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Ingredient file // Plant protein

Soy Flour

Useful plant protein with a stool tradeoff

Soy flour is finely ground soybean, sold with its oil intact or with most of it removed. It supplies protein that dogs digest. In one feeding trial, the soy flour diet produced more stool than diets made with more refined soy proteins.

Role in the food Supporting nutrient
What it is
Finely milled, usually dehulled soybeans or soybean flakes, sold in full fat and defatted forms.
Made from
Dehulled soybeans or defatted soybean flakes
Main job
Plant protein for the recipe
Typical amount
No usual amount published; one trial used about 45%
Watch for
Soy allergy diagnosed by food challenge
Not the same as
Soy protein isolate

Straight answer

Is Soy Flour safe for dogs?

Count soy flour as protein on the bag

Ingredients are listed by weight, so soy flour near the top means it is a substantial part of the recipe. Count it as plant protein when you assess the other protein sources, then check the nutritional adequacy statement. If your dog has a diagnosed soy reaction, choose a food without ordinary soy flour.

Why it is in the food
Plant protein for the recipe

Our read // In our catalog

In 1 of every 68 foods we track

Share of foods that list it

1%

47 of the 3,205 foods with an ingredient list on file, from 5 brands. 36 wet dog food, 11 dry dog food.

Each square is 1% of the catalog

Where it sits on the label

Median position 9. In the top five of 6 foods, so it is usually a supporting ingredient.

Top five List position, heaviest first

Above the salt

95%

Almost always listed before the salt, so there is more of it than a pinch.

Price per lb

Foods with it $1.88
All foods $3.25

Median of the cheapest bag price across 8 priced foods, 42% below the catalog. The price is the food's, not the ingredient's.

Who leans on it

85%

of the foods that list it are from Purina. 5 brands use it in total.

What it is

How it is made

Soy flour often comes from the same processing lines that make soybean oil. Full fat flour keeps the bean's oil. Defatted flour uses flakes left after oil extraction; both are milled into fine powder.4,5

  1. 01 // Source Soybeans Cleaned beans enter a processing line that also makes soybean oil and other soy ingredients.
  2. 02 // Process Hulls removed Processors crack the beans and separate the hulls from the protein rich inner parts.
  3. 03 // Process Oil extracted Defatted flour uses flakes after oil extraction; full fat flour skips this step.
  4. 04 // Process Heated and dried Heating reduces compounds that interfere with protein digestion, and drying prepares the material for milling.
  5. 05 // Output Fine soy flour The dried material is ground into a powder that a food plant weighs into its recipe.

What is in it

Composition, dry matter

46.6-59

% protein

Typical values for full fat and defatted flour. Removing oil raises protein's share, so the name alone does not tell you its concentration.

Crude protein 46.6-59%5
Total dietary fiber 16.2%4
Crude fat 0.9-22.1%5
Crude fiber 2.1-2.6%5
Ash 5.2-6.4%5

These ranges compare typical full fat and defatted flours, not batches of one grade. The total dietary fiber value comes from one tested flour and measures more material than crude fiber.4,5

Why it is in the bag

Real plant protein that also helps hold water

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

Soy flour adds real protein: typical flours run 46.6 to 59% protein on a dry basis, and dogs digested protein well in a controlled trial of a soy flour diet. Makers also use it because it absorbs water, which helps shape mixtures, and FAO has described it as an economical protein. Labels rank ingredients by weight, not protein, so a lower list position means a smaller share of the recipe by weight, not necessarily a minor share of the protein.1,4,5,6

  1. 01

    Adds plant protein

    Soy flour raises the recipe's protein content. Dogs digested protein well in a soy flour test diet, though that result belongs to the complete recipe.1,4,5

  2. 02

    Holds water in mixtures

    Soy flour absorbs water, a property food makers use when shaping mixtures. The amount used and the other ingredients still determine the finished texture.4,5

  3. 03

    Uses an oil mill stream

    Defatted flour turns flakes left after oil extraction into a protein ingredient. FAO described soy flour as economical, though its published price comparison is historical.5

How much A dog trial used 45.16% soy flour in one test diet; that is a tested amount, not a usual recipe amount.1,4

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

    Soy flour gives dogs digestible protein

    Evidence

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

    A controlled trial compared 6 protein sources. Its soy flour diet had 87.3% total tract protein digestibility. That supports its use as protein, but the result cannot stand for every flour or recipe.1,4

