Diet-dependent acid load and type 2 diabetes: pooled results from three prospective cohort studies

Evaluation of the relationship between dietary acid load and cardiovascular risk factors in patients with type 2 diabetes: a case-control study

Backround

Diets high in dietary acid load are thought to be associated with metabolic diseases. However, the number of studies examining the relationship between dietary acid load and metabolic diseases in Turkey is insufficient. The aim of this study was to investigate the relationship between cardiovascular disease risk factors and dietary acid load in individuals with type 2 diabetes.

Materials and methods

In this case-control study, 51 participants aged 30-65 years with type 2 diabetes and 59 participants in the control group were included. Blood pressure and biochemical findings were measured. Anthropometric measurements and body composition measurements were made. Dietary intake was assessed using a 3-day (1 day on weekends, 2 days on weekdays) food consumption record. Dietary acid load scores, including potential renal acid load (PRAL) and net endogenous acid production (NEAP), were calculated based on dietary intake. NEAP and PRAL scores were categorized as low and high according to the median value. Smoking status, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), trigylceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL), waist-hip ratio (WHR), waist-to- height ratio (WtHR), hemoglobin and fat mass (%) were evaluated as cardiovascular risk factors.

Results

The cut-off values of PRAL and NEAP were 3.61 and 44.78 mEq/d, respectively. After adjustment for various covariates, a significant positive association between PRAL and TG levels was observed in the diabetic group [odds ratio (OR), 5.98; 95% CI, 1.45-24.67; p = 0.013]. In contrast, a negative association was found between PRAL and SBP in the control group [odds ratio (OR), 0.21; 95% CI, 0.05-0.83; p = 0.026]. However, these associations were not observed for NEAP values in either group.

Conslusions

A higher PRAL value was consistently associated with higher TG level, but other cardiovascular risk factors were not. More longitudinal and interventional studies are needed to better establish a causal effect between dietary acid load and cardiovascular risk factors in individuals with diabetes.

The association between dietary inflammatory index (DII) scores and c-reactive protein (CRP) and nonalcoholic fatty liver disease (NAFLD) in a general population cohort

BACKGROUND AND AIMS

Although there is extensive literature showing the ability of the dietary inflammation index (DII®) to predict concentrations of plasma inflammatory markers, few studies are testing the association between DII scores and nonalcoholic fatty liver disease (NAFLD). Considering the high prevalence of NAFLD and its complications, we conducted a validation study of DII scores and examined its association with NAFLD in the general adult population of Iran.

METHODS

This cross-sectional study was conducted on 3110 adult participants in the Amol Cohort Study (AmolCS) who underwent abdominal ultrasonography to diagnose NAFLD. DII and energy-adjusted DII (E-DII™) scores were computed using data from a valid semi-quantitative 168-item food frequency questionnaire (FFQ). Multivariable logistic regression adjusting for socio-demographic, lifestyle, and health-related factors was used to assess association.

RESULTS

The EDII was associated with CRP inflammatory biomarker. Participants in the highest, i.e., most pro-inflammatory tertile had the highest odds of NAFLD by ultrasound in all models [fully adjusted model: OR (95 % CI) tertile3vs.1:1.54 (1.05-2.05); Ptrend = 0.04, and 1.63 (1.19-2.21); Ptrend = 0.03 in women and men, respectively]. The highest tertile had the highest OR for NAFLD by fatty liver index (FLI) only in men [fully adjusted model OR (95 % CI) tertile3vs.1: 1.77 (1.15-2.71); Ptrend = 0.01]. Similar results were also obtained for NAFLD by hepatic steatosis index (HSI) in women [fully adjusted model: OR (95 % CI) tertile3vs.1: 1.70 (1.12-2.58); Ptrend = 0.03]. The results of the fully adjusted multivariable model of liver markers and NAFLD status, stratified by gender and abdominal obesity, revealed that the highest tertiles had the highest OR for NAFLD by ultrasound and NAFLD by FLI only in men without abdominal obesity [fully adjusted model: OR (95 % CI) tertile3vs.1: 1.83 (1.17-2.84); Ptrend = 0.03, and, respectively]. NAFLD by FLI tended to increase strongly with tertile E-DII scores in men without abdominal obesity in crude and three adjusted models [full-adjusted model: OR (95 % CI) tertile3vs.1: 3.64 (1.56-8.46); Ptrend = 0.005]. By contrast, women with abdominal obesity in the highest tertile had the highest OR for NAFLD by ultrasound in all models [full-adjusted model: OR (95 % CI) tertile3vs.1: 1.67 (1.07-2.62); Ptrend = 0.02].

CONCLUSIONS

Our results suggest that diet plays a role in regulating inflammation. Additionally, we observed an inflammatory diet predicts the risk of NAFLD in Iranian adults. However, longitudinal studies are required in order to further substantiate the utility of the DII in the development of more effective dietary interventions among populations at risk of chronic disease.

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).

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.

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.

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.

Association Between Serum Bicarbonate Levels and Prediabetes and Subclinical Inflammation in Young Healthy Adults: A Cross-sectional Study

PURPOSE

Low bicarbonate, a hallmark of metabolic acidosis is associated with various diseases. This study investigated associations between bicarbonate levels with prediabetes and subclinical inflammation among healthy young adults in Qatar.

PATIENTS AND METHODS

A cross-sectional study was carried out with 825 participants aged 18-40 years, devoid of any known comorbidities, using data from the Qatar Biobank. For each participant, blood samples were taken for measurements of bicarbonate, prediabetes, and subclinical inflammation biomarkers. Prediabetes was defined using HbA1c between 5.7 and 6.4% and subclinical inflammation was defined using monocyte to high density lipoprotein (HDL) cholesterol ratio (MHR). Associations between bicarbonate levels and the outcomes were analyzed using multivariable linear and logistic regression and then stratified by gender.

RESULTS

A total of 825 participants with mean age 29.2 years (5.9) of which 365 (44.2%) were males. After multivariable logistic regression, each unit increase in serum bicarbonate was associated with a 17% decreased risk of prediabetes (OR: 0.83, 95%CI: 0.70-0.99, p=0.034), in males but no association was observed for females. Similarly, after multivariable linear regression, a unit increase in serum bicarbonate was associated with a 0.18 unit decrease in MHR (beta -0.18, 95%CI: -0.29, -0.07, p=0.002), again with no association observed in females.

CONCLUSION

In a healthy young adult population, higher serum bicarbonate levels were inversely associated with both prediabetes and subclinical inflammation in males, but not in females.

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 modifies the effects of ApoA2-265 T > C polymorphism on lipid profile and serum leptin and ghrelin levels among type 2 diabetic patients

This investigation with aimed the effect of APOA2-265 T > C polymorphism and dietary acid load (DAL) as either potential renal acid load (PRAL) and net endogenous acid production (NEAP) intake interaction on metabolic markers in type 2 diabetes mellitus (T2DM). In present cross-sectional study, 737 patients with T2DM (290 men and 447 women) were enlisted from diabetes centers in Tehran. The dietary intakes of all participants during the last year was acquired by a validated semi-quantitative food frequency (FFQ) questionnaire. Polymerase chain reaction (PCR) was used for genotyping the APOA2-265 T > C. Biochemical indises containing leptin, ghrelin, total cholesterol (Bailey et al., J Clin Invest 97:1147-1453, 1996), low-density lipoprotein cholestrol (LDL-C), high-density lipoprotein cholestrol (HDL-C), triglyceride (TG), superoxide dismutase (SOD), high sensitivy C-reactive protein (hs-CRP), total antioxidant capacity (TAC), pentraxin-3 (PTX3), prostaglandin F2α (PGF2α) and interleukin 18 (IL18) were measured by standard method. Atherogenic indices (AIP, AC, CR-I, CR-II) were calculated. The gene-diet interactions were evaluated using an GLM. The frequency overall prevalence of rs5082 genotypes was 63.82 and 36.17% for T-allele and C-allele respectively. TG, Ghrelin, and hs-CRP concentrations were significantly higher among carriers with C allele than TT homozygotes. However, TC/CC genotypes have lower PTX3 than TT homozygotes (P < 0.05). C-allele carriers had highest mean of BMI (P_NEAP=0.04, P_PRAL = 0.006), WC (P_NEAP=0.04, P_PRAL = 0.04), TC (P_NEAP=0.03, P_PRAL = 0.01), ghrelin (P_NEAP=0.01, P_PRAL = 0.04), and leptin (P_NEAP=0.04, P_PRAL = 0.03) when placed in top tertiles of NEAP and PRAL.BMI, WC, TC, ghrelin, and leptin levels may be modified in C carriers by decreasing DAL, though, further investigations are required to confirm these findings.

