Which Diet for Calcium Stone Patients: A Real-World Approach to Preventive Care

Influence of Dietary Heritage in a Restricted Geographic Area and Role of Food Additives on Risk of Recurrent Kidney Stone

Dietary factors may be implicated in the formation of kidney stones and should be closely monitored. To achieve this aim, patients are routinely assessed by means of generic dietary recall, a tool widely used by authors in a range of extensive patient populations to record food intake; the findings obtained, however, may be skewed due to dietary variations and underestimation of the effect of food additives. Fifty Frequent Kidney Stone Formers (FKSFs, mean age: 54.3 ± 13.9 years) with normal kidney function, absence of comorbidities, and reliable compliance were selected from a total of 68 patients' resident in Sardinia, an Italian island where genetic admixtures have been relatively rare for generations. The study, conducted from 1 January 2020 to 31 December 2023, was aimed at assessing nutritional values based on the meticulous recording of food quantities, quality, and potential modifications related to food preparation. Patients were selected during an initial clinical check-up and all efforts made to ensure they were capable of reliably recording all food and drinks consumed. A seven-day food diary was provided in which food and drink intake and their impact on 24 h urine output was recorded. The following parameters were measured in both foods and urine output: citrates, oxalates, calcium, phosphorous, uric acid, proteins and nitrogen compounds, magnesium, sulfates, potassium, carbohydrates, free fatty acids. Study outcomes established the presence of hypocitraturia, hyperoxaluria, hypercalciuria, and moderately high levels of nitrogen compounds. Univariate analysis followed by multivariate analysis for further confirmation were performed and the following observations made. Citrate intake correlated with citraturia but did not promote oxaluria; calcium intake promoted onset of sulfaturia, azoturia, and ammoniuria, whilst magnesium correlated with magnesiuria but not with oxaluria, calciuria, phosphaturia, and azoturia; sulfate intake elicited onset of azoturia but not kaliuresis; potassium intake promoted oxaluria and protein intake resulted in onset of ammoniuria and azoturia. (A) The chemical composition of urine based on dietary intake is hard to predict without taking into account the presence of dietary and urinary interferents; (B) the geographic isolation of patients studied underlines the importance of epigenetics in maintaining a traditional dietary heritage. (C) Moreover, the widespread use of food additives should consistently be taken into account to ensure a correct diagnosis of FKSF and set up a valid treatment plan.

Causal associations between 45 dietary intake habits and urolithiasis: insights from genetic studies

Background

Different dietary habits can have varying effects on human health and metabolism, and these can be intervened and regulated. Kidney stones, as a disease caused by multiple factors, are largely attributed to diet and metabolism, but the potential causal relationship with dietary intake habits remains unclear. Therefore, this study aims to link the predicted dietary intake based on 45 genetic factors with urolithiasis and explore the potential causal relationship.

Methods

We extracted complete genome-wide association studies (GWASs) data on 45 dietary intake traits from the UK Biobank study. Data on kidney stones were obtained from the FinnGen database. In both univariable and multivariable Mendelian randomization analyses, we used inverse variance weighted (IVW) as the primary method to calculate P values, odds ratios (ORs), and 95% confidence intervals (CIs). We examined result heterogeneity using Cochran's Q test. We also carefully investigated potential sources of horizontal pleiotropy using the Mendelian randomization (MR)-PRESSO and MR-Egger methods, and conducted linkage disequilibrium score regression (LDSC) analysis on the corrected P values.

Results

Through univariable analysis, we identified 11 dietary habits that potentially causally associate with kidney stones among the 45 examined traits, including 9 protective factors and 2 risk factors. Based on the corrected results with false discovery rate (FDR) and sensitivity analysis, we found one relatively robust evidence. We controlled for common stone risk factors, such as body mass index and smoking, as confounders in multivariable analysis, and no significant results were observed after controlling for these confounders. Based on the LDSC analysis, most of the evidence supports significant genetic correlations with urolithiasis among the 11 traits with potential causal associations.

Conclusions

This study confirms the impact of certain dietary factors on the development of kidney stones. Our findings contribute to providing evidence for dietary adjustments in daily life or dietary guidance specifically targeting kidney stone patients.

