The association between dietary acid load with cardiometabolic risk factors and inflammatory markers amongst elderly men: A cross-sectional study

A high dietary acid load can potentially exacerbate cardiometabolic risk factors: An updated systematic review and meta-analysis of observational studies

AIMS

Chronic metabolic acidosis has been shown to be associated with cardiometabolic risk factors. The aim of the currently updated meta-analysis was to explore the association between Potential Renal Acid Load (PRAL) and Net Endogenous Acid Production (NEAP) with these risk factors.

DATA SYNTHESIS

Databases were searched up to May 2023. The mean of waist circumference (WC), body mass index (BMI), high- and low-density lipoprotein-cholesterol (HDL-C and LDL-C), triglyceride (TG), total cholesterol (TC), fasting blood sugar (FBS), and systolic- and diastolic blood pressure (SBP and DBP) in highest category vs lowest categories of NEAP and PRAL were recorded. Effect sizes were generated as weighted mean difference (WMD). Results showed that SBP, DBP, and WC had a significant difference in the upper and lower categories of PRAL (WMDSBP: 1.466 mmHg; 95% CI: 2.121, -0.811; P<0.001, WMDDBP: 0.710 mmHg; 95 % CI: 1.170, -0.249; P=0.003, and WMDWC: 0.819 cm; 95% CI: 1.446, -0.192; P=0.010) or NEAP (WMDSBP: 1.690 mmHg; 95% CI: 2.789, -0.591; P=0.003, WMDDBP: 1.076 mmHg, and WMDWC: 1.325 cm; 95% CI: 1.901, -0.749; P<0.001; 95% CI: 1.938, -0.214; P =0.014). The lowest versus highest categories of dietary PRAL were associated with lower BMI (WMDPRAL: 0.297 kg/m2; 95 % CI: 0.440, -0.154; P<0.001) and TG (WMD: 2.280 mg/dl; 95%CI: 3.828, -0.732; P=0.004; I2=99.4 %; P<0.001).

CONCLUSIONS

High DAL can be considered as an independent risk factor for increasing anthropometric indices, blood pressure, and TG. This study registered in the PROSPERO database (Registration No. CRD42023402985).

Higher dietary acid load is associated with an increased risk of metabolic syndrome

There have been inconsistent reports regarding the association between dietary acid load and Metabolic Syndrome (MetS). We aimed to investigate the association between dietary acid load and MetS in an Iranian adult population. In this cross-sectional study, 1945 participants aged 35-65 years were recruited from MASHAD cohort study. Dietary intakes were assessed using a 24-h dietary recall. Diet-based acidity was assessed as the net endogenous acid production (NEAP), potential renal acid load (PRAL), and dietary acid load (DAL). To define MetS, the International Diabetes Federation (IDF) criteria were used. Multivariable logistic regression models were applied to determine the association between diet-based acid load scores and MetS. Participants' mean age and BMI were 47.13 ± 7.78 years and 27.57 ± 4.48 kg/m2, respectively. Around 57% of the population was female. Overall, 31.9% had MetS. According to the full-adjusted model, there was a significant association between higher quartiles of PRAL, NEAP, and DAL and MetS (Q4 PRAL; OR (95%CI) 1.42(1.05-1.91), Q4 NEAP; OR (95%CI) 1.48(1.11-1.98), Q4 DAL; OR (95%CI) 1.44(1.05-1.91)). This study showed a significant positive association between different dietary acid load indicators (PRAL, NEAP, and DAL) and odds of MetS among Iranian adults.

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.

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 1995 potential renal acid load (PRAL) values may no longer adequately reflect the actual acid-base impact of certain foods: A hypothesis

Background: In 1995, Remer and Manz reported potential renal acid load (PRAL) values of various foods, quantifying their estimated impact on acid-base balance. Their estimation considered ionic dissociation, sulphur metabolism and intestinal absorption rates for several micronutrients and proteins. Notably, PRAL values are based on food content data from the early 1990s and may nowadays no longer adequately reflect accurate estimates. Some foods' macronutrient and mineral content has declined over the past three decades due to changes in soil mineral health. Aim: We hypothesize that the 1995 PRAL values no longer adequately reflect reliable estimates of the current acid-base impact of some foods. Methods: Based on specific examples, we argue that these values overestimate the alkalizing effects of various fruits and vegetables. Conclusion: Discussing evidence in favour of (and against) our hypothesis, we conclude that the 1995 PRAL estimates should nowadays rather be used as a relative guidance and reviewed carefully.

