Estimation of net endogenous noncarbonic acid production in humans from diet potassium and protein contents

Dietary acid load and risk of diminished ovarian reserve: a case-control study

BACKGROUND

The epidemiologic evidence on the association between acid load potential of diet and the risk of diminished ovarian reserve (DOR) is scarce. We aim to explore the possible relationship between dietary acid load (DAL), markers of ovarian reserve and DOR risk in a case-control study.

METHODS

370 women (120 women with DOR and 250 women with normal ovarian reserve as controls), matched by age and BMI, were recruited. Dietary intake was obtained using a validated 80-item semi-quantitative food frequency questionnaire (FFQ). The DAL scores including the potential renal acid load (PRAL) and net endogenous acid production (NEAP) were calculated based on nutrients intake. NEAP and PRAL scores were categorized by quartiles based on the distribution of controls. Antral follicle count (AFC), serum antimullerian hormone (AMH) and anthropometric indices were measured. Logistic regression models were used to estimate multivariable odds ratio (OR) of DOR across quartiles of NEAP and PRAL scores.

RESULTS

Following increase in PRAL and NEAP scores, serum AMH significantly decreased in women with DOR. Also, AFC count had a significant decrease following increase in PRAL score (P = 0.045). After adjustment for multiple confounding variables, participants in the top quartile of PRAL had increased OR for DOR (OR: 1.26; 95%CI: 1.08-1.42, P = 0.254).

CONCLUSION

Diets with high acid-forming potential may negatively affect ovarian reserve in women with DOR. Also, high DAL may increase the risk of DOR. The association between DAL and markers of ovarian reserve should be explored in prospective studies and clinical trials.

The impact of dietary acid load on super-agers with exceptional cognitive abilities: a propensity score analysis of national health and nutrition examination survey (NHANES) 2011-2014

OBJECTIVES

'Super-agers,' individuals over 80 with memory abilities comparable to those 20-30 years younger. The relationship between super-agers and dietary acid load (DAL) is an area that warrants further investigation. We aim to examine the link between DAL and super-agers and assess DAL's effects on cognitive functions across different age groups and cognitive domains.

DESIGN

Employing a cross-sectional analysis of the 2011-2014 National Health and Nutrition Examination Survey (NHANES) data, we utilized propensity score analysis and multivariate-adjusted regression to mitigate confounding factors.

SETTING

Older adults aged 60 and above in the United States.

PARTICIPANTS

Our primary analysis encompassed 985 older adults, supplemented by a sensitivity analysis with 2,522 participants.

MEASUREMENTS

DAL was assessed through potential renal acid load (PRAL), estimated net acid excretion (NAEes), and net endogenous acid production (NEAP) indices.

RESULTS

Super-agers demonstrate a preference for alkaline diets, shown by their lower DAL indices. After inverse probability of treatment weighting (IPTW), multivariate-adjusted logistic regression reveals that each unit reduction in NAEes and PRAL increases the chances of being a super-ager by 3.9% and 3.0%, respectively. The DAL's impact on cognitive function becomes more pronounced with age. Lower PRAL and NAEes scores are significantly linked to higher situational memory and overall cognitive performance scores in those over 70, with these effects being even more pronounced in participants over 80.

CONCLUSION

This research pioneers in demonstrating that super-agers prefer an alkaline diet, highlighting the potential role of alkaline diet in countering cognitive decline associated with aging.

Higher potassium intake is associated with a lower risk of chronic kidney disease: population-based prospective study

BACKGROUND

High-potassium intake is associated with a lower risk of cardiovascular disease. However, the association between potassium intake and the development of chronic kidney disease (CKD) remains unclear.

OBJECTIVE

The objective of this study was to investigate whether potassium intake is associated with outcomes of incident CKD.

METHODS

This is a population-based prospective observational cohort study from the UK Biobank cohort between 2006 and 2010. We included 317,162 participants without CKD from the UK Biobank cohort. The main predictor was spot urine potassium-to-creatinine ratio (KCR). The primary outcome was incident CKD, which was defined by the International Classification of Disease 10 codes or Operating Procedure Codes Supplement 4 codes.

RESULTS

At baseline, individuals with higher KCR had lower blood pressure, body mass index, and inflammation, and were less likely to have diabetes and hypertension. During a median follow-up of 11.9 y, primary outcome events occurred in 15,246 (4.8%) participants. In the cause-specific model, the adjusted hazard ratio (aHR) per 1-standard deviation increase in KCR for incident CKD was 0.90 [95% confidence interval (CI): 0.89, 0.92]. Compared with quartile 1 of KCR, the aHRs (95% CIs) for quartiles 2-4 were 0.98 (0.94, 1.02), 0.90 (0.86, 0.95), and 0.80 (0.76, 0.84), respectively. In sensitivity analysis with different definitions of CKD, the results were similar. In addition, further analysis with dietary potassium intake also showed a negatively graded association with the primary outcome.

CONCLUSIONS

Higher urinary potassium excretion and intake were associated with a lower risk of incident CKD.

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.

Dietary acid load and markers of malnutrition, inflammation, and oxidative stress in hemodialysis patients

Aims

The present study was conducted to examine the association between dietary acid load (DAL) and markers of inflammation, oxidative stress, and malnutrition in a group of Iranian hemodialysis (HD) patients.

Methods

This cross-sectional study was performed on individuals aged ≥18 years who were on HD at least 6 months before their enrollment in the study. A 4-day dietary recall was used for the evaluation of dietary intake. DAL was calculated using two methods including potential renal acid load (PRAL) and net endogenous acid production (NEAP). For assessing the malnutrition status, we used the subjective global assessment (SGA), dialysis malnutrition score (DMS), and malnutrition inflammation score (MIS). Fasting blood samples were collected from each participant to assess serum levels of high-sensitivity C-reactive protein (hs-CRP), soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular adhesion molecule-1 (sVCAM-1), sE-selectin, malondialdehyde (MDA), nitric oxide (NO), and endothelin-1.

Results

In total, 291 patients with a mean age of 57.73 ± 0.88 years and HD vintage of 4.27 ± 0.25 months were enrolled in the current study. Significant positive associations were observed between PRAL and hs-CRP (β = 1.77, 95% CI: 0.88, 2.65), sICAM-1 (β = 83.21, 95% CI: 10.39, 156.04), sVCAM-1 (β = 194.63, 95% CI: 74.68, 314.58), and sE-selectin (β = 6.66, 95% CI: 1.81, 11.50) among participants with the highest PRAL scores, compared to those with the lowest PRAL scores. NEAP was positively correlated with hs-CRP (β = 1.34, 95% CI: 0.46, 2.22), sICAM-1 (β = 88.83, 95% CI: 16.99, 160.67), and MDA (β = 0.35, 95% CI: 0.005, 0.71). Additionally, marginally significant higher odds of SGA (OR = 1.98, 95% CI: 0.95, 4.11) and DMS (OR = 1.94, 95% CI: 0.92, 4.05) were observed in individuals in the third tertile of PRAL vs. the first tertile of PRAL. NEAP had also a marginally significant positive correlation with DMS (OR = 2.01, 95% CI: 0.93, 4.31).

Conclusion

This study illustrates that higher consumption of acidic foods is correlated with markers of inflammation, oxidative stress, and malnutrition in HD patients.

A Therapeutic Approach in the Management of Chronic Kidney Disease: Plant-Based Dietary Models and Associated Parameters

PURPOSE OF REVIEW

Chronic kidney disease is one of the leading causes of death worldwide today. Nutrition and nutrition-related factors have a very important role in both the prevention and management of the disease. Plant-based dietary practices are one of the promising approaches to chronic kidney disease. This review aims to examine the potential benefits and risks of plant-based diet models on symptoms and indices used in diet quality in chronic kidney disease.

RECENT FINDINGS

Recently, a growing body of evidence has shown that, unlike animal-based diets, diets rich in plant-based nutrients may play an active role in the incidence of chronic kidney disease in many ways and the management of common symptoms, such as metabolic acidosis, uremic toxicity, and hyperphosphatemia. Implementation of existing plant-based dietary patterns in patients with chronic kidney disease may increase the efficacy of the diet and improve patients' quality of life by expanding their food choices. While there are concerns about creatine deficiency, dietary adequacy, and accessibility regarding plant-based diets, available information is limited.

The Role of the Endocrine System in the Regulation of Acid-Base Balance by the Kidney and the Progression of Chronic Kidney Disease

Systemic acid-base status is primarily determined by the interplay of net acid production (NEAP) arising from metabolism of ingested food stuffs, buffering of NEAP in tissues, generation of bicarbonate by the kidney, and capture of any bicarbonate filtered by the kidney. In chronic kidney disease (CKD), acid retention may occur when dietary acid production is not balanced by bicarbonate generation by the diseased kidney. Hormones including aldosterone, angiotensin II, endothelin, PTH, glucocorticoids, insulin, thyroid hormone, and growth hormone can affect acid-base balance in different ways. The levels of some hormones such as aldosterone, angiotensin II and endothelin are increased with acid accumulation and contribute to an adaptive increase in renal acid excretion and bicarbonate generation. However, the persistent elevated levels of these hormones can damage the kidney and accelerate progression of CKD. Measures to slow the progression of CKD have included administration of medications which inhibit the production or action of deleterious hormones. However, since metabolic acidosis accompanying CKD stimulates the secretion of several of these hormones, treatment of CKD should also include administration of base to correct the metabolic acidosis.