Nanoparticles and nanofiltration for wastewater treatment: From polluted to fresh water

Water pollution poses significant threats to both ecosystems and human health. Mitigating this issue requires effective treatment of domestic wastewater to convert waste into bio-fertilizers and gas. Neglecting liquid waste treatment carries severe consequences for health and the environment. This review focuses on intelligent technologies for water and wastewater treatment, targeting waterborne diseases. It covers pollution prevention and purification methods, including hydrotherapy, membrane filtration, mechanical filters, reverse osmosis, ion exchange, and copper-zinc cleaning. The article also highlights domestic purification, field techniques, heavy metal removal, and emerging technologies like nanochips, graphene, nanofiltration, atmospheric water generation, and wastewater treatment plants (WWTPs)-based cleaning. Emphasizing water cleaning's significance for ecosystem protection and human health, the review discusses pollution challenges and explores the integration of wastewater treatment, coagulant processes, and nanoparticle utilization in management. It advocates collaborative efforts and innovative research for freshwater preservation and pollution mitigation. Innovative biological systems, combined with filtration, disinfection, and membranes, can elevate recovery rates by up to 90%, surpassing individual primary (<10%) or biological methods (≤50%). Advanced treatment methods can achieve up to 95% water recovery, exceeding UN goals for clean water and sanitation (Goal 6). This progress aligns with climate action objectives and safeguards vital water-rich habitats (Goal 13). The future holds promise with advanced purification techniques enhancing water quality and availability, underscoring the need for responsible water conservation and management for a sustainable future.

2022 Recommendations of the AFU Lithiasis Committee: Medical management - from diagnosis to treatment

The morphological-compositional analysis of urinary stones allows distinguishing schematically several situations: dietary, digestive, metabolic/hormonal, infectious and genetic problems. Blood and urine testing are recommended in the first instance to identify risk factors of urinary stone disease in order to avoid recurrence or progression. The other objective is to detect a potential underlying pathology associated with high risk of urinary stone disease (e.g. primary hyperparathyroidism, primary or enteric hyperoxaluria, cystinuria, distal renal tubular acidosis) that may require specific management. Lifestyle-diet measures are the basis of the management of all stone types, but pharmacological treatments may be required. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendation (CPR) method and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU 2022] and their adaptability to the French context.

Lifestyle and Diet as Risk Factors for Urinary Stone Formation: A Study in a Taiwanese Population

Background and Objectives: Urinary tract stones have long been a common ailment afflicting the population, with a high incidence and a wide distribution across different age groups. Effectively preventing the occurrence of urinary tract stones is of paramount importance. The primary aim of this study is to investigate the correlations between individual characteristics, water consumption habits, dietary habits, exercise habits, and the occurrence of urinary tract stones in a Taiwanese population. Materials and Methods: This study is cross-sectional research conducted over one month in 2022. One hundred eligible urinary stone cases were recruited through physician screening at outpatient clinics, and an additional one hundred samples from surgical outpatients without urinary tract stones were included as the control group. A questionnaire survey was employed to gather information on demographic variables, dietary habits, water consumption, and exercise habits of the cases. Descriptive statistics, chi-square tests, and logistic regression were used to explore the impact of relevant factors on urinary stone formation. Results: The analysis results revealed that among the demographic variables, males exhibited a higher risk of contracting urinary tract stones than females, and the majority of cases fell within the 40- to 49-year-old age group. Unhealthy lifestyle habits such as smoking and betel nut chewing also demonstrated a higher susceptibility to urinary tract stones. A logistic regression analysis showed that individuals who engaged in physical activity more than three times per week and those with inadequate water intakes had a higher risk of developing urinary tract stones. Conclusions: There is a close relationship between lifestyle and urinary tract stones. It is recommended that individuals continue to hydrate adequately during exercise.

