Low grade, controversial or vague ingredient we usually recommend avoiding
Vegetable protein extracts in dog food
Vegetable protein extract (or isolate) is another term that doesn't shed any real light on what is in the food. It gives no indication of which vegetables are used, nor does it say how the protein is extracted, although the most common methods involve chemical reactions that are far from what most people would regard as 'natural'.
For dogs, vegetable proteins are nutritionally inferior to those found in meat. Common sources of vegetable protein include soya, maize and wheat which have all been linked to dietary intolerance and, in our opinion, should be avoided with sensitive dogs.
Some nutritionists have also speculated that vegetable protein extracts might also be a pseudonym for MSG (monosodium glutamate), the controversial food additive that some believe to be mildly addictive.