Similar foods, different metabolic burden: contemporary aspects of nutritional therapy in chronic kidney disease

Nutritional therapy represents an essential component of comprehensive chronic kidney disease (CKD) management. Traditional dietary recommendations have primarily focused on quantitative restriction of protein, sodium, potassium, and phosphorus. However, contemporary evidence indicates that the metabolic impact of food is not determined solely by the absolute content of individual nutrients. Nutrient source and bioavailability, degree of food processing, presence of food additives, and preparation methods significantly influence the actual metabolic and electrolyte burden.The aim of this narrative review is to analyse the factors responsible for differences in metabolic burden between apparently similar food products in patients with CKD. Particular attention is given to organic versus inorganic phosphorus, naturally occurring versus added potassium, sodium content in minimally processed and ultra-processed foods, and the metabolic implications of plant and animal protein sources.Current recommendations support an individualized nutritional strategy in which food choices are based not only on total mineral content but also on nutrient bioavailability and the food matrix. Inorganic phosphate and potassium additives represent an important source of potentially underestimated dietary exposure. Conversely, indiscriminate restriction of plant foods in all patients with CKD may lead to unnecessary dietary limitations and reduced nutritional quality.An approach incorporating food quality, processing, nutrient source, and bioavailability allows a more precise assessment of metabolic impact and is consistent with the contemporary concept of personalized nutritional therapy in CKD.