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).
CONCLUSIONS: 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.

Selenium (Se) accumulation in rice (Oryza sativa L.) has become a major global concern. Se offers multiple health benefits in humans; however, its inadequate or excessive intake can be harmful. Therefore, determining the factors driving Se abundance and bioavailability in paddy soils is essential to ensure the safety of human Se intake. This study investigated the accumulation, bioavailability, and distribution of Se in 820 paddy soil and rice grain samples from Luxi County, China to assess how soil properties (soil organic matter [SOM], cation exchange capacity [CEC], and pH), geographical factors (parent materials, elevation, and mean annual precipitation [MAP] and temperature [MAT]), and essential micronutrients (copper [Cu], zinc [Zn], and manganese [Mn]) govern Se accumulation and bioavailability in paddy soils. Results showed that the average soil Se content was 0.36 mg kg-1, which was higher than that in China (0.29 mg kg-1). Alternatively, the average rice grain Se content was 0.032 mg kg-1, which was lower than the minimum allowable content in Se-rich rice grains (0.04 mg kg-1). Five studied parent materials all had a significant effect on soil Se content but had little effect on Se bioavailability (p < 0.05). CEC, elevation, and SOM, as well as the soil contents of Cu, Zn, and Mn were positively correlated with soil Se content, but pH, MAP, and MAT were negatively correlated. Correspondingly, Se bioavailability was negatively correlated with SOM and soil Zn content, but positively correlated with MAP and grain contents of Cu, Zn, and Mn. Furthermore, partial least squares path analysis revealed the interactive impacts of the influencing factors on Se accumulation and bioavailability in soils. On this basis, prediction models were established to predict Se accumulation and bioavailability in paddy soils, thereby providing theoretical support for developing efficient control measures to meet Se challenges in agriculture.

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.

Diabetes is a chronic disease that can cause various complications and has a high prevalence. Evidence increasingly shows that acid-base homeostasis is critical to maintaining normal metabolic function. This case-control study aims to evaluate the relationship between dietary acid load and the risk of type 2 diabetes.
This study recruited 204 participants, 92 of whom had just been diagnosed with type 2 diabetes, and 102 healthy controls who were matched in age and gender as controls. Twenty-four dietary recall was used for dietary intake assessments. Dietary acid load was approximated using two different methods: potential renal acid load (PRAL) and net endogenous acid production (NEAP), both calculated from dietary recalls.
In the case and control groups, the dietary acid load mean scores were 4.18±26.8, 20.84±29.54 mEq/day for PRAL, and 55.11±29.23, 68.43±32.23 mEq/day for NEAP, respectively. When it came to the multiple possible confounders, the participants in the highest tertile of PRAL (OR 4.43, 95% CI: 1.38-23.81, ptrend<0.001) and NEAP (OR: 3.15, 95% CI: 1.53-9.59, ptrend<0.001) had a significantly higher risk of developing type 2 diabetes compared to those in the lowest tertile.
The findings of the present study suggest that a high acid load in the diet may increase the risk of type 2 diabetes. Therefore, it is possible that limiting dietary acid load could lower type 2 diabetes risk in vulnerable individuals.

BACKGROUND: This study aims to explore the association between dietary acid load and hyperuricemia in Chinese adults.
METHODS: A case-control study was conducted. Adult participants with hyperuricemia were recruited as the cases and those without hyperuricemia were as the controls. Food consumption was evaluated by food frequency questionnaire (FFQ). Dietary acid load was assessed by potential renal acid load (PRAL) and net endogenous acid production (NEAP). Dietary acid load was divided into four levels: the first quartile (Q1), the second quartile (Q2), the third quartile (Q3) and the fourth quartile (Q4). Logistic regression model was applied for exploring the association between dietary acid load (PRAL and NEAP) and hyperuricemia. Odds ratio (OR) and its correspondence confidence interval (CI) were computed.
RESULTS: A total of 290 participants were eligible in this study, in which there were 143 individuals in case group and 147 in control group. A higher level of PRAL was found to be associated with odds of hyperuricemia. ORs of hyperuricemia for Q2, Q3 and Q4 of PRAL were 2.74 (95%CI: 1.94 ~ 3.88, p-value: 0.004), 2.90 (95%CI: 2.05 ~ 4.10, p-value: 0.002) and 3.14 (95%CI: 2.22 ~ 4.45, p-value: 0.001), respectively. There was a positive association between elevated NEAP and hyperuricemia. OR of hyperuricemia for Q2 was not material significance (OR:1.54, 95%CI: 0.93 ~ 2.53, p-value: 0.210), however, ORs of hyperuricemia for Q3 (OR: 2.40, 95%CI: 1.70 ~ 3.38, p-value: 0.011) and Q4 (OR: 3.27, 95%CI: 2.31 ~ 4.62, p-value: 0.001) were statistically significant.
CONCLUSIONS: Higher level of dietary acid load was found to be associated with hyperuricemia in Chinese adults, indicative of advocation of a well-balanced diet in this population.

