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Ingredient file // Vitamin or mineral

L-Ascorbyl-2-Polyphosphate

Stable vitamin C with limited dog evidence

L-Ascorbyl-2-Polyphosphate is a manufactured vitamin C source modified to resist losses during feed making. It supplies vitamin C, but healthy dogs make their own. Its place on a label does not prove an antioxidant or immune benefit.

Role in the food Supporting nutrient
What it is
A manufactured vitamin C compound bonded to phosphate so the vitamin resists oxidation during feed making.
Made from
Ascorbic acid and phosphate compounds
Main job
Stable vitamin C source
Typical amount
Not published
Watch for
Added vitamin C in calcium oxalate stone diets
Not the same as
Plain ascorbic acid

Straight answer

Is L-Ascorbyl-2-Polyphosphate safe for dogs?

Read it as a vitamin and move on

This name belongs with the added vitamins near the end of an ingredient list. It tells you the form used, not the amount that survived processing or a benefit your dog will feel. Judge the food by its complete nutrient profile and the substantial ingredients above the vitamin premix.

Why it is in the food
Stable vitamin C source

Our read // In our catalog

In 1 of every 3 foods we track

Share of foods that list it

30%

961 of the 3,204 foods with an ingredient list on file, from 45 brands. 800 dry dog food, 147 wet dog food, 9 dog food topper.

Each square is 1% of the catalog

Where it sits on the label

Median position 23. In the top five of 1 food, so it is usually a minor ingredient.

Top five List position, heaviest first

Above the salt

10%

Usually listed after the salt, which caps it at roughly 1% of the recipe in 90% of foods.

Price per lb

Foods with it $3.30
All foods $3.25

Median of the cheapest bag price across 661 priced foods, about level with the catalog. The price is the food's, not the ingredient's.

Who leans on it

15%

of the foods that list it are from Royal Canin. 45 brands use it in total.

What it is

How it is made

Feed additive makers modify manufactured vitamin C because plain ascorbic acid loses activity during feed processing and storage. The resulting phosphate compound is dried into a powder for use in vitamin premixes.3,4,8

  1. 01 // Source Manufactured vitamin C Production starts with ascorbic acid and phosphate reagents, rather than vitamin C extracted from fruit.
  2. 02 // Process Phosphate bonded Bonding phosphate to ascorbic acid protects the part of the molecule most prone to oxidation.
  3. 03 // Process Spray dried The material is dried into a powder; some suppliers add calcium carbonate or silica during preparation.
  4. 04 // Output Vitamin powder The finished powder is weighed into a vitamin premix for addition to animal feed.

What is in it

Composition, dry matter

38-44

% vitamin C

Calculated vitamin C equivalents in tested commercial powders. Phosphate, mineral salts and sometimes carriers make up the rest.

Ascorbic acid equivalent 37.7-43.6%4
Sodium 10.9-14.6%4
Phosphorus 10.2-11.2%4
Calcium 5.9-12.1%4

These dry matter bounds are calculated from EFSA's as-sold batch ranges and reported drying losses. They are not paired dry analyzes. Suppliers use different mineral salts and carriers, so the mineral shares vary.4

Why it is in the bag

Adds vitamin C, though healthy dogs make their own

  1. Main nutrition
  2. Supporting nutrient
  3. Does a job
  4. Mostly filler

Makers add it to put a set amount of vitamin C in the food, using a form that holds up through processing better than plain ascorbic acid. Healthy dogs make vitamin C in the liver and AAFCO sets no requirement, so this is a top-up, not a fix. It often sits near the end of the list with the other vitamins. Labels list ingredients by weight, so it is likely a tiny share of the food. It is not filler.3,4,5,7,9

  1. 01

    Retains vitamin activity

    The phosphate bond slows oxidation. In a trout feed test, plain vitamin C lost activity during steam pelleting while the protected form showed no apparent loss.3

  2. 02

    Sets a vitamin target

    Manufacturers weigh the powder into a premix to add vitamin C. Dogs synthesize their own, so this is a formulation choice for healthy dogs.4,5

  3. 03

    Limits processing overage

    Better retention lets a formulator allow for less processing loss when setting a finished-feed target. That is an economic inference from feed stability tests, not measured dog-food savings.3

How much One dog trial measured 41 to 63 mg vitamin C/kg in supplemented kibble; that one recipe does not show a typical commercial amount.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.

