The ketogenic diet, initially introduced in the early nineteenth century, refers to a diet pattern that is low in carbohydrates and high in fat with a moderate proportion of protein (1.2–1.5 g/kg).
A pooled incidence of kidney stones at 5.6% in patients treated with a ketogenic diet after four years. The incidence of nephrolithiasis in the general population is reported at 0.3% per year in men and 0.25% per year in women [32].
Uric acid stones are the most common stones in patients receiving the ketogenic diet, followed by calcium-based stones and uric acid–calcium mixed stones. In contrast, calcium oxalate stones are the most common stones in the general population [32]. The exact mechanism of nephrolithiasis following the ketogenic diet is unclear. However, it is likely related to hypocitraturia and acidosis, common in people consuming a high-protein and low-alkali diet [20]. Acidosis contributes to significant reabsorption of citrate in the proximal tubule, further contributing to hypocitraturia [25][33][34][35][36][37][38]. A more generous amount of free calcium is available for stone formation in a low-citrate environment [33][39]. Chronic acidosis also leads to demineralization of the bone and increased calcium excretion [17][20]. Hypercalciuria, immobilization, anti-epileptic drugs, and fat malabsorption further precipitate urinary calcium. Moreover, the low urine pH seen in patients with a low-alkali diet contributes to uric acid crystals [33]. Obesity, insulin resistance, and an animal-protein diet are associated with low urine pH [40]. The uric acid stone may act as a nidus for calcium-based nephrolithiasis formation [33]. Furthermore, fluid intake restriction is traditionally applied to children receiving the ketogenic diet, making them susceptible to stone formation [33].
This entry is adapted from the peer-reviewed paper 10.3390/diseases9020039