New research published in Cell Reports Medicine from a recent clinical trial shows that adhering to a ketogenic diet can effectively control polycystic kidney disease (PKD). The clinical study is the first randomized trial of its kind that examining the ketogenic metabolic therapy as a treatment strategy for PKD. The trial was a collaboration between researchers at University of California (UC) Santa Barbara, and the University of Cologne, Germany.
“If you have PKD, the dogma is that it’s a genetic disease and no matter what you do, you progress toward kidney failure and diet doesn’t make any difference, which unfortunately most patients are told to this day,” said Thomas Weimbs, a biologist at UC Santa Barbara whose lab participated in the study. “We now have the first evidence in humans that the cysts really don’t like to be in ketosis and that they don’t seem to grow.”
For the trial, the German investigators, led by Roman Müller, PhD, of the University of Cologne, recruited 66 patients which were randomly split into three groups. The controls received routine PKD counseling, a second group underwent a three-day water fast every month and a third group observed a low-carbohydrate, high-fat ketogenic diet. All patients were followed closely with data collected via blood draws and MRI.
After the three-month trial period, the control group exhibited an expected level of growth of their kidneys, while they ketogenic diet patient group’s kidneys stopped growing and even appeared to be shrinking, though the level of shrinkage over that time frame was found not to be statistically significant.
Most notable was the improved, statistically significant, kidney function of the patient on the ketogenic diet, measure by concentration of a protein called cystatin C—higher levels of which indicate faltering filtration ability. Weimbs noted that this outcome was not expected and is counter to the prevailing notion that PKD only gets worse over the passage of time.
The trial also polled the participants on the feasibility of adhering to a ketogenic diet to mitigate PKD, and the patients said it was “highly feasible.”
“Doctors often assume that their patients cannot adhere to a diet anyway, so they don’t even try,” Weimbs said. “Clearly, this is not true. People with PKD are highly motivated to do something about their condition.”
Weimbs emphasized there is no one-size-fits-all ketogenic diet, and patients should consult with physicians and nutritionists to design a form of the diet that works for them. The study also introduces the Ren.Nu plant-focused ketogenic diet, developed by Weimbs and renal dietitians specifically for PKD patients.
Weimbs, who has been studying the cellular mechanisms underlying PKD for more than 20 years, built the new trial around a chance finding in his lab—that mice undergoing caloric restriction had their kidney cysts shrink.
Building on these findings, the team is now aiming to design clinical trials to commence in 2024 in Toronto and Tokyo that will test the effects of a medical food specifically developed to help PKD patients reach ketosis. The studies will enroll larger cohort—80 people in Toronto and 200 in Tokyo— and will extend the length of the trail to one year.
“We want to investigate the longer-term effects,” Weimbs said. “If this trend of kidney volume change we saw in the three-month study holds true, we would expect to see a larger and statistically significant difference there as well.