Metabolic syndrome in relation to dietary acid load: a dose-response meta-analysis of observational studies

Background and aim

Several studies have identified that dietary acid load (DAL) may be associated with the odds of metabolic syndrome (MetS); however, the evidence is inconclusive. This dose-response meta-analysis aimed to examine the relation of DAL to MetS.

Methods

A systematic literature search was carried out in PubMed and Scopus up to April 2023 for pertinent studies evaluating the relation of DAL scores, including potential renal acid load (PRAL) and net endogenous acid production (NEAP), to the odds of MetS. The odds ratios (OR) with 95% confidence intervals (CI) were pooled using a random-effects meta-analysis to test the association.

Results

Eight studies, with an overall sample size of 31,351 participants, were included in this meta-analysis. Higher DAL scores were significantly related to the elevated odds of MetS (NEAP: OR = 1.42, 95%CI = 1.12-1.79; PRAL: OR = 1.76, 95%CI = 1.11-2.78), with significant evidence of heterogeneity across studies. The linear dose-response analysis proposed that a 10 mEq/day elevation in NEAP and PRAL was linked to a 2% (OR = 1.02, 95%CI = 1.001-1.05) and 28% (OR = 1.28, 95%CI = 1.11-1.47) increased odds of MetS, respectively. No non-linear association was observed between MetS and NEAP (P-non-linearity = 0.75) and PRAL (P-non-linearity = 0.92).

Conclusion

This study revealed a significant direct relationship between DAL and MetS. Therefore, lower acidogenic diets are suggested for the prevention of MetS.

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 (DAL), Glycated Hemoglobin A1c (HbA1c), and Metabolic Syndrome (MeS) Mediate the Association of the Adherence to the Dietary Approaches to Stopping Hypertension (DASH) and Mediterranean Diet (MeD) With Nonalcoholic Fatty Liver Disease

The study aimed to investigate the association of adults adhering to Dietary Approaches to Stop Hypertension (DASH) and Mediterranean diet (MeD) with nonalcoholic fatty liver disease (NAFLD) using structural equation modeling (SEM) in Iran. In this population-based cross-sectional study, 3,220 adults (44.65% female) aged ≥18 years were selected from the Amol Cohort Study (AmolCS). The dietary intakes were assessed by a validated 168-item semi-quantitative food-frequency questionnaire (FFQ). Residual method energy adjustment of MeD and DASH scores were calculated. Demographic characteristics and anthropometric and laboratory measurements were collected. NAFLD was diagnosed by an expert radiologist via ultrasound sonography. Based on the primary hypothesis, DASH, MeD, and NAFLD were fitted into models. Metabolic syndrome (MeS) as a potential risk factor directly affected NAFLD risk in all these models. In both genders, the higher adherence to DASH negatively affected NAFLD risk indirectly through the two following paths. (1) Dietary acid load (DAL) and metabolic syndrome (2) DAL and hemoglobin A1c (HbA1c). In addition, the higher DAL positively affected NAFLD risk among male participants indirectly via increasing HbA1c level and MeS (from DAL to HbA1c: β = 0.07, P < 0.001; from HbA1c to MeS: β = 0.10, P < 0.001). Similarly, in both genders, the relationship between MeD and NAFLD was mediated through (1) DAL, HbA1c, and MeS and (2) DAL and MeS. Further, among male participants, the MeD and NAFLD risk were also associated via the mediators of HbA1c and MeS. In female participants, the higher MeD score was directly associated with a reduction of NAFLD risk (β = -0.07, P = 0.008). The present study found three important mediators, including DAL, HbA1c, and MeS, in the association of DASH and MeD scores with NAFLD risk. Preventive and therapeutic interventions should target the mediators, including DAL, HbA1c, MeS, and its components, to reduce NAFLD incidence in the general population.

