Primary Contributors to Dietary Acid Load in Patients With Urolithiasis

Magnesium Supplementation Increases Urine Magnesium and Citrate in Stone Formers With Hypomagnesuria

OBJECTIVES

To compare the effects of magnesium repletion by a foods-alone approach or by magnesium supplementation on urinary magnesium and citrate excretion in patients with urine magnesium <70 mg/day.

METHODS

We reviewed medical records of patients in our stone prevention practice who were advised to start a magnesium supplement (Sup), 250-500 mg/day, or increase dietary magnesium consumption. We included adults with 24-hour urine magnesium (UMg) <70 mg, those who received magnesium recommendations (corroborated by the dietitian's clinical notes), and those with a follow-up 24-hour urine collection ≤18 months. Urine results were assessed by group.

RESULTS

Groups [No Sup (n = 74) and Sup (n = 56)] were not different for age, gender, stone history, malabsorption, or other clinical indices. All patients raised UMg (53-69 and 47-87 mg/day for No Sup and Sup, respectively); however, the increase was significantly higher in the Sup group. Moreover, while 88% of Sup patients achieved UMg ≥70 mg/day, only 58% in the No Sup group did so. Within-group increases in urine citrate were significant only in the Sup group.

CONCLUSION

Among patients with low UMg, both higher consumption from foods and magnesium supplementation significantly increased UMg. However, those who supplemented were significantly more likely to reach or exceed UMg 70 mg/day and achieved higher mean UMg. The change in urine citrate was significant only among those in the Sup group.

Association Between Potential Renal Acid Load and 10-Year Mortality in Patients on Hemodialysis

OBJECTIVES

Higher dietary acid load (DAL) has been linked to elevated incidence and progression of chronic kidney disease. However, the association between DAL and mortality in patients on maintenance hemodialysis (MHD) has not been evaluated.

METHODS

We retrospectively analyzed baseline laboratory data, self-administered diet history questionnaire results, and 10-year mortality rates in 44 patients (26 men, 67.9 ± 10.4 years) on MHD who participated in a randomized, double-blind, crossover pilot trial of rice endosperm protein supplementation, which was conducted in 2013. DAL was estimated from nutrition intake using potential renal acid load (PRAL), and patients were divided into tertiles using this score.

RESULTS

During the 10-year observation period, 19 patients (43%) died. A higher PRAL score was significantly associated with higher all-cause mortality. The multivariable-adjusted hazard ratio for all-cause mortality in the highest tertile of PRAL versus the lowest tertile was 3.88 (95% confidence interval [CI], 1.10-13.61). Multiple logistic regression analysis showed a significant association between higher PRAL and lower intake of green and yellow vegetables (odds ratio, 5.40; 95% CI, 1.37-21.26) and fruits (odds ratio, 4.76; 95% CI, 1.30-16.76).

CONCLUSIONS

Higher PRAL is positively associated with all-cause mortality, and these associations might be affected by a lower intake of fruits and vegetables in Japanese patients on MHD.

Positive associations between dietary potential acid load and renal cancer incidence and mortality: Results from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening trial

OBJECTIVES

To explore the relationships between dietary potential acid load and renal cancer (RC) incidence and mortality.

STUDY DESIGN

A prospective cohort study involving 97,166 U S. adults aged 55-74 years.

METHODS

Data utilized in this study were drawn from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO). Dietary potential acid load was assessed by dietary acid load (DAL), potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores using a validated Diet History Questionnaire (DHQ). Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs) for RC incidence and mortality with adjustment for potential confounders. Restricted cubic spline (RCS) plots were utilized to reveal whether there were nonlinear associations between the DAL, PRAL, and NEAP scores and RC incidence and mortality.

RESULTS

During a follow-up period of 859,907 and 1,467,573 person-years, 423 RC cases and 221 mortality cases were documented. DAL, PRAL, and NEAP scores were positively associated with RC incidence (DAL: HR 1.41; 95% CI 1.05, 1.90; P-trend = 0.010; PRAL: HR 1.45; 95% CI 1.10, 1.91; P-trend = 0.010; NEAP: HR 1.39; 95% CI 1.04, 1.85; P-trend = 0.029). Similar associations were observed between DAL, PRAL, and NEAP scores and RC mortality. The RCS plots demonstrated a nonlinear association between DAL score and RC risk, while a linear association was observed between DAL score and RC mortality. Similar linear associations were found between PRAL and NEAP scores and RC incidence and mortality.

CONCLUSION

A higher dietary potential acid load was associated with higher risk of RC incidence and mortality in American adults.

