Published on November 20, 2023 | Each year, the PKD Foundation funds research grants and fellowships to increase understanding of the genetic and pathological processes involved in PKD and to accelerate the development of potential therapies for PKD patients. In 2020, that included Roman-Ulrich Müller, M.D., a researcher investigating the ketogenic diet and PKD.

In 2019, studies in animal models of autosomal dominant polycystic kidney disease (ADPKD) showed the extremely positive effects of a ketogenic diet. This finding attracted a lot of attention among nephrologists, scientists, and patients. The change in diet inhibited both cyst growth and the loss of kidney function. A great scientific success. Several questions were quickly raised. Firstly, should all patients with ADPKD now eat a ketogenic diet? And secondly, what does that even mean? Until now, data in humans or from clinical studies was lacking. However, similar to the approval of drugs, these are an essential step before medical recommendations can be made.

Recently published in the renowned Cell Reports Medicine, the KETO-ADPKD study addressed this issue. This study was conducted in the translational nephrology unit at the University Hospital of Cologne.

So, what are the key takeaways of this study from Dr. Müller’s point of view? Let’s dive in.

Ketogenic Diet—What is It?

The ketogenic diet leads to a metabolic change in which ketone bodies are formed as a metabolic product, hence the name. In a nutshell, in order to achieve this metabolic shift, the amount of carbohydrates (i.e. sugar) is significantly reduced and the amount of fat in the diet is greatly increased. This involves avoiding classic bread or desserts, and consuming more olive oil or fatty fish instead, for example.

Is a Ketogenic Diet Feasible for Patients with ADPKD in everyday life?

Dietary changes aren’t always easy. This was an important question in the KETO-ADPKD study. Feasibility was measured using questionnaires, and the ketone bodies in the blood and breath were also determined. The bottom line? Yes. This diet was indeed feasible over the three-month period studied. However, there were some hurdles that to overcome in everyday life.  For instance, eating in a restaurant requires more planning.

Did the ketogenic diet have an effect on kidney growth in KETO-ADPKD?

Normally, polycystic kidneys continue growing over time. With the study’s control group, participants who continued eating as usual, this was also the case. On the ketogenic diet, the kidney volume decreased. However, this difference was not statistically significant. The effect could also be a coincidence, so that question doesn’t have a clear answer yet.

What did KETO-ADPKD show regarding kidney function?

Over time, kidney function continuously decreases in ADPKD. This was also seen in the control group. In contrast, kidney function increased over the course of the three months on a ketogenic diet. This result was statistically significant, so we assume there was a real effect. However, KETO-ADPKD only studied the diet for three months. We don’t know yet whether this would be beneficial in the longer term.

Were there any side effects?

The only side effect reported more frequently by participants were symptoms of the so-called “keto flu.” This is a well-known phenomenon. In the first few days of the dietary change, participants experienced symptoms similar to an infection, such as headaches or tiredness. These symptoms can also appear in those not affected by ADPKD starting a ketogenic diet. After a few days, the effect passes.

In addition, some patients showed an increase in cholesterol levels (blood lipid levels). Whether this has negative consequences under a ketogenic diet, will need clarification. The duration of KETO-ADPKD was certainly still too short to make a statement about kidney stones. In other studies on ketogenic diets in patients not affected by ADPKD, they occurred more frequently. Data on both aspects will need to be collected in future studies over a longer period of time.

Should patients with ADPKD now follow a ketogenic diet?

All patients should discuss dietary changes with the physician and dietician, as the answer depends on a wholistic view of their health and disease state. Although the results from KETO-ADPKD are promising, they aren’t yet sufficient to make a general recommendation on a ketogenic diet for ADPKD. This will require a study with a larger number of participants (e.g. 200-300, currently only 63 participants), over two to three years (currently only three months) at several centers. Such a study is actively being planned. However, acquiring the relevant amount of funding is a challenge.

Such a multi-center study is necessary to clarify whether a positive effect of the ketogenic diet is really achieved in the long term and whether it’s safe for patients with ADPKD over many years. Regardless, the data from KETO-ADPKD is already helping us in advising and caring for patients who decide to change their diet on their own.

If you’re interested in learning more about Dr. Müller’s study, read the full article here.

*The PKD Foundation does not give medical advice. You should not rely on this information as a substitute for, nor does it replace, professional medical advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with your physician or other healthcare professionals.