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.
CONCLUSIONS: 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.

BACKGROUND: A high dietary acid load (DAL) can produce metabolic acidosis, which is linked to cancer development through mechanisms of inflammation and cell transformation. There is limited epidemiological evidence linking DAL and cancer risk; however, none of the published studies focused on DAL and esophageal cancer (EC) risk in particular. Therefore, we sought to explore this association in the present study.
METHODS: A case-control study was performed in 1295 male patients (185 squamous cell EC cases and 1110 age-frequency and urban/rural residence matched controls) through a multitopic inquiry, including a food frequency questionnaire. Food-derived nutrients were calculated from available databases. The DAL was calculated based on two validated measures: Potential renal acid load (PRAL) score and net endogenous acid production (NEAP) score. Odds ratios (OR) and their 95% confidence intervals (95% CI) were estimated by unconditional logistic regression, adjusting for confounders.
RESULTS: We found direct, significant associations between dietary acid load and EC risk: (OR = 2.28, 95% CI: 1.44-3.61, ptrend <0.0001) and (OR = 2.17, 95% CI: 1.38-3.41, ptrend <0.0001) for highest PRAL and NEAP tertiles, respectively. Our data raise the possibility that a high DAL may contribute to EC development. Both acid load scores were directly associated with animal-based foods (mainly meat) and inversely associated with the intake of plant-based foods.
CONCLUSIONS: To the best of our knowledge, this is the first epidemiological case-control study analyzing associations of DAL and squamous cell EC risk. Further research is warranted to confirm our findings.

The higher acid-forming potential of a diet, could be associated with diabetes. No study has been done to investigate the association between Dietary Acid Load (DAL) and polyneuropathy in patients with diabetes. This study aimed to examine the linkage between the DAL and Diabetic Sensory-motor Polyneuropathy (DSPN) in a case-control study.
This case-control study was performed at Diabetes Research Center, Endocrinology and Metabolism Clinical Sciences Institute, in Kermanshah, Iran between April 2020 and August 2020. A total of 185 subjects with DSPN and 185 sex- and age-matched people in the control group (30-60 years old) participated in this study. Dietary intakes of all people were assessed using a validated food frequency questionnaire. DAL was evaluated through the Potential Renal Acid Load (PRAL) and Net Endogenous Acid Production (NEAP). Toronto clinical neuropathy score was applied to define DSPN. Anthropometrics data, and fasting blood glucose levels were measured.
The Binary logistic regression was used to estimate the Odds Ratios (ORs) and 95% Confidence Intervals (95% CIs) of NEAP and PRAL in relation to DSPN. After adjustment for age, sex, energy people with higher DAL had increased odds for DSPN (ORPRAL = 3.0; 95%CI: 1.8-5.1; p-trend <0.001 and ORNEAP = 3.8; 95%CI: 2.2-6.5; p-trend <0.001). Additional adjustment for physical activity, education, smokers, and economic status strengthened the association (ORPRAL = 3.3; 95%CI:1.9-5.8; p-trend <0.001 and ORNEAP = 3.7; 95%CI: 2.2-6.5; p-trend<0.001). Finally, after additional adjustment for BMI in the full adjustment model, compared to people in the first tertile of DAL, participants in the third tertile had approximately 3.5 times significant greater odds for DSPN (ORPRAL = 3.3; 95%CI: 1.9-5.7; p-trend <0.001 and ORNEAP = 3.6; 95%CI: 2.2-6.2; p-trend<0.001).
Patients with a higher acidic diet had greater odds for DSPN compared to people with lower DAL.

The present study aimed to investigate the association between dietary acid load and the risk of type 2 diabetes (T2D) in Iranian adults.
This was a case-control study including 125 newly diagnosed T2D patients as cases and 190 healthy individuals as controls. A 168-item semi-quantitative food frequency questionnaire was applied to collect the participant\'s dietary intake information. Potential renal acid load (PRAL), net endogenous acid production (NEAP), protein/potassium ratio, animal protein/potassium ratio, and plant protein/potassium ratio were derived from the nutrient intake.
We found that higher PRAL and NEAP scores are positively associated with the chance of T2D in the unadjusted model. Such that, when multiple potential confounders were taken into account, participants in the highest tertile of PRAL (OR: 4.37; 95% CI: 1.35-14.18) and NEAP score (OR: 2.24; 95% CI: 1.01-7.03) had a greater risk of T2D. No significant association was found between other indices including total protein/potassium ratio, animal protein/potassium ratio, and plant protein/potassium ratio, and T2D risk.
The present findings suggest that high dietary acid load could be associated with the risk of T2D disease.

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.