Vitamins as regulators of calcium-containing kidney stones - new perspectives on the role of the gut microbiome

Calcium-based kidney stone disease is a highly prevalent and morbid condition, with an often complicated and multifactorial aetiology. An abundance of research on the role of specific vitamins (B6, C and D) in stone formation exists, but no consensus has been reached on how these vitamins influence stone disease. As a consequence of emerging research on the role of the gut microbiota in urolithiasis, previous notions on the contribution of these vitamins to urolithiasis are being reconsidered in the field, and investigation into previously overlooked vitamins (A, E and K) was expanded. Understanding how the microbiota influences host vitamin regulation could help to determine the role of vitamins in stone disease.

Stone diet and dietary change: understanding determinants for dietary change behaviour in patients following urinary stones

BACKGROUND

Dietary habit is one of the most important methods to prevent and treat urinary stones. However, only limited evidence of the experiences of dietary management among urinary stone patients in Malaysia is available. This study aimed to explore participants' current dietary practices after the diagnosis of urinary stones and to identify the factors that facilitate their dietary changes.

METHODS

A qualitative study with purposive sampling was conducted using face-to-face semistructured interviews. A total of 20 participants from a tertiary general hospital in Kuantan, Malaysia, were recruited in this study. Data were analysed using framework analysis.

RESULTS

Two themes emerged from the analysis. The first theme explained the changes in the dietary practice of the participants postdiagnosis. The second theme revealed that the participants' dietary changes were greatly influenced by personal factors and external support from professionals, family and peers.

CONCLUSIONS

Urinary stone patients highlighted the fear of complications, self-determination and knowledge of nutrition as the main drivers of their dietary change postdiagnosis. Emphasising proper nutritional care by assessing and evaluating dietary self-management among patients can facilitate effective self-care in stone prevention management.

The pH of Drinking Water and Its Effect on the pH of Urine

AIM

The aim was to determine whether urine pH changed or not with different pH values of drinking water. With the results obtained from animal studies, comments can be made about the effect of water with different pH levels that people drink on kidney stones.

METHOD

A total of 24 Wistar Albino rats were divided into three groups containing eight rats each: the first group was given water with pH 5.5, the second group was given water with pH 7 and the third group was given water with pH 8.2 in the same environment and conditions during 13 days. All rats consumed water in line with their natural feeding habits. All rats had urine pH measurements performed and recorded every day at the same time. The groups were later compared in terms of daily pH values.

RESULTS

When daily urine pH values were compared, there were statistically significant differences between pH measurements on the first, fourth and seventh day (p=0.02, p=0.017 and p=0.007, respectively). When first-day values are compared with post-hoc analyses, the urine pH in Group 2 was identified to be lower compared to Group 1 and Group 3 (p<0.001). When the fourth-day values were assessed, the urine pH of Group 2 was observed to be higher than Group 1 and Group 3 (p<0.001). On the seventh day, Group 3 had higher urine pH compared to the other groups (p<0.001).

CONCLUSION

The variation in drinking water pH does not directly change urine pH; however, it causes a change in the urine pH on different days.

Exploring the Potential Benefits of Natural Calcium-Rich Mineral Waters for Health and Wellness: A Systematic Review

This systematic review investigates the potential health and wellness benefits of natural calcium-rich mineral waters. It emphasizes the importance of dietary calcium sourced from natural mineral waters in promoting bone health, maintaining cardiovascular function, aiding in weight management, and enhancing overall well-being. The review process involved the comprehensive analysis of peer-reviewed articles, clinical trials, and experimental studies published within the last decade. Findings reveal that consuming calcium-rich mineral water can contribute significantly to daily calcium intake, particularly for those with lactose intolerance or individuals adhering to plant-based diets. The unique bioavailability of calcium from such waters also appears to enhance absorption, thus potentially offering an advantage over other calcium sources. The potential benefits extend to the cardiovascular system, with some studies indicating a reduction in blood pressure and the prevalence of cardiovascular diseases. Emerging evidence suggests that calcium-rich mineral water might have a role in body weight management, though further research is needed. The review identifies several areas requiring additional research, such as the potential interaction between calcium-rich mineral water and other dietary components, the effects on populations with specific health conditions, and the long-term effects of consumption. In conclusion, natural calcium-rich mineral waters show promise as a readily accessible and bioavailable sources of dietary calcium, potentially beneficial for a broad range of individuals. However, further investigation is required to fully understand its range of health impacts and define optimal intake levels.

