Ingredient file // Plant protein
Rice Protein Concentrate
A real plant protein, short on lysine, not filler
Rice protein concentrate is what is left when the starch is washed out of rice, dried into a powder that is mostly protein. It digests well and adds real protein, but it is too low in lysine to replace meat.
- What it is
- Protein separated from rice once the starch is washed out, then dried into a high-protein powder.
- Made from
- Rice or broken rice from milling
- Main job
- Concentrated plant protein
- Typical amount
- Not published for dogs; cat trials used 2.5 to 28%
- Watch for
- Protein figure lifted by plants instead of meat
- Not the same as
- Brewers rice or rice bran
Our read // In our catalog
In 1 of every 1298 foods we track
Share of foods that list it
0%
2 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 5.5. In the top five of 1 food, so it is usually a main ingredient.
Above the salt
Almost always listed before the salt, so there is more of it than a pinch.
Price per lb
Median of the cheapest bag price across 2 priced foods, 101% above the catalog. The price is the food's, not the ingredient's.
Who leans on it
100%
of the foods that list it are from Hill's. 1 brand use it in total.
The story
How a rice starch leftover survived the 2007 melamine scandal
Rice is only about 6 to 7% protein, so pulling that protein out takes a reason, and the reason is starch. Plants that make rice starch and glucose soak and grind the grain, often broken kernels left from milling, then wash the starch away. A 2022 review of rice proteins calls what remains a byproduct of glucose and starch manufacturing. Dried into a powder, that leftover is sold as a protein for food and feed.1,12
Owners first heard the name in April 2007. Wilbur-Ellis, a San Francisco importer, found a pink bag stenciled with the word melamine inside a shipment of rice protein concentrate from Binzhou Futian Biology Technology in China. FDA tests then found melamine in the white bags too. The ingredient had gone to 5 pet food makers in Utah, New York, Kansas and Missouri. By April 19, Natural Balance had recalled its venison dog foods after reports of dogs and cats with kidney failure.8,13
The harm came from a pairing. Pathologists examined 16 dogs and cats from outbreaks in 2004 and 2007 and found the same striated crystals in the kidneys of every animal, with melamine and cyanuric acid in the tissue. In November 2007, a UC Davis feeding study in cats showed that either chemical alone caused no ill effects, while the 2 together brought on acute kidney failure.9,10
The ingredient itself came back under study. In 2023, Hill's Pet Nutrition researchers fed it to 24 cats at up to 28% of the food and reported it well accepted and highly digestible. Hill's then took it to FDA's Animal Food Ingredient Consultation process, and on November 14, 2025 the agency completed consultation number 0001, for use as a source of protein.1,3
What it is
How it is made
Plants that make rice starch and glucose wash the starch out of rice, often broken grains from milling. The protein left behind is a co-product, dried and sold for food and feed.1,5,6,12
- 01 // Source Rice or brokens Whole rice or broken kernels, a co-product of milling husked rice into white rice.
- 02 // Process Soaked and ground The rice is soaked in water and ground. The protein is then dissolved out of the mash.
- 03 // Process Starch removed Insoluble starch is decanted off and goes on to starch and glucose production.
- 04 // Process Precipitated and dried The dissolved protein is made to settle out, then dried into a fine powder.
- 05 // Output Protein powder A dry powder of roughly 79 to 84% protein as sold, ready for the kibble plant.
What is in it
Composition, as fed
84
% protein
Crude protein in a commercial product tested in cat diets. With the starch washed out, it is close to a pure protein ingredient.
Benefits
What it does for your dog
Each benefit carries the same evidence grade as the claims below.