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.

The Importance of Recognizing and Addressing the Spectrum of Acid Stress

Acid accumulation sufficient to reduce plasma bicarbonate concentration, thereby recognized as chronic metabolic acidosis, harms bones and muscles and appears to enhance progression of CKD. Evolving evidence supports that progressive acid accumulation that is not enough to cause chronic metabolic acidosis nevertheless has deleterious effects. Measurable acid retention without reduced plasma bicarbonate concentration, called eubicarbonatemic acidosis, also appears to cause kidney injury and exacerbate CKD progression. Furthermore, chronic engagement of mechanisms to mitigate the ongoing acid challenge of net acid-producing diets of developed societies also appears to be deleterious, including for kidney health. This review challenges clinicians to consider the growing evidence for a spectrum of acid-accumulation disorders that include lesser degrees of acid accumulation than metabolic acidosis yet are harmful. Further research will develop clinically useful tools to identify individuals suffering from these earlier stages of acid stress and determine if the straightforward and comparatively inexpensive intervention of dietary acid reduction relieves or eliminates the harm they appear to cause.

Dietary Acid Load Is Positively Associated With Risk of Gestational Diabetes Mellitus in a Prospective Cohort of Chinese Pregnant Women

Background

Growing evidence suggests that dietary acid load plays an important role in the development of type 2 diabetes. However, prospective studies on the relationship between dietary acid load and gestational diabetes mellitus (GDM) are limited in the pregnant population. This study aimed to investigate the effect of dietary acid load during early pregnancy on the risk of GDM in Chinese pregnant women.

Methods

A total of 1,327 pregnant women were enrolled from an ongoing prospective study of the Tongji Birth cohort (TJBC) in Wuhan, China. Dietary intake was assessed before 20 weeks using a 74-item semiquantitative food frequency questionnaire (FFQ). The dietary acid load was estimated using potential renal acid load (PRAL), net endogenous acid production (NEAP), and animal protein to potassium ratio (A:P ratio). A 75g 2-h oral glucose tolerance test (OGTT) was performed at 24-28 gestational weeks to diagnose GDM.

Results

The mean (standard deviation) values for PRAL score, NEAP score, and A:P ratio were 0.8 ± 11.3 mEq/day, 45.3 ± 16.5 mEq/day, and 9.8 ± 6.0, respectively. There was a significant positive correlation of dietary acid load with the intake of red meat, poultry, fish, and eggs, and a negative correlation with the intake of vegetables, fruits, nuts, and legumes (all P < 0.05). Compared to the lowest tertile, the highest tertile of dietary acid load, including PRAL score (odds ratio [OR]: 2.26, 95% confidence interval [CI] = 1.38–3.71, P-trend = 0.002), NEAP score (OR: 2.02, 95% CI = 1.25–3.27, P-trend = 0.009), and A:P ratio (2.08, 95% CI = 1.30–3.31, P-trend = 0.005), significantly increased the risk of GDM. In addition, the dietary acid load was also significantly associated with an increase in 1-h and 2-h post-load blood glucose concentrations (all P-trend < 0.05).

Conclusion

We found a significant positive association between dietary acid load during early pregnancy and the risk of GDM in a Chinese population, suggesting that the reduction of food sources of dietary acid load may be an effective strategy for preventing the risk of GDM.

Dietary Acid Load is Associated with Hypertension and Diabetes in the Elderly

BACKGROUND

Diet can affect the body's acid-base balance due to its content of acid or base precursors. There is conflicting evidence for the role of metabolic acidosis in the development of cardiometabolic disorders, hypertension (HT), and insulin resistance (IR).

OBJECTIVE

We hypothesize that dietary acid load (DAL) is associated with adverse metabolic risk factors and we aimed to investigate this in the elderly.

METHODS

A total of 114 elderly participants were included in the study. The participants were divided into four groups such as HT, diabetes (DM), both HT and DM, and healthy controls. Anthropometric, biochemical, and clinical findings were recorded. Potential renal acid load (PRAL) and net endogenous acid production (NEAP) results were obtained from three-day, 24-hour dietary records via a nutrient database program. (BeBiS software program).

RESULTS

The groups were matched for age, gender, and BMI. There was a statistically significant difference between the groups in terms of NEAP (p=0.01) and no significant difference for PRAL (p=0.086). The lowest NEAP and PRAL levels were seen in the control group while the highest in the HT group. Both NEAP and PRAL were correlated with waist circumference (r=0,325, p=0.001; r=0,231, p=0,016, respectively).

CONCLUSION

Our data confirmed that subjects with HT and DM had diets with greater acid-forming potential. High NEAP may be a risk factor for chronic metabolic diseases, particularly HT. PRAL couldn't be shown as a significantly different marker in all participants. Dietary content has a significant contribution to the reduction of cardiovascular risk factors such as HT, DM, and obesity.

Favorable association between Mediterranean diet (MeD) and DASH with NAFLD among Iranian adults of the Amol Cohort Study (AmolCS)

Nonalcoholic fatty liver disease (NAFLD) is an emerging cause of chronic liver diseases and a major health problem worldwide. Dietary patterns may play a critical role in controlling and preventing this disease, but the available evidence is scarce. The current study aims to ascertain the association of adherence to the Dietary Approach to Stop Hypertension (DASH) diet and Mediterranean diet (MeD) with nonalcoholic fatty liver disease (NAFLD) among Iranian adults of the Amol Cohort Study (AmolCS). In a cross-sectional analysis among 3220 adults (55.3% men), age ≥ 18 years (46.96 ± 14.67), we measured usual dietary intake with a validated food frequency questionnaire (FFQ) and then calculated dietary pattern scores for DASH and MeD. Sociodemographic and lifestyle factors were collected by a structured questionnaire. The presence and degree of NAFLD were also determined by abdominal sonography. Multiple regression models were used to estimate NAFLD odds across tertiles of DASH and Mediterranean dietary scores. Dietary DASH and Mediterranean components were adjusted for total energy intake, based on the residual methods. After adjusting for multiple potential confounders, we found an inverse association of DASH and MeD with NAFLD (Ptrend = 0.02, and Ptrend = 0.002, respectively). Those in the highest tertiles of adherence to the DASH and MeD had the lowest risk for NAFLD (OR = 0.80, 95%CI = 0.66–0.96, OR = 0.64, 95%CI = 0.52–0.78, respectively). The results of logistic analysis of MeD, stratified by gender and abdominal obesity, revealed the favorable association was more pronounced in women (OR = 0.42, 95%CI = 0.29–0.61, Ptrend = 0.004), and in participants with or without abdominal obesity (OR = 0.62, 95% CI = 0.47–0.81, Ptrend = 0.03, OR = 0.64, 95%CI = 0.475–0.91, Ptrend = 0.04, respectively). Similar results were obtained for the adherence to DASH diet score with the prevalence of NAFLD patients with abdominal obesity (OR = 0.75, 95% CI = 0.57–0.97, Ptrend = 0.04). The findings suggested the favorable association between DASH and MeD with NAFLD in Iranian adults, especially women and subjects with or without abdominal obesity. Further prospective investigations are needed to confirm the integrity of our findings.

