To my knowledge there isnt one because the pet food companies fund all the studies and they want people to buy the RX diets. The problem is that all the studies-the few there are (to my knowledge) used food that was BOTH low in phosphorus, AND low protein . So there is no way to prove that it was the low phos and not the low protein.
From
http://www.catinfo.org Dr. Lisas site
"Please also note the following list of the first four ingredients of Hill's Prescription dry k/d after reviewing this section on reading a pet food label - and bearing in mind that your cat is a carnivore. This is a diet that would never find its way into a food bowl owned by any cat in my care. The first three ingredients are not even a source of meat and the fourth ingredient is a by-product meal which is not necessarily an unhealthy source of protein but it would be nice to see some muscle meat ("chicken") in this product.
Brewers rice, corn gluten meal, pork fat (preserved with mixed tocopherols and citric acid), chicken by-product meal
The purpose of this prescription diet is to restrict protein which, unfortunately, it certainly does. However, please understand that there are no studies showing that restricting protein to this level will prevent further deterioration of kidney function.
k/d restricts protein to the point that some cats - those that are not consuming enough of the diet to provide for their protein calorie needs - will catabolize (use for fuel) their own muscle mass which results in muscle wasting and weight loss. This internal breakdown of the cat’s own muscle mass will cause an increase in creatinine which needs to be cleared by the kidneys. The rise in creatinine, and muscle wasting, can lead to an often-erroneous conclusion that the patient’s CKD is worsening.
Of course, the same deterioration can occur in any cat that is not consuming enough protein, but the level of protein in this diet is not only at an extremely low level, it is in an incomplete form for a carnivore. Note that it is made up mainly of plant proteins - not meat proteins. It is also water-depleted as is the very definition of all dry foods. "
http://www.holisticat.com/crf/Diet-what ... ssues.html
http://mousabilities.com/nutrition/crf/ ... ein_RD.pdf
pdf link from Feline outreach
http://www.felineoutreach.org/Education/Kidney.html
http://www.littlebigcat.com/index.php?a ... w&item=003
http://www.felinecrf.org/nutritional_requirements.htm