Analysis of Nephrolithiasis Treatment in Highest Reference Hospital-Occurrence of Acromegaly in the Study Group

BACKGROUND

Urolithiasis is one of the most common diseases of the urinary system, the incidence of which is assumed to be up to 100,000 cases per million (10% of the population). The cause of it is dysregulation of renal urine excretion. Acromegaly is a very rare endocrine disorder that causes a somatotropic pituitary adenoma producing higher amounts of growth hormone. It occurs approximately in 80 cases per million (about 0.008% of the population). One of the acromegaly complications may be urolithiasis.

METHODS

Clinical and laboratory results of 2289 patients hospitalized for nephrolithiasis in the highest reference hospital were retrospectively analyzed, distinguishing a subgroup of patients with acromegaly. Statistical analysis was performed to compare the prevalence of the disease in the analyzed subgroup with the epidemiological results available in up-to-date literature.

RESULTS

The distribution of nephrolithiasis treatment was definitely in favor of non-invasive and minimally invasive treatment. The methods used were as follows: ESWL (61.82%), USRL (30.62%), RIRS (4.15%), PCNL (3.1%), and pyelolithotomy (0.31%). Such a distribution limited the potential complications of the procedures while maintaining the high effectiveness of the treatment. Among two thousand two hundred and eighty-nine patients with urolithiasis, two were diagnosed with acromegaly before the nephrological and urological treatment, and seven were diagnosed de novo. Patients with acromegaly required a higher percentage of open surgeries (including nephrectomy) and also had a higher rate of kidney stones recurrence. The concentration of IGF-1 in patients with newly diagnosed acromegaly was similar to those treated with somatostatin analogs (SSA) due to incomplete transsphenoidal pituitary surgery.

CONCLUSIONS

In the population of patients with urolithiasis requiring hospitalization and interventional treatment compared to the general population, the prevalence of acromegaly was almost 50-fold higher (p = 0.025). Acromegaly itself increases the risk of urolithiasis.

Vitamin D and Calcium Supplementation and Urolithiasis: A Controversial and Multifaceted Relationship

Patients with urolithiasis, and particularly those with hypercalciuria, frequently have a marked reduction of bone mineral content up to the levels of osteoporosis, with a significant increase in bone fracture risk. For these reasons, the indication to prescribe vitamin D and/or calcium supplementations is very frequent in such patients. On the other hand, both calcium supplementation, and even more vitamin D therapy, can worsen the risk of developing urolithiasis by increasing calcium, phosphate, and oxalate urinary excretion. Despite the clinical and practical relevance of this issue, the evidence on this topic is scarce and contradictory. Therefore, some concerns exist about how and whether to prescribe such supplements to a patient with a history of kidney stones. In this narrative review, we resume some pivotal pathophysiological concepts strictly related to the dealt topic, and we draw some considerations and personal opinions on the pros and cons of such prescriptions. Finally, we share with the reader our pragmatic algorithm for handling the urolithiasis risk in patients who have strong indications to be prescribed vitamin D and calcium supplementations.

A case-based review of dietary management of calcium oxalate stones

PURPOSE

The purpose of this paper is to help patients with calcium oxalate stones to access prevention and treatment options with dietary management.

METHODS

Typical cases in our hospital and other hospitals were selected for case review; combined with literature review through PubMed search, comprehensive analysis and suggestions were put forward.

RESULTS

By retrieving the literature with sufficient evidence, selecting, and summarizing, analysis of dietary liquid, oxalate and oxalate precursors, calcium, protein, fruits and vegetables, salt, high dietary fiber, and other content with high evidence index was carried out, respectively.

CONCLUSION

Through the retrospective analysis of typical cases and literature review, the importance of diet management in the prevention and treatment of calcium oxalate stones was emphasized again, and suggestions were put forward to promote the prevention and treatment of calcium oxalate stones.

Kidney Stone Prevention: Is There a Role for Complementary and Alternative Medicine?