Dietary acid load in children with chronic kidney disease

BACKGROUND/OBJECTIVES

Western diet is characterized by a high acid load that could generate various degrees of metabolic acidosis, of which at least the stronger forms are known to contribute to the progression of chronic kidney disease (CKD). The aim of this study was to estimate the potential renal acid load (PRAL) and acid base status in CKD patients attended at the Children's Hospital J.M. de los Ríos in Caracas, Venezuela from April 2015 to February 2016.

SUBJECTS/METHODS

Twenty-seven children with CKD were included. Diet composition was evaluated by a food frequency questionnaire and a 24-h intake reminder. PRAL was calculated by the Remer and Manz method. Laboratory tests included serum creatinine, electrolytes and venous gases.

RESULTS

Protein intake was above recommendations in 21 patients (78.6%). Average vegetable and fruit intake was 0.4 and 1.5 servings per day, respectively. Mean PRAL was 16 ± 10.7 mEq/day. PRAL correlated positively with energy (p = 0.005), protein (p = 0.001) and fat intake (p = 0.0001), daily servings of dairy (p = 0.04) meat (p = 0.001) and cereals (0.001) and negatively with vegetable intake (p = 0.04). Serum pH and bicarbonate were 7.3 ± 0.08 and 20.46 ± 4.5 mEq/L, respectively. Twenty-one patients (80.7%) with metabolic acidosis were treated with sodium bicarbonate.

CONCLUSIONS

Dietary pattern of Venezuelan children with CKD may constitute a risk factor for the progression of the disease by promoting metabolic acidosis via unfavorable dietary acid loads. PRAL should be assessed as a valuable guide for nutritional counseling in children with CKD.

Dietary Acid Load and Its Interaction with IGF1 (rs35767 and rs7136446) and IL6 (rs1800796) Polymorphisms on Metabolic Traits among Postmenopausal Women

The objective of this study was to explore the effects of dietary acid load (DAL) and IGF1 and IL6 gene polymorphisms and their potential diet–gene interactions on metabolic traits. A total of 211 community-dwelling postmenopausal women were recruited. DAL was estimated using potential renal acid load (PRAL). Blood was drawn for biochemical parameters and DNA was extracted and Agena^® MassARRAY was used for genotyping analysis to identify the signalling of IGF1 (rs35767 and rs7136446) and IL6 (rs1800796) polymorphisms. Interactions between diet and genetic polymorphisms were assessed using regression analysis. The result showed that DAL was positively associated with fasting blood glucose (FBG) (β = 0.147, p < 0.05) and there was significant interaction effect between DAL and IL6 with systolic blood pressure (SBP) (β = 0.19, p = 0.041). In conclusion, these findings did not support the interaction effects between DAL and IGF1 and IL6 single nucleotide polymorphisms (rs35767, rs7136446, and rs1800796) on metabolic traits, except for SBP. Besides, higher DAL was associated with higher FBG, allowing us to postulate that high DAL is a potential risk factor for diabetes.

Food insecurity, dietary acid load, dietary energy density and anthropometric indices among Iranian children

OBJECTIVES

Food insecurity significantly influences diet quality which in turn has an impact on individual health. This study aimed to determine the association of food insecurity, dietary energy density (DED), dietary acid load (DAL), and the anthropometric status of children.

STUDY DESIGN

A cross-sectional study.

METHODS

This study was conducted in 788 6-year-old girls who were referred to health care centers affiliated with Tehran University of Medical Sciences in the south of Tehran from October 2017 to March 2018. Food frequency questionnaires (168 food items) were assessed to calculate DAL and DED. Food insecurity was assessed using the 18-item United States Department of Agriculture questionnaire. Weight and height of children were measured as anthropometric indices.

RESULTS

Protein and energy intake were higher in participants with a higher DAL and DED, respectively. Energy, fat, carbohydrate, fiber, potassium, phosphorus, calcium, iron, folate, vitamin B12, mono- and poly-unsaturated fatty acid intake was inversely related to DAL. Children characterized as food insecure were more likely to be defined as thin (OR 5.36; 95% CI 3.41-8.40) than overweight (OR 0.18; 95% CI 0.12-027) and obese (OR 0.28; 95% CI 0.08-0.98, respectively). There was no significant association between DED, potential renal acid load (PRAL), and food security status. Moreover, there was no significant association between anthropometric measure and PRAL.

CONCLUSION

Findings from our study revealed that there was no association between DAL and food insecurity. However, food insecure children were more likely to be characterized as thin than children categorized as food secure. More studies need to be performed in both genders to confirm our findings.

LEVEL OF EVIDENCE

Level V cross-sectional descriptive study.

Dietary Acid Load and the Risk of Pancreatic Cancer: A Prospective Cohort Study

BACKGROUND

Modern Western diets are rich in acidogenic foods. Human and in vitro studies suggest a potential link between dietary acid load and cancer risk. However, no epidemiologic studies have investigated the association of dietary acid load with the risk of pancreatic cancer. Therefore, we conducted a prospective cohort study to fill this gap.

METHODS

A population-based cohort of 95,708 American adults was identified. Potential renal acid load (PRAL) and net endogenous acid production (NEAP) were used to assess dietary acid load of each subject, with greater values indicating greater dietary acid load. Cox regression was used to estimate risk estimates for pancreatic cancer incidence. Predefined subgroup analysis was used to identify the potential effect modifiers.

RESULTS

A total of 337 pancreatic cancer cases were observed during 848,534.0 person-years of follow-up. PRAL score was found to be positively associated with the risk of pancreatic cancer [fully adjusted HR_{quartile 4 vs. 1}: 1.73; 95% confidence interval (95% CI), 1.21-2.48; P _trend = 0.001] in a nonlinear dose-response pattern (P _nonlinearity = 0.012). Subgroup analysis found that the positive association of PRAL score with the risk of pancreatic cancer was more pronounced in subjects aged <65 years than in those ≥65 years (P _interaction = 0.018). Similar results were obtained for NEAP score.

CONCLUSIONS

Higher dietary acid load is associated with a higher risk of pancreatic cancer. Future studies should validate our findings in other populations and settings.

IMPACTS

This is the first epidemiologic study suggesting that reducing dietary acid load may be useful in primary prevention of pancreatic cancer.

Positive association between dietary acid load and future insulin resistance risk: findings from the Korean Genome and Epidemiology Study

Background

Acid-base homeostasis is increasingly being recognized to play an important role in normal metabolic function. However, prospective studies on the relationship between diet-induced acid-base imbalance and insulin resistance among Asian populations have been limited. Thus, we investigated whether diet-induced metabolic acidosis was prospectively associated with insulin resistance risk in middle-aged and older Korean adults.

Methods

In total, 5406 participants from the Korean Genome and Epidemiology Study without type 2 diabetes, insulin resistance, cancer, or renal diseases at baseline examination were included in this study. To estimate diet-induced metabolic acidosis, we used potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores calculated from the usual dietary intake assessed by a validated 103-item food frequency questionnaire at baseline. Multivariable Cox proportional hazard models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of insulin resistance incidence.

