SANTA BARBARA, CA, July 26, 2026. Santa Barbara Nutrients (SBN) is pleased to announce the publication of a new peer reviewed case series in Frontiers in Nutrition demonstrating that the long term Ren-Nu™ ketogenic metabolic therapy, combined with SBN’s medical food KetoCitra®, can halt or even reverse kidney volume enlargement in individuals with Autosomal Dominant Polycystic Kidney Disease (ADPKD).

The new findings provide compelling, longitudinal imaging evidence that dietary carbohydrate restriction, intermittent fasting, and targeted exogenous ketone supplementation can fundamentally alter the structural progression of ADPKD over extended periods ranging from six months to approximately four years.

Years of Sustained Organ Volume Stabilization and Reduction

This retrospective case series, authored by researchers from the University of California, Santa Barbara, and Santa Barbara Nutrients, followed four self referred individuals (ages 33 to 71) with genetically confirmed, high risk truncating PKD1 variants.These genetic profiles are typically associated with more severe disease and earlier progression.

Historically, total kidney volume (TKV) in ADPKD patients increases steadily and relentlessly over time. Spontaneous downward shifts in TKV are not a known feature of the disease. However, across all four cases, MRI-based volumetric analyses revealed that participants experienced a stabilization or outright reduction in TKV relative to their prior growth trends following the implementation of their individualized metabolic interventions.

Figure 2 Above: Clinical and Imaging Trajectory of a 40-Year-Old Male

This graphic tracks the patient's metabolic and renal markers over a four-year period. It demonstrates sustained nutritional ketosis and normoglycemia, alongside a distinct reduction in total kidney volume (TKV) after peaking in 2023. The data also highlights preserved estimated glomerular filtration rate (eGFR) and a favorable downward shift in the patient's Mayo imaging classification from high-risk 1C toward 1B following the layered introduction of ketogenic nutrition, supplementation, and intermittent fasting.

Key Findings from the Case Series Include:

• Sustained Kidney Volume Reduction and Stabilization: Among the participants, TKV was reduced or stabilized relative to prior documented phases of volumetric growth. The intervention periods, lasting up to four years, demonstrate that metabolic therapy can yield durable structural benefits in the kidneys.

• Significant Mayo Classification Improvements: One participant transitioned from Mayo Class 1C to a lower-risk 1B classification. The remaining three demonstrated favorable downward trajectory shifts within their existing Mayo classifications, indicating a reduced risk of disease progression.

• Stable Kidney Function: Estimated glomerular filtration rate (eGFR) remained preserved across all participants throughout their respective intervention periods, indicating that kidney function was protected alongside the volume reductions.

• Liver Volume Benefits: In cases where patients also suffered from polycystic liver disease, reductions or attenuated increases in liver volume were observed, demonstrating that the metabolic benefits extend to extra-renal manifestations of ADPKD.

• Tolerability and Safety: The metabolic interventions, supported by the daily use of KetoCitra®, were reported to be feasible, sustainable, and well-tolerated long-term. Notably, none of the participants developed kidney stones—a known risk of standard ketogenic diets—thanks to the protective alkalizing citrate formulation of KetoCitra®.

A Qualitatively Different Magnitude of Effect

These results are best understood in the context of what has previously been achievable in ADPKD management. In natural history cohorts and even in trials for the only currently approved pharmacotherapy for ADPKD, the primary goal has been to slow the rate at which kidneys continue to grow.

In this case series, TKV did not just grow more slowly, it stabilized or decreased. While these are retrospective data in a small cohort and require confirmation in prospective controlled trials, the qualitative difference is striking: metabolic interventions are producing kidney volume reductions that standard pharmaceutical approaches have not been shown to achieve.

From Mechanism to Disease Modifying Therapy: The Role of KetoCitra® and Ren Nu™

The interventions implemented by the participants shared core metabolic strategies: achieving nutritional ketosis through carbohydrate restriction, time restricted eating, and the daily consumption of KetoCitra®.

These same core strategies form the foundation of SBN’s Ren-Nu™ program, a comprehensive, dietitian led nutrition and lifestyle program already available to individuals with ADPKD. Ren-Nu™ provides the educational and clinical framework for patients to safely reach nutritional ketosis, emphasizing low oxalate intake and renal safe nutrient ratios.

KetoCitra® delivers exogenous beta hydroxybutyrate (BHB) to support nutritional ketosis, together with alkaline citrate, calcium, and magnesium. This specific combination is designed to help normalize urinary citrate and pH, significantly reducing the risk of calcium oxalate and uric acid microcrystal formation that can otherwise accelerate kidney damage or cause kidney stones during metabolic shifts. The formulation effectively addresses the unique dietary management needs of individuals with ADPKD.

Expert Commentary

“These longitudinal cases strengthen the growing body of evidence that ketogenic metabolic therapy is doing something fundamentally different from conventional approaches to ADPKD,” said Dr. Thomas Weimbs, Chief Scientific Officer of Santa Barbara Nutrients, Professor at the University of California, Santa Barbara, and co-author of the study. “Seeing total kidney volume actually decrease or stabilize in patients with high-risk genetic variants over periods of up to four years is remarkable. The preclinical biology tells us that cysts are highly dependent on glucose to grow, and that BHB acts as a signaling molecule to suppress that growth. We are now seeing human imaging data over multi-year periods that perfectly aligns with those mechanistic predictions.”

Looking Ahead

While limited by sample size and the retrospective, self-directed nature of the interventions, this case series provides powerful, hypothesis-generating data. It bridges the gap between successful preclinical animal models and human application, strongly supporting the rationale for ongoing and future prospective, randomized controlled clinical trials evaluating metabolic therapies in ADPKD.

About Santa Barbara Nutrients

Santa Barbara Nutrients is a Public Benefit Corporation dedicated to bringing science-based metabolic therapies to the kidney community. Its flagship offerings, the Ren-Nu™ program and KetoCitra®, represent the frontier of metabolic nephrology.

For more information, please visit www.SantaBarbaraNutrients.com, Ren-Nu.org, or contact info@sbnutrients.com.