Assessing the role of dietary acid load in the development of hypertensive disorders during pregnancy: uncovering the association through prospective cohort analysis

BACKGROUND

Hypertensive disorders of pregnancy (HDPs) are common complications encountered in pregnancy that affect between 5% and 15% of pregnancies worldwide. Some studies have associated adherence to a diet with a high acid load with an increased risk of HDPs. This study investigates the association between Dietary Acid Load (DAL) and the incidence of preeclampsia, chronic hypertension (HTN), and gestational hypertension (GHTN).

METHODS

Pregnant women aged 18 to 45 in the first trimester of pregnancy were selected and followed up until delivery. Diet was evaluated using a 168-question semi-quantitative food frequency questionnaire (FFQ). After calculating the DAL score, the inverse probability weight of the propensity scores, estimated from augmented generalized models, was used to obtain a causal risk ratio (RR) adjusted for potential confounders.

RESULTS

Out of 1,856 women, 92 (4.95%) developed preeclampsia. The potential renal acid load (PRAL) score ranged from - 16.14 to 0.58, while the net endogenous acid production (NEAP) score ranged from 34.61 to 50.15. Multivariable analysis revealed a significant association between PRAL and preeclampsia in the first (aRR: 1.87, 95% CI: 1.01, 3.49, p = 0.048) and third (aRR: 2.01, 95% CI: 1.07, 3.81, p = 0.030) quartiles compared to the reference group (Q2). No significant linear association was found in continuous analyses. For chronic HTN, significant associations were observed in the first (aRR: 2.56, 95% CI: 1.21, 5.42, p = 0.014) and fourth (aRR: 4.79, 95% CI: 2.37, 9.71, p < 0.001) PRAL quartiles, with similar findings for NEAP. Continuous analysis showed a significant linear association between both PRAL and NEAP scores and chronic HTN. Regarding GHTN, significant associations were found in the first (aRR: 1.48, 95% CI: 1.02, 2.16, p = 0.041) and fourth (aRR: 1.88, 95% CI: 1.31, 2.70, p = 0.001) PRAL quartiles, and in Q4 for NEAP (aRR: 1.56, 95% CI: 1.10, 2.21, p = 0.012), with no significant linear association in continuous analysis.

CONCLUSION

Extremes in DAL, as indicated by PRAL and NEAP, are associated with an increased risk of preeclampsia, chronic HTN, and GHTN, particularly in the highest and lowest quartiles. These findings highlight the potential impact of DAL on HDPs.

Inquiry of the Metabolic Traits in Relationship with Daily Magnesium Intake: Focus on Type 2 Diabetic Population

Magnesium (Mg), an essential nutrient with a wide area of physiological roles, stands as a cofactor in over 600 enzymatic reactions involved in the synthesis of proteins and nucleic acids, DNA repair, neuromuscular functions, neuronal transmission, cardiac rhythm regulation, and the modulation of metabolic pathways, as well as acting as a natural blocker for the calcium channels. Our objective was to highlight the most recent clinical data with respect to daily Mg intake (DMI) and metabolic traits, particularly type 2 diabetes mellitus (DM). This was a PubMed-based review of the English-language medical papers across different key terms of search; the time frame was from January 2019 until April 2024. We included (clinically relevant) original studies and excluded cases reports, series, reviews, editorials, opinion, experimental studies, and non-human data as well as studies that did not specifically assessed DMI and only provided assays of serum Mg, studies on patients diagnosed with type 1 or secondary DM. A total of 30 studies were included and we organized the key findings into several sections as follows. Studies investigating DMI in relationship with the adherence to local recommendations in diabetic subjects (n = 2, one transversal and another retrospective cohort; N = 2823) found that most of them had lower DMI. Deficient DMI was correlated with the risk of developing/having DM across five studies (n = 5, one prospective and four of cross-sectional design; N = 47,166). An inverse correlation between DMI and DM prevalence was identified, but these data are presented amid a rather heterogeneous spectrum. Four novel studies (N = 7279) analysed the relationship between DMI and DM control according to various methods (HbA1c, fasting and postprandial glycaemia, and insulin); the association may be linear in diabetic subjects only at certain levels of DMI; additionally, the multifactorial influence on HBA1c should take into consideration this dietary determinant, as well, but there are no homogenous results. Three studies concerning DMI and diabetic complications (one cross-sectional, one prospective, and another case-control study) in terms of retinopathy (n = 1, N = 3794) and nephropathy (n = 2, N = 4805) suggested a lower DMI was associated with a higher risk of such complications. Additionally, two other studies (one prospective and one retrospective cohort) focused on mortality (N = 6744), which, taking only certain mortality indicators into consideration, might be decreased in the subgroups with a higher DMI. Seven studies (N = 30,610) analysed the perspective of DMI in the general population with the endpoint of different features amid glucose profile, particularly, insulin resistance. Concerning HOMA-IR, there were three confirmatory studies and one non-confirmatory, while fasting plasma glucose was highlighted as inversely correlated with a DMI (n = 1). The highest level of evidence regarding Mg supplementation effects on glucose metabolism stands on seven randomised controlled trials (N = 350). However, the sample size was reduced (from 14 to 86 individuals per study, either diabetic or pre-diabetic) and outcomes were rather discordant. These clinical aspects are essential from a multidisciplinary perspective and further trials are mandatory to address the current areas of discordant results.

