Wednesday, January 27, 2010

low protein diets and long term well being

OK, this is making me crazy.

I'm getting questions from both veterinarians and pet owners based on bad information from the 'holistic' websites. Essentially, the rumor is that low protein diets used for kidney disease lead to muscle atrophy long term.

These diets (examples are Hill's K/D, Royal Canin LP, and Purina NF)contain protein levels that are more than adequate for maintenance and can even sustain growth. (Not that you would want to try that on your puppy or kitten). That's PLENTY of protein to maintain muscle mass when all else is normal, like calorie intake and exercise.

The reason chronic renal patients lose weight and muscle long term is that *they are not eating enough*. They are starving. When they don't get adequate food, they don't get adequate calories or protein. Starvation leads to fat and muscle loss.

If your kidney patient is losing muscle mass, the thing to do is find out why he or she isn't eating well enough, and correct that problem.

Really - the low protein diets are not the problem!

Not that some would believe a veterinarian trained in nutrition above a random self taught expert on the internet, but that's another issue. Rant over. Thanks for listening.


  1. I agree with what you're saying - that animals losing weight/muscle are probably not getting enough protein and calories because they're not eating enough.

    However, my understanding of the protein level issue is that one does not need to have low protein until late-stage renal failure. (of course testing the individual animal is key)

    If the animal was eating a diet with plenty of appropriate, digestible protein and fat (and getting appropriate supplements to help their body process it) that the inappetence would be less damaging because they would be getting more nutrient-dense meals, even small ones.

    I look foward to your feedback.

  2. What we know about kidney disease is that it progresses faster if phosphorus levels in the body are high. That occurs when the kidney is unable to eliminate it, but dietary phosphorus is one thing that we can control. The most phosphorus-dense food group is protein. So while *protein* does not accelerate kidney disease, phosphorus independantly does, and the way to control phosphorus levels is to decrease protein. We do that in a staged manner, according to the IRIS staging, with no restriction at Stage 1, increasing the restriction to its lowest at Stage 4.

    About the 'nutrient-dense meals' - sure, you can supply minimal or low or moderate protein levels in meals that are almost 100% meat, but that makes a VERY small amount of food. Most animals are still hungry eating these small meals. Renal diets are designed to give them more bulk (and hence tend to satiate them better) with carbs and fat, and are complete and balanced as well.

    So whether the animal is getting a phosphorus-restricted diet in a very small meal with mostly protein and other nutrients to balance it, or a bigger meal with appropriate nutrients - that's immaterial except from the standpoint of the dog's happiness and the owner's comfort with the situation.

    Also, I think the issue of an "appropriate" protein is a matter of personal philosophy. When mid to late stage renal failure is present, the most appropriate protein is egg because it is the one with the most complete amino acid profile, hence the one that can be most restricted.

  3. I am learning so much! Thank you.