  1. Brands say

    Survives feed processing better than plain vitamin C

    Evidence

    1. Strong
    2. Some
    3. Thin
    4. None

    In a steam-pelleted trout feed test, plain ascorbic acid lost 46% while this protected form showed no apparent loss. That supports the stability claim, although the comparison was not run in dog kibble.3

  2. Brands say

    Protects dogs from oxidative damage

    Outruns the evidence

    Evidence

    1. Strong
    2. Some
    3. Thin
    4. None

    An 84-day trial in 40 dogs found less DNA damage with antioxidant-enriched food. Vitamin E and beta-carotene changed alongside this vitamin C source, so the effect cannot be assigned to it. Hill's funded the study.1

  3. Brands say

    Boosts a healthy dog's immune defenses

    Outruns the evidence

    Evidence

    1. Strong
    2. Some
    3. Thin
    4. None

    The 40-dog antioxidant-blend trial measured immune cell protection, not resistance to infection. It changed vitamin E and beta-carotene alongside this ingredient. Those results do not show that this vitamin C source strengthens immunity.1

  4. Owners say

    Dogs need added vitamin C every day

    Outruns the evidence

    Evidence

    1. Strong
    2. Some
    3. Thin
    4. None

    Dogs synthesize vitamin C in the liver, and AAFCO sets no dietary requirement for it. A label listing this compound shows an added vitamin source, not a deficiency that the food had to correct.5,7

Straight answers

What owners ask

  1. Q01

    Is it just filler?

    No

    It is a vitamin additive, not an ingredient used to bulk up kibble. Its practical job is to deliver vitamin C through feed making. The evidence for an added health benefit in healthy dogs is limited.3,4,5

  2. Q02

    Does my dog need it?

    Usually no

    Healthy dogs make vitamin C, and AAFCO has no dietary requirement for it. A complete dog food does not become deficient simply because this ingredient is absent.5

  3. Q03

    Does it preserve the kibble?

    Not shown

    The phosphate bond protects the vitamin itself. Vitamin C is sometimes used in food preservation, but the feed test measured retention of this ingredient, not whether finished dog food stayed fresh longer.3,5

Who uses it

Brands, best sellers and the company it keeps

Top brands, by foods that list it

  1. Royal Canin 144 / 160
  2. Blue 113 / 186
  3. Hill's 104 / 116
  4. Nulo 61 / 117
  5. Purina 53 / 185
  6. NutriSource 50 / 91
  7. Nutro 40 / 71
  8. Solid Gold 29 / 46
  9. Go! Solutions 28 / 46
  10. Now Fresh 26 / 35

Foods that list it / all the brand's recipes we track.

Plus 35 more brands.

Amazon best sellers that list it

  1. #1 Blue Life Protection Formula Adult Chicken and Brown Rice Recipe Dry Dog Food
  2. #3 Purina Pro Plan Adult Complete Essentials Shredded Blend Chicken & Rice Formula Dry Dog Food
  3. #4 Hill’s Science Diet Light Small & Mini Chicken Recipe Dry Dog Food
  4. #5 Blue Life Protection Formula Adult Small Breed Chicken and Brown Rice Recipe Dry Dog Food
  5. #6 Hill’s Science Diet Adult Sensitive Stomach & Skin Chicken Recipe Dry Dog Food
  6. #9 Purina Pro Plan Adult Sensitive Skin & Stomach Salmon & Rice Formula Dry Dog Food
  7. #10 Iams Proactive Health MiniChunks Chicken & Whole Grains Dry Dog Food
  8. #13 Hill’s Science Diet Adult 1-6 Small Bites Chicken & Barley Recipe 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

  1. Chicken Fat 47%
  2. Mixed Tocopherols 43%
  3. Natural Flavor 40%
  4. Chicken 40%
  5. Chicken Meal 33%
  6. Peas 33%
  7. Brown Rice 30%
  8. Flaxseed 27%
  9. Brewers Rice 23%
  10. Dried Plain Beet Pulp 22%
  11. Oatmeal 20%
  12. Barley 18%

On the shelf

Foods that list L-Ascorbyl-2-Polyphosphate

961 foods in our catalog list it. These 60 list it highest on the label.