Complementary and alternative medicine (CAM) is often implemented in kidney stone patients. It consists of preparations including different ingredients, such as herbs, probiotics, and vitamins, often together with alkali, that are classified within the dietary supplementation category. The majority of dietary supplements claiming to treat or prevent kidney stones contain ingredients with conflicting or no scientific evidence to support their claims. Clinicians should advise stone formers that the effects of most supplements are unknown or unstudied in humans and that the absence of evidence does not imply absence of potential harm. Unfortunately, the CAM preparation consists of a mix of different molecules, often including alkali, with different potential mechanisms of action and, even when favorable results are reported, the role of the single molecules cannot be assessed. Despite all these concerns, CAM products remain quite popular among kidney stone patients. The scarce knowledge in this field prevents one from recommending CAM products in daily clinical practice; only a weak suggestion for their use in kidney stone patients may be reasonable.

Evaluating outcomes of patient-centered enhanced recovery after surgery (ERAS) in percutaneous nephrolithotomy for staghorn stones: An initial experience

Objective

To evaluate the outcomes of patient-centered enhanced recovery after surgery (ERAS) in -percutaneous nephrolithotomy (PCNL) for staghorn stones.

Patients and methods

A retrospective analysis of 106 patients with staghorn calculi who underwent PCNL treatment at the Third Xiangya Hospital from October 01, 2018 to September 30, 2021 was performed. The patients were divided into the ERAS group (n = 56) and traditional group (n = 50). The ERAS program focused on a patient-centered concept, with elaboration on aspects, such as patient education, nutritional support, analgesia, body warming, early mobilization, nephrostomy tube removal, and strict follow-up.

Results

The total stone free rate and total complication rate were similar in both groups. The visual analogue scale (VAS) 6 h after surgery, ambulation off bed time, indwelling fistula time, indwelling catheter time, and postoperative hospital stays were lower in the ERAS group than in the traditional group (P < 0.05). The multiple session rate in the ERAS group (19, 28.57%) was lower than that in the traditional group (30, 60%) (P = 0.007). The 1-year stone recurrence rate in the ERAS group (7, 17.5%) was lower than that in the traditional group (14, 38.9%) (P = 0.037).

Conclusion

The patient-centered ERAS in PCNL for staghorn stones accelerated rehabilitation by relieving postoperative pain, shortening hospitalization time, accelerating early ambulation, and reducing multiple session rate and 1-year stone recurrence rate, which have socioeconomic benefits.

Computational Analysis of Influencing Factors and Multiple Scoring Systems of Stone Clearance Rate after Flexible Ureteroscopic Lithotripsy

Our research aims at the analysis of various stone scoring systems which are referred to as STONE scoring system (SSS) in this study. GUY's scoring system and RUSS scoring system (RSS) are utilized to predict stone-free status (SFS) after surgery and problems after percutaneous nephrolithotomy (PCNL) for harder stones. The data of 68 patients with renal calculi who received FURL in Ren Ji Hospital from Jan 2020 to Mar 2021 are collected as the study subjects. There were 44 male and 24 female patients, with an average age of 55.6 ± 11.4 years. Reliability analysis of related influencing factors (IF) of stone clearance rate (SCR) and multiple scoring systems after flexible ureteroscopic lithotripsy (FURL) was performed. Relevant factors with statistical significance for postoperative SCR were selected for logistic regression analysis (RA). According to the SSS score, GSS classification, and RUSS score, the SCR after FURL was statistically analyzed. The results showed that the P values corresponding to stone position (lower caliceal), cumulative stone diameter (CSD), urinary tract infection, and external physical vibration lithecbole (EPVL) were less than 0.05. The area under the ROC curve of RUSS score, SSS score, and GSS grading was 0.932, 0.841, and 0.533, respectively. The main IF of SCR after FURL were stone location (lower caliceal), CSD, urinary tract infection, and EPVL. The RUSS score system was the best in the evaluation of SCR after FURL. In the previous research, the score systems such as CROES (CRS), SSS, S-ReS, C, and GSS for the prediction of SFS were compared. In our analysis, we have compared the RUSS scoring system which has proven to be giving better results as compared to SSS and GSS. We also performed the regression analysis and found that the stone location shows the strongest correlation of all the other factors for stone clearing rate.

