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

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.

Dietary acid load, depression, and anxiety: results of a population-based study

BACKGROUND

Dietary acid load seems to be associated with psychological disorders through several mechanisms, and may barricade their treatment and recovery. The aim of current study was to evaluate the relationship between dietary acid load, using potential renal acid load (PRAL) and dietary acid load (DAL) scores, with the severity of depression and anxiety among Iranian adults.

METHODS

A total of 6531 participants aged 35-65 years were recruited in this cross-sectional study. A validated food frequency questionnaire (FFQ) was used to assess dietary intakes of participants. DAL was estimated using PRAL and DAL scores. Depression and anxiety were screened using Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI).

RESULTS

In the fully adjusted model, women with the highest DAL or PRAL had higher odds of more severe depression compared to those in the lowest category (OR = 1.20; 95% CI = 1.03-1.42 and OR = 1.20; 95% CI = 1.03-1.39, respectively). No significant association was observed between DAL and PRAL and depression severity in men and in the population as a whole. Regarding the association between PRAL and anxiety severity, there was no significant association when separated by sex. However, in the fully adjusted model for the whole population, participants in the highest tertile of PRAL had 13% greater odds of more severe anxiety than the lowest tertile (OR: 1.13, 95% CI: 1.01-1.13). No significant association was observed between DAL and anxiety severity in women, men or in the whole population.

CONCLUSION

Women, but not men, with higher dietary acid load had significantly higher odds of having more severe depression. A significant positive association was also observed between dietary acid load and anxiety in the whole population.

How Well Do Low-PRAL Diets Fare in Comparison to the 2020-2025 Dietary Guidelines for Americans?

The regular consumption of net acid-producing diets can produce "acid stress" detrimental to human health. Alkalizing diets characterized by a negative potential renal acid load (also called low-PRAL diets (LPD)) enjoy uninterrupted popularity. However, the nutritional adequacy of said diets has rarely been assessed in large populations. Using data from the National Health and Nutrition Examination Surveys, we estimated nutrient intake in individuals consuming an LPD and contrasted the results in an age- and sex-specific manner to individuals on an acidifying diet (high-PRAL diet, HPD). Both groups were compared with the daily nutritional goals (DNG) specified in the 2020-2025 Dietary Guidelines for Americans (DGA). Our analysis included 29,683 individuals, including 7234 participants on an LPD and 22,449 participants on an HPD. Individuals on an LPD numerically met more nutritional goals than individuals on an HPD, yet both failed to meet the goals for several nutrients of public health concern (vitamin D and calcium). As opposed to individuals on an HPD, LPD consumers met the DGA recommendations for saturated fat and potassium. Individuals on an LPD consumed significantly more fiber than individuals on an HPD, as well as yielded a more favorable potassium-to-sodium intake ratio.

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 and esophageal cancer risk: A case-control study

Background

A high dietary acid load (DAL) can produce metabolic acidosis, which is linked to cancer development through mechanisms of inflammation and cell transformation. There is limited epidemiological evidence linking DAL and cancer risk; however, none of the published studies focused on DAL and esophageal cancer (EC) risk in particular. Therefore, we sought to explore this association in the present study.

Methods

A case‐control study was performed in 1295 male patients (185 squamous cell EC cases and 1110 age‐frequency and urban/rural residence matched controls) through a multitopic inquiry, including a food frequency questionnaire. Food‐derived nutrients were calculated from available databases. The DAL was calculated based on two validated measures: Potential renal acid load (PRAL) score and net endogenous acid production (NEAP) score. Odds ratios (OR) and their 95% confidence intervals (95% CI) were estimated by unconditional logistic regression, adjusting for confounders.

Results

We found direct, significant associations between dietary acid load and EC risk: (OR = 2.28, 95% CI: 1.44–3.61, ptrend <0.0001) and (OR = 2.17, 95% CI: 1.38–3.41, ptrend <0.0001) for highest PRAL and NEAP tertiles, respectively. Our data raise the possibility that a high DAL may contribute to EC development. Both acid load scores were directly associated with animal‐based foods (mainly meat) and inversely associated with the intake of plant‐based foods.

Conclusion

To the best of our knowledge, this is the first epidemiological case–control study analyzing associations of DAL and squamous cell EC risk. Further research is warranted to confirm our findings.