Evanger’s Super Premium Heritage Classic Chicken & Rice Dog Food TopperEvanger'sEvanger’s Super Premium Heritage Classic Chicken & Rice Dog Food TopperTopper // No. 5 on the labelEvanger’s Grain Free Braised Beef Chunks with Gravy - packed by hand! Wet Dog FoodEvanger'sEvanger’s Grain Free Braised Beef Chunks with Gravy - packed by hand! Wet Dog FoodWet // No. 6 on the labelAgainst the Grain The Good Egg - Steak ‘n Egg Wet Dog FoodAgainst the GrainAgainst the Grain The Good Egg - Steak ‘n Egg Wet Dog FoodWet // No. 7 on the labelAgainst the Grain The Good Egg - Bacon N Eggs Scramble Wet Dog FoodAgainst the GrainAgainst the Grain The Good Egg - Bacon N Eggs Scramble Wet Dog FoodWet // No. 7 on the labelGather Free Acres Organic Free-Run Chicken Recipe for Adult Dogs Grain-Free Dry Dog FoodGatherGather Free Acres Organic Free-Run Chicken Recipe for Adult Dogs Grain-Free Dry Dog FoodDry // No. 9 on the labelRoyal Canin Veterinary Selected Protein PW Moderate Calorie Grain-Free Dry Dog FoodRoyal CaninRoyal Canin Veterinary Selected Protein PW Moderate Calorie Grain-Free Dry Dog FoodDry // No. 10 on the labelNature’s Recipe Healthy Skin Vegetarian Recipe Dry Dog FoodNature's RecipeNature’s Recipe Healthy Skin Vegetarian Recipe Dry Dog FoodDry // No. 10 on the labelRachael Ray Nutrish Real Chicken & Apple Recipe Whole Health Blend Premium Paté Wet Dog FoodRachael Ray NutrishRachael Ray Nutrish Real Chicken & Apple Recipe Whole Health Blend Premium Paté Wet Dog FoodWet // No. 11 on the labelNatural Balance Limited Ingredient Bison & Sweet Potato Recipe Paté Wet Dog FoodNatural BalanceNatural Balance Limited Ingredient Bison & Sweet Potato Recipe Paté Wet Dog FoodWet // No. 11 on the labelRoyal Canin Veterinary Early Cardiac Dry Dog FoodRoyal CaninRoyal Canin Veterinary Early Cardiac Dry Dog FoodDry // No. 11 on the labelInstinct Limited Ingredient Diet Grain-Free Recipe with Real Turkey Dry Dog FoodInstinctInstinct Limited Ingredient Diet Grain-Free Recipe with Real Turkey Dry Dog FoodDry // No. 11 on the labelInstinct Original Grain-Free Recipe with Real Duck Dry Dog FoodInstinctInstinct Original Grain-Free Recipe with Real Duck Dry Dog FoodDry // No. 11 on the label
Show 48 more
Evanger’s Heritage Classic Lamb & Rice Dinner Wet Dog FoodEvanger'sEvanger’s Heritage Classic Lamb & Rice Dinner Wet Dog FoodWet // No. 6 on the labelEvanger’s Roasted Chicken Drummet Dinner - packed by hand! Grain-Free Wet Dog FoodEvanger'sEvanger’s Roasted Chicken Drummet Dinner - packed by hand! Grain-Free Wet Dog FoodWet // No. 6 on the labelEvanger’s EVX Restricted Diet: Weight Management Wet Dog FoodEvanger'sEvanger’s EVX Restricted Diet: Weight Management Wet Dog FoodWet // No. 6 on the labelEvanger’s Heritage Classic Senior & Weight Management Wet Dog FoodEvanger'sEvanger’s Heritage Classic Senior & Weight Management Wet Dog FoodWet // No. 7 on the labelEvanger’s Super Premium EVX Restricted Diet: Skin & Coat Wet Dog FoodEvanger'sEvanger’s Super Premium EVX Restricted Diet: Skin & Coat Wet Dog FoodWet // No. 7 on the labelEvanger’s Chunky Chicken Casserole - packed by hand! Wet Dog FoodEvanger'sEvanger’s Chunky Chicken Casserole - packed by hand! Wet Dog FoodWet // No. 8 on the labelEvanger’s EVX Restricted Diet: Digestion Bland Diet Wet Dog FoodEvanger'sEvanger’s EVX Restricted Diet: Digestion Bland Diet Wet Dog FoodWet // No. 8 on the labelEvanger’s Grain Free Duck & Sweet Potato Dinner Wet Dog FoodEvanger'sEvanger’s Grain Free Duck & Sweet Potato Dinner Wet Dog FoodWet // No. 8 on the labelEvanger’s Grain Free; Super Premium Chicken Dinner Wet Dog FoodEvanger'sEvanger’s Grain Free; Super Premium Chicken Dinner Wet Dog FoodWet // No. 8 on the labelEvanger’s Organic Turkey with Potato & Carrots Dinner for Dogs Grain-Free Wet Dog FoodEvanger'sEvanger’s Organic Turkey with Potato & Carrots Dinner for Dogs Grain-Free Wet Dog FoodWet // No. 9 on the labelEvanger’s Grain Free LID Venison + Beef Dinner Wet Dog FoodEvanger'sEvanger’s Grain Free LID Venison + Beef Dinner Wet Dog FoodWet // No. 9 on the labelEvanger’s EVX Restricted Diet: Hip & Joint and Senior Support Grain-Free Wet Dog FoodEvanger'sEvanger’s EVX Restricted Diet: Hip & Joint and Senior Support Grain-Free Wet Dog FoodWet // No. 10 on the labelEvanger’s Super Premium Lamb & Rice Dinner Wet Dog FoodEvanger'sEvanger’s Super Premium Lamb & Rice Dinner Wet Dog FoodWet // No. 10 on the labelEvanger’s Super Premium Beef Dinner for Dogs Grain-Free Wet Dog FoodEvanger'sEvanger’s Super Premium Beef Dinner for Dogs Grain-Free Wet Dog FoodWet // No. 10 on the labelEvanger’s Organic Chicken & Turkey Dinner Grain-Free Wet Dog FoodEvanger'sEvanger’s Organic Chicken & Turkey Dinner Grain-Free Wet Dog FoodWet // No. 11 on the labelHill’s Prescription Diet d/d Salmon Skin Care Wet Dog FoodHill'sHill’s Prescription Diet d/d Salmon Skin Care Wet Dog FoodWet // No. 12 on the labelDr. Tim’s Momentum Highly Active Dry Dog FoodDr. Tim'sDr. Tim’s Momentum Highly Active Dry Dog FoodDry // No. 12 on the labelRoyal Canin Veterinary Selected Protein PW Large Breed Grain-Free Dry Dog FoodRoyal CaninRoyal Canin Veterinary Selected Protein PW Large Breed Grain-Free Dry Dog FoodDry // No. 12 on the labelVerus Advanced Opticoat Menhaden Fish Meal and Potato Formula Dry Dog FoodVerusVerus Advanced Opticoat Menhaden Fish Meal and Potato Formula Dry Dog FoodDry // No. 12 on the labelNature’s Recipe Easy to Digest Chicken Meal, Rice, & Barley Recipe Dry Dog FoodNature's RecipeNature’s Recipe Easy to Digest Chicken Meal, Rice, & Barley Recipe Dry Dog FoodDry // No. 12 on the labelNature’s Recipe Original Small Bites Chicken Meal & Rice Recipe Dry Dog FoodNature's RecipeNature’s Recipe Original Small Bites Chicken Meal & Rice Recipe Dry Dog FoodDry // No. 12 on the labelNature’s Recipe Original Senior Lamb Meal & Rice Recipe Dry Dog FoodNature's RecipeNature’s Recipe Original Senior Lamb Meal & Rice Recipe Dry Dog FoodDry // No. 12 on the labelInstinct Limited Ingredient Diet Grain-Free Recipe with Real Salmon Dry Dog FoodInstinctInstinct Limited Ingredient Diet Grain-Free Recipe with Real Salmon Dry Dog FoodDry // No. 12 on the labelInstinct Original Grain-Free Recipe with Real Chicken Dry Dog FoodInstinctInstinct Original Grain-Free Recipe with Real Chicken Dry Dog FoodDry // No. 12 on the labelInstinct Original Grain-Free Recipe with Real Beef Dry Dog FoodInstinctInstinct Original Grain-Free Recipe with Real Beef Dry Dog FoodDry // No. 12 on the labelPurina Pro Plan Complete Essentials Senior Beef Rice Gravy Wet Dog FoodPurinaPurina Pro Plan Complete Essentials Senior Beef Rice Gravy Wet Dog FoodWet // No. 13 on the labelPurina Pro Plan Adult Large Breed Chicken & Rice Entrée In Gravy Wet Dog FoodPurinaPurina Pro Plan Adult Large Breed Chicken & Rice Entrée In Gravy Wet Dog FoodWet // No. 13 on the labelRachael Ray Nutrish Gentle Digestion Chicken, Pumpkin & Salmon Paté Wet Dog FoodRachael Ray NutrishRachael Ray Nutrish Gentle Digestion Chicken, Pumpkin & Salmon Paté Wet Dog FoodWet // No. 13 on the labelNature’s Recipe Original Stew Lamb, Rice & Barley Recipe Wet Dog FoodNature's RecipeNature’s Recipe Original Stew Lamb, Rice & Barley Recipe Wet Dog FoodWet // No. 13 on the labelNutro Limited Ingredient Diet Turkey & Potato Recipe Grain-Free Wet Dog FoodNutroNutro Limited Ingredient Diet Turkey & Potato Recipe Grain-Free Wet Dog FoodWet // No. 13 on the labelRachael Ray Nutrish Limited Ingredient Lamb Meal & Brown Rice Dry Dog FoodRachael Ray NutrishRachael Ray Nutrish Limited Ingredient Lamb Meal & Brown Rice Dry Dog FoodDry // No. 13 on the labelVerus Canine Small Breed Fish Formula Dry Dog FoodVerusVerus Canine Small Breed Fish Formula Dry Dog FoodDry // No. 13 on the labelRoyal Canin Veterinary Hydrolyzed Protein PS Grain-Free Dry Dog FoodRoyal CaninRoyal Canin Veterinary Hydrolyzed Protein PS Grain-Free Dry Dog FoodDry // No. 13 on the labelInstinct Limited Ingredient Diet Small Breed Grain-Free Recipe with Real Turkey Dry Dog FoodInstinctInstinct Limited Ingredient Diet Small Breed Grain-Free Recipe with Real Turkey Dry Dog FoodDry // No. 13 on the labelGather Wild Ocean Line-Caught Cod Recipe for Adult Dogs Grain-Free Dry Dog FoodGatherGather Wild Ocean Line-Caught Cod Recipe for Adult Dogs Grain-Free Dry Dog FoodDry // No. 13 on the labelHill’s Adult Chicken & Barley Entrée Wet Dog FoodHill'sHill’s Adult Chicken & Barley Entrée Wet Dog FoodWet // No. 14 on the labelBlue Boo Bars Pumpkin & Cinnamon Crunchy Dog TreatsBlueBlue Boo Bars Pumpkin & Cinnamon Crunchy Dog TreatsDog Treats // No. 14 on the labelDr. Tim’s Glacier Athletic Blend Dry Dog FoodDr. Tim'sDr. Tim’s Glacier Athletic Blend Dry Dog FoodDry // No. 14 on the labelDr. Tim’s Metabolite Weight Management Dry Dog FoodDr. Tim'sDr. Tim’s Metabolite Weight Management Dry Dog FoodDry // No. 14 on the labelRoyal Canin Veterinary Skin Support Dry Dog FoodRoyal CaninRoyal Canin Veterinary Skin Support Dry Dog FoodDry // No. 14 on the labelRoyal Canin Veterinary Selected Protein PD Grain-Free Dry Dog FoodRoyal CaninRoyal Canin Veterinary Selected Protein PD Grain-Free Dry Dog FoodDry // No. 14 on the labelRoyal Canin Veterinary Selected Protein Adult PV Dry Dog FoodRoyal CaninRoyal Canin Veterinary Selected Protein Adult PV Dry Dog FoodDry // No. 14 on the labelHill’s Healthy Advantage Adult Oral+ Chicken Flavor Dry Dog FoodHill'sHill’s Healthy Advantage Adult Oral+ Chicken Flavor Dry Dog FoodDry // No. 14 on the labelHill’s Prescription Diet i/d Sensitive Digestive Care Rice & Egg Formula Dry Dog FoodHill'sHill’s Prescription Diet i/d Sensitive Digestive Care Rice & Egg Formula Dry Dog FoodDry // No. 14 on the labelRoyal Canin Maltese Adult Dry Dog FoodRoyal CaninRoyal Canin Maltese Adult Dry Dog FoodDry // No. 14 on the labelRoyal Canin Jack Russell Terrier Puppy Dry Dog FoodRoyal CaninRoyal Canin Jack Russell Terrier Puppy Dry Dog FoodDry // No. 14 on the labelRoyal Canin Setter Adult Dry Dog FoodRoyal CaninRoyal Canin Setter Adult Dry Dog FoodDry // No. 14 on the labelInstinct Limited Ingredient Diet Grain-Free Recipe with Real Lamb Dry Dog FoodInstinctInstinct Limited Ingredient Diet Grain-Free Recipe with Real Lamb Dry Dog FoodDry // No. 14 on the label