Modification effect of changes in cardiometabolic traits in association between kidney stones and cardiovascular events

Backgrounds

Whether longitudinal changes in metabolic status influence the effect of kidney stones on cardiovascular disease (CVD) remains unclarified. We investigated the modification effect of status changes in metabolic syndrome (MetS) in the association of kidney stones with risk of incident CVD events.

Methods

We performed a prospective association and interaction study in a nationwide cohort including 129,172 participants aged ≥ 40 years without CVDs at baseline and followed up for an average of 3.8 years. Kidney stones information was collected by using a questionnaire and validated by medical records. The repeated biochemical measurements were performed to ascertain the metabolic status at both baseline and follow-up.

Results

4,017 incident total CVDs, 1,413 coronary heart diseases (CHDs) and 2,682 strokes were documented and ascertained during follow-up. Kidney stones presence was significantly associated with 44%, 70% and 31% higher risk of CVDs, CHDs and stroke, respectively. The stratified analysis showed significant associations were found in the incident and sustained MetS patients, while no significant associations were found in the non-MetS at both baseline and follow-up subjects or the MetS remission ones, especially in women. For the change status of each single component of the MetS, though the trends were not always the same, the associations with CVD were consistently significant in those with sustained metabolic disorders, except for the sustained high blood glucose group, while the associations were consistently significant in those with incident metabolic disorders except for the incident blood pressure group. We also found a significant association of kidney stone and CVD or CHD risk in the remain normal glucose or triglycerides groups; while the associations were consistently significant in those with incident metabolic disorders except for the incident blood pressure group. We also found a significant association of kidney stone and CVD or CHD risk in the remain normal glucose or triglycerides groups.

Conclusions

A history of kidney stones in women with newly developed MetS or long-standing MetS associated with increased risk of CVD. The mechanisms link kidney stones and CVD risk in the metabolic and non-metabolic pathways were warranted for further studies.

Faculty Service-Learning Students as Home-Visitors: Outcomes of a Lifestyle Modification Program for Vulnerable Families With Residents in Rural Indonesian Communities

Background: Risks attributed to chronic diseases, cancer, musculoskeletal discomfort, and infectious diseases among Indonesians were found to be associated with lifestyle behaviors, particularly in rural areas. The aim of this study was to examine the outcomes of a home-visiting lifestyle modification program on improving health risk behaviors among Indonesians living in rural areas. Methods: A total of 160 Indonesians living in rural hamlets in the Yogyakarta Region of Indonesia participated in the program in the period of June 21 to July 21, 2019. In the pre-intervention home interview, learning needs of diet, exercise, hand hygiene, and substance use were identified by using structured assessment tools. In the next home visit, the visitors provided health education and facilitated lifestyle planning based on the related affective and cognitive domains of learning. Subsequent follow-up interviews were conducted 3 weeks after intervention. Results: The results showed that the self-reported intake of vegetables, fruits, meat and salt, cooking with less oil, hand hygiene before eating, number of cigarettes smoked, and symptoms of muscle stiffness significantly improved after the intervention. The lifestyle modification program consisted of the affective and cognitive domains of learning, and could lead to the target behavioral changes in self-reported and observable measures over 1 month. Conclusions: The findings contributed to the framework of community-based health education for health risk reduction and behavioral modification in developing rural communities where health care resources were limited. Further studies with control groups and vigorous objective measures were recommended to elucidate its long-term impacts. The factors leading to its sustainability concerning collaborative care partnerships between community residents and faculty resources are worthy of continued exploration.

Higher Dietary Acid Load Is Associated With an Increased Risk of Calcium Oxalate Kidney Stones

OBJECTIVES

Diet-dependent net acid load may influence the risk of kidney stone formation by affecting calcium and citrate excretion. However, to date, little research has investigated the relationship between dietary acid load and kidney stones. Therefore, this study sought to assess whether a diet high in potential acid load was related to the risk of calcium oxalate stone formation.