Results

During a mean follow-up period of 7.4 years, we documented 3449 insulin resistance cases. In the fully adjusted model, the future insulin resistance risk was significantly higher among participants in the highest quartiles of PRAL (HR: 1.30, 95% CI: 1.13–1.48, P_trend = 0.0002) and NEAP (HR: 1.30, 95% CI: 1.14–1.49, P_trend = 0.0008) than among those in the lowest quartiles. Associations were slightly strengthened among men, adults < 50 years old, obese participants, or those with low physical activity levels.

Conclusions

Our findings suggested that diet-dependent acid load was positively associated with the future development of insulin resistance, suggesting effect modification by sex, age, the presence of obesity, and physical activity levels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-020-00653-6.

Effects of Rice with Different Amounts of Resistant Starch on Mice Fed a High-Fat Diet: Attenuation of Adipose Weight Gain

Increasing the amount of resistant starch (RS) in the diet may confer protective effects against chronic diseases. Rice, a good dietary source of carbohydrates, also contains RS. However, it remains unclear if RS at the amount consumed in cooked rice has a health benefit. To address the question, we examined the effects of cooked rice containing different levels of RS in a diet-induced obesity rodent model. Rice containing RS as low as 1.07% attenuated adipose weight and adipocyte size gain, induced by a moderately high-fat (HF) diet, which correlated with lower leptin levels in plasma and adipose tissue. Rice with 8.61% RS increased fecal short-chain fatty acid levels, modulated HF-diet-induced adipose triacylglycerol metabolism and inflammation-related gene expression, and increased fecal triglyceride excretion. Hence, including rice with RS level at ≥1.07% may attenuate risks associated with the consumption of a moderately HF diet.

The associations between major dietary patterns and risk of periodontitis

AIM

To prospectively investigate the associations between major dietary patterns and incidence of periodontitis.

METHODS

We included 34,940 men from the Health Professionals Follow-Up Study, free of periodontal disease and major illnesses at baseline. Detailed medical and dental history was collected through biennial mailed questionnaires, and dietary information was provided through quadrennial food frequency questionnaires. Using principal component analysis, we identified two major dietary patterns ("prudent" and "Western"). We used Cox proportional hazard models to examine the associations between the two dietary patterns and self-reported incidence of periodontitis over a 24-year follow-up period. We investigated each pattern separately.

RESULTS

There was no overall association between Western or prudent dietary patterns and periodontitis. Among obese, however, the Western dietary pattern was significantly associated with incident periodontitis. The hazard ratio for those in the highest quintile of Western diet versus those in the lowest (reference) was 1.83 (95% confidence interval: 1.21-2.76).

CONCLUSIONS

There was no overall association between Western or prudent dietary patterns and periodontitis; however, in subgroups analysis, the Western diet was significantly associated with higher periodontitis risk only among obese men, a finding that requires replication and biological explication.

Dietary Acid Load and Cardiometabolic Risk Factors-A Narrative Review

The Western, diet rich in acidogenic foods (e.g., meat, fish and cheese) and low in alkaline foods (e.g., vegetables, fruits and legumes), is deemed to be a cause of endogenous acid production and elevated dietary acid load (DAL), which is a potential cause of metabolic acidosis. Multiple authors have suggested that such a dietary pattern increases the excretion of calcium and magnesium, as well as cortisol secretion. In addition, it is associated with decreased citrate excretion. All of these seem to increase blood pressure and insulin resistance and may contribute to the development of cardiometabolic disorders. However, there are inconsistencies in the results of the studies conducted. Therefore, this narrative literature review aims to present the outcomes of studies performed in recent years that investigated the association between DAL and the following cardiometabolic risk factors: blood pressure, hypertension, carbohydrate metabolism and lipid profile. Study outcomes are divided into (i) statistically significant positive association, (ii) statistically significant inverse association, and (iii) no statistically significant association.

Diet-dependent acid load and the risk of colorectal cancer and adenoma: a case-control study

OBJECTIVES

Colorectal cancer (CRC) is the third and second most prevalent cancer in men and women, respectively. Various epidemiological studies indicated that dietary factors are implicated in the aetiology of CRC and its precursor, colorectal adenomas (CRA). Recently, much attention has been given to the role of acid-base balance in the development of chronic diseases including cancers. Therefore, the aim of the current study is to examine the association of diet-dependent acid load and the risk of CRC and CRA.

DESIGN

In this case-control study, potential renal acid load (PRAL) was computed based on dietary intake of participants assessed via a validated FFQ. Negative PRAL values indicated a base-forming potential, while positive values of PRAL implied acid-forming potential of diet. Logistic regression was used to derive OR and 95 % CI after adjusting for confounders.

SETTING

Tehran, Iran.

PARTICIPANTS

A total of 499 participants aged 30-70 years were included in the study (240 hospital controls, 129 newly diagnosed CRC and 130 newly diagnosed CRA). The current study was conducted between December 2016 and September 2018.

RESULTS

After adjusting for potential confounders, a higher PRAL was associated with increased odds of CRC and CRA. The highest v. the lowest tertile of PRAL for CRC and CRA was OR 4·82 (95 % CI 2·51-9·25) and OR 2·47 (95 % CI 1·38-4·42), respectively.

CONCLUSIONS

The findings of the current study suggested that higher diet-dependent acid load is associated with higher risk of CRC and CRA.

Intracellular pH Regulation of Skeletal Muscle in the Milieu of Insulin Signaling

Type 2 diabetes (T2D), along with obesity, is one of the leading health problems in the world which causes other systemic diseases, such as cardiovascular diseases and kidney failure. Impairments in glycemic control and insulin resistance plays a pivotal role in the development of diabetes and its complications. Since skeletal muscle constitutes a significant tissue mass of the body, insulin resistance within the muscle is considered to initiate the onset of diet-induced metabolic syndrome. Insulin resistance is associated with impaired glucose uptake, resulting from defective post-receptor insulin responses, decreased glucose transport, impaired glucose phosphorylation, oxidation and glycogen synthesis in the muscle. Although defects in the insulin signaling pathway have been widely studied, the effects of cellular mechanisms activated during metabolic syndrome that cross-talk with insulin responses are not fully elucidated. Numerous reports suggest that pathways such as inflammation, lipid peroxidation products, acidosis and autophagy could cross-talk with insulin-signaling pathway and contribute to diminished insulin responses. Here, we review and discuss the literature about the defects in glycolytic pathway, shift in glucose utilization toward anaerobic glycolysis and change in intracellular pH [pH]_i within the skeletal muscle and their contribution towards insulin resistance. We will discuss whether the derangements in pathways, which maintain [pH]_i within the skeletal muscle, such as transporters (monocarboxylate transporters 1 and 4) and depletion of intracellular buffers, such as histidyl dipeptides, could lead to decrease in [pH]_i and the onset of insulin resistance. Further we will discuss, whether the changes in [pH]_i within the skeletal muscle of patients with T2D, could enhance the formation of protein aggregates and activate autophagy. Understanding the mechanisms by which changes in the glycolytic pathway and [pH]_i within the muscle, contribute to insulin resistance might help explain the onset of obesity-linked metabolic syndrome. Finally, we will conclude whether correcting the pathways which maintain [pH]_i within the skeletal muscle could, in turn, be effective to maintain or restore insulin responses during metabolic syndrome.