Dietary Acid Load but Not Mediterranean Diet Adherence Score Is Associated With Metabolic and Cardiovascular Health State: A Population Observational Study From Northern Italy

Diet plays a pivotal role in shaping the trajectory of chronic diseases. In this regard, the Mediterranean diet has been widely shown to exert beneficial effects on cardiometabolic health. On the contrary, the Western diet, which has also been reported to be an acidogenic dietary pattern, elicits detrimental effects on both metabolic and cardiovascular (CV) health. However, the role of dietary acid load (DAL) as a predictor of cardiometabolic prognosis remains to be elucidated. Thus, this study aims to compare Mediterranean diet adherence (MDA) and DAL focusing on their relationship with metabolic and CV prognosis. A total of 448 individuals aged 55–80 years were grouped depending on their MDA, assessed using food frequency questionnaires, or DAL, evaluated using potential renal load acid (PRAL) and net-endogenous acid production (NEAP). Study participants underwent anthropometric and biochemical measurements. The metabolic syndrome (MetS) prevalence was evaluated according to the National Cholesterol Education Program-Adult Treatment Panel III. Finally, the CV risk was evaluated using three independent algorithms: atherosclerotic cardiovascular disease (ASCVD), European Systematic COronary Risk Evaluation (SCORE), and Cuore risk scores. Mediterranean diet adherence was negatively associated with PRAL and NEAP. Individuals in the higher MDA tertile group had higher HDL cholesterol as well as lower homeostasis model assessment index (HOMA-IR) and fat mass relative to the lowest MDA tertile. However, in the high-MDA tertile group, there was neither a significantly lower MetS prevalence nor CV risk. Instead, both the MetS prevalence and CV risk were higher in individuals in the higher acid PRAL quartile relative to the lower alkaline PRAL quartile. Dietary acid load, especially assessed using PRAL but not MDA, was associated with indices of metabolic and CV prognosis. Thus, DAL assessed by 24-h dietary recalls may represent a better predictor of cardiometabolic health if compared to MDA evaluated using food frequency questionnaires.

Nutrient Intake and Dietary Acid Load of Special Diets in the NHANES: A Descriptive Analysis (2009-2018)

Western diets are characterized by a high dietary acid load (DAL), which has been associated with adverse clinical outcomes, including type-2-diabetes and metabolic syndrome. Effective dietary strategies to lower DAL are urgently warranted. Plant-based diets (PBD), including vegetarian and vegan diets, are an effective measure to reduce DAL. Notably, not every individual wishes to adopt a PBD. Instead, many people rely on special diets promising comparable health benefits. The effects of those diets on DAL have rarely been investigated. Using data from the National Health and Nutrition Examination Surveys, we aimed to quantify DAL and nutrient intake in the most popular special diets in the United States, including weight-loss, low fat, low salt, low sugar, and diabetic diets. Our analysis included 3552 individuals on a special diet. The most popular diets were the weight-loss diet (n = 1886 individuals) and the diabetic diet (n = 728). Energy intake was below 2000 kcal/d for all diets; however, there were no statistically significant intergroup differences. DAL scores were positive for all special diets (>9 mEq/d), suggesting acidifying properties. Acid load scores of special diets did not differ significantly and were comparable to a standard Western diet. None of the examined diets was associated with alkaline properties.

A Vegan Diet Is Associated with a Significant Reduction in Dietary Acid Load: Post Hoc Analysis of a Randomized Controlled Trial in Healthy Individuals

The composition of diet strongly affects acid–base homeostasis. Western diets abundant in acidogenic foods (meat and cheese) and deficient in alkalizing foods (fruits and vegetables) increase dietary acid load (DAL). A high DAL has been associated with numerous health repercussions, including cardiovascular disease and type-2-diabetes. Plant-based diets have been associated with a lower DAL; however, the number of trials exploring this association is limited. This randomized-controlled trial sought to examine whether an isocaloric vegan diet lowers DAL as compared to a meat-rich diet. Forty-five omnivorous individuals were randomly assigned to a vegan diet (n = 23) or a meat-rich diet (n = 22) for 4 weeks. DAL was determined using potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores at baseline and after 3 and 4 weeks, respectively. After 3 weeks, median PRAL (−23.57 (23.87)) and mean NEAP_R (12.85 ± 19.71) scores were significantly lower in the vegan group than in the meat-rich group (PRAL: 18.78 (21.04) and NEAP_R: 60.93 ± 15.51, respectively). Effects were mediated by a lower phosphorus and protein intake in the vegan group. Our study suggests that a vegan diet is a potential means to reduce DAL, whereas a meat-rich diet substantially increases the DAL burden.