on control. Matching the best food in a 177-dog trial would take cod liver at about 14% of dry matter, over twice AAFCO's vitamin D top.1,5,6,7
-
Owners say
Cod liver will give dogs vitamin A poisoning
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
Even pure cod liver holds about 29,000 IU vitamin A per 1,000 kcal. In a 49-puppy trial, 100,000 IU per 1,000 kcal caused no more adverse events than the lowest dose. Vitamin D is the nutrient to watch.1,8
Straight answers
What owners ask
-
Q01
Is it the same as cod liver oil?
NoCod liver is the whole organ: 36% water, some protein, and the oil inside. Cod liver oil is extracted from it. Some brands purify their oil in several steps to cut pollutants, and cold-pressed oils carry some of the highest levels.1,11
-
Q02
Is it a protein source?
NoOn a dry basis it is about 92% fat and under 9% protein. Count it with the fats in the recipe, not with the fish meals listed above it.1
-
Q03
Why is it so far down the list?
Vitamin DAt about 56,000 IU of vitamin D per kg dry, even 5% of the diet nearly reaches AAFCO's adult top level of 3,000 IU/kg. It has to stay small.1,7
-
Q04
Should I add cod liver oil too?
Not on kibbleA complete food already carries its vitamin D. Stacking cod liver oil on top adds more of it, and FDA warns that toxic vitamin D levels cause kidney failure and death in dogs.7,9
Who uses it
Brands, best sellers and the company it keeps
Top brands, by foods that list it
Usually listed with, share of the foods that list it
- Pollock 100%
- Sole 100%
- Halibut 100%
- Dried Chicken 100%
- Herring Meal 100%
- Chicken Fat 100%
- Tapioca Starch 100%
- Dried Egg Product 100%
- Dried Tomato Pomace 100%
Our read // On the bag
Count it as fish fat, not protein
Cod liver near the end of the list, behind named fish or meat, is doing its real job: a small dose of omega-3s and vitamin D. It does not turn a food into a joint diet, so look for a stated EPA and DHA figure. Do not add cod liver oil on top.
Sources
What we read
Checked October 1, 2026.
- 1 Cod liver, raw
- 2 Fish oil
- 3 Geographical and seasonal differences in lipid composition and relative weight of by-products from gadiform species
- 4 Upgrading Marine Oils from Cod (Gadus morhua) On-Board the Deep-Sea Vessels-From Waste to Value
- 5 Evaluation of the effects of dietary supplementation with fish oil omega-3 fatty acids on weight bearing in dogs with osteoarthritis
- 6 Dose-titration effects of fish oil in osteoarthritic dogs
- 7 Increased dietary vitamin D was associated with increased circulating vitamin D with no observable adverse effects in adult dogs
- 8 Safety evaluation of vitamin A in growing dogs
- 9 FDA Alerts Pet Owners about Potentially Toxic Levels of Vitamin D in Several Dry Pet Foods
- 10 Fish and shrimp data from the Barents Sea
- 11 Is cod liver oil healthy even though it contains environmental toxins?