The effect of body acid-base state and manipulations on body glucose regulation in human

Long-term exposure to high dietary acid load has been associated with insulin resistance and type 2 diabetes in epidemiological studies. However, it remains unclear whether the acid load of the diet translates to mild metabolic acidosis and whether it is responsible for the impairment in glucose regulation in humans. Previously, in a cross-sectional study we have reported that dietary acid load was not different between healthy individuals with normal weight and those with overweight/obesity, irrespective of insulin sensitivity. However, 4-week high acid load diet increased plasma lactate (a small component of the anion gap) and increased insulin resistance in healthy participants. The change in plasma lactate correlated significantly with the change in insulin resistance. Because cause-and-effect could not be evaluated in these settings, we sought to directly test the effect of an alkalizing treatment preload on postprandial glucose regulation. In a randomized placebo-controlled study with a crossover design, we administered sodium bicarbonate (NaHCO₃, 1.68 g) prior to high acid load meal to healthy individuals. We found that while the bicarbonate preload attenuated the post meal decrease in pH observed with placebo, no effect on postprandial glucose regulation (glucose, insulin, and C-peptide) was observed. Following 3-month treatment of nondiabetic individuals with bicarbonate, others have reported no change in insulin resistance markers, consistent with our findings. Together, studies in human suggest that insulin resistance associated with longstanding obesogenic diet may be mediated by mild metabolic acidosis. However, buffering the Western diet with bicarbonate and increasing body pH does not change glucose homeostasis in nondiabetic individuals. Further studies are required to shed light on the role of body acid-base balance and glucose homeostasis in health and disease.

What is the best diet for cardiovascular wellness? A comparison of different nutritional models

Cardiovascular diseases (CVD) represent to date the leading cause of mortality in both genders in the developed countries. In this context, a strong need for CVD prevention is emerging through lifestyle modification and nutrition. In fact, several studies linked CVD with unhealthy nutrition, alcohol consumption, stress, and smoking, together with a low level of physical activity. Thus, the primary aim is to prevent and reduce CVD risk factors, such as impaired lipid and glycemic profiles, high blood pressure and obesity. Different types of diet have been, therefore, established to optimize the approach regarding this issue such as the Mediterranean diet, Dietary Approaches to Stop Hypertension diet (DASH), vegetarian diet, ketogenic diet, and Japanese diet. Depending on the diet type, recommendations generally emphasize subjects to increase vegetables, fruits, whole grains, and pulses consumption, but discourage or recommend eliminating red meat, sweets, and sugar-sweetened beverages, along with processed foods that are high in sugar, salt, fat, or low in dietary fiber. In particular, we evaluated and compared the peculiar aspects of these well-known dietary patterns and, thus, this review evaluates the critical factors that increase CVD risk and the potential application and benefits of nutritional protocols to ameliorate dietary and lifestyle patterns for CVD prevention.

Association of Dietary Acid Load with the Prevalence of Metabolic Syndrome among Participants in Baseline Survey of the Japan Multi-Institutional Collaborative Cohort Study

The association between dietary acid load and metabolic syndrome (MetS) has not been fully investigated. A cross-sectional study was performed on 14,042 men and 14,105 women (aged 35-69 years) who participated in a baseline survey of the Japan Multi-Institutional Collaborative Cohort study. Dietary acid load was assessed using the net-endogenous-acid-production (NEAP) score that is closely correlated with the rate of renal net acid excretion. MetS was diagnosed according to the Joint Interim Statement Criteria of 2009 using body-mass index instead of waist circumference. After adjusting for potential confounders, higher NEAP scores were associated with a significantly increased odds ratio (OR) of MetS, obesity, high blood pressure, and high fasting blood glucose. These associations remained significant after further adjustment for carbohydrate intake or two nutrient-pattern scores significantly associated with MetS. After adjustment for fiber, iron, potassium, and vitamin pattern scores, the OR of MetS for the highest quartile of NEAP scores, relative to the lowest quartile, was 1.25 (95% confidence interval 1.12-1.39). There was no significant interaction between sex, age, or body-mass index and NEAP. Higher dietary acid load was associated with a higher prevalence of MetS and several of its components, independently of carbohydrate intake or nutrient patterns.

Dietary acid load, blood pressure, fasting blood sugar and biomarkers of insulin resistance among adults: Findings from an updated systematic review and meta-analysis

OBJECTIVES

There is no clear summarised report of the association between dietary acid load components including potential renal acid load (PRAL) and net-endogenous acid production (NEAP) with cardiometabolic risk factors. In the current meta-analysis, we aimed to systematically review and summarise the eligible observational studies evaluating the association between PRAL and NEAP with blood pressure and hypertension and markers of glucose haemostasis among adults.

DESIGN AND SETTING

In a systematic search from PubMed, SCOPUS, Web of Sciences and Cochrane electronic databases up to May 2019, relevant studies were included in the literature review. Observational studies evaluating the association between PRAL and NEAP with the systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting blood glucose, insulin, homeostatic model assessment of insulin resistance (HOMA-IR), haemoglobin A₁ C (HbA₁ C), HOMA-β and quantitative insulin check index (QUICKI) and also prevalence or odds of hypertension, hyperglycaemia and diabetes were included.

RESULTS

Total number of studies included in the 14 separate meta-analyses were as follows: Mean (SD) of SBP (PRAL, n = 12; NEAP, n = 6), mean (SD) of DBP (PRAL, n = 8; NEAP, n = 3), mean (SD) of FBS (PRAL, n = 12; NEAP, n = 5), mean (SD) of HbA₁ C (PRAL, n = 6; NEAP, n = 4), mean (SD) of HOMA-IR (PRAL, n = 7), mean (SD) of insulin (PRAL, n = 7; NEAP, n = 2); OR of type 2 diabetes mellitus (T₂ DM) (PRAL, n = 8; NEAP; n = 6), HTN prevalence (PRAL, n = 9; NEAP, n = 9), T₂ DM prevalence (PRAL, n = 7; NEAP, n = 6). According to our results, being in the highest PRAL categories was associated with higher SBP (WMD = 0.98; CI: 0.51, 1.45; P < .001), DBP (WMD = 0.61; CI: 0.089, 1.135; P = .022), insulin (WMD = -0.235, CI: 0.070, 0.400; P = .005), higher odds of diabetes (OR = 1.19; CI: 1.092, 1.311; P < .001), higher prevalence of T₂ DM (13% and 11% in highest vs lowest category). While, being in the highest category of NEAP was only associated with higher odds of diabetes (OR = 1.22; CI: 1.14, 1.31, P < .001). In subgroup analysis for finding the possible source of heterogeneity, the continent, dietary assessment tool, sample size and gender were the potent sources of heterogeneity. No association between PRAL and NEAP with HbA₁ C, HOMA-IR was reported.

CONCLUSIONS

In the current meta-analysis, we found potent negative effects of high dietary acid load particularly higher PRAL scores cardiometabolic risk factors. Therefore, lower acidogenic food ingredients in the diets are suggested for the prevention of cardiovascular risk factors and diabetes.

Diet-Dependent Acid Load-The Missing Link Between an Animal Protein-Rich Diet and Nonalcoholic Fatty Liver Disease?

OBJECTIVE

Our group recently showed that animal protein was independently associated with nonalcoholic fatty liver disease (NAFLD). We hypothesize that this may be explained by a high diet-dependent acid load [dietary acid load (DAL)].

METHODS

This cross-sectional study is embedded in a prospective population-based cohort. We estimated DAL proxies via food-frequency questionnaires using potential renal acid load (PRAL; using dietary protein, phosphorus, potassium, calcium, and magnesium intake), net endogenous acid production (NEAP; using protein and potassium intake), and the animal protein-to-potassium ratio (A:P). We defined NAFLD using ultrasound after excluding secondary steatogenic causes. We used logistic regression models-adjusted for sociodemographic, lifestyle, and metabolic traits-on categorized [quartile (Q)1 to 4] and continuous DAL proxies (allowing for nonlinearity) and NAFLD.