Dietary acid load and cirrhosis-related mortality: a prospective cohort study

As a global health concern, cirrhosis contributes significantly to morbidity and mortality. This prospective cohort study aimed to investigate the association between dietary acid load (DAL) and cirrhosis-related mortality. Present study was conducted on 121 patients with newly diagnosed cirrhosis who were followed up for 48 months. Anthropometric measures, nutritional status and dietary intakes were assessed and DAL was estimated based on potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores. Crude and multivariable-adjusted hazard ratios (HR) with 95% confidence intervals (CI) were estimated using Cox proportional hazard analyses. Participants in the high PRAL and NEAP scores had significantly higher intakes of grains and lower intakes of fruits and vegetables. Also, the intake of dairy products and legumes, nuts and seeds decreased significantly with increasing NEAP score. After adjustment of all the confounders, the risk of mortality in the second and third tertiles of PRAL was 5.9 times and 10.97 higher than those in the first tertile, respectively (P trend: 0.006). Similarly, comparing the risk of mortality in the second and third tertiles with the first tertile of NEAP showed a 4.46-fold and 12.3-fold increased risk, respectively (P trend: 0.010). Our findings suggested that DAL was significantly associated with cirrhosis-related mortality and highlight the need for further research to understand the underlying mechanisms and establish optimal DAL levels in cirrhotic patients.

Dietary acid load and the risk of events of mortality and kidney replacement therapy in people with chronic kidney disease: the Progredir Cohort Study

BACKGROUND/OBJECTIVES

The association between dietary acid load (DAL) and chronic kidney disease (CKD) progression remains controversial. Also, there is a gap in the literature on the association between DAL and mortality. In this study, we evaluated the association between NEAP (net endogenous acid production) and PRAL (potential renal acid load) and the risk of events of all-cause mortality and kidney replacement therapy (KRT) in people with CKD.

SUBJECTS/METHODS

We included 442 patients (250 diabetics) from the Progredir Cohort Study, based in São Paulo, Brazil. We estimated NEAP and PRAL from dietary intake. Events of death before KRT and KRT were ascertained after a median follow-up of 5.8 and 5.1 years, respectively. Cox proportional hazards regression, Weibull regression, and competing risk models were performed.

RESULTS

Median NEAP and PRAL were 49.5 and 4.8 mEq/d. There were 200 deaths and 75 KRT events. Neither NEAP nor PRAL were associated with mortality or KRT when all participants were analyzed. After stratification for diabetes, both estimates were positively related to the risk of KRT even after adjustment for age, sex, weight status, glomerular filtration rate, serum bicarbonate, and intakes of protein, phosphorus, and energy (HR 1.31; 95% CI 1.07, 1.60 for NEAP, and HR 1.27; 95% CI 1.04, 1.57 for every 10 mEq/d increments). Competing risk analyses confirmed these findings.

CONCLUSIONS

DAL estimates were associated with the risk of KRT in people with CKD and diabetes but not in non-diabetics. There was no association between all-cause mortality and DAL.

The association of diet-dependent acid load with colorectal cancer risk: a case-control study in Korea

Acid-base disequilibrium is a contributor to cancer development because it affects molecular activities such as insulin-like growth factor 1 levels and adiponectin production. However, evidence of an association of diet-induced acid-base imbalance with colorectal cancer (CRC) is limited. We examined whether colorectal carcinogenesis is attributable to a diet with a high acid load. We recruited a total of 923 CRC cases and 1846 controls at the National Cancer Center in Korea for inclusion in a case-control study. We collected information on nutrient intake and specific clinical parameters of CRC by using a semiquantitative FFQ and medical records, respectively. Potential renal acid load (PRAL) and net endogenous acid production (NEAP) were used to estimate diet-dependent acid load. We used an unconditional logistic regression model to analyse the association. Dietary acid load scores had a positive association with the odds of CRC (OR = 2·31 (95 % CI 1·79, 2·99) and OR = 2·14 (95 % CI 1·66, 2·76) for PRAL and NEAP, respectively, Pfor trend < 0·001). A stronger positive association was observed for females (OR = 3·09, 95 % CI 1·93, 4·94) than for males (OR = 1·71, 95 % CI 1·27, 2·31). Furthermore, acidogenic diets appeared to affect rectal cancer more strongly than colon cancer in females. Our study contributes to reinforcing epidemiological evidence regarding a detrimental effect of acidogenic diets on colorectal carcinogenesis. Thus, it is important to pay attention to the balance of acidogenic (e.g. poultry and red meat) and alkalinogenic foods (e.g. fruits and vegetables) in CRC prevention, especially for females.

Association of Dietary Acid Load with Nonalcoholic Fatty Liver Disease and Advanced Liver Fibrosis in US Adults: Evidence from NHANES 1999-2018

Background

Evidence for an association between dietary acid load (DAL) and non-alcoholic fatty liver disease (NAFLD) is scarce and controversial. We aimed to address whether an association exists between DAL and NAFLD/advanced liver fibrosis (AHF) among US adults in a nationally representative study.

Methods

This was a cross-sectional study. We included adult participants from the National Health and Nutrition Examination Survey 1999-2018. Potential renal acid load (PRAL) and estimated net endogenous acid production (NEAP) was calculated from the literature and NAFLD/AHF was diagnosed by noninvasive markers. We comprehensively explored these relationships using multivariate adjusted regression models, restricted cubic spline, stratification analysis, and sensitivity analysis.

Results

We enrolled a total of 18,855 participants. All DAL metrics were positively and nonlinearly associated with NAFLD (all p-values < 0.0001), whereas NEAPF and NEAPR may be associated with AHF. In the stratified analysis, we found that the correlation between DAL and NAFLD exists in all ages and genders, but the effect of DAL seems to be more obvious in middle-aged, elderly and women. Similarly, we found that the effect of DAL on AHF was more significant in 45-60-year-olds and women. Sensitivity analyses revealed stability of all results.

Conclusion

DAL including PRAL and NEAP were positively associated with NAFLD in a large nationally representative cross-sectional study. NEAPF and NEAPR may be associated with increased odds of AHF. Adjustment for diet-dependent DAL requires age- and sex-specific strategies. Future prospective studies are needed to validate our findings.

Association of Dietary Acid Load With Metabolic Syndrome and Its Components in Iranian Adults: A Cross-Sectional Study

Introduction Metabolic syndrome (MetS) remains one of the leading health challenges worldwide. A combination of genetic and environmental factors has been implicated in the etiology of MetS. Diet is a changeable environmental risk factor, and dietary modifications could significantly reduce the incidence and mortality of numerous diseases, including MetS. Certain dietary factors may contribute to MetS by affecting the acid-base balance within the body. This study examined the association of dietary acid load (DAL) with MetS and its components in Iranian adults. Materials and methods This cross-sectional study was conducted in 2022 on 6356 Iranian adults aged 35-70 years. Potential renal acid load (PRAL) and net endogenous acid production (NEAP) as two indicators of DAL were calculated based on nutrient intake data from validated food frequency questionnaires. MetS and its components were defined according to the Adult Treatment Panel III criteria. Logistic regression analysis was used to explore the associations between DAL and MetS and its components. Age, energy intake, physical activity, education, marital status, home ownership, socioeconomic status, history of obesity-related disease, and calcium supplements were included in model I. Further adjustment in model II was made for body mass index. Results Higher NEAP scores were associated with increased odds of low high-density lipoprotein cholesterol (HDL-C) in the crude model (OR: 1.26, 95% CI: 1.01-2.56, p trend = 0.06) in women, which was confirmed in the adjusted models. In model I, women in the last quintile of NEAP had 54% greater odds of having hypertriglyceridemia compared to the first quintile (OR: 1.54, 95% CI: 1.007-2.36, p trend = 0.02). This association was still significant and even stronger after further adjustment for BMI (OR: 1.55, 95% CI: 1.01-2.40, p trend = 0.01). In addition, in model I, men in the fourth quintile of NEAP had 5.68-fold greater odds of hyperglycemia compared to the first quintile (OR: 5.68, 95% CI: 1.18-27.25, p trend = 0.11). Similar results were found in the fully adjusted model (OR: 5.89, 95% CI: 1.19-28.99, p trend = 0.54). Conclusion There was no significant association between DAL and MetS. DAL was positively associated with the odds of low HDL-C and hypertriglyceridemia in women. Moreover, moderate DAL (NEAP) was associated with an increased odds of hyperglycemia in men.

Health Inequities in the USA: a Role for Dietary Acid Load? Results from the National Health and Nutrition Examination Surveys

BACKGROUND

Cardiovascular disease and obesity affect racial and ethnic minorities disproportionally. Public health research suggests that suboptimal diet is an important contributor to health disparities. Limited evidence points at an increased dietary acid load (DAL) in certain ethnic groups. DAL is determined by the balance of acidifying foods and alkaline foods, and elevated DAL scores have been associated with numerous chronic lifestyle-related conditions. The present analysis investigated DAL scores among ethnic groups in the USA.

