Non-Traditional Aspects of Renal Diets: Focus on Fiber, Alkali and Vitamin K1 Intake

Abstract

Renal diets for advanced chronic kidney disease (CKD) are structured to achieve a lower protein, phosphate and sodium intake, while supplying adequate energy. The aim of this nutritional intervention is to prevent or correct signs, symptoms and complications of renal insufficiency, delaying the start of dialysis and preserving nutritional status. This paper focuses on three additional aspects of renal diets that can play an important role in the management of CKD patients: the vitamin K1 and fiber content, and the alkalizing potential. We examined the energy and nutrients composition of four types of renal diets according to their protein content: normal diet (ND, 0.8 g protein/kg body weight (bw)), low protein diet (LPD, 0.6 g protein/kg bw), vegan diet (VD, 0.7 g protein/kg bw), very low protein diet (VLPD, 0.3 g protein/kg bw). Fiber content is much higher in the VD and in the VLPD than in the ND or LPD. Vitamin K1 content seems to follow the same trend, but vitamin K2 content, which could not be investigated, might have a different pattern. The net endogenous acid production (NEAP) value decreases from the ND and LPD to the vegetarian diets, namely VD and VLPD; the same finding occurred for the potential renal acid load (PRAL). In conclusion, renal diets may provide additional benefits, and this is the case of vegetarian diets. Namely, VD and VLPD also provide high amounts of fibers and Vitamin K1, with a very low acid load. These features may have favorable effects on Vitamin K1 status, intestinal microbiota and acid-base balance. Hence, we can speculate as to the potential beneficial effects on vascular calcification and bone disease, on protein metabolism, on colonic environment and circulating levels of microbial-derived uremic toxins. In the case of vegetarian diets, attention must be paid to serum potassium levels.

Inflammation-Related Mechanisms in Chronic Kidney Disease Prediction, Progression, and Outcome

“…The Mediterranean diet, consisting mainly of carbohydrates, basically unrefined grains, fruits and vegetables, nuts, olive oil, fish, moderate red wine, dairy products, and red meat, represents one of the most promising nutritional strategies, having protective effects on CKD conditions, potentially restoring microbiota balance and slowing down CKD progression, as many studies have depicted [ 59 – 61 ]. Additional benefits in reducing the burden of uremic toxins, generated both by microbiota and CKD condition, were noticed under a vegetarian diet; however, increasing attention must be paid in regard to serum potassium levels [ 62 , 63 ]. Other promising diets have been proposed as potential beneficent therapies, including vegan diet, DASH diet, and the modern dietary pattern, all exhibiting protective effects on both CKD progression [ 64 , 65 ] or on intestinal microbiota homeostasis [ 62 ].…”

“…Additional benefits in reducing the burden of uremic toxins, generated both by microbiota and CKD condition, were noticed under a vegetarian diet; however, increasing attention must be paid in regard to serum potassium levels [ 62 , 63 ]. Other promising diets have been proposed as potential beneficent therapies, including vegan diet, DASH diet, and the modern dietary pattern, all exhibiting protective effects on both CKD progression [ 64 , 65 ] or on intestinal microbiota homeostasis [ 62 ]. In contrast, the Western diet, excessively rich in proteins and low in fruits and vegetables, grains, and fibers, exerts a detrimental effect on CKD, by increasing the risk of rapid eGFR decline [ 66 ].…”

Dietary Fiber and Gut Microbiota in Renal Diets

“…The analysis of nutrients content of four different types of diets for renal patients, shows an average amount of 7.66 g/1000 Kcal for conventional Low Protein Diet (0,6 g protein/kg), 16 g/1000 Kcal of low-protein Vegan diet (0,6 g protein/kg), 11.6 g/1000 Kcal for very low protein diet (VLPD), and 10.4 g/1000 Kcal for a 0,8 g protein/kg diet [46].…”

Chronic hyperkalemia in non-dialysis CKD: controversial issues in nephrology practice

“…A major point is that energy intake must cover the energy requirement (30–35 Kcal/kg/day) to allow metabolic adaptation in the course of protein-restricted regimens, thus preventing negative nitrogen balance and protein-energy wasting. Diets rich in plant-based foods, as vegan or vegetarian regimes [ 39 ], provide additional favorable effects related to high amounts of alkali and fibers [ 40 ]. Lower net acid load and favorable effects on intestinal motility and microbiota are expected, but the resulting high potassium load is of concern.…”