The impact of a vegetarian diet on chronic kidney disease (CKD) progression - a systematic review

L-shaped association between dietary niacin intake and chronic kidney disease among adults in the USA: a cross-sectional study

BACKGROUND

Chronic kidney disease (CKD), which has become a global public health issue, is associated with mitochondrial dysfunction. Niacin is a necessary coenzyme for mitochondrial energy metabolism. However, the association between dietary niacin intake and CKD remains uncertain. This study aimed to investigate the association between dietary niacin intake and CKD in American adults.

METHODS

This is a cross-sectional study. 25,608 individuals aged ≥20 years from the National Health and Nutrition Examination Survey from 2007 to 2018 were involved.Dietary niacin intake was estimated based on 24-hour dietary recalls conducted by trained personnel. CKD was determined by an estimated glomerular filtration rate (eGFR) (<60 ml/min/1.73 m2) or a urinary albumin-to-creatinine ratio (ACR) (≥30mg/g). The association between dietary niacin intake and CKD was investigated using multivariable logistic regression analysis.

RESULTS

Of 25,608 participants, 17.14% (4388/25,608) had CKD. Compared to individuals with lower niacin intake (quartile [Q]1, ≤15.30 mg/day), those with higher niacin intake in Q2 (15.31-22.07 mg/day), Q3 (22.08-31.09 mg/day), and Q4 (≥31.10 mg/day) exhibited adjusted odds ratios for CKD of 0.89 (95% confidence interval [CI]:0.81-0.99, p = 0.024), 0.83 (95% CI:0.75-0 .92, p < 0 .001), and 0.83 (95% CI:0.75-0.93, p = 0.001) respectively. The relationship between dietary niacin intake and CKD among U.S. adults follows an L-shaped pattern, with an inflection point at approximately 28.04 mg/day.

CONCLUSIONS

These results suggest an L-shaped association between dietary niacin intake and CKD. Individuals with low dietary niacin intake levels should be alert to the risk of CKD.

Plant-based diets for kidney disease prevention and treatment

PURPOSE OF REVIEW

Plant-based diets are associated with a lower risk of hypertension, diabetes, cardiovascular disease, and mortality. Using the most recent evidence, we critically appraised the role of plant-based diets in primary and secondary prevention of chronic kidney disease (CKD) with a focus on key nutritional factors (dietary acid load, phosphorus, potassium, sodium, and fiber).

RECENT FINDINGS

In healthy individuals, observational studies found that greater intake of plant protein and higher adherence to plant-based diets (overall, healthful, and provegetarian) was associated with a lower risk of CKD. In those with CKD, plant-based diets were associated with a lower risk of mortality, improved kidney function, and favorable metabolic profiles (fibroblast growth factor-23, uremic toxins, insulin sensitivity, inflammatory biomarkers). Only few studies reported nutrient content of plant-based diets. These studies found that plant-based diets had lower dietary acid load, lower or no significant difference in phosphorus and sodium, and higher potassium and fiber. One study reported that vegetarian diets were associated with severe vitamin D deficiency compared to nonvegetarian diets.

SUMMARY

Plant-based diets provide several benefits for prevention and management of CKD, with little risk for individuals with CKD. Incorporation of vitamin D rich foods in plant-based diets may be helpful.

Vegetarian Nutrition in Chronic Kidney Disease

There is rising interest globally with respect to the health implications of vegetarian or plant-based diets. A growing body of evidence has demonstrated that higher consumption of plant-based foods and the nutrients found in vegetarian and plant-based diets are associated with numerous health benefits, including improved blood pressure, glycemic control, lipid levels, body mass index, and acid-base parameters. Furthermore, there has been increasing recognition that vegetarian and plant-based diets may have potential salutary benefits in preventing the development and progression of chronic kidney disease (CKD). While increasing evidence shows that vegetarian and plant-based diets have nephroprotective effects, there remains some degree of uncertainty about their nutritional adequacy and safety in CKD (with respect to protein-energy wasting, hyperkalemia, etc.). In this review, we focus on the potential roles of and existing data on the efficacy/effectiveness and safety of various vegetarian and plant-based diets in CKD, as well as their practical application in CKD management.

The Role of Plant-Based Diets in Preventing and Mitigating Chronic Kidney Disease: More Light than Shadows

Chronic kidney disease (CKD) is a non-communicable disease that affects >10% of the general population worldwide; the number of patients affected by CKD is increasing due in part to the rise in risk factors such as obesity, hypertension, and diabetes mellitus. As many studies show, diet can be an important tool for preventing and mitigating the onset of non-communicable diseases. Plant-based diets (PBDs) are those that emphasize the consumption of plant foods and may or may not include small or moderate amounts of animal foods. Recently, these diets have received increasing interest because they have been associated with favourable effects on health and also appear to protect against the development and progression of CKD. PBDs, which are associated with protein restrictions, seem to offer adjunctive advantages in patients with chronic kidney disease, as compared to conventional low-protein diets that include animal proteins. The principal aims of this review are to provide a comprehensive overview of the existing literature regarding the role of plant-based diets and low-protein, plant-based diets in the context of chronic kidney disease. Moreover, we try to clarify the definition of plant-based diets, and then we analyse possible concerns about the use of PBDs in patients with chronic kidney disease (nutritional deficiency and hyperkalaemia risk). Finally, we offer some strategies to increase the nutritional value of plant-based low-protein diets. In the Materials and Methods section, many studies about plant-based diets and low-protein plant-based diets (e.g., the very-low-protein diet and vegan low-protein diet, LPD) in chronic kidney disease were considered. In the Results and Conclusion section, current data, most from observational studies, agree upon the protective effect of plant-based diets on kidney function. Moreover, in patients with advanced CKD, low-protein plant-based options, especially a very-low-protein diet supplemented with heteroanalogues (VLPDs), compared to a conventional LPD appear to offer adjunctive advances in terms of delaying dialysis and mitigating metabolic disturbances. However, further studies are necessary to better investigate the possible metabolic and cardiovascular advantages of plant-based LPDs versus conventional LPDs.

Biotics (Pre-, Pro-, Post-) and Uremic Toxicity: Implications, Mechanisms, and Possible Therapies

In recent years, more scientific data have pointed out the close connection between intestinal microbial community, nutritional habits, lifestyle, and the appearance of various affections located at certain anatomical systems. Gut dysbiosis enhances the formation and accumulation of specific metabolites with toxic potential that induce the appearance of kidney-associated illnesses. Intestinal microbes are involved in the degradation of food, drugs, or other ingested products that lead to the formation of various metabolites that end up in renal tissue. Over the last few years, the possibilities of modulating the gut microbiota for the biosynthesis of targeted compounds with bioactive properties for reducing the risk of chronic illness development were investigated. In this regard, the present narrative review provides an overview of the scientific literature across the last decade considering the relationship between bioactive compounds, pre-, pro-, and post-biotics, uremic toxicity, and kidney-associated affections, and the possibility of alleviating the accumulation and the negative effects of uremic toxins into the renal system.