METHODS

This case-control study was conducted on 430 participants (including 215 newly diagnosed patients with calcium oxalate stones and 215 controls matched for sex and age). Dietary intake was assessed using a validated food frequency questionnaire over the preceding year. Dietary acid load was estimated based on the potential renal acid load (PRAL) and net endogenous acid production (NEAP). The association between dietary acid load indices and kidney stone was examined using multivariable logistic regression.

RESULTS

Mean PRAL (standard error) was significantly lower in cases versus controls (-5.3 ± 1.3 vs. -1.7 ± 1.3, P = .048). Corresponding values for NEAP were 39.4 ± 0.8 and 41.8 ± 0.8, respectively (P = .032). After adjustment for potential confounders, the odds ratios (95% confidence intervals) of calcium oxalate stones in the top tertile of PRAL and NEAP were 1.45 (0.89-2.38, P = .136) and 1.88 (1.14-3.09, P = .013), respectively. Adjustment for potassium and protein in 2 separate models did not substantially change the results.

CONCLUSIONS

A diet high in potential acid load, measured by NEAP, was associated with higher risk of calcium oxalate stone formation, independent of potassium and protein intake. Prospective longitudinal studies are warranted to confirm the veracity of our results.

Dietary Oxalate Intake and Kidney Outcomes

Oxalate is both a plant-derived molecule and a terminal toxic metabolite with no known physiological function in humans. It is predominantly eliminated by the kidneys through glomerular filtration and tubular secretion. Regardless of the cause, the increased load of dietary oxalate presented to the kidneys has been linked to different kidney-related conditions and injuries, including calcium oxalate nephrolithiasis, acute and chronic kidney disease. In this paper, we review the current literature on the association between dietary oxalate intake and kidney outcomes.

A Specific Urinary Amino Acid Profile Characterizes People with Kidney Stones

Background

Urolithiasis is the process of stone formation in the urinary tract. Its etiology is only partly known, and efficient therapeutic approaches are currently lacking. Metabolomics is increasingly used in biomarkers discovery for its ability to identify mediators of relevant (patho)physiological processes. Amino acids may be involved in kidney stone formation. The aim of the present study was to investigate the presence of an amino acid signature in stone former urine through a targeted metabolomic approach.

Methods

A panel of 35 amino acids and derivatives was assessed in urines from 15 stone former patients and 12 healthy subjects by UPLC-MS. Partial Least Squares Discriminant Analysis (PLS-DA) was used to define amino acid profiles of cases and controls. Results and Discussion. Our approach led to the definition of a specific amino acid fingerprint in people with kidney stones. A urinary amino acid profile of stone formers was characterized by lower levels of α-aminobutyric acid, asparagine, ethanolamine, isoleucine, methionine, phenylalanine, serine, tryptophan, and valine. Metabolomic analysis may lend insights into the pathophysiology of urolithiasis and allow tracking this prevalent condition over time.

Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian-Vegan Diets

Nephrolithiasis is a common medical condition influenced by multiple environmental factors, including diet. Since nutritional habits play a relevant role in the genesis and recurrence of kidney stones disease, dietary manipulation has become a fundamental tool for the medical management of nephrolithiasis. Dietary advice aims to reduce the majority of lithogenic risk factors, reducing the supersaturation of urine, mainly for calcium oxalate, calcium phosphate, and uric acid. For this purpose, current guidelines recommend increasing fluid intake, maintaining a balanced calcium intake, reducing dietary intake of sodium and animal proteins, and increasing intake of fruits and fibers. In this review, we analyzed the effects of each dietary factor on nephrolithiasis incidence and recurrence rate. Available scientific evidence agrees on the harmful effects of high meat/animal protein intake and low calcium diets, whereas high content of fruits and vegetables associated with a balanced intake of low-fat dairy products carries the lowest risk for incident kidney stones. Furthermore, a balanced vegetarian diet with dairy products seems to be the most protective diet for kidney stone patients. Since no study prospectively examined the effects of vegan diets on nephrolithiasis risk factors, more scientific work should be made to define the best diet for different kidney stone phenotypes.