-
01
Protein the dog absorbs well
With the starch washed out, it is mostly protein. In a Hill's cat trial, the whole food digested better as it replaced animal protein, and Hill's dog records showed no loss as plant protein rose.1,2
- Strong
- Some
- Thin
- None
-
02
Building blocks for muscle and repair
It supplies the essential amino acids dogs must get from food, matching egg for most of them. Lysine and cysteine run low, so it works only beside meat or added lysine.1,4
- Strong
- Some
- Thin
- None
-
03
Firm, normal stools
In 24 cats, fecal scores rose, meaning firmer stools, as rice protein reached 28% of the food, and every food stayed in the normal range. No dog stool data exist.1
- Strong
- Some
- Thin
- None
Why it is in the bag
What the manufacturer gets
-
01
Protein in a small scoop
At about 84% protein, 5% of a recipe adds roughly 4 points of crude protein. That lets a formula hit its protein target with less meat.5
-
02
Digests well
In a 24-cat trial, true protein digestibility rose from 90.3% to 95.8% as it replaced animal protein up to 28% of the food, and stools got firmer.1
-
03
Cheaper than soy concentrate
It is a co-product of rice starch and glucose plants. In weaned pigs it replaced soy protein concentrate, which the researchers called the costlier option.11,12
-
04
An uncommon allergen
Rice was the trigger in only 5 of 297 food-allergic dogs in one review, about 2%, fewer than soy at 18 dogs or corn at 13.7
How much No dog inclusion level is published. A Hill's trial fed it at up to 28% of a cat food, with digestibility rising and stools staying normal.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.
-
Critics say
Rice protein is short on lysine
Evidence
- Strong
- Some
- Thin
- None
The product analyzed for a 24-cat trial met or beat whole egg in every amino acid except lysine and cysteine. In pigs, only 80% of its lysine was digested. A recipe needs meat or added lysine.1,4
-
Critics say
It pads the protein number without meat
Evidence
- Strong
- Some
- Thin
- None
This is arithmetic. Crude protein counts protein from any source, and at about 84% protein, 5% of a recipe adds roughly 4 points. The label never says how much of the figure came from meat.5
-
Brands say
A highly digestible, gentle protein
Evidence
- Strong
- Some
- Thin
- None
In a Hill's trial of 24 cats, true protein digestibility rose from 90.3% to 95.8% at 28% of the food. For dogs there is only a Hill's records review showing no loss as plant protein rose. No controlled dog trial is published.1,2
-
Brands say
Rice protein is hypoallergenic
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
Rice was the trigger in 5 of 297 food-allergic dogs, about 2%. The review warns such rankings may only mirror what dogs were fed. It is still intact protein, and no trial has tested it in allergic dogs.7
-
Owners say
Rice protein concentrate poisoned pets
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
In 2007, rice protein concentrate from one Chinese supplier tested positive for melamine, which fakes a higher protein reading. That was fraud, not the ingredient. FDA completed a review of it as a dog and cat protein in 2025.3,8,10
The research
Studies worth knowing
Published research we read for this page, dog studies first.
-
2020 // Review of past feeding trials
Dogs absorbed protein just as well as plant share rose2
226 dogs and 296 cats from Hill's digestibility trials
Found. Looking back at Hill's trials, each with at least 6 animals per food, researchers found protein digestibility in dogs stayed unchanged as plant protein rose. In dry cat food it rose 5.5% with half the protein from plants.
What it means. On this evidence, plant protein does not cost a dog digestibility. It was not a rice protein trial, and Hill's ran it.
-
2007 // Autopsy and tissue tests
Melamine crystals turned up in kidneys of every sick pet9
16 dogs and cats from 2004 and 2007 outbreaks
Found. All 16 animals, 2 dogs in 2004 and 10 cats and 4 dogs in 2007, had the same striated crystals in their kidney tubules. Melamine and cyanuric acid were present in kidney tissue from both outbreaks.
What it means. The kidney damage traced to melamine paired with cyanuric acid. The study does not say which ingredient carried them, so it is no verdict on rice protein itself.
-
2023 // Feeding trial, 4 foods
Cats digested more protein as rice protein replaced meat1
24 adult cats; Hill's funded; no dog trial exists
Found. Foods held 0, 7, 14 or 28% rice protein concentrate, each fed for 15 days. True protein digestibility climbed from 90.3% to 95.8%, cats ate more of the rice protein foods, and stools stayed normal.