METHODS

Using cross-sectional data from the National Health and Nutrition Examination surveys (NHANES, 2007-2016), we contrasted several markers of DAL (potential renal acid load (PRAL) and net endogenous acid production (NEAP)) between Non-Hispanic Whites, Non-Hispanic Blacks, Mexican Americans, Other Hispanics, and Other Race. The comparison included crude scores and adjusted scores following multivariate linear regression.

RESULTS

The sample for this analysis comprised 19,565 participants, which may be extrapolated to represent 156,116,471 United States Americans. When compared to Non-Hispanic Whites, Non-Hispanic Blacks and Mexican Americans had significantly higher crude DAL scores. PRALR was highest in Mexican Americans (20.42 (0.61) mEq/day), followed by Non-Hispanic Blacks (17.47 (0.42) mEq/day). Crude NEAPF was highest in Non-Hispanic Blacks (64.66 (0.43) mEq/day), and almost 9 mEq/day higher compared to Non-Hispanic Whites (55.78 (0.39) mEq/day). Multivariate linear regression adjusting for confounders revealed comparable interracial DAL differences.

CONCLUSIONS

We found significant DAL differences across the investigated ethnic groups. Whether these differences potentially play a role in population health inequity in the USA will be subject to additional research.

The association between dietary acid load and odds of non-alcoholic fatty liver disease: A case-control study

Background: Data on the association between dietary acid load and non-alcoholic fatty liver disease (NAFLD) are scarce and controversial. Aim: This study aimed to assess the association between dietary acid-base loads and odds of NAFLD. Methods: In the current study, 196 cases of NAFLD (proven by a gastroenterologist using Fibroscan) and 803 age-matched controls were enrolled from the same clinic. Dietary intakes of patients with NAFLD and controls without hepatic steatosis were evaluated using a validated food frequency questionnaire. Dietary acid load was estimated using the validated potential renal acid load (PRAL) algorithm. Multivariable logistic regression model was used to estimate the odds of NAFLD across quintiles of PRAL. Results: The mean ± SD age of the study population (43% male) was 43.28 ± 14.02 years. The mean ± SD of PRAL was -1.90 ± 7.12 for all participants. After adjustment for all known confounders, subjects in the third quintile of PRAL (nearly with neutral PRAL) had a 54% lower odds of NAFLD compared with those in the lowest quintiles of the PRAL [(OR: 0.46; 95%CI: 0.24-0.89), (P = 0.021)]. However, the odds of NAFLD in the highest quintiles of PRAL was not different in comparison to the lowest quintiles (OR: 0.90; 95%CI: 0.41-1.57). Conclusion: In conclusion, our results have shown a modest U shaped relationship between PRAL and NAFLD. Further studies with acid-base biomarkers are needed to confirm the role of dietary acid load in the development of NAFLD and its potential mechanisms.

Association between Dietary Acid Load and Hypertension in Chinese Adults: Analysis of the China Health and Nutrition Survey (2009)

(1) Background: Current studies show conflicting results regarding the relationship between dietary acid load (DAL) and blood pressure. (2) Methods: The study used data from the Chinese Health and Nutrition Survey (CHNS) 2009. DAL was assessed on the basis of potential renal acid load (PRAL) and net endogenous acid production (NEAP). To examine the link between DAL and the risk of hypertension, a multivariate logistic regression model was utilized. (3) Results: A total of 7912 subjects were enrolled in the study, of whom 2133 participants had hypertension, a prevalence of 27.0%. After accounting for potential covariates, higher PRAL and NEAP scores were associated with a greater likelihood of developing hypertension, with ORs of 1.34 (95% CI, 1.10-1.62) and 1.29 (95% CI, 1.09-1.53) for PRAL and NEAP scores in Q4, respectively, compared with Q1. In the male group, PRAL and NEAP scores were positively linked to hypertension risk, with ORs of 1.33 (95% CI, 1.06-1.67) and 1.46 (95% CI, 1.14-1.85) for PRAL and NEAP scores in Q4, respectively, compared with Q1, while no significant associations were observed in the female group. Correlations between PRAL scores and hypertension risk lacked significance in the subgroup analyses for participants aged <60 years. There was a significant nonlinear connection observed in the dose-response relationship between DAL (based on PRAL) and hypertension; (4) Conclusions: In Chinese adults, higher PRAL and NEAP scores were positively linked to hypertension risk. This implies that a diet with a low DAL may be a favorable dietary pattern for lowering blood pressure.

Association of Higher Intake of Plant-Based Foods and Protein With Slower Kidney Function Decline in Women With HIV

BACKGROUND

We investigated whether there exists an association between dietary acid load and kidney function decline in women living with HIV (WLWH) receiving antiretroviral therapy (ART).

SETTING

One thousand six hundred eight WLWH receiving ART in the WIHS cohort with available diet data and a baseline estimated glomerular filtration rate (eGFR) ≥15 mL/minute/1.73 m2.

METHODS

A brief dietary instrument conducted from 2013 to 2016 under the Food Insecurity Sub-Study was used for assessing fruits and vegetables (FV) and protein intake. A mixed-effects model with random intercept and slope was used to estimate subjects' annual decline rate in eGFR and the association between FV intake and eGFR decline, adjusting for sociodemographics, serum albumin, comorbidities, time on ART, ART drugs, HIV markers, and baseline eGFR. We evaluated whether markers of inflammation mediated the effect of FV intake on decline in eGFR, using causal mediation analysis.

RESULTS

We found a dose-response relationship for the association of FV intake and eGFR decline, with lesser annual decline in eGFR in the middle and highest tertiles of FV intake. An increase of 5 servings of FV intake per day was associated with a lower annual eGFR decline (-1.18 [-1.43, -0.94]). On average, 39% of the association between higher FV intake and slower eGFR decline was explained by decreased levels of inflammation.

CONCLUSIONS

Plant-rich diet was associated with slower decline in kidney function. Inflammation is a potential path through which diet may affect kidney function. The findings support an emerging body of literature on the potential benefits of plant-rich diets for prevention of chronic kidney disease.

Association of dietary acid load with metabolic syndrome in overweight and obese women

Background: There is increasing evidence supporting the association between dietary acid load and metabolic syndrome (MetS) components. However, to the best of our knowledge, there are rare and inconsistent studies to examine the association of dietary acid load and MetS score. The aim of this research was to assess dietary acid loads as measured by potential renal acid load (PRAL) in relation to MetS. Methods: The current study involved 246 overweight or obese women. Dietary assessment was performed using a validated 147-item food frequency questionnaire (FFQ). Remer's equation was used to calculate PRAL score. MetS was defined as the National Cholesterol Education Program (NCEP)/Adult Treatment Panel ΙΙΙ (ATP). Multivariable logistic regression models were used to find the association between PRAL score and MetS. Results: The mean age and BMI of participants were 36.49±8.38 years old and 31.04±4.31 kg/m2, respectively. Overall, 32 percent of participants had MetS. According to the final model, although not statistically significant, there was a trend which suggested that being in the highest quartile of adherence to dietary acid load, evaluated by PRAL score, compared to the lowest quartile was associated with higher odds of MetS [(OR: 2.80; 95% CI: 0.95-8.26), (P=0.06)]. Conclusions: Our study shows a borderline non-significant association between PRAL and odds of MetS in overweight or obese women. However, definitive clarification of this relationship requires future intervention studies.

Dietary acid load in children with chronic kidney disease: its association with nutritional status and health-related quality of life

BACKGROUND

This study aimed to determine the dietary acid load of children with chronic kidney disease (CKD) and to evaluate the relationship between dietary acid load, nutritional status, and health-related quality of life (HRQOL).

METHOD

A total of 67 children aged 3-18 years with a diagnosis of CKD stages II-V were included in the study. Anthropometric measurements (body weight, height, mid-upper arm circumference, waist, and neck circumference) and 3-day food consumption records were taken to evaluate the nutritional status. The net endogenous acid production (NEAP) score was calculated to determine the dietary acid load. "Pediatric Inventory of Quality of Life (PedsQL)" was used to assess the participants' HRQOL.

RESULTS

The mean NEAP was 59.2 ± 18.96 mEq/day. Stunted and malnourished children had significantly higher NEAP than those who were not (p < 0.05). There were no significant differences in terms of HRQOL scores according to NEAP groups. The multivariate logistic regression analysis showed that waist circumference (OR: 0.890, 95% CI: 0.794-0.997), serum albumin (OR: 0.252, 95% CI: 0.068-0.929), and glomerular filtration rate (GFR) (OR: 0.985, 95% CI: 0.970-1.000) were negatively associated with high NEAP.

CONCLUSION

This study shows that a diet shifted in an acidic direction in children with CKD and a higher dietary acid load are associated with lower serum albumin, GFR, and waist circumference, but not HRQOL. These results suggest that dietary acid load might affect nutritional status and CKD progression in children with CKD. Future studies with larger samples are needed to confirm these results and to understand underlying mechanisms. A higher resolution version of the Graphical abstract is available as Supplementary information.

