Porus One and Its Impact on Chronic Renal Failure

New Supplement Helps Remove Toxins

Lauri Henry
Physician Assistant (retired)
MCMS (Master of Clinical Medical Science)
Singita Burmese Cattery

 

Porus One is a dietary supplement that might help some cats experiencing Chronic Renal Failure (CRF) feel better. This is a new option for cats, and there is not a lot of information available about it at present.

Chronic Renal Failure refers to the permanent loss of kidney function. It affects 30 percent of cats over the age of 10 and 80 percent of cats over the age of 15.1 The kidneys have a lot of roles in the body. When they fail, a constellation of issues can arise, making the cat feel ill. The rate of progression of CRF is variable, and some cats can live a long time while progressing slowly. Although we can’t reverse this disease, we can attempt to make our cats feel better while they are still with us.

What is Porus One?

Porus One is a patented form of activated charcoal, also known as “Renaltec.” It is classified as a “veterinary nutritional supplement,” and as such is a nonprescription product that is available for purchase through many different pet supply resources. An internet search will offer a number of options. Intended to be mixed into wet food or treats, it is black and looks like finely ground charcoal. The charcoal material has been modified to include microscopic channels and to carry a positive molecular charge.2 These modifications are intended to collect and hold waste material. The manufacturer claims that the amount of Porus One in one packet has the absorptive surface area of three tennis courts. While Porus One does change the appearance of the food, it does not seem to change the palatability.

There is no known toxicity to Porus One according to the package insert. Historically, activated charcoal has been used to mitigate poisoning in both human and veterinary medicine, which suggests that it would not likely be toxic on its own. Interestingly, forms of charcoal have also been used as adjunct treatments for renal failure in human medicine.3 Although Porus One is new to the United States’ feline community, similar carbon-based products have been available in Asia since 1991; Kremezin is the feline product and AST 120 is the human focused product.4,5

Porus One cannot be absorbed from the gut. Once it has picked up toxins, it carries material out of the body in fecal matter. This process is called adsorption (when a substance sticks to a surface, rather than dissolving into another substance – absorption).2 In short, Porus One hopes to remove certain toxins before they reach the kidneys. This helps take some stress off the kidneys and possibly helps preserve the remaining kidney function for a little longer.

More About Toxins

One of the functions of the kidneys is filtration. Almost 150 different toxins have been identified that may be circulating when kidney filtration is impaired, and these can have an impact on feline health.6,7

Currently, feline kidney function is clinically measured from a blood sample drawn  at a veterinary office by levels of BUN, creatinine, and SDMA. BUN (blood urea nitrogen) measures hydration status and waste products leaving the liver. Creatinine shows levels of waste products related to normal muscle mass and waste leftover from protein metabolism.1 SDMA is a newer test which measures levels of an amino acid (symmetric dimethylarginine) and is an indication of glomerular filtration rate, or how well the kidneys filter blood. The SDMA test shows declines in kidney function sooner than the older tests, since levels of SDMA rise earlier than BUN and Creatinine levels.8

Researchers are also investigating the importance of other contributors to uremic toxins. At present, Indole and p-cresol are of particular interest, as both originate from protein metabolism.  (see: chart one digestion without Porus One)  Dietary protein is broken down into individual amino acids in the stomach. The stomach then sends the amino acids to the gut where intestinal microbes ferment them. Two of these amino acids are tryptophan and tyrosine. The intestines produce indole from the amino acid tryptophan and p-cresol from the amino acid tyrosine. Next, indole and p-cresol are both sent to the liver where they are modified to become indoxyl sulfate and p-cresol sulfate: Both of these are uremic toxins. At this point, both are transported from the liver to the kidneys. In cats with healthy kidneys, they are filtered out of the body. In CRF cats, filtration is impaired, and they will continue to circulate as uremic toxins.

In the presence of Porus One, (see: chart two) the precursors indole and p-cresol are picked up in the intestines and transported out of the body in feces. The kidneys are not involved in this process.

In cats, indoxyl sulfate and p-cresol sulfate are known to promote inflammation and damage in the kidney tubules. Both of these rise disproportionately in CRF cats. The precursors (indole and p-cresol) are both targeted by Porus One in the intestines.7

While researchers are able to measure indoxyl sulfate and p-cresol in a laboratory setting, there is no way to measure clinically if a cat is benefiting from Porus One treatment at home. Even though they are not followed in clinical practice, both indoxyl sulfate and p-cresol are important contributors to uremic toxins. One study investigated the relationship between indoxyl sulfate and CRF disease progression and concluded that indoxyl sulfate  levels served as “a biomarker of progression risk” in kidney disease in both dogs and cats.9

One issue that may be addressed in future studies is the possibility of Porus One causing a dietary deficiency in the amino acids tryptophan and tyrosine. Both of these are considered to be “essential amino acids” in cats, which means that they must be acquired from dietary sources.  Whether or not Porus One can potentially create any type of dietary deficiency is yet unknown and there is not sufficient published literature available at present to draw any conclusion.

Finally, it is important to consider the basics of CRF management. The first intervention recommended to decrease uremic toxins in cats is to lower their dietary protein. However, cats are obligate carnivores and it is difficult to eliminate protein from their diets. With that in mind, the search continues for other interventions to help CRF cats.7

Porous One client information is available here.