What it means. It digests well even in a strict carnivore. Dogs were not tested, so read this as a strong hint, not proof for your dog.
-
n.d. // Taste test and feeding trial
Small swaps kept cat kibble just as tasty and digestible5
Cats, 30 per taste group and 8 per food; no dog trial exists
Found. Rice protein concentrate at 0, 2.5 or 5% of a chicken kibble left palatability unchanged in a test offering 2 bowls. Dry matter, protein and fiber digestibility were similar across the 3 foods.
What it means. At small amounts it stood in for some chicken protein without cats eating less or digesting less. This comes from a conference abstract.
-
2006 // Digestion trial, 5 foods
Pigs absorbed only 80% of its lysine4
6 young pigs; no dog data exist
Found. Each pig ate 5 cornstarch diets in turn, with samples taken from the end of the small intestine. Only 80.0% of the lysine in rice protein concentrate had been absorbed by that point.
What it means. Part of its lysine, already in short supply, goes unabsorbed, so a recipe still needs meat or added lysine.
Straight answers
What owners ask
-
Q01
Is it just filler?
NoOne tested product was 84% protein, and in a Hill's cat trial its protein was more than 90% digestible. Filler adds bulk without nutrition. This adds real protein, just not a complete one.1,5
-
Q02
Can it replace meat protein?
Not aloneIts amino acids match or beat egg except lysine and cysteine, which run low. Paired with meat or added amino acids it does its job. On its own it would leave a dog short.1
-
Q03
Has FDA looked at it?
Yes, in 2025Hill's asked FDA to review it as a protein source for dogs and cats, and the agency completed that consultation in November 2025. That covers the ingredient, not every supplier's batches.3
-
Q04
Is it the same as brewers rice?
NoBrewers rice is broken kernels of white rice, mostly starch. Rice protein concentrate is what remains after the starch is washed out of rice, so it supplies protein instead of carbohydrate.1
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
- Brewers Rice 100%
- Brown Rice 100%
- Egg Product 100%
- Soybean Oil 100%
- Dried Beet Pulp 100%
- Coconut Oil 100%
- Flaxseed 100%
- Fish Oil 100%
- Natural Flavor 50%
- Hydrolyzed Chicken Flavor 50%
On the shelf
Foods that list it
2 foods in our reviews list it. Here are some of them.
Our read // On the bag
Count it as protein, then check the meat
Rice protein concentrate is real protein, so a recipe can post a high protein figure with less meat. Look at what sits above it. A named meat or meal near the top means it is topping up. If it sits beside other plant proteins high on the list, the protein number leans on plants.
Sources
What we read
Checked October 1, 2026.
- 1 Rice protein concentrate is a well-accepted, highly digestible protein source for adult cats
- 2 Cats Have Increased Protein Digestibility as Compared to Dogs and Improve Their Ability to Absorb Protein as Dietary Protein Intake Shifts from Animal to Plant Sources
- 3 Current Animal Food Ingredient Consultation Inventory
- 4 Amino acid and energy digestibility of protein sources for growing pigs
- 5 PS7-4. Performance of Rice Protein Concentrate as Complementary Protein Sources in Extruded Cat Diets
- 6 Is rice protein a suitable ingredient for cat food?
- 7 Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats
- 8 Rice Protein Concentrate Distributor Issues Recall
- 9 Outbreaks of renal failure associated with melamine and cyanuric acid in dogs and cats in 2004 and 2007
- 10 Study Identifies Deadly Chemical Duo in Contaminated Pet Food
- 11 Rice protein concentrate in weaning pig diets (reference record)
- 12 A Narrative Review on Rice Proteins: Current Scenario and Food Industrial Application
- 13 Melamine in Rice Protein Concentrate Prompts Natural Balance Recall