Dietary acid load decreases with age and is associated with sagittal abdominal diameter: a nationally representative quantification study in US adults

BACKGROUND

Dietary acid load (DAL) has been associated with frailty and hip fractures in older adults, who often have a reduced kidney function and thus compromised buffering capacities. Studies to quantify DAL in older adults are scarce and controversies persist as to whether DAL in- or decreases with age.

AIM

To enhance the understanding of DAL in older individuals, we examined its relationship with increasing age and selected anthropometric data in a well-characterized sample of US adults.

METHODS

Secondary data analysis of nationally representative data from the National Health and Nutrition Examination Surveys data (NHANES 2011-2016). The sample included n = 3018 adults aged 60+, which may be extrapolated to represent n = 45,113,471 Americans. DAL was estimated using 4 formulas, including Potential Renal Acid Load (PRAL) and Net Endogenous Acid Production (NEAP).

RESULTS

All employed DAL scores tended to decline with increasing age. Participants aged 80 years or older yielded the lowest DAL scores. The average US citizen aged 60+ consumed an acidifying diet, yet there were sex-specific differences in the adjusted means for some scores. NEAP was positively correlated with both body mass index (r = 0.26, p < 0.001) and the sagittal abdominal diameter (r = 0.31, p < 0.001) in this nationally representative sample.

CONCLUSION

The previously reported phenomenon of increasing DAL values in older people in non-Western countries may not apply to the US. Our findings may constitute an important step towards a better understanding of DAL in older US adults, and highlight the need for additional population-specific research in the field.

The Synergistic Effect of Dietary Acid Load Levels and Cigarette Smoking Status on the Risk of Chronic Obstructive Pulmonary Disease (COPD) in Healthy, Middle-Aged Korean Men

We investigated whether cigarette smoking and dietary acid load (DAL) are associated with a risk of chronic obstructive pulmonary disease (COPD) in healthy, middle-aged Korean men. Healthy men without diagnosed chronic disease (aged 40-64 years) from the KNHANES-VI (2013-2015) were included in the analysis (n = 774) and were subdivided by smoking status and DAL levels, as estimated using the quartile of net endogenous acid production (NEAP). The current smokers tended to have a higher risk of COPD than the never-smokers before and after adjustment. When divided by the DAL quartile, the Q4 group tended to have a higher risk of COPD than the Q1 group. Additionally, the current smokers with lower (Q2), modest (Q3), and the highest NEAP scores (Q4) showed risks of COPD that were more than fourfold higher than those of the never-smokers with the lowest NEAP scores (Q1). The ex-smokers with higher NEAP scores (Q3 and Q4) showed risks of COPD that were more than fourfold higher than those of the Q1 group. Interestingly, the risk of COPD was also more than sixfold higher in the never-smokers with the highest NEAP scores compared to that in the Q1 group. The NEAP scores and smoking status synergistically increased the risk of COPD in healthy, middle-aged Korean men. This suggests that DAL levels are an important factor in the prevention and management of COPD.

Dietary acid load is associated with waist circumference in university students with low adherence to the Mediterranean diet: The potential role of ultra-processed foods

BACKGROUND AND AIMS

Dietary acid load (DAL), as expressed by potential renal acid load (PRAL) and net acid production (NEAP), is connected to cardiometabolic disorders and obesity. Mediterranean diet relates to lower, while western diets to higher DAL values. The present study aimed to assess the association of PRAL and NEAP with adiposity measures in young adults (19.61 ± 3.15 years, mean ± standard deviation) and explore the implication of Mediterranean diet adherence and ultra-processed foods (UPF) intake in this relation.

METHODS

346 students (269 women) participated. Anthropometry was performed, and a food frequency questionnaire was administered. The MedDietScore was calculated, UPF consumption was calculated based on the NOVA classification and PRAL/NEAP was estimated from published equations. Waist Circumference (WC) was transformed to WC^-1 (1/WC) in order to achieve normality and run linear regression models.

RESULTS

In subjects with MedDietScore ≤ 28.00, PRAL and NEAP were negatively associated with 1/WC (B = -1.594 × 10-5± 8 × 10-6, p = 0.044 for PRAL and B = -2.84 × 10-5 ± 1 × 10-5, p = 0.048 for NEAP). Moreover, in this subgroup, subjects with medium to high UPF intake i.e., in the 2nd or 3rd tertile of UPF intake representing more than 34.16% of energy, PRAL (2nd tertile B = -0.00007, SE = 0.00003, p = 0.018; 3rd tertile B = -0.00002, SE = 0.00001, p = 0.024) and NEAP (2nd tertile B = -0.00004, SE = 0.00002, p = 0.040; 3rd tertile B = -0.00007, SE = 0.00004, p = 0.055) were connected to central obesity. In similar models, PRAL and NEAP were not significant predictors of BMI.

CONCLUSION

The DAL may be related to central obesity, especially in individuals with worse dietary quality, as reflected by lower adherence to the Mediterranean diet, and high intake of UPF. Nutrition guidance aiming at the reduction of DAL may be useful in the reduction of central obesity in these subgroups.

Hidden chronic metabolic acidosis of diabetes type 2 (CMAD): Clues, causes and consequences

Interpretation of existing data revealed that chronic metabolic acidosis is a pathognomic feature for type 2 diabetes (T2D), which is described here as "chronic metabolic acidosis of T2D (CMAD)" for the first time. The biochemical clues for the CMAD are summarised in the following; low blood bicarbonate (high anionic gap), low pH of interstitial fluid and urine, and response to acid neutralization, while the causes of extra protons are worked out to be; mitochondrial dysfunction, systemic inflammation, gut microbiota (GM), and diabetic lung. Although, the intracellular pH is largely preserved by the buffer system and ion transporters, a persistent systemic mild acidosis leaves molecular signature in cellular metabolism in diabetics. Reciprocally, there are evidences that CMAD contributes to the initiation and progression of T2D by; reducing insulin production, triggering insulin resistance directly or via altered GM, and inclined oxidative stress. The details about the above clues, causes and consequences of CMAD are obtained by searching literature spanning between 1955 and 2022. Finally, the molecular bases of CMAD are discussed in details by interpretation of an up-to-date data and aid of well constructed diagrams, with a conclusion unravelling that CMAD is a major player in T2D pathophysiology. To this end, the CMAD disclosure offers several therapeutic potentials for prevention, delay or attenuation of T2D and its complications.

Higher Dietary Acid Load Might Be a Potent Derivative Factor for Multiple Sclerosis: The Results from a Case-Control Study

This study aimed to investigate the association between dietary acid load (DAL) and multiple sclerosis (MS), through the potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores. In a hospital-based case-control study of 109 patients with MS and 130 healthy individuals, a validated 168-item semi-quantitative food frequency questionnaire and a logistic regression model were used to evaluate the association between the DAL and MS. After adjusting for age (years), gender (male/female), body mass index (Kg/m2), and total calories (Kcal), the MS odds were 92% lower for those in the highest tertile of total plant-based protein (OR: 0.08, 95%CI: 0.03, 0.23; p-value < 0.001) and about four times higher for those in the highest tertile of the PRAL (OR: 4.16, 95%CI: 1.94, 8.91; p-value < 0.001) and NEAP scores (OR: 3.57, 95%CI: 1.69, 7.53; p-value < 0.001), compared to those in the lowest tertile. After further adjusting for sodium, saturated fatty acid, and fiber intake, the results remained significant for total plant-based protein intake (OR: 0.07, 95%CI: 0.01, 0.38; p-value = 0.002). In conclusion, a higher NEAP or PRAL score may be associated with increased odds of MS, while a higher intake of plant-based protein instead of animal-based protein may be protective.

Dietary Acid Load and Cancer Risk: A Review of the Uruguayan Experience

Dietary acid load (DAL) is recognized as a risk factor for several chronic disorders, including obesity, diabetes, and osteoporosis. Recent evidence suggests that an elevated DAL, as measured by the validated potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores, could also increase the risk for several cancers. This narrative review summarizes the potential role of DAL in Uruguayan cancer patients and outlines the potentially involved pathophysiological pathways that mediate the role of DAL in both cancer development and growth. Although Uruguay is a developing country, its average diet is a heavily meat-based Western one, translating into a supraphysiological acid burden from diet. In recent years, we have published epidemiologic evidence based on ten case-control studies involving 3736 cancer cases and 9534 hospital-based controls. Odds ratios and 95% confidence intervals were estimated for each interest variable to analyze the association between the exposure levels of DAL scores and cancer, calculated by unconditional logistic regression. In a majority of the cases, the highest DAL scores tended to double the cancer risk as compared to the lowest category. We also found high risks for methionine intake, an acidifying amino acid found in higher concentrations in animal-based foods, which may increase cancer risks at least by a joint action based on the pH and the proliferation enhancing properties of the amino acid itself.

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.

Dietary acid load and its interaction with CETP TaqB1 polymorphisms on lipid profile among patients with Type 2 diabetes mellitus

OBJECTIVE

Gene-diet interaction plays a key role in the inter-individual differences in lipid abnormalities as a major risk factor for cardiovascular diseases (CVDs). Thus, we explored the interaction between CETP TaqB1 polymorphism with dietary acid load (DAL) on lipid profile among type 2 diabetes mellitus (T2DM).