  2. Critics say

    Soy flour is a common dog allergen

    Outruns the evidence

    Evidence

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

    Soy triggered reactions in 18 of 297 dogs collected from food challenge reports. Those dogs were selected for food reactions, so the count does not show how often soy allergy occurs among dogs generally.2

  3. Owners say

    Soy flour harms a dog's thyroid

    Outruns the evidence

    Evidence

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

    A trial followed 20 dogs fed diets with different soy isoflavone levels for up to 1 year. Most measured hormones did not differ. It tested a soy isolate diet, not soy flour, and did not show thyroid disease.3

  4. Critics say

    Soy flour is just filler

    Outruns the evidence

    Evidence

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

    Typical flours contain 46.6 to 59% protein on a dry basis, and dogs digested protein in a soy flour test diet. More stool in that trial is a fair drawback; calling the ingredient filler ignores its protein.1,4,5

  5. Owners say

    Soy flour always makes dogs gassy

    Outruns the evidence

    Evidence

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

    The soy flour trial measured stool output, not gas. A separate study of soybean meal diets found no difference in flatulence. Neither result proves what every dog will experience with soy flour.1,4

Straight answers

What owners ask

  1. Q01

    Is it just filler?

    No

    Soy flour supplies substantial protein, and dogs digested it in a controlled feeding trial. Its drawback in that trial was greater stool output. Read it as a plant protein ingredient with a digestive tradeoff.1,4,5

  2. Q02

    Will it give my dog gas?

    Not shown

    The soy flour feeding trial found more stool but did not measure gas. A study of soybean meal found no flatulence difference, though meal is a different ingredient. Judge any change in your dog's stool against the whole new food.1,4

  3. Q03

    Is it soy protein isolate?

    No

    Isolate undergoes further processing that removes much of the carbohydrate. Soy flour retains more of the bean's other material. Hydrolyzed soy used in some therapeutic foods is processed differently again.4,5

Who uses it

Brands, best sellers and the company it keeps

Top brands, by foods that list it

  1. Purina 40 / 186
  2. Cesar 3 / 45
  3. Gravy Train 2 / 6
  4. 4health 1 / 10
  5. Authority 1 / 34

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

Amazon best sellers that list it

  1. #15 Purina One True Instinct with a Blend of Real Turkey & Venison 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 68%
  2. Wheat Gluten 68%
  3. Liver 66%
  4. Meat By-Products 49%
  5. Corn Starch-Modified 40%
  6. Beef 38%
  7. Carrots 38%
  8. Brown Rice 30%
  9. Chicken Broth 28%
  10. Water 26%
  11. Potassium Chloride 21%
  12. Spinach 19%

On the shelf

Foods that list Soy Flour

47 foods in our catalog list it, highest on the label first.