RESULTS

We included 3882 participants, of which 1337 had NAFLD. All DAL proxies were higher, meaning more acidic, in individuals with NAFLD (PRAL, -2.9 vs -5.5 mEq/d; NEAP, 37.0 vs 35.1 mEq/d; and A:P, 13.3 vs 12.4; all P < 0.001). The highest Q of DAL proxies was associated with NAFLD independent of sociodemographic and lifestyle confounders, but significance dissipated after correction for metabolic confounders and multiple testing. However, the P value for nonlinearity was significant in all DAL proxies (P < 0.001). Natural cubic splines performed better with than without DAL proxies in the fully adjusted model (all P ≤ 0.038). The highest probability of NAFLD was found for an acidic diet.

CONCLUSIONS

This study showed an independent nonlinear association between an acidic diet and NAFLD. Further studies with acid-base biomarkers are needed, but our findings might provide a mechanistic explanation for the harmful association between an animal protein-rich diet and NAFLD.

Macronutrient intake and frailty: the Rotterdam Study

Purpose

To investigate the longitudinal association between the macronutrient composition of the diet and frailty.

Methods

Data were obtained from 5205 Dutch middle-aged and older adults participating in the Rotterdam Study. Frailty was measured using a frailty index based on the accumulation of 38 health-related deficits, score between 0 and 100, and a higher score indicating more frailty. Frailty was assessed at baseline and 11 years later (range of 23 years). Macronutrient intake was assessed using food-frequency questionnaires. The association between macronutrients and frailty over time was evaluated using multivariable linear regression, adjusted for the frailty index at baseline, energy intake, and other relevant confounders. All analyses were performed in strata of BMI.

Results

Median frailty index score was 13.8 points (IQR 9.6; 19.1) at baseline and increased by a median of 2.3 points (IQR − 2.0; 7.6) after 11 years. Overall, we found no significant associations between intake of carbohydrates or fat and frailty over time. We did observe a significant positive association between an iso-energetic intake of 10 g protein and frailty over time (β 0.31 (95% CI 0.06; 0.55)) which was mainly driven by animal protein (β 0.31 (95% CI 0.07; 0.56)). It did not depend on whether it was substituted fat or carbohydrates.

Conclusions

Our findings suggest that a reduction in the intake of animal protein may improve the overall health status over time in a relatively healthy population. More research is needed on the optimal macronutrient composition of the diet and frailty in more vulnerable populations.

Electronic supplementary material

The online version of this article (10.1007/s00394-019-02131-0) contains supplementary material, which is available to authorized users.

Dietary acid load significantly predicts 10-years survival in patients underwent coronary artery bypass grafting (CABG) surgery

BACKGROUNDS

Numerous studies have revealed the role of dietary acid load as a potential risk factor for cardiovascular events and blood pressure. However, its role in predicting the mortality rate in patients underwent coronary artery bypass grafting surgery (CABG) has not been reported. In the current study we aimed to evaluate the relationship of dietary acid load and cardio-metabolic risk factors with ten year survival among patients underwent CABG.

METHODS

The current prospective cohort study comprises 454 patients underwent CABG. Anthropometric, clinical and biochemical measurements were performed. Dietary acid load was calculated as either potential renal acid load (PRAL) or net endogenous acid production (NEPA) using the data obtained from a semi-quantitative food frequency questionnaire (FFQ). Survival analysis was performed using Kaplan-Meier method followed by log-rank test. The association between all-cause mortality and study parameters was performed with Cox-proportional hazard model.

RESULTS

Patients in the higher PRAL and NEAP quartiles had lower BMI and lower ejection fraction rate (P <0.05). Moreover, lower hematocrit values were observed in patients of higher PRAL quartiles. Higher PRAL scores were associated with higher mortality rate and reduced survival days (adjusted hazard ratio: 1.023 (1.00-1.04; P-value = 0.01). However, there was no relationship between NEAP and survival.

CONCLUSIONS

We revealed that high PRAL scores are positive predictors of 10-year mortality in patients underwent CABG. The results of our study suggest that maintaining an adequate acid-base balance can contribute to longevity by reducing the risk of mortality.

Reproducibility and validity of an FFQ in the Henan Rural Cohort Study

OBJECTIVE

The present study aimed to evaluate the validity and reproducibility of a thirteen-item FFQ regarding identification of dietary conditions in a rural population in China.

DESIGN

A reproducibility study repeated the first FFQ (FFQ1) approximately 4 weeks later (FFQ2). A validity study evaluated the mean of three consecutive 24 h diet recalls as the reference measure.

SETTING

Cross-sectional study.

PARTICIPANTS

Residents of a rural area in Henan Province, which is located in the central region of China.

RESULTS

A total of 295 individuals participated in the reproducibility study. In addition, 123 people agreed to participate in the validity study. Spearman's correlation coefficients between the two FFQ ranged from 0·06 (vegetables) to 0·58 (eggs). Spearman's correlation coefficients between the two methods of collection ranged from 0·01 for cereal to 0·49 for staple foods. The mean of the intraclass correlation coefficients of the two FFQ (FFQ1 v. FFQ2) was 0·19. Bland-Altman analysis indicated good agreement for most food groups across the range of intake for the two studies.

CONCLUSIONS

The study demonstrated that our FFQ design could be used as a representative tool to conduct a dietary evaluation of a rural population.

Associations between Dietary Acid Load and Biomarkers of Inflammation and Hyperglycemia in Breast Cancer Survivors

Metabolic acidosis can lead to inflammation, tissue damage, and cancer metastasis. Dietary acid load contributes to metabolic acidosis if endogenous acid-base balance is not properly regulated. Breast cancer survivors have reduced capacities to adjust their acid-base balance; yet, the associations between dietary acid load and inflammation and hyperglycemia have not been examined among them. We analyzed data collected from 3042 breast cancer survivors enrolled in the Women's Healthy Eating and Living (WHEL) Study who had provided detailed dietary intakes and measurements of plasma C-reactive protein (CRP) and hemoglobin A1c (HbA1c). Using a cross-sectional design, we found positive associations between dietary acid load and plasma CRP and HbA1c. In the multivariable-adjusted models, compared to women with the lowest quartile, the intakes of dietary acid load among women with the highest quartile showed 30-33% increases of CRP and 6-9% increases of HbA1c. Our study is the first to demonstrate positive associations between dietary acid load and CRP and HbA1c in breast cancer survivors. Our study identifies a novel dietary factor that may lead to inflammation and hyperglycemia, both of which are strong risk factors for breast cancer recurrence and comorbidities.

Higher dietary acid load potentially increases serum triglyceride and obesity prevalence in adults: An updated systematic review and meta-analysis

Background

In the current meta-analysis, we aimed to systematically review and summarize the eligible studies evaluating the association between dietary acid load in terms of potential renal acid load (PRAL) and net-endogenous acid production (NEAP) with anthropometric parameters and serum lipids in adult population.

Methods

In a systematic search from PubMed, Scopus, Web of Sciences and Cochrane electronic databases up to December 2018, relevant studies were included. Cross-sectional, case control or cohort studies evaluating the association between PRAL and NEAP with the mean values of body mass index (BMI), waist circumference (WC), low and high density lipoprotein cholesterol (LDL, HDL), triglyceride (TG), total cholesterol (TC) and the prevalence of obesity were included.

Results

According to our results, having higher dietary acid load content in terms of high PRAL scores was associated with higher triglyceride concentrations (weighted mean difference (WMD): 3.468; confidence interval (CI): -0.231, 7.166, P = 0.04) and higher obesity prevalence (30% and 27% in highest versus lowest categories). Accordingly, being in the highest category of NEAP was associated with higher prevalence of obesity (25% and 22% in highest versus lowest category). In subgroup analysis, higher PRAL scores was associated with higher BMI in women (WMD: 0.122; CI: -0.001, 0.245; P = 0.049) and higher NEAP in men (WMD: 0.890; CI: 0.430, 1.350; P < 0.001). There was no association between dietary acid load and other studied parameters.

