You Are What You Eat: Should It Be All Meat?

Introduction: Fad diets have exploded in popularity with the advent of social media. Support for one such diet, the carnivore diet, stems solely from historical and anecdotal evidence. The effect of the carnivore diet on kidney stones is of interest as its effect has not been described, and higher animal protein diets are counter to current management guidelines. Case Description: A 73 y/o man with a history of kidney stone disease, gout, and hypertension presented to nephrology for follow up. Kidney stones were first seen incidentally on X-Ray at age 45 followed by first stone passage at age 55 and 9 lithotripsies. He was referred to stone clinic in 2012 for 90% CaOx/10% CaP stones and started HCTZ and a low sodium, low protein diet. He subsequently was increased to 25 mg chlorthalidone in 2018 due to continued stone growth, after which he no longer formed more stones. 6 months before his nephrology appointment in 2023, the patient had 2 gout attacks 2 weeks apart. His PCP advised him to view a popular physician-made YouTube video on the carnivore diet as a treatment for gout. Following advice from his PCP, the patient modified his diet to include 90% meat with rare fruit and vegetable consumption. Table 1 shows 24-hr urine studies done six months before and six months after the change to the carnivore diet. Discussion: Urine studies demonstrate a doubling of uric acid and uric acid supersaturation despite similar volumes, increasing risk for uric acid and calcium oxalate stones. Urine studies also demonstrate an increase in urine calcium, likely due to increased sodium intake or increased acid load from high purine consumption. Citrate decreased as expected, likely due to acid load and reduced fruit/vegetable. The increase in oxalate confirms disputed study findings that urinary oxalate excretion increases in high animal protein diets. One rationale is that lower dairy intake may have increased intestinal oxalate absorption due to reduced calcium to bind oxalate. Our patient demonstrates an increased risk of stone formation after adoption of the carnivore diet. This presents a need for high-quality evidence to examine fad diets and necessitates informing patients of the potential harms of pursuing health information on social media. - Vol SS CaOx Ca Ox Cit SS CaP pH SS UA UA Before Carnivore Diet: 2.95 3.47 181 47 303 0.25 5.631 1.14 0.883 After Carnivore Diet: 2.99 2.71 129 35 342 0.17 5.602 0.54 0.395 Reference Range: 0.5-4 6-10 <250 20-40 >450 0.5-2 5.8-6.2 0-1 <0.8