METHOD

This cross-sectional study conducted on 220 Iranian patients with T2DM. Dietary acid load (PRAL and NEAP) was calculated via a validated food-frequency questionnaire (FFQ). The polymerase chain reaction (PCR) used for genotyping Taq1B polymorphism. Biochemical markers were measured by standard protocol. The interaction between CETP Taq1B polymorphism and DAL (PRAL and NEAP) on lipid profile was performed by a generalized linear regression model (GLM).

RESULTS

The overall prevalence of rs708272 genotypes was 8.6%, 72.7% and 18.6% for B1B1, B1B2 and B2B2 genotype respectively. This study showed that people with the B1B1 genotype had greater LDL, TC, LDL/HDL, and TG when they consumed diets that scored higher on the NEAP and PRAL indexes than those with the B1B2 and B2B2 genotypes. Besides, carriers of the B1B1 allele who were in the highest tertile of NEAP, had lower HDL (P Interaction < 0.05).

CONCLUSIONS

In summary, the lipid profile might be improved in B1B1 homozygotes by less adherence to DAL indexes, however, the findings should be validated in high-quality interventional studies.

Dietary Acid Load Correlates with Serum Amino Acid Concentrations after a Four-Week Intervention with Vegan vs. Meat-Rich Diets: A Secondary Data Analysis

Chronic low-grade metabolic acidosis is now a common phenomenon in the Western world. The high dietary intake of sulfur-containing amino acids in the form of processed meats results in an excessive release of acid in the form of protons and non-metabolizable acidic anions. The kidneys produce increasing amounts of ammonia to excrete this acid. This process requires the breakdown of the nitrogenous amino acid glutamine, which the body provides by breaking down muscle tissue. Hitherto not examined, we hypothesized that a high dietary acid load (DAL) could alter the serum concentrations of selected amino acids. Using secondary data from a 4-week dietary intervention study conducted in 2017, we examined the associations between various amino acids and DAL in n = 42 individuals who either consumed a meat-rich or vegan diet. Results from this secondary data analysis suggested that DAL (as measured by the potential renal acid load and net endogenous acid production) is positively correlated with higher serum concentrations of lysine and 1-methyl-histidine (r = 0.50 and 0.43, respectively) and negatively correlated with glutamine and glycine (r = -0.43 and -0.47, respectively). The inverse association with glycine and glutamine warrants special attention, as both play an important role in many metabolic disorders and the immune system.

The Impact of Plant-Based Diets on Dietary Acid Load Metrics in Venezuela: A Cross-Sectional Study

Dietary acid load (DAL) is an important determinant of the acid-base balance in humans and has been associated with several chronic non-communicable diseases. Plant-based diets, including vegetarian and vegan diets, decrease DAL-although their alkalizing potential varies substantially. Their net effect on common DAL scores, including potential renal acid load and net endogenous acid production, has been insufficiently quantified and is poorly understood-particularly in populations outside of Europe and North America. We assessed the associations between three plant-based dietary patterns (flexitarian vs. lacto-ovo-vegetarian vs. vegan diet) and DAL scores in a healthy Venezuelan population in the metropolitan area of Puerto La Cruz, Venezuela. Substantial differences in DAL scores were observed, whereby the vegan diet yielded the highest alkalizing potential, followed by the lacto-ovo-vegetarian and the flexitarian diet. DAL scores were substantially lower in comparison to European and North American plant-based populations, probably due to the higher potassium intake (exceeding 4000 mg/d in vegans), the higher magnesium intake (390.31 ± 1.79 mg/d in vegans) and the lower intake of protein in vegans and lacto-ovo-vegetarians. Additional studies in other non-industrialized populations are warranted to allow for a better understanding of the (numeric) impact of plant-based dietary patterns on DAL scores, potentially allowing for an establishment of reference ranges in the near future.

Nutritional Epidemiology and Dietary Assessment for Patients With Kidney Disease: A Primer

Nutritional epidemiology seeks to understand nutritional determinants of disease in human populations using experimental and observational study designs. Though randomized controlled trials provide the strongest evidence of causality, the expense and difficulty of sustaining adherence to dietary interventions are substantial barriers to investigating dietary determinants of kidney disease. Therefore, nutritional epidemiology commonly employs observational study designs, particularly prospective cohort studies, to investigate long-term associations between dietary exposures and kidney disease. Due to the covarying nature and synergistic effects of dietary components, holistic characterizations of dietary exposures that simultaneously consider patterns of foods and nutrients regularly consumed are generally more relevant to disease etiology than single nutrients or foods. Dietary intakes have traditionally been self-reported and are subject to bias. Statistical methods including energy adjustment and regression calibration can reduce random and systematic measurement errors associated with self-reported diet. Novel approaches that assess diet more objectively are gaining popularity but have not yet fully replaced self-report and require refinement and validation in populations with chronic kidney disease. More accurate and frequent diet assessment in existing and future studies will yield evidence to better personalize dietary recommendations for the prevention and treatment of kidney disease.

Association between Dietary Acid Load and Hyperuricemia in Chinese Adults: Analysis of the China Health and Nutrition Survey (2009)

BACKGROUND

This study evaluates the association between dietary acid load (DAL) and hyperuricemia in Chinese adults.

METHODS

The China Health and Nutrition Survey (CHNS) in 2009 was used in this cross-sectional study. Potential renal acid load (PRAL) and net endogenous acid production (NEAP) were applied to estimate DAL. A multiple logistic regression model was used to test the relationship between DAL and hyperuricemia risk.

RESULTS

A total of 7947 participants were included in this study, of whom 1172 had hyperuricemia. The PRAL score was positively related to the prevalence of hyperuricemia, even when potential covariates were taken into account. In comparison with Q1, the ORs were 1.12 (95% CI, 0.92-1.38), 1.20 (95% CI, 0.97-1.47) and 1.42 (95% CI, 1.16-1.75) in Q2, Q3 and Q4. However, there was no significant relationship between NEAP scores and hyperuricemia. Every 10 g increase in energy-adjusted fat, protein and animal protein intakes caused a 10%, 17% and 18% increase in hyperuricemia risk, respectively (OR: 1.10, 95% CI: 1.04-1.16; OR: 1.17, 95% CI: 1.11-1.25; OR: 1.18, 95% CI: 1.12-1.24, respectively). An obvious linear correlation was also suggested by the restricted cubic spline.

CONCLUSIONS

Hyperuricemia risk was associated with higher PRAL among Chinese adults. This means that a diet low in PRAL scores could be a very valuable uric acid-lowering dietary pattern.

Mediators of dietary diversity score (DDS) on NAFLD in Iranian adults: a structural equation modeling study

BACKGROUND

The current study examines the association between the Dietary Diversity Score (DDS) and nonalcoholic fatty liver disease (NAFLD) in Iranian adults using structural equation modeling (SEM).

METHODS

A sample of 3220 adults from the Amol Cohort Study was recruited for this cross-sectional study. Dietary acid load (DAL) and DDS were calculated using the data obtained from a validated food frequency questionnaire. Anthropometric parameters, blood pressure, biochemical measurements, and liver ultrasonography were evaluated according to standard protocols.

RESULTS

DDS was neither directly nor indirectly associated with a greater prevalence of NAFLD. In the second model (DDS sub-scores model), the association of DAL with NAFLD was fully mediated through waist circumference (WC) (of DAL to WC: β = 0.14, P < 0.0001, and of WC to NAFLD: β = 0.50, P < 0.001). Vegetable and fruit diversity scores had a significant negative indirect relationship with NAFLD prevalence through DAL (β = -0.06, P = 0.001, β = -0.10, P < 0.001, respectively). Meat diversity score was positively associated with NAFLD prevalence in a full mediational process through DAL (β = 0.12, P < 0.001). The SEM fit indices suggested a reasonably adequate fit of the data to the DDS model (Χ2/df = 4.76, GFI = 0.98, AGFI = 0.97, IFI = 0.97, CFI = 0.97, RMSEA = 0.03, and SRMR = 0.02) and its sub-scores model (Χ²/df = 4.72, GFI = 0.98, AGFI = 0.97, IFI = 0.95, CFI = 0.95, RMSEA = 0.03, and SRMR = 0.02).

CONCLUSION

Meat diversity and lack of vegetable and fruit diversity were indirectly associated with NAFLD prevalence through DAL and WC mediators. Interventions for NAFLD may be more successful if they target a lower intake of animal protein sources and dietary diversity, particularly vegetable and fruit diversity.

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.

The association of dietary acid load (DAL) with estimated skeletal muscle mass and bone mineral content: a cross-sectional study

BACKGROUND & AIMS

Dietary patterns that promote mild metabolic acidosis may have a negative effect on bone and muscle, and a high dietary acid load (DAL) may be detrimental to skeletal muscle mass and bone mineral content. However, the association between skeletal muscle mass and bone mineral content with dietary acid load has not been consistently reported in previous studies. The objective of the study was to evaluate the association of potential renal net acid load (PRAL) and net endogenous acid production (NEAP) with bone mineral content and skeletal muscle mass in pre-menopause women with overweight or obesity in Iran.