Conclusions

In the current meta-analysis, high dietary acid load content was associated with higher serum triglyceride concentrations and higher obesity prevalence. Reducing dietary acid load content might be a useful preventive strategy against obesity and metabolic disorders.

Targeting acidity in cancer and diabetes

While cancer is commonly described as "a disease of the genes", it is also a disease of metabolism. Indeed, carcinogenesis and malignancy are highly associated with metabolic re-programming, and there is clinical evidence that interrupting a cancer's metabolic program can improve patients' outcomes. Notably, many of the metabolic adaptations observed in cancer are similar to the same perturbations observed in diabetic patients. For example, metformin is commonly used to reduce hyperglycemia in diabetic patients, and has been demonstrated to reduce cancer incidence. Treatment with PI3K inhibitors can induce hyperinsulinemia, which can blunt therapeutic efficacy if unchecked. While commonalities between metabolism in cancer and diabetes have been extensively reviewed, here we examine a less explored and emergent convergence between diabetic and cancer metabolism: the generation of lactic acid and subsequent acidification of the surrounding microenvironment. Extracellular lactic acidosis is integral in disease manifestation and is a negative prognostic in both disease states. In tumors, this results in important sequela for cancer progression including increased invasion and metastasis, as well as inhibition of immune surveillance. In diabetes, acidosis impacts the ability of insulin to bind to its receptor, leading to peripheral resistance and an exacerbation of symptoms. Thus, acidosis may be a relevant therapeutic target, and we describe three approaches for targeting: buffers, nanomedicine, and proton pump inhibitors.

Population attributable fractions of the main type 2 diabetes mellitus risk factors in women: Findings from the French E3N cohort

BACKGROUND

Although many type 2 diabetes mellitus (T2DM) risk factors have been identified, little is known regarding their contributions to the diabetes burden at the population level.

METHODS

The study included 72 655 French women from the Etude Epidemiologique de Femmes de la Mutuelle Générale de l'Education Nationale (E3N) prospective cohort followed between 1993 and 2011. Cox multivariable models including the main T2DM risk factors (metabolic, dietary, clinical, socioeconomic and hormonal) and a healthy lifestyle index combining five characteristics (smoking, body mass index [BMI], alcohol consumption, fruit and vegetable consumption, and physical activity) were used to estimate hazard ratios and population attributable fractions (PAFs) for T2DM.

RESULTS

In multivariate models, factors with the strongest effect on T2DM risk were, in decreasing order, BMI ≥ 30 kg/m² (PAF = 43%; 95% confidence interval [CI] 37-47), high adherence to a Western dietary pattern (PAF = 30%; 95% CI 20-40), hypertension (PAF = 26%; 95% CI 20-32), an acidogenic diet (PAF = 24%; 95% CI 16-32), a family history of diabetes (PAF = 20%; 95% CI 17-22), and, with a negative correlation, moderate alcohol consumption (PAF-19%; 95% CI -34, -4). The PAF for an unhealthy lifestyle was 57% (95% CI 50-63).

CONCLUSIONS

We have been able to sort out and quantify the effect of various dietary and biological T2DM risk factors simultaneously in a single population, and to highlight the importance of a healthy lifestyle for primary prevention: more than half the T2DM cases could have been prevented through a healthier lifestyle.

Dietary Acid Load: mechanisms and evidence of its health repercussions

Diet composition has long been known to influence acid-base balance by providing acid or base precursors. In general, foods rich in protein, such as meat, cheese, eggs, and others, increase the production of acid in the body, whereas fruit and vegetables increase alkalis. The capacity of acid or base production of any food is called potential renal acid load (PRAL). Diets high in PRAL induce a low-grade metabolic acidosis state, which is associated with the development of metabolic alterations such as insulin resistance, diabetes, hypertension, chronic kidney disease, bone disorders, low muscle mass and other complications. The aim of this paper is to review the available evidence which evaluates the association of the PRAL of the diet with the incidence of chronic diseases and metabolic disorders, as well as related mechanisms involved in their development.

The dietary acid load is higher in subjects with prediabetes who are at greater risk of diabetes: a case-control study

BACKGROUND

We aimed to examine the association of dietary acid load and prediabetes in a case-control study.

METHODS

This study recruited 297 subjects including 147 prediabetic subjects and 150 controls referred to diabetes screening center in Shahreza, Iran. Participants were frequency-matched by sex and age. Blood pressure, anthropometric measures and blood glucose levels were measured. Dietary intake was assessed using a validated 168-items food frequency questionnaire (FFQ). The dietary acid load 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. Logistic regression models were used to estimate multivariable odds ratio (OR) of prediabetes across the energy-adjusted and sex-specific quartiles of NEAP and PRAL scores.

RESULTS

Participants of control group in the higher quartiles of NEAP and PRAL tended to have higher body weight compared to the lower quartiles (P-trend < 0.04). After adjustment for multiple confounding variables, participants in the highest quartiles of NEAP and PRAL had increased OR for prediabetes (OR = 14.48 95% CI 5.64-37.19), and (OR = 25.61 95% CI 9.63-68.08) (P-trend < 0.001), respectively.

CONCLUSION

Our data indicated subjects with prediabetes had diets with more acid-forming potential than control group. Our findings suggest that higher dietary acid load was associated with increased prediabetes morbidity. Interventional studies are warranted to elucidate the role of acidogenic diets in the development of prediabetes.

Higher diet-dependent acid load is associated with risk of breast cancer: Findings from the sister study

Dietary factors that contribute to chronic low-grade metabolic acidosis have been linked to breast cancer risk, but to date no epidemiologic study has examined diet-dependent acid load and breast cancer. We used data from 43,570 Sister Study participants who completed a validated food frequency questionnaire at enrollment (2003-2009) and satisfied eligibility criteria. The Potential Renal Acid Load (PRAL) score was used to estimate diet-dependent acid load. Higher scores reflect greater consumption of protein and phosphorus, and lower consumption of potassium, calcium and magnesium. The association between PRAL and breast cancer was evaluated using multivariable Cox proportional hazards regression. We identified 1,614 invasive breast cancers diagnosed at least 1 year after enrollment (mean follow-up, 7.6 years). The highest PRAL quartile, reflecting greater acid-forming potential, was associated with increased risk of breast cancer (HR_{highest vs. lowest quartile} : 1.21 [95% CI, 1.04-1.41], p_trend = 0.04). The association was more pronounced for estrogen receptor (ER)-negative (HR_{highest vs. lowest quartile} : 1.67 [95% CI, 1.07-2.61], p_trend = 0.03) and triple-negative breast cancer (HR_{highest vs. lowest quartile} : 2.20 [95% CI, 1.23-3.95], p_trend = 0.02). Negative PRAL scores, representing consumption of alkaline diets, were associated with decreased risk of ER-negative and triple-negative breast cancer, compared to a PRAL score of 0 representing neutral pH. Higher diet-dependent acid load may be a risk factor for breast cancer while alkaline diets may be protective. Since PRAL scores are positively correlated with meat consumption and negatively correlated with fruit and vegetable intake, results also suggest that diets high in fruits and vegetables and low in meat may be protective against hormone receptor negative breast cancer.