Purina Dog Chow Soft Bites Smoked Chicken Dry Dog FoodPurinaPurina Dog Chow Soft Bites Smoked Chicken Dry Dog FoodDry // No. 2 on the labelPurina One True Instinct High Protein with Real Chicken & Duck Dry Dog FoodPurinaPurina One True Instinct High Protein with Real Chicken & Duck Dry Dog FoodDry // No. 3 on the labelPurina One True Instinct Formula with Real Salmon & Tuna Dry Dog FoodPurinaPurina One True Instinct Formula with Real Salmon & Tuna Dry Dog FoodDry // No. 3 on the labelPurina Dog Chow High Protein with Real Chicken in Gravy Wet Dog FoodPurinaPurina Dog Chow High Protein with Real Chicken in Gravy Wet Dog FoodWet // No. 6 on the labelAuthority Everyday Health Tender Blends Adult Dry Dog FoodAuthorityAuthority Everyday Health Tender Blends Adult Dry Dog FoodDry // No. 6 on the labelPurina Beneful Steak & Green Beans in Gravy Wet Dog FoodPurinaPurina Beneful Steak & Green Beans in Gravy Wet Dog FoodWet // No. 8 on the labelPurina Pro Plan Small Breed Chicken Carrots Gravy Wet Dog FoodPurinaPurina Pro Plan Small Breed Chicken Carrots Gravy Wet Dog FoodWet // No. 8 on the labelGravy Train Chunks In Gravy With Beef Chunks Wet Dog FoodGravy TrainGravy Train Chunks In Gravy With Beef Chunks Wet Dog FoodWet // No. 8 on the labelPurina Pro Plan Adult Small Breed Beef & Green Beans Entrée in Gravy Wet Dog FoodPurinaPurina Pro Plan Adult Small Breed Beef & Green Beans Entrée in Gravy Wet Dog FoodWet // No. 9 on the labelGravy Train Beefy Classic Dry Dog FoodGravy TrainGravy Train Beefy Classic Dry Dog FoodDry // No. 9 on the label4health Shreds Large Breed Adult Chicken Formula Dry Dog Food4health4health Shreds Large Breed Adult Chicken Formula Dry Dog FoodDry // No. 9 on the labelPurina Beneful IncrediBites Small Breed with Real Chicken in Gravy Wet Dog FoodPurinaPurina Beneful IncrediBites Small Breed with Real Chicken in Gravy Wet Dog FoodWet // No. 10 on the label
Show 35 more
Purina One True Instinct Formula with Real Beef & Bison Dry Dog FoodPurinaPurina One True Instinct Formula with Real Beef & Bison Dry Dog FoodDry // No. 3 on the labelPurina ONE True Instinct Tender Cuts Beef & Salmon Wet Dog FoodPurinaPurina ONE True Instinct Tender Cuts Beef & Salmon Wet Dog FoodWet // No. 5 on the labelPurina ONE True Instinct Tender Cuts in Gravy Chicken & Duck Wet Dog FoodPurinaPurina ONE True Instinct Tender Cuts in Gravy Chicken & Duck Wet Dog FoodWet // No. 5 on the labelPurina Dog Chow High Protein with Real Lamb in Gravy Wet Dog FoodPurinaPurina Dog Chow High Protein with Real Lamb in Gravy Wet Dog FoodWet // No. 6 on the labelPurina ONE True Instinct Tender Cuts in Gravy Beef & Bison Wet Dog FoodPurinaPurina ONE True Instinct Tender Cuts in Gravy Beef & Bison Wet Dog FoodWet // No. 6 on the labelPurina Beneful Chicken & Peas in Gravy Wet Dog FoodPurinaPurina Beneful Chicken & Peas in Gravy Wet Dog FoodWet // No. 7 on the labelPurina ONE True Instinct Muscle Support Beef Dry Dog FoodPurinaPurina ONE True Instinct Muscle Support Beef Dry Dog FoodDry // No. 7 on the labelPurina Dog Chow High Protein with Real Beef in Gravy Wet Dog FoodPurinaPurina Dog Chow High Protein with Real Beef in Gravy Wet Dog FoodWet // No. 7 on the labelPurina ONE True Instinct Tender Cuts in Gravy Turkey & Venison Wet Dog FoodPurinaPurina ONE True Instinct Tender Cuts in Gravy Turkey & Venison Wet Dog FoodWet // No. 7 on the labelPurina One SmartBlend True Instinct High Protein with Real Beef & Salmon Dry Dog FoodPurinaPurina One SmartBlend True Instinct High Protein with Real Beef & Salmon Dry Dog FoodDry // No. 7 on the labelPurina One True Instinct with a Blend of Real Turkey & Venison Dry Dog FoodPurinaPurina One True Instinct with a Blend of Real Turkey & Venison Dry Dog FoodDry // No. 8 on the labelPurina ONE Lamb & Brown Rice Tender Cuts in Gravy Wet Dog FoodPurinaPurina ONE Lamb & Brown Rice Tender Cuts in Gravy Wet Dog FoodWet // No. 8 on the labelPurina ONE Chicken & Brown Rice Skin & Coat Wet Dog FoodPurinaPurina ONE Chicken & Brown Rice Skin & Coat Wet Dog FoodWet // No. 8 on the labelPurina ONE Chicken & Brown Rice Brain & Heart Wet Dog FoodPurinaPurina ONE Chicken & Brown Rice Brain & Heart Wet Dog FoodWet // No. 8 on the labelPurina ONE Chicken & Brown Rice Bone & Joint Wet Dog FoodPurinaPurina ONE Chicken & Brown