METHOD

Three hundred and ninety women with a body mass index (BMI) of 25 were included in this cross-sectional study. We used a validated 147-item semi-quantitative food frequency questionnaire (FFQ) for evaluating the dietary intake. Based on the dietary data, potential renal net acid load (PRAL) and net endogenous acid production (NEAP) were calculated. Muscle mass and bone mineral content were estimated by a bioelectrical impedance analyzer (BIA).

RESULTS

After controlling for potential confounders, we discovered a significant linear relationship between PRAL (β = -0.027, 95%CI = -0.049 to -0.004, P = 0.02) and NEAP (β = -0.05, 95%CI = -0.097 to -0.003, P = 0.03) and skeletal muscle mass index. However, there was no significant difference between SMM and BMC across PRAL and NEAP tertiles.

CONCLUSION

PRAL and NEAP were found to be inversely related to skeletal muscle mass index among overweight/obese women. Further research is required to establish whether this relationship is important for musculoskeletal health in these populations.

Increasing Serum Bicarbonate is Associated with Reduced Risk of Adverse Kidney Outcomes in Patients with CKD and Metabolic Acidosis

Introduction

Low serum bicarbonate at a single point in time is associated with accelerated kidney decline in patients with chronic kidney disease (CKD). We modeled how changes in serum bicarbonate over time affect incidence of adverse kidney outcomes.

Methods

We analyzed data from Optum's deidentified Integrated Claims-Clinical data set of US patients (2007-2019) with ≥1 year of prior medical record data, CKD stages G3 to G5, and metabolic acidosis (i.e., index serum bicarbonate 12 to <22 mmol/l). The primary predictor of interest was the change in serum bicarbonate, evaluated at each postindex outpatient serum bicarbonate test as a time-dependent continuous variable. The primary outcome was a composite of either a ≥40% decline in estimated glomerular filtration rate (eGFR) from index or evidence of dialysis or transplantation, evaluated using Cox proportional hazards models.

Results

A total of 24,384 patients were included in the cohort with median follow-up of 3.7 years. A within-patient increase in serum bicarbonate over time was associated with a lower risk of the composite kidney outcome. The unadjusted hazard ratio (HR) per 1-mmol/l increase in serum bicarbonate was 0.911 (95% confidence interval [CI]: 0.905-0.917; P < 0.001). After adjustment for baseline eGFR and serum bicarbonate, the time-adjusted effect of baseline eGFR and other covariates, the HR per 1-mmol/l increase in serum bicarbonate was largely unchanged (0.916 [95% CI: 0.910-0.922; P < 0.001]).

Conclusion

In a real-world population of US patients with CKD and metabolic acidosis, a within-patient increase in serum bicarbonate over time independent of changes in eGFR, was associated with a lower risk of CKD progression.

Dietary Acid Load and Predialysis Serum Bicarbonate Levels in Patients With End-Stage Renal Disease

OBJECTIVES

Maintaining the predialysis serum bicarbonate at a recommended level is critical in patients undergoing hemodialysis. Therefore, the present study investigated the association between dietary acid load (DAL) and serum predialysis bicarbonate levels in patients with end-stage renal disease.

METHODS

Adult patients undergoing hemodialysis were enrolled in this cross-sectional study. Diet was assessed using a semiquantitative food frequency questionnaire. DAL was calculated with 2 validated indices: potential renal acid load (PRAL) and net endogenous acid production (NEAP). Values regarding predialysis serum bicarbonate level and serum electrolytes were obtained from the participant's medical records. The multiple linear regression analysis was used to determine the association between DAL indices and predialysis serum bicarbonate level.

RESULTS

The number of hemodialysis patients eligible for this study was 122. The participants' mean age and body mass index was 57.14 ± 3.8 years and 25.2 ± 4.9 kg/m², respectively. About 65.6% of participants were male. The mean serum levels of predialysis bicarbonate were 21.59 ± 3.1 mEq/L. Also, 47.5% of patients had predialysis serum bicarbonate levels below the recommended value. The mean values of PRAL and NEAP were -2.8 ± 7.48 and 42.7 ± 10.1 mEq/day, respectively. PRAL significantly and inversely predicted predialysis serum bicarbonate level independent of covariates (standardized β = -0.38; P < .001). Also, NEAP was independently and inversely associated with predialysis bicarbonate level (standardized β = -0.40; P < .001). Consuming vegetables such as lettuce, tomato, cucumber, spinach, and dried fruits as well as low-fat milk, plain yogurt, and cream cheese were positively correlated to predialysis serum bicarbonate level. However, the canned tuna had a negative correlation with the predialysis serum bicarbonate.

CONCLUSIONS

The study's findings showed that the lower DAL was associated with higher predialysis serum bicarbonate levels in patients with end-stage renal disease. Due to the cross-sectional nature of the present study, prospective cohorts or well-controlled clinical trials are needed to confirm our result.

Primary Contributors to Dietary Acid Load in Patients With Urolithiasis

OBJECTIVES

In susceptible individuals, high dietary acid load may contribute to the formation of certain types of kidney stones via lowering urine pH and citrate excretion. The objective of this study is to determine the contribution of dietary acid from food groups in people with urolithiasis.

DESIGN AND METHODS

Patients with calcium urolithiasis (n = 83) who completed food records were used for this retrospective analysis. Descriptive statistics were calculated for nutrients, potential renal acid load (PRAL), and estimated net endogenous acid production (NEAP_est). Pearson's correlations were calculated between PRAL and NEAP_est with each nutrient.

RESULTS

Data from a total of 83 patients were used. Average PRAL was positively correlated with energy (r = 0.260, P = .02), total protein (r = 0.463, P < .001), animal protein (r = 0.555, P < .001), total fat (P = .399, P < .001), sodium (r = 0.385, P < .001), and phosphorus (r = 0.345, P < .001) intake. PRAL was negatively correlated with fiber (r = -0.246, P = .03) intake. NEAP_est was positively correlated with total protein (r = 0.269, P = .01), animal protein (r = 0.377, P < .001), fat (r = 0.222, P = .04), and sodium (r = 0.250, P = .02) intake. NEAP_est was negatively correlated with fiber (r = -0.399, P < .001), potassium (r = -0.360, P < .001), and magnesium (r = -0.233, P = .03) intake. For PRAL, meat contributed the highest acid load (52.7%), followed by grains (19.6%) and combination foods (19.6%). Beverages contributed the greatest alkali load (35.1%), followed by vegetables (30.6%) and fruits (28.6%). For NEAP_est, cheese contributed the highest acid load (21.8%), followed by grains (19.3%) and meat (18.1%).

CONCLUSIONS

For individuals with urolithiasis promoted by acidic urine and/or low urine citrate, dietary patterns with a high dietary acid load may contribute to recurrence risk. Meat and grains were the major contributors to dietary acid load in this cohort of patients with a history of kidney stones, whereas beverages, fruits, and vegetables contributed net alkali.

Long-term dietary acid load is associated with depression in multiple sclerosis, but less evidence was found with fatigue and anxiety

BACKGROUND

Diet-dependent acid-base load has been associated with worsening in mental health, but to date no study has examined this in people with multiple sclerosis (PwMS). We examined the association between potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores and depression, anxiety, and fatigue in PwMS.

METHODS

Participants with a first clinical diagnosis of CNS demyelination were followed prospectively as part of the AusLong Study (aged 18-59 years at cohort entry). At baseline, 5- and 10-year reviews, PRAL and NEAP scores were calculated using dietary intake in the preceding 12 months calculated from a food frequency questionnaire. At 5- and 10-year reviews, the Hospital Anxiety and Depression Scale was used to assess depression and anxiety, and the Fatigue Severity Scale assessed fatigue.

RESULTS

Higher PRAL and NEAP scores were associated with increased subsequent absolute value and change in HADS depression scores over five years' follow-up (e.g., highest vs lowest PRAL quartile, 5-year change in HADS-D score: β=+3.01, 95%CI= 1.54, 4.48, p<0.001). The level of depression at the 10-year review was determined by both the baseline dietary acid scores and baseline-5-year changes in dietary acid scores (e.g., PRAL change from baseline to 5-year review, 10-year review HADS-D score: β=+0.09, 95%CI= 0.03, 0.15, p<0.001, NEAP change from baseline to 5-year review, 10-year review HADS-D score: β=+0.07, 95%CI= 0.01, 0.14, p=0.03). Some associations were observed with anxiety and fatigue but were much weaker and less consistent.

CONCLUSION

Our findings indicate that a higher dietary acid load potentially has a long-term influence on the level of depression in PwMS. The evidence is less convincing for anxiety and fatigue.

The association between dietary acid load and body composition in physical education students aged 18-25 years

AIM

To find the association between dietary acid load (DAL) and body composition in physical education students.

METHODS

This study was carried out on 207 students of both genders aged 18-25 years. DAL was calculated based on potential renal acid load (PRAL) and net endogenous acid production (NEAP) methods. Anthropometric indices were measured. Bioelectric impedance was used to assess body composition and other related items.