Dosing

The package label recommends once-daily dosing by mixing one packet into wet food or a wet treat. The few published studies available used wet treats and not the cats’ regular diet. One study noted better results with twice-daily dosing: They divided the packet in half and gave it in two different wet treats on the same day. They reported that twice daily dosing resulted in a significantly larger decrease in indoxyl sulfate at the end of the 56-day study period.10

According to the package insert, Porus One has the potential to interfere with the absorption of other medications and dietary additives.  It should therefore be given at least two hours after other medications.

What Porus One is Not

Porus One does not reverse existing kidney damage. Therefore, the routine measures of kidney function, BUN, creatinine and SDMA are not expected to improve, and it is likely that they will continue worsening over time as they typically do in CRF.

Porus One is not a cure and it is not a subsititute for a low protein diet. However, it might be an accessory treatment that could potentially lower the quantity of circulating uremic toxins.

Clinical Trials

There are two related clinical trials that are actively enrolling cats in Porus One studies at present. One is located at Texas A&M Veterinary School. The Texas trial is enrolling participants who are within driving distance of College Station, Texas.11 The other trial is located at Ohio State University and is also actively enrolling participants.12

A Personal Note about our Cat Kimbia

Kimbia is, above all things, an amazing pet. He is also our first Regional Winner and our first Grand Premier. He was born in our first litter and, in fact, was born in our bed. He is by every measure a remarkable Burmese.

Kimbia’s kidney functions had been slowly declining on routine labs over several years.  Suddenly, in September of 2024, he grew visibly ill: He began hiding; his weight dropped by 20 percent within a few weeks; he wouldn’t eat or play. His veterinarian believed that his condition had become dire, with his disease going from slow progression to very quickly nearing the final phase. With the help of our veterinarians, we aggressively changed his medical management. His appetite stimulant was changed, and the new medication worked. Since he had started eating on his own again, we decided to try Porus One. Fortunately, he ate it without hesitation. Within two weeks his weight had stabilized, and we began to see big improvements in his behavior. He had improved so much that we imagined his kidney failure had also stabilized. Unfortunately, even with visible improvement at home, his follow up labwork showed that his creatinine and SDMA were still worsening. In short, his quality of life had improved, but his kidneys were continuing to decline.

At the time of writing this article, we are now five months past when I thought we would lose Kimbia. We will never know if it was Porus One or the change of appetite stimulants that are responsible for keeping him with us a little longer. It is also important to keep in mind that there is risk involved when trying unproven dietary supplements. In the absence of any evidence of harm, trying Porus One was a chance we were willing to take.

 

 

References

 

  1. Kornya, Matthew; EveryCat Foundation, YouTube lecture January 2025 https://www.youtube.com/watch?v=DSWwibVrSxU
  2. Dechra Pharmaceuticals, Porus One Website https://www.dechra-us.com/our-products/us/companion-animal/cat/non-prescription/porus-one
  3. Huizen, Jennifer, BS, MS. Medically reviewed by Alicia D. Sellers, BS Pharmacy, PharmD (updated 23 January 2024); What are the uses of activated charcoal? https://www.medicalnewstoday.com/articles/322609
  4. Asai, Mayumi; Kumakura, Sei, Kikuchi, Mami; Review of the efficacy of AST-120 (KREMEZIN) on renal function in chronic kidney disease patients, Ren Fail 2019 Feb 7; 41 (1) 47-56 https://pmc.ncbi.nlm.nih.gov/articles/PMC6374968/
  5. Schulman, Gerald; Vanholder, Raymond; Niwa, Toshimitsu, AST-120 for the management of progression of chronic kidney disease; Int J Nephrol Renovasc Dis. 2014 Jan 30;7:49–56. doi: 10.2147/IJNRD.S41339 https://pmc.ncbi.nlm.nih.gov/articles/PMC3912158/
  6. Summers, Stacie C., Quimby, Jessica M., Insights into the gut-kidney axis and implications for chronic kidney disease management in cats and dogs, The Veterinary Journal, Volume 306, August 2024, 106181 https://www.sciencedirect.com/science/article/pii/S1090023324001205
  7. Summers, Stacie C. and Quimby Jessica M The Feline Gut Kidney Axis Royal Canin Issue 33.1 published 31/05/2023 https://vetfocus.royalcanin.com/en/scientific/the-feline-gut-kidney-axis-food-for-thought
  8. eClinPath.com, Cornell University https://eclinpath.com/chemistry/kidney/sdma/ February 20, 2025
  9. Chen, CN; Chou, CC; Tsai, PSJ, Lee, YJ Plasma indoxyl sulfate concentration predicts progression of chronic kidney disease in dogs and cats YJ Veterinary Journal 232 pp33-39 (2018) https://pubmed.ncbi.nlm.nih.gov/29428089/
  10. Paschall, Rene E; Quimby, Jessica M; Lourenco, Bianco; Summers, Stacie C; Schmiedt, Chad W: The Effect of Renaltec on Serum Uremic Toxins in Cats with Experimentally Induced Chronic Kidney Disease, Vet Sci 2024, 11(8), 379; https://doi.org/10.3390/vetsci11080379
  11. Clinical Trial Announcement: Evaluating a treatment for the management of feline chronic kidney disease https://studypages.com/s/evaluating-a-treatment-for-the-management-of-feline-chronic-kidney-disease-387799/\
  12.  Clinical Trial Announcement: Effect of Porus One on Reducing Uremic Toxins in Cats with Chronic Kidney Disease (CKD) https://vmc.vet.osu.edu/clinical-trials/effect-porus-one-reducing-uremic-toxins-cats-chronic-kidney-disease-ckd