Citrate-based dietary alkali supplements available in Germany: an overview

BACKGROUND

Fruits and vegetables are abundant in alkali precursors and effectively reduce the Potential Renal Acid Load (PRAL) from diet. Oral alkali supplements are supposed to exert comparable alkalizing effects on the human body, and have been shown to beneficially affect bone and kidney health. A comparative analysis of the available dietary alkali supplements in Germany was performed, contrasting their potential PRAL-lowering potential.

METHODS

We reviewed the currently available dietary citrate-based alkali supplements sold in Germany with a special focus on their mineral content, their PRAL-lowering potential and other characteristics inherent to each product. Supplements containing either potassium-, calcium- or magnesium citrate or any combination of these organic salts were reviewed. The total alkali load (TAL) was calculated based on the recommended daily dosage (RDD).

RESULTS

Sixteen supplements with a mean alkali powder content of 220.69 ± 111.02 g were identified. The mean magnesium content per RDD was 239.93 ± 109.16 mg. The mean potassium and median calcium content were 550 ± 325.58 mg and 280 (240) mg, respectively. Median TAL was 1220 (328.75) mg. The PRAL-lowering potential from a single RDD ranged from - 51.65 mEq to -8.32 mEq. Substantial price differences were found, and the mean price of the examined supplements was 16.67 ± 5.77 Euros. The median price for a 1 mEq PRAL-reduction was 3.01 (3.14) cents, and ranged from 0.77 cents to 10.82 cents.

CONCLUSIONS

Noticeable differences between the identified alkali supplements were encountered, warranting an individual and context-specific approach in daily clinical practice.

Dietary acid load in health and disease

Maintaining an appropriate acid-base equilibrium is crucial for human health. A primary influencer of this equilibrium is diet, as foods are metabolized into non-volatile acids or bases. Dietary acid load (DAL) is a measure of the acid load derived from diet, taking into account both the potential renal acid load (PRAL) from food components like protein, potassium, phosphorus, calcium, and magnesium, and the organic acids from foods, which are metabolized to bicarbonate and thus have an alkalinizing effect. Current Western diets are characterized by a high DAL, due to large amounts of animal protein and processed foods. A chronic low-grade metabolic acidosis can occur following a Western diet and is associated with increased morbidity and mortality. Nutritional advice focusing on DAL, rather than macronutrients, is gaining rapid attention as it provides a more holistic approach to managing health. However, current evidence for the role of DAL is mainly associative, and underlying mechanisms are poorly understood. This review focusses on the role of DAL in multiple conditions such as obesity, cardiovascular health, impaired kidney function, and cancer.

Dieta de la Milpa: A Culturally-Concordant Plant-Based Dietary Pattern for Hispanic/Latine People with Chronic Kidney Disease

Chronic kidney disease (CKD) disproportionately affects minorities in the United States, including the Hispanic/Latine population, and is a public health concern in Latin American countries. An emphasis on healthy dietary patterns, including the Mediterranean and the Dietary Approaches to Stop Hypertension (DASH) diets, has been suggested as they are associated with a lower incidence of CKD, slower CKD progression, and lower mortality in kidney failure. However, their applicability may be limited in people from Latin America. The Dieta de la Milpa (Diet of the Cornfield) was recently described as the dietary pattern of choice for people from Mesoamerica (Central Mexico and Central America). This dietary pattern highlights the intake of four plant-based staple foods from this geographical region, corn/maize, common beans, pumpkins/squashes, and chilies, complemented with seasonal and local intake of plant-based foods and a lower intake of animal-based foods, collectively classified into ten food groups. Limited preclinical and clinical studies suggest several health benefits, including cardiometabolic health, but there is currently no data concerning CKD. In this narrative review, we describe and highlight the potential benefits of the Dieta de la Milpa in CKD, including acid-base balance, protein source, potassium and phosphorus management, impact on the gut microbiota, inflammation, and cultural appropriateness. Despite these potential benefits, this dietary pattern has not been tested in people with CKD. Therefore, we suggest key research questions targeting measurement of adherence, feasibility, and effectiveness of the Dieta de la Milpa in people with CKD.