RESULTS

The mean score of NEAP and PRAL was 80.18 ± 31.30 and 33.94 ± 22.11, respectively. The mean weight and fat mass of subjects were 64.05 ± 9.72 kg and 20.28 ± 0.67 kg, respectively. Participants in the highest tertile of PRAL had a higher weight (64.56 ± 1.14 kg) in comparison with participants in the lowest tertile (61.65 ± 1.19 kg) (P = 0.027). After adjusting for confounders, a significant positive association was found between NEAP score and hip circumference (β = 0.206, P = 0.039), body mass index (β = 0.214, P = 0.031), fat mass (β = 0.218, P = 0.001) and body adiposity index (β = 0.182, P = 0.037). Furthermore, a statistically significant negative association was observed between total body water and NEAP score (β = - 0.217, P = 0.001) and the percentage of fat-free mass and NEAP (β = - 0.229, P = 0.001).

CONCLUSION

Individuals with a higher DAL score may have a higher weight, fat mass and hip circumference and a lower fat-free mass. In addition, there might be an association between DAL and obesity.

Chronic Sub-Clinical Systemic Metabolic Acidosis - A Review with Implications for Clinical Practice

When arterial serum pH remains near the lower pH limit of 7.35 for protracted periods of time, a low-grade, sub-clinical form of acidosis results, referred to in this review as chronic, sub-clinical, systemic metabolic acidosis (CSSMA). This narrative review explores the scientific basis for CSSMA, its consequences for health, and potential therapeutic interventions. The major etiology of CSSMA is the shift away from the ancestral, alkaline diet which was rich in fruit and vegetables, toward the contemporary, acidogenic 'Westernized' diet characterized by higher animal protein consumption and lack of base forming minerals. Urine pH is reduced with high dietary acid load and may be a convenient marker of CSSMA. Evidence suggests further that CSSMA negatively influences cortisol levels potentially contributing significantly to the pathophysiology thereof. Both CSSMA and high dietary acid load are associated with the risk and prognosis of various chronic diseases. Clinical trials show that CSSMA can be addressed successfully through alkalizing the diet by increasing fruit and vegetable intake and/or supplementing with alkaline minerals. This review confirms the existence of a significant body of evidence regarding this low-grade form of acidosis as well as evidence to support its diverse negative implications for health, and concludes that CSSMA is a condition warranting further research.

Associations of Metabolic Syndrome and Abdominal Obesity with Anion Gap Metabolic Acidosis among US Adults

BACKGROUND

Obesity is a recently identified risk factor for metabolic acidosis and anion gap elevations in the absence of CKD. Metabolic acidosis is a treatable condition with substantial adverse effects on human health. Additional investigations are needed to characterize at-risk populations and explore potential mechanisms. We hypothesized metabolic syndrome (MetS) and waist circumference (WC) would be closely associated with this pathology.

METHODS

Adult participants from NHANES 1999-2018 meeting study criteria were compiled as main (n=31,163) and fasting (n=12,860) cohorts. Regression models adjusted for dietary acid, eGFR, and other factors examined associations of WC and MetS features with anion gap metabolic acidosis and its components (serum bicarbonate ≤23 mEq/L and anion gap >95th percentile).

RESULTS

Greater WC and MetS features were associated with progressively lower bicarbonate, higher anion gap, and greater odds ratios (OR) of metabolic acidosis (MA) and anion gap metabolic acidosis (AGMA). Compared with the reference, participants with the highest WC had ORs for MA and AGMA of 2.26; 95% CI, 1.96 to 2.62 and 2.89; 95% CI, 1.97 to 4.21; those with three and four versus zero MetS features had ORs for AGMA of 2.52; 95% CI, 1.95 to 2.94 and 3.05; 95% CI, 2.16 to 3.82. Associations of body mass index with outcomes were attenuated or absent after adjustment for WC or MetS. Findings were preserved after excluding eGFR <90 ml/min per 1.73 m² and albuminuria. A lower MA cutoff (<22 mEq/L) raised the estimate of association between MetS and MA (OR for three and four vs zero features: 3.56; 95% CI, 2.53 to 5.02 and 5.44; 95% CI, 3.66 to 8.08).

CONCLUSIONS

Metabolic diseases are characterized by metabolic acidosis and anion gap elevations. Metabolic dysfunction may predispose patients without CKD to systemic acidosis from endogenous sources. Comprehensive acid-base analyses may be informative in patients with metabolic diseases.

Back to basic: Trials and tribulations of alkalizing agents in cancer

"Dysregulated" metabolism is a characteristic of the cancer cell phenotype. This includes persistent use of glycolytic metabolism in normoxic environments (Warburg effect) leading to increased acid production and accumulation of protons in the interstitial space. Although often thought to be disordered, altered cancer metabolism is the outcome of intense Darwinian selection and, thus, must have evolved to maximize cancer cell fitness. In an evolutionary context, cancer-induced acidification of the microenvironment represents a niche construction strategy to promote proliferation. Ecological advantages conferred on the cancer population included remodeling of the extracellular matrix to promote local invasion, suppression of potential competitive proliferation of fibroblasts, and suppression of host immune response. Preclinical data demonstrates that increasing the serum buffering capacity (through, for example, oral sodium bicarbonate and TRIS) can neutralize the acidic tumor microenvironment with inhibition local invasion and proliferation which can be synergistic with the effects of chemotherapy and immunotherapy agents. Here, we describe the proton dynamics in cancer and their influence on tumor progression and metastasis. Additionally, we will discuss targeting the tumor acidosis with alkalizing agents including our bicarbonate clinical trial results.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov, identifier NCT01350583, NCT01198821 and NCT01846429.

The association between dietary acid load and odds and severity of irritable bowel syndrome in adults

No study has been conducted to investigate the association between dietary acid load and irritable bowel syndrome (IBS). So, this cross-sectional study was performed to investigate the association between dietary acid load and odds of IBS, its severity, and IBS subtypes. A sample of 3362 Iranian subjects was selected from health centers in Isfahan province. A validated semi-quantitative food frequency questionnaire (DS-FFQ) was applied to estimate dietary intakes. The dietary acid load was measured using net endogenous acid production (NEAP), dietary acid load (DAL), and potential renal acid load (PRAL) scores. In crude models, the highest compared with the lowest category of the PRAL score was significantly associated with increased odds of IBS severity in participants with BMI ≥ 25 (kg/m²) (OR = 1.54; 95% CI = (1.03-2.32). Also, the results indicated a significant positive association between the PARL and odds of mixed subtype of IBS (OR = 1.74; 95% CI = (1.11-2.74); P trend = 0.02). In propensity score-adjusted model with potential confounders, only a positive association was found between PRAL and odds of mixed subtype of IBS (OR = 1.78; 95% CI = (1.05-3.00); P trend = 0.03). The DAL and NEAP scores tended to show non-significant similar findings. This study indicates that dietary acid load might be associated with odds of mixed type of IBS. However, further research is warranted to infer these findings.

Observational and clinical evidence that plant-based nutrition reduces dietary acid load

Contemporary diets in Western countries are largely acid-inducing and deficient in potassium alkali salts, resulting in low-grade metabolic acidosis. The chronic consumption of acidogenic diets abundant in animal-based foods (meats, dairy, cheese and eggs) poses a substantial challenge to the human body's buffering capacities and chronic retention of acid wherein the progressive loss of bicarbonate stores can cause cellular and tissue damage. An elevated dietary acid load (DAL) has been associated with systemic inflammation and other adverse metabolic conditions. In this narrative review, we examine DAL quantification methods and index observational and clinical evidence on the role of plant-based diets, chiefly vegetarian and vegan, in reducing DAL. Quantitation of protein and amino acid composition and of intake of alkalising organic potassium salts and magnesium show that plant-based diets are most effective at reducing DAL. Results from clinical studies and recommendations in the form of expert committee opinions suggest that for a number of common illnesses, wherein metabolic acidosis is a contributing factor, the regular inclusion of plant-based foods offers measurable benefits for disease prevention and management. Based on available evidence, dietary shifts toward plant-based nutrition effectively reduces dietary-induced, low-grade metabolic acidosis.

Dietary acid load, alternative healthy eating index score, and bacterial vaginosis: is there any association? A case-control study

Background:

Changing the dietary pattern may be an alternative treatment for bacterial vaginosis, the prevalent vaginal infection in women.

Methods:

One hundred and forty-three bacterial vaginosis-affected women diagnosed by Amsel criteria and 151 healthy controls aged 18 to 45 entered the current case-control research. To calculate the alternative healthy eating index and dietary acid load score, food consumption was recorded with an accurate and precise food frequency questionnaire. The dietary acid load was measured by potential renal acid load (PRAL) and net endogenous acid production (NEAP) indices. Using logistic regression models, the association between the alternative healthy eating index and dietary acid load score with bacterial vaginosis was investigated.

Results:

The last tertile of the alternative healthy eating index had a 75% decreased odds of experiencing bacterial vaginosis in the adjusted model (adjusted odds ratio (aOR) = 0.25, 95% confidence interval (CI) = 0.12–0.53, P for trend = 0.001). Besides, vegetables (aOR = 0.34, 95% CI = 0.17–0.69, P for trend = 0.003), nuts and legumes (aOR = 0.44, 95% CI = 0.23–0.87, P for trend = 0.028), and meats (aOR = 0.31, 95% CI = 0.16–0.60, P for trend = 0.001) intake was linked to a decreased bacterial vaginosis odds. However, sugar-sweetened beverages and fruit juice (aOR = 3.47, 95% CI = 1.68–7.17, P for trend < 0.001), trans fatty acids (aOR = 2.29, 95% CI = 1.18–4.43, P for trend = 0.005), and sodium (aOR = 3.44, 95% CI = 1.67–7.06, P for trend = 0.002) intake were directly associated with bacterial vaginosis odds. There was no evidence of a link between dietary acid load and bacterial vaginosis.

