Potato in Dog Food - Dog Nutrition DB

Potatoes in dog food provide mainly starch and protein. Some manufacturers use whole or dried potatoes while others include isolated fiber, starch or protein in their products.

Contents

About Potatoes

Potatoes (Solanum tuberosum) are starchy tubers and a staple food for humans in many parts of the world.

They originated from the Andes and were brought to mainland Europe in the 16th century. Today, potatoes are the world’s fourth most important food crop after corn, wheat, and rice^[5].

Potato plants belong to the nightshade family (Solanaceae) and are related to tomatoes or eggplants.

After the potato harvest, the surplus from not-so-pretty or discarded potatoes is usually used as animal feed.

And with some processing, potato starch, protein or fiber can be isolated and used as separate ingredients.

With the rise of grain-free formulas, some manufacturers switched to alternative carbohydrates such as potato, sweet potato or tapioca.

Potatoes are also used in pet foods as a protein source.

Today, pet food businesses include about 37.500 tons of potatoes in their products each year which is still not that much compared to the over 1.900.000 tons of corn^[2].

Just like us, dogs can’t digest raw potato starch. Raw potatoes also contain toxic glycoalkaloids such as solanine and other antinutritional factors such as enzyme inhibitors^[5].

But after cooking, potatoes are safe and highly digestible.

However, cooked potatoes contain lots of water and have a short shelf-life. So dog food manufacturers mainly use dried potatoes in the form of potato flour or potato flakes in their recipes.

Some manufacturers use “dried potato products“. These are the dried inexpensive leftovers of potato processing for human foods made from peels, cull potatoes, and potato pieces^[1].

In 2018, the FDA began investigating reports of canine dilated cardiomyopathy (DCM) in dogs eating pet foods that contained a high proportion of pulses and/or potatoes as main ingredients.

At this point, however, the possible relationship between potatoes and dietary changes in taurine intake and other factors is not clear, as most research has focused on legumes^[8].

Dried Potatoes

A 2016 study analyzed the composition of different carbohydrate sources^[6]. Dried potato flakes were about 73% starch. No wonder dried potatoes in dog food are used as a carbohydrate source.

Potatoes also contain about 8% water, 10% crude protein, 1% fat, 3% insoluble and 4% soluble fiber, and some minerals^[6].

Aside from starch, whole potatoes don’t have that many nutrients.

Raw potatoes provide some water-soluble vitamins such as niacin, thiamin, riboflavin, folic acid, and vitamins C and B₆ (much of which is lost when cooking)^[10].

Their mineral content is low except for potassium^[6].

Depending on the cultivar, potato skin can also be rich in phytochemicals such as polyphenols and carotenoids.

Potato Starch

Larger amounts of tubers, such as potatoes, are found mainly in grain-free dog foods. Since many manufacturers include potatoes as a substitute for starch from cereal grains it is obvious to just use the extracted potato starch instead of whole potatoes.

Potatoes produce lots of starch in their tubers to store energy.

This starch is used as a starting material for many commercial products and is widely available. Potato starch processed in dry extruded foods is nearly completely digested by dogs^[4].

But not all of the starch in potatoes is broken down directly by your dog’s digestive enzymes.

Dried potato flakes not only contain about 67% of digestible starch but also about 6% of resistant starch^[6].

Resistant starches escape digestive enzymes in the small intestine and are fermented by bacteria in the colon.

This makes them a prebiotic known to also reduce the glycemic index of the foods or increase satiety^[5].

Potato starch has been shown to also increase the digestibility of protein in puppies^[3]. But flour made from whole potatoes (including protein and fiber) has the opposite effect^[4].

The reason behind the positive effects of potato starch on energy and nutrient digestibility may lie in their starch composition.

Potatoes contain a little more amylopectin than corn which in turn causes better starch gelatinization while processing and produces a less dense kibble with higher digestibility^[3].

So, although many of us prefer “whole ingredients,” isolated potato starch in dog food may be better than whole potatoes.

Potato Protein

Fresh potatoes only contain about 1-2% of protein.

But protein from whole potato flour is less digestible than that of grains such as barley, corn, rice, sorghum, and wheat^[4].

If manufacturers want to enrich their products with potato protein, they use concentrated potato protein instead of flour or flakes made from whle potatoes.

Essential Amino Acids	Potato Protein^[13]	Potato Flakes^[6]
Arginine	4.88%	0.46%
Histidine	2.19%	0.24%
Isoleucine	5.73%	0.40%
Leucine	9.95%	0.76%
Lysine	7.72%	0.36%
Methionine	2.19%	0.18%
Phenylalanine	6.28%	0.52%
Threonine	5.39%	0.35%
Tryptophan	0.88%	0.10%
Valine	6.92%	0.49%

Essential amino acids as a percentage of dry matter

Potato protein is a by-product of starch extraction.

For processing, fresh potatoes are cleaned and finely ground into potato juice from which starch can be extracted.

The de-starched potato juice is then heat-treated to coagulate the protein fraction, which is then dehydrated to a powder^[1].

This results in a concentrate of almost pure protein which is highly available and a very cost-effective ingredient. And this makes it popular with dog food manufacturers.

Potato protein is very rich in protein compared with other plant protein concentrates (about 80% crude protein in dry matter)^[13].

The major protein in potatoes is patatin^[7]. This is also the most common allergen in humans with a potato allergy.

Fortunately, this is very uncommon in dogs, potatoes are often used in hypoallergenic recipes.

A 2020 study evaluated the protein quality of different plant-sourced concentrates for pet food. They found all the essential amino acids in potato protein to be highly digestible^[13].

However, potatoes may be limiting in digestible tryptophan and methionine, the latter being a sulfur-containing amino acid and precursor of taurine^[5,6,13,14].

In summary, potato protein seems to be one of the better pant-sourced protein concentrates. But it should be complemented with other proteins to balance out the lacking amino acids and ensure dogs get all the essential amino acids they need.

Potato Fiber

Potato pulp is another by-product of starch production.

It contains all the substances in the potato juice that are insoluble in water such as skin and cell fragments plus some starch residue.

Dietary fiber is resistant to digestion in your dog’s small intestine. But soluble fiber can be completely or partially fermented in the large intestine by your dog’s gut bacteria.

While fiber is not an essential nutrient it can be added to dog food for its prebiotic effect or to add bulk, improve gut motility, aid in digestion and provide other benefits^[10,11].

A 2013 study found potato fiber to contain about 55% total dietary fiber (23% soluble, 32% insoluble) 29% resistant and digestible starches, 4% crude protein, and 2% crude fat^[9,10].

The soluble fiber in potato pulp consists mainly of pectins and the insoluble fiber consists of cellulose and hemicellulose^[10].

Potato fiber is an adequate fiber source with plenty of fermentable fiber and has no negative effects on nutrient digestibility.

About Potatoes

Dried Potatoes

Potato Starch

Potato Protein

Potato Fiber

Further Reading