The effect of drinking water pH on the human gut microbiota and glucose regulation: results of a randomized controlled cross-over intervention

Studies in rodent models have shown that alterations in drinking water pH affect both the composition of the gut microbiota and host glucose regulation. To explore a potential impact of electrochemically reduced alkaline (pH ≈ 9) versus neutral (pH ≈ 7) drinking water (2 L/day) on human intestinal microbiota and host glucose metabolism we conducted a randomized, non-blinded, cross-over study (two 2-week intervention periods, separated by a 3-week wash-out) in 29 healthy, non-smoking Danish men, aged 18 to 35 years, with a body mass index between 20.0 to 27.0 kg m-2. Volunteers were ineligible if they had previously had abdominal surgery, had not been weight stabile for at least two months, had received antibiotic treatment within 2 months, or had a habitual consumption of caloric or artificially sweetened beverages in excess of 1 L/week or an average intake of alcohol in excess of 7 units/week. Microbial DNA was extracted from faecal samples collected at four time points, before and after each intervention, and subjected to 16S rRNA gene amplicon sequencing (Illumina MiSeq, V4 region). Glycaemic regulation was evaluated by means of an oral glucose tolerance test.No differential effect of alkaline versus neutral drinking water was observed for the primary outcome, overall gut microbiota diversity as represented by Shannon's index. Similarly, neither a differential effect on microbiota richness or community structure was observed. Nor did we observe a differential effect on the abundance of individual operational taxonomic units (OTUs) or genera. However, analyses of within period effects revealed a significant (false discovery rate ≤5%) increase in the relative abundance of 9 OTUs assigned to order Clostridiales, family Ruminococcaceae, genus Bacteroides, and species Prevotella copri, indicating a potential effect of quantitative or qualitative changes in habitual drinking habits. An increase in the concentration of plasma glucose at 30 minutes and the incremental area under the curve of plasma glucose from 0 30 and 0 120 minutes, respectively, was observed when comparing the alkaline to the neutral intervention. However, results did not withstand correction for multiplicity. In contrast to what has been reported in rodents, a change in drinking water pH had no impact on the composition of the gut microbiota or glucose regulation in young male adults. The study is registered at www.clinicaltrials.gov (NCT02917616).

Population-based studies of relationships between dietary acidity load, insulin resistance and incident diabetes in Danes

BACKGROUND

It has been suggested that the acidity of the diet may be related to increased risk of type 2 diabetes. To investigate this hypothesis, we tested if the acidity of the diet, measured as the Potential Renal Acid Load (PRAL) score, was associated with incident diabetes and diabetes-related intermediary traits.

METHODS

A total of 54,651 individuals from the Danish Diet, Cancer and Health (DCH) cohort were included in the prospective cox regression analyses of incident diabetes over a 15 years follow-up period. Moreover, 5724 Danish individuals with baseline data from the Inter99 cohort were included in the cross sectional, multivariate and logistic regression analyses of measures of insulin sensitivity, insulin release and glucose tolerance status derived from an oral glucose tolerance test (OGTT).

RESULTS

In the DCH cohort a trend analysis showed that quintiles of PRAL score were, after multifactorial adjustment, associated with a higher incidence of diabetes (p_trend = 6 × 10^- 7). HR for incident diabetes was 1.24 (1.14; 1.35) (p = 7 × 10^- 7) between first and fifth PRAL score quintile. In Inter99 higher PRAL score associated with insulin resistance as estimated by lower BIGTT-Si (an OGTT-derived index of insulin sensitivity) (p = 4 × 10^- 7) and Matsuda index of insulin sensitivity (p = 2 × 10^- 5) as well as higher HOMA-IR (p = 0.001). No association was observed for measures of insulin release, but higher PRAL score was associated with lower OGTT-based disposition index.

CONCLUSIONS

A high dietary acidity load is associated with a higher risk of diabetes among middle-aged Danes. Although adjustment for BMI attenuated the effect sizes the association remained significant. The increased risk of diabetes may be related to our finding that a high dietary acidity load associates with impaired insulin sensitivity.

The Associations of Dietary Acid Load with Insulin Resistance and Type 2 Diabetes: A Systematic Review of Existing Human Studies

BACKGROUND

Type 2 diabetes is a multifactorial disorder influenced by both genetic and environmental factors and is rising dramatically throughout the world. Recently, consideration to dietary acid-base load has been raised as a nutritional indicator that could have metabolic effects.

OBJECTIVE

The aim of this study was to systematically investigate the associations of dietary acid load indices with glucose/insulin homeostasis and type 2 diabetes in a patent based review.

METHODS

Systematic literature review was conducted using PubMed, Scopus and Google Scholar, from inception up to 10 January 2018. All human studies publications investigated the association of dietary acid load indices (PRAL or NEAP or Pro:K) and incidence of diabetes or glucose/insulin metabolism were included.

RESULTS

In all, 174 studies were included for the title and abstract screening. A total of 164 articles were excluded because they did not meet the inclusion criteria. Finally, 10 articles (five crosssectional studies and five cohort studies) in accordance with our inclusion criteria were chosen for further evaluations that were published between 2008 and 2017.

CONCLUSION

Although there are some evidence of an association between dietary acid load and type 2 diabetes, definitive declarations in this regard will be needed to intervention human studies modifying acid-base dietary intake.

Insulin Sensitivity and Glucose Homeostasis Can Be Influenced by Metabolic Acid Load

Recent epidemiological findings suggest that high levels of dietary acid load can affect insulin sensitivity and glucose metabolism. Consumption of high protein diets results in the over-production of metabolic acids which has been associated with the development of chronic metabolic disturbances. Mild metabolic acidosis has been shown to impair peripheral insulin action and several epidemiological findings suggest that metabolic acid load markers are associated with insulin resistance and impaired glycemic control through an interference intracellular insulin signaling pathways and translocation. In addition, higher incidence of diabetes, insulin resistance, or impaired glucose control have been found in subjects with elevated metabolic acid load markers. Hence, lowering dietary acid load may be relevant for improving glucose homeostasis and prevention of type 2 diabetes development on a long-term basis. However, limitations related to patient acid load estimation, nutritional determinants, and metabolic status considerably flaws available findings, and the lack of solid data on the background physiopathology contributes to the questionability of results. Furthermore, evidence from interventional studies is very limited and the trials carried out report no beneficial results following alkali supplementation. Available literature suggests that poor acid load control may contribute to impaired insulin sensitivity and glucose homeostasis, but it is not sufficiently supportive to fully elucidate the issue and additional well-designed studies are clearly needed.

Stability of potential renal acid load

AIM

The potential renal acid load (PRAL) has been described in relation to different health outcomes. Outcomes over time and conclusions made are often based on baseline dietary intake values. However, to study reliable long-term associations, parameters calculated based on dietary intake data, such as PRAL, must be stable over time. Therefore, the aim of the present study was to assess the stability of PRAL and its components over a 10-year time period.

METHODS

PRAL values of three-day dietary intake data from 197 women and 373 men on two assessment moments (2002-2004 and 2012-2014) were calculated. Pearson correlation and intra-class correlation coefficients were used for assessing the stability of PRAL and its components. Level of agreement between the two assessment moments was estimated after splitting up subjects in quintiles of PRAL, calculating kappa values and changes of quintiles over time.

RESULTS

No significant differences in mean PRAL over time were found. Stability of PRAL and its components was low. Poor agreement between the first and second assessment was shown by low kappa values and change of most of the subjects to an adjacent and non-adjacent quintile after 10 years.

CONCLUSIONS

Based on nutrition assessments carried out using three-day dietary records, stability of PRAL over a 10-year time period could not be confirmed, even though no significant difference between mean PRAL and its components over time was found. Therefore, interpretation of longitudinal outcomes based on PRAL and its component calculated at baseline should be interpreted with caution.