Rice Bone & Joint Wet Dog FoodWet // No. 8 on the labelPurina ONE Beef & Barley Tender Cuts in Gravy Wet Dog FoodPurinaPurina ONE Beef & Barley Tender Cuts in Gravy Wet Dog FoodWet // No. 9 on the labelPurina ONE Chicken & Brown Rice Tender Cuts in Gravy Wet Dog FoodPurinaPurina ONE Chicken & Brown Rice Tender Cuts in Gravy Wet Dog FoodWet // No. 9 on the labelPurina One True Instinct High Protein Real Chicken Duck Dry Puppy Dry Dog FoodPurinaPurina One True Instinct High Protein Real Chicken Duck Dry Puppy Dry Dog FoodDry // No. 9 on the labelPurina Beneful Kitchen Creations Chicken & Veggies Wet Dog FoodPurinaPurina Beneful Kitchen Creations Chicken & Veggies Wet Dog FoodWet // No. 10 on the labelPurina Beneful Freshly Prepared Blends with Turkey, Sweet Potatoes, Brown Rice and Spinach Wet Dog FoodPurinaPurina Beneful Freshly Prepared Blends with Turkey, Sweet Potatoes, Brown Rice and Spinach Wet Dog FoodWet // No. 10 on the labelPurina Beneful Freshly Prepared Blends with Beef, Carrots, Peas and Barley Wet Dog FoodPurinaPurina Beneful Freshly Prepared Blends with Beef, Carrots, Peas and Barley Wet Dog FoodWet // No. 10 on the labelCesar Loaf & Topper in Sauce Rotisserie Chicken with Bacon & Cheese Wet Dog FoodCesarCesar Loaf & Topper in Sauce Rotisserie Chicken with Bacon & Cheese Wet Dog FoodWet // No. 10 on the labelCesar Loaf & Topper in Sauce Angus Beef with Bacon & Cheese Wet Dog FoodCesarCesar Loaf & Topper in Sauce Angus Beef with Bacon & Cheese Wet Dog FoodWet // No. 10 on the labelPurina Beneful Freshly Prepared Meals Beef Pouch Wet Dog FoodPurinaPurina Beneful Freshly Prepared Meals Beef Pouch Wet Dog FoodWet // No. 11 on the labelPurina Beneful Freshly Prepared Meals Chicken Pouch Wet Dog FoodPurinaPurina Beneful Freshly Prepared Meals Chicken Pouch Wet Dog FoodWet // No. 11 on the labelPurina Beneful Prepared Meals Simmered Chicken Wet Dog FoodPurinaPurina Beneful Prepared Meals Simmered Chicken Wet Dog FoodWet // No. 11 on the labelPurina Beneful Freshly Prepared Blends Lamb Wet Dog FoodPurinaPurina Beneful Freshly Prepared Blends Lamb Wet Dog FoodWet // No. 11 on the labelPurina Beneful Freshly Prepared Blends Chicken Wet Dog FoodPurinaPurina Beneful Freshly Prepared Blends Chicken Wet Dog FoodWet // No. 11 on the labelPurina Beneful Prepared Meals Simmered Beef Wet Dog FoodPurinaPurina Beneful Prepared Meals Simmered Beef Wet Dog FoodWet // No. 11 on the labelPurina Beneful Kitchen Creations Lamb Veggies Wet Dog FoodPurinaPurina Beneful Kitchen Creations Lamb Veggies Wet Dog FoodWet // No. 11 on the labelPurina Pro Plan Bright Mind Adult 7+ Beef & Brown Rice Entrée Wet Dog FoodPurinaPurina Pro Plan Bright Mind Adult 7+ Beef & Brown Rice Entrée Wet Dog FoodWet // No. 11 on the labelCesar Loaf Topper Sauce Filet Mignon Flavor With Bacon & Potato Wet Dog FoodCesarCesar Loaf Topper Sauce Filet Mignon Flavor With Bacon & Potato Wet Dog FoodWet // No. 11 on the labelPurina Beneful Freshly Prepared Blends Salmon Wet Dog FoodPurinaPurina Beneful Freshly Prepared Blends Salmon Wet Dog FoodWet // No. 12 on the labelPurina Beneful Freshly Prepared Meals Lamb Pouch Wet Dog FoodPurinaPurina Beneful Freshly Prepared Meals Lamb Pouch Wet Dog FoodWet // No. 13 on the labelPurina Beneful Prepared Meals Beef Chicken Wet Dog FoodPurinaPurina Beneful Prepared Meals Beef Chicken Wet Dog FoodWet // No. 13 on the label

Sources

What we read

Checked October 1, 2026.

  1. 1 Ileal and total tract nutrient digestibilities and fecal characteristics of dogs as affected by soybean protein inclusion in dry, extruded diets Journal of Animal Science, 2001 // Journal
  2. 2 Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats BMC Veterinary Research, 2016 // Journal
  3. 3 Effects of dietary soy isoflavones on health, steroidogenesis, and thyroid gland function in dogs American Journal of Veterinary Research, 2009 // Journal
  4. 4 Evaluation of Soybean Ingredients in Pet Foods Applications: Systematic Review Animals, 2024 // Journal
  5. 5 Edible Soybean Flours and Grits Food and Agriculture Organization of the United Nations, 1992 // Government
  6. 6 Reading Labels Association of American Feed Control Officials, 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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