Conclusion:

According to the present study’s findings, there is no correlation between dietary acid load and the likelihood of developing bacterial vaginosis. However, following a plant-based dietary pattern based on the healthy eating index may lead to a lower odds of bacterial vaginosis.

Urinary Citrate Is Associated with Kidney Outcomes in Early Polycystic Kidney Disease

Low urinary citrate and crystal deposition accelerated cystogenesis in an experimental model of polycystic kidney disease (PKD).Hypocitraturia, frequently observed in patients with autosomal dominant PKD (ADPKD) could contribute to disease progression.Present findings suggest lower urinary citrate in early PKD was associated with faster eGFR decline and worse kidney survival.

Carbohydrate Intake and Its Association With Dietary Acid Load in U.S. Adults: Results From a Cross-Sectional Study

Background: The safety profile of low-carbohydrate diets is controversial and poorly understood. We investigated the effects of low-moderate carbohydrate intake on dietary acid load (DAL), an emerging health risk factor and novel clinical marker associated with numerous adverse clinical outcomes. Methods: We used data from the National Health and Nutrition Examination Surveys to investigate how low-moderate carbohydrate intake quantitatively affects DAL (as assessed by PRAL and NEAP scores) and to contrast the results to DAL scores in individuals that meet carbohydrate intake recommendations. Results: We analyzed data from 23 825 individuals, of which 4891 consumed a low-moderate carbohydrate diet. Said individuals derived 37.84% of energy from carbohydrates, tended to be male, had a mean BMI of 28.47 kg/m2, and consumed significantly more energy from fat and protein ( P≤.01 for both) than individuals that met carbohydrate recommendations Low-moderate carbohydrate intake was associated with a significantly higher DAL. Mean PRALR, NEAPR, and NEAPF values were 26.12, 71.02, and 68.98 mEq/d, respectively. Multivariate regression revealed the highest DAL scores in individuals on a low-carbohydrate diet, obtaining <26% of energy from carbohydrates. Conclusions: Low-moderate carbohydrate intake is associated with increased DAL scores, which has been repeatedly associated with various health repercussions.

Dietary acid load is associated with primary osteoporosis in postmenopausal women aged 50-65 years: A cross-sectional study

This study aimed to investigate the association between dietary acid load (DAL) and primary osteoporosis. This was a cross-sectional study. Among 850 randomly selected postmenopausal women aged 50-65 years, 232 women consisted of 124 women with normal bone mineral density (BMD) and 108 with primary osteoporosis were selected after examining the eligibility criteria. Demographic characteristics, anthropometric indices, and physical activity were collected through questionnaires. Osteoporosis was diagnosed using the dual-energy X-ray absorptiometry method. DAL was assessed by a valid and reliable semiquantitative food frequency questionnaire during the last year. Independent t-test, Mann-Whitney, Chi-square, and adjusted binary logistic regression were used for data analysis through SPSS/24. There were significant differences between the two groups in terms of age, body mass index (BMI), number of deliveries, and years after menopause (p < .05). The mean (standard deviation (SD)) potential renal acid load (PRAL) and net endogenous acid production (NEAP) were higher in postmenopausal women with osteoporosis than those with normal BMD (PRAL: -13.1 ± 11.1 mEq/day vs. -10.8 ± 12.7 mEq/day; NEAP: 29.5 ± 8.5 mEq/day vs. 31.2 ± 9.2 mEq/day). The mean consumption of potassium, magnesium, and calcium in the osteoporosis group was significantly lower than in the other group (p < .05). There were significant associations between osteoporosis with PRAL (odds ratio (OR) = 1.030; 95% confidence interval (CI): 1.001 to 1.060, p = .027) and NEAP scores (OR = 1.041; 95% CI: 1.003 to 1.081, p = .037). The odds of osteoporosis increased by 3% following one unit increase in PRAL score. Similarly, it increased by 4% with increasing NEAP score up to one unit. Therefore, dietary patterns that produce high DAL can have a detrimental effect on bone health.

Longitudinal association of dietary acid load with kidney function decline in an older adult population with metabolic syndrome

Background

Diets high in acid load may contribute to kidney function impairment. This study aimed to investigate the association between dietary acid load and 1-year changes in glomerular filtration rate (eGFR) and urine albumin/creatinine ratio (UACR).

Methods

Older adults with overweight/obesity and metabolic syndrome (mean age 65 ± 5 years, 48% women) from the PREDIMED-Plus study who had available data on eGFR (n = 5,874) or UACR (n = 3,639) at baseline and after 1 year of follow-up were included in this prospective analysis. Dietary acid load was estimated as potential renal acid load (PRAL) and net endogenous acid production (NEAP) at baseline from a food frequency questionnaire. Linear and logistic regression models were fitted to evaluate the associations between baseline tertiles of dietary acid load and kidney function outcomes. One year-changes in eGFR and UACR were set as the primary outcomes. We secondarily assessed ≥ 10% eGFR decline or ≥10% UACR increase.

Results

After multiple adjustments, individuals in the highest tertile of PRAL or NEAP showed higher one-year changes in eGFR (PRAL, β: -0.64 ml/min/1.73 m2; 95% CI: -1.21 to -0.08 and NEAP, β: -0.56 ml/min/1.73 m2; 95% CI: -1.13 to 0.01) compared to those in the lowest category. No associations with changes in UACR were found. Participants with higher levels of PRAL and NEAP had significantly higher odds of developing ≥10% eGFR decline (PRAL, OR: 1.28; 95% CI: 1.07-1.54 and NEAP, OR: 1.24; 95% CI: 1.03-1.50) and ≥10 % UACR increase (PRAL, OR: 1.23; 95% CI: 1.04-1.46) compared to individuals with lower dietary acid load.

Conclusions

Higher PRAL and NEAP were associated with worse kidney function after 1 year of follow-up as measured by eGFR and UACR markers in an older Spanish population with overweight/obesity and metabolic syndrome.

Self-reported Resistance Training Is Associated With Better HR-pQCT-derived Bone Microarchitecture in Vegan People

CONTEXT

A plant-based lifestyle is a global trend; lower bone mineral density and increased fracture risk in vegan people are reported.

OBJECTIVE

The primary objective was to assess trabecular and cortical bone microarchitecture in vegans and omnivores. Secondary objectives were to evaluate relationships between bone microarchitecture, nutrition parameters, and physical activity.

METHODS

This was an observational study at the Medical Department II, St. Vincent Hospital (tertiary referral center for gastrointestinal, metabolic, and bone diseases, and teaching hospital of the Medical University of Vienna), including 43 healthy nonobese female and male subjects on a plant-based diet for at least 5 years, and 45 healthy nonobese female and male subjects on an omnivore diet for at least 5 years. The main outcome measures were the parameters of trabecular and cortical bone microarchitecture (high-resolution peripheral quantitative computed tomography), serum markers of bone turnover, nutrient intake (nutrition protocol), and self-reported resistance training (physical activity questionnaires).

RESULTS

In the vegan group, trabecular and cortical structure were altered compared with omnivores. Vegans not reporting resistance training had diminished bone microarchitecture compared with omnivores not reporting resistance training. In vegans and omnivores reporting resistance training, bone structure was similar. In both vegan subgroups (resistance training and not resistance training), a small number of correlations between nutrient intake and bone microarchitecture were observed without a conclusive pattern.

CONCLUSION

Bone microarchitecture in vegans differed from matched omnivores but could not be explained solely by nutrient uptake. These differences were attenuated between the subgroups reporting resistance training. In addition to a well-planned diet, progressive resistance training on a regular basis should be part of the vegan lifestyle.

Dietary Acid Load Was Positively Associated with the Risk of Hip Fracture in Elderly Adults

Previous studies have shown that dietary acid load (DAL) harms bone health, but the evidence is inconsistent and insufficient. This study examined the relationships between DAL and the risk of hip fracture. This case−control study contained 1070 pairs of 1:1 age-, city-, and gender-matched incident cases and controls (mean age, 71 years) recruited in Guangdong, China. Dietary information was collected using a validated 79-item food frequency questionnaire through face-to-face interviews. DAL was estimated based on established algorithms for the potential renal acid load (PRAL) and net endogenous acid production (NEAP). Higher PRAL and NEAP were dose-dependently associated with a higher risk of hip fracture in both the conditional logistic regression model and restricted cubic spline analysis after adjusting for potential covariates. The multivariate-adjusted odds ratios and 95% CI of hip fracture for tertiles 2 and 3 (vs. 1) of DAL were 1.63 (1.18, 2.25) and 1.92 (1.36, 2.71) for PRAL and 1.81 (1.30, 2.53) and 2.55 (1.76, 3.71) for NEAP in all participants (all p-trends < 0.001), respectively. Subgroup analyses showed more pronounced associations in participants with a lower body mass index. Our findings suggested positive associations between the estimated DAL and the risk of hip fractures in the elderly Chinese population.