Sources

What we read

Checked October 1, 2026.

  1. 1 Effect of dietary antioxidants on free radical damage in dogs and cats Journal of Animal Science, 2024 // Journal
  2. 2 Supplemental vitamin C appears to slow racing greyhounds The Journal of Nutrition, 2002 // Journal
  3. 3 Polyphosphorylated L-ascorbic Acid: A Stable Form of Vitamin C for Aquaculture Feeds Journal of the World Aquaculture Society, 1989 // Journal
  4. 4 Assessment of the feed additives consisting of ascorbic acid (3a300), sodium ascorbate (1b301), calcium ascorbate (1b302), ascorbyl palmitate (1b304), sodium calcium ascorbyl phosphate (3a312) and sodium ascorbyl phosphate (3a311) (as sources of vitamin C) for all animal species for the renewal of their authorisations (DSM Nutritional Products Ltd., NHU Europe GmbH and Orffa Additives B.V.) EFSA Journal, 2025 // Journal
  5. 5 Nutritional Requirements of Small Animals Merck Veterinary Manual, 2024 // Book
  6. 6 Use of Therapeutic Diets not Related to Weight Loss American Animal Hospital Association, 2021 // Nonprofit
  7. 7 Official Names and Definitions of Feed Ingredients AAFCO, 2024 // Regulator
  8. 8 L-Ascorbate-2-phosphate Feed Grade (Vitamin C 35%) Specification NHU Europe, 2026 // Industry
  9. 9 21 CFR 501.4: Food; designation of ingredients Legal Information Institute, Cornell Law School (US Code of Federal Regulations), 2026 // Regulator
An ingredient on its own tells you very little. What matters is how much of it there is and where it sits in the list. That is why we weigh the top five rather than reacting to any single name further down. Back to the wiki

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