Current Data on Dietary Sodium, Arterial Structure and Function in Humans: A Systematic Review

Dietary Sodium Consumption and 3-Year Progression of Subclinical Arterial Damage in Adults with Cardiovascular Risk Factors

Background/Objectives: Available data regarding associations between sodium (Na) intake and biomarkers of subclinical arterial damage (SAD) are scarce. This study aimed to investigate the possible associations between Na intake and the 3-year progression of SAD in subjects with cardiovascular disease (CVD) risk factors. Methods: Participants underwent CVD risk assessment, vascular assessment [arterial stiffness by pulse wave velocity (PWV), and atheromatosis, as the existence of carotid and/or femoral plaques], anthropometric measurements [at baseline and 3-year follow-up (FU)], and dietary assessment at FU. Results: A total of 675 adults (47.9% males, 55.02 ± 13.79 years) were included. Na daily consumption quartiles (Qs) ranged from very low consumption in Q1 (811.72 ± 241.81 mg) up to twice the recommendations in Q4 (3487.92 ± 1025.92 mg). No statistically significant associations were observed between Na intake and changes in SAD biomarkers, after adjustment for age, sex, presence of hypertension, presence of dyslipidemia, smoking, mean arterial pressure, BMI, chronic inflammatory diseases, and energy intake. The results remained the same, even after the assessment of misreporting and the correction of Na intake. Conclusions: Dietary Na intake was not significantly associated with changes in PWV and carotid or femoral plaques, even in the high Q that was twice as high as the recommended intake. Research in different additional adult cohorts is needed to further investigate whether Na consumption independently affects vascular health.

Dietary Intake and Arterial Stiffness in Children and Adolescents: A Systematic Review

Arterial stiffness is a risk factor for cardiovascular disease that is affected by diet. However, research understanding how these dietary risk factors are related to arterial stiffness during childhood is limited. The purpose of this review was to determine whether various dietary factors were associated with arterial stiffness in the pediatric population. Five databases were systematically searched. Intervention studies, cross-sectional and cohort studies were included that investigated nutrient or food intake and outcomes of arterial stiffness, primarily measured by pulse wave velocity (PWV) and augmentation index (AIx), in the pediatric population (aged 0-18 years). A final 19 studies (six intervention and 13 observational) were included. Only two intervention studies, including a vitamin D and omega-3 supplementation trial, found protective effects on PWV and AIx in adolescents. Findings from observational studies were overall inconsistent and varied. There was limited evidence to indicate a protective effect of a healthy dietary pattern on arterial stiffness and an adverse effect of total fat intake, sodium intake and fast-food consumption. Overall, results indicated that some dietary factors may be associated with arterial stiffness in pediatric populations; however, inconsistencies were observed across all study designs. Further longitudinal and intervention studies are warranted to confirm the potential associations found in this review.

Eater-oriented knowledge framework for reducing salt and dietary sodium intake (scoping review)

Salt and dietary sodium are ubiquitously present in daily food practices and, at the same time, reducing salt intake presents an important public health issue. Given such an ambivalent position of salt in human diet, we argue that public health guidelines toward dietary sodium reduction require an eater-oriented knowledge framework. In this article we are making the first steps toward a flexible interdisciplinary database which would include nutritional, socio-economic, cultural, material, and socio-psychological determinants of salt consumption for comprehensive public health campaigns. We employ an explorative scoping review of academic articles and reports, limiting our review to the original data on salt or sodium consumption published in English or French between 2000 and 2022. We describe salt consumption as research object, identifying its representation in different research fields, data sources, methodologies, samples, and links with nutritional recommendations. We synthesize existing approaches via four eater-oriented categories: Socio-demographic and cultural descriptors of salt consumers; Knowledge, attitudes, and beliefs on nutritional norms; Salt practices associated with dietary or medical regimes; Salt materialities: interactions and contexts. In each category, we identify the dominant relational features, i.e., what kind of 'eater-salt' relation is being put forward. We thus build an interdisciplinary documentary base of dietary sodium consumption factors. We discuss the results, suggesting that comprehensive nutritional policies for global salt reduction require interdisciplinary eater-oriented data frameworks.

Dietary sodium intake and sodium load is associated with arterial stiffness in children and young adults

OBJECTIVE

The aim of this study was to examine the association of sodium intake (g/day) and sodium load (Na-L; mg/kcal/day) on arterial stiffness in youth.