Alkaline Water: Help or Hype for Uric Acid and Cystine Urolithiasis?

PURPOSE

The consumption of alkaline water, water with an average pH of 8 to 10, has been steadily increasing globally as proponents claim it to be a healthier alternative to regular water. Urinary alkalinization therapy is frequently prescribed in patients with uric acid and cystine urolithiasis, and as such we analyzed commercially available alkaline waters to assess their potential to increase urinary pH.

MATERIALS AND METHODS

Five commercially available alkaline water brands (Essentia, Smart Water Alkaline, Great Value Hydrate Alkaline Water, Body Armor SportWater, and Perfect Hydration) underwent anion chromatography and direct chemical measurements to determine the mineral contents of each product. The alkaline content of each bottle of water was then compared to that of potassium citrate (the gold standard for urinary alkalinization) as well as to other beverages and supplements used to augment urinary citrate and/or the urine pH.

RESULTS

The pH levels of the bottled alkaline water ranged from 9.69 to 10.15. Electrolyte content was minimal, and the physiologic alkali content was below 1 mEq/L for all brands of alkaline water. The alkali content of alkaline water is minimal when compared to common stone treatment alternatives such as potassium citrate. In addition, several organic beverages, synthetic beverages, and other supplements contain more alkali content than alkaline water, and can achieve the AUA and European Association of Urology alkali recommendation of 30 to 60 mEq per day with ≤ 3 servings/d.

CONCLUSIONS

Commercially available alkaline water has negligible alkali content and thus provides no added benefit over tap water for patients with uric acid and cystine urolithiasis.

Dietary Acid Load Is Not Associated with Serum Testosterone in Men: Insights from the NHANES

The dietary acid load (DAL) is a novel marker of overall diet quality, which has been associated with overweight, type 2 diabetes and altered glucocorticoid secretion. A potential association with sex hormones is thus not inconceivable. We investigated whether DAL was associated with serum total testosterone concentrations of men in the National Health and Nutrition Examination Survey. The DAL scores, including the potential renal acid load (PRAL) and net endogenous acid production (NEAP), were estimated and compared between participants with low and normal testosterone levels. The investigated sample encompassed n = 377 males with a mean age of 49.50 years. Approximately 73% of the sample were of Non-Hispanic White origin. None of the examined DAL scores showed significant associations with serum testosterone levels. We observed no significant differences in the crude DAL scores between individuals with low testosterone levels and individuals with normal testosterone levels. Multivariate regression models adjusting for covariates confirmed the lack of associations between the PRAL and serum testosterone. Our results are of particular importance for those individuals who wish to lower their DAL in light of the presumable health effects of a more alkaline diet. Our data suggest that diet modifications toward a lower intake of animal protein and refined grains (which consecutively translates into a lower DAL) may not negatively affect men's testosterone levels.

Diet and Metabolism in CKD-Related Metabolic Acidosis

Metabolic acidosis is a common complication in patients with chronic kidney disease that occurs when the daily nonvolatile acid load produced in metabolism cannot be excreted fully by the kidney. A reduction in urine net acid excretion coupled with a high nonvolatile acid load may play a role in its pathogenesis. Diet is important in generation of the nonvolatile acid load. Acids are produced from metabolism of dietary protein and from the endogenous production of organic anions from neutral precursors. Acids can be balanced by alkali precursors ingested in the diet in the form of combustible organic anions. These typically are reflected indirectly by the excess of mineral cations to mineral anions in a food or diet. These principles underscore widely used methods to estimate the nonvolatile acid load from dietary intake using formulas such as the net endogenous acid production equation and the potential renal acid load equation. Empiric data largely validate these paradigms with high net endogenous acid production and potential renal acid load contributed by foods such as protein, grains, and dairy, and low net endogenous acid production and potential renal acid load contributed by fruits and vegetables along with corresponding dietary patterns. Although further studies are needed to understand the health benefits of altering nonvolatile acid load via diet, this review provides a detailed assessment on our current understanding of the role of diet in chronic kidney disease-related acidosis, providing an updated resource for researchers and clinicians.