METHODS

A cross-sectional analysis of 723 youth enrolled in a study evaluating the cardiovascular effects of obesity and type 2 diabetes mellitus (T2DM). Three measures of arterial stiffness were evaluated: brachial distensibility (BrachD), carotid-femoral pulse wave velocity (PWVcf) and augmentation index (AIx). Three-day diet histories yielded mean daily sodium and calorie intake. Youth were divided into Na-L tertiles: Low (≤1.67 mg/kcal per day); Medium (1.68--1.98 mg/kcal per day) and High (>1.98 mg/kcal per day). General linear models adjusting for demographics, % body fat, T2DM and SBP z-score evaluated the independent association of Na-L with arterial stiffness.

RESULTS

Mean age was 17.9 years (10-24 years), 35% male, 59% nonwhite and 31% T2DM. Mean (±standard deviation) dietary intake was calories = 2074 (±797) kcal/day; Na = 3.793 (±1567) g/day; Na- = 1.86 (±0.753) mg/kcal per day. With higher levels of dietary Na intake and Na-L, measures of arterial stiffness worsened: BrachD decreased (Na intake: beta = -0.09, P = 0.003; Na-L: beta = -0.28, P < 0.0001), PWVcf increased (Na intake: beta = 0.07, P = 0.007; Na-L: beta = 0.21, P < 0.0001) but AIx did not change (Na intake: beta = -0.4, P = 0.2; Na-L: beta = 0.89, P = 0.11). In multivariable analysis, High Na-L was independently associated with BrachD, PWVcf and AIx (P < 0.05 for all), with age modifying the association of High Na-L with PWVcf and AIx.

CONCLUSION

Sodium intake and load are associated with arterial stiffness, a preclinical measure of CVD, among a paediatric population. Paediatricians should stress healthy dietary choices to reduce accelerated vascular ageing.

Does Sodium Intake Induce Systemic Inflammatory Response? A Systematic Review and Meta-Analysis of Randomized Studies in Humans

Experimental studies suggest that sodium induced inflammation might be another missing link leading to atherosclerosis. To test the hypothesis that high daily sodium intake induces systemic inflammatory response in humans, we performed a systematic review according to PRISMA guidelines of randomized controlled trials (RCTs) that examined the effect of high versus low sodium dose (HSD vs. LSD), as defined per study, on plasma circulating inflammatory biomarkers. Eight RCTs that examined CRP, TNF-a and IL-6 were found. Meta-analysis testing the change of each biomarker in HSD versus LSD was possible for CRP (n = 5 studies), TNF-a (n = 4 studies) and IL-6 (n = 4 studies). The pooled difference (95% confidence intervals) per biomarker was for: CRP values of 0.1(-0.3, 0.4) mg/L; TNF-a -0.7(-5.0, 3.6) pg/mL; IL-6 -1.1(-3.3 to 1.1) pg/mL. Importantly, there was inconsistency between RCTs regarding major population characteristics and the applied methodology, including a very wide range of LSD (460 to 6740 mg/day) and HSD (2800 to 7452 mg/day). Although our results suggest that the different levels of daily sodium intake are not associated with significant changes in the level of systemic inflammation in humans, this outcome may result from methodological issues. Based on these identified methodological issues we propose that future RCTs should focus on young healthy participants to avoid confounding effects of comorbidities, should have three instead of two arms (very low, "normal" and high) of daily sodium intake with more than 100 participants per arm, whereas an intervention duration of 14 days is adequate.

Dietary sodium and cardiovascular morbidity/mortality: a brief commentary on the 'J-shape hypothesis'

The last decade, a growing number of evidence support J-shape or inverse - instead of positive linear -- associations between dietary sodium intake and cardiovascular morbidity/mortality. A careful evaluation of these studies leads to the following observations: less accurate methods for dietary sodium assessment are usually used; most studies included high-risk participants, enhancing the possibility of a 'reverse causality' phenomenon. However, these limitations do not explain all the findings. Few carefully designed randomized clinical trials comparing different levels of sodium intake that address the issue of the optimal and safe range exist; therefore, current guidelines recommend a higher cut-off instead of a safe range of intake. Given the demonstrated harmful effects of very low sodium diets leading to subclinical vascular damage in animal studies, the 'J-shape hypothesis' cannot yet be either neglected or verified. There is a great need of well-designed general population-based prospective randomized clinical trials to address the issue.

A Comprehensive Study on the Influence of Sodium Chloride on the Technological Quality Parameters of Soft Wheat Dough

This study aimed at understanding how the presence or absence of NaCl influences dough rheological performance of soft wheat cvs. currently used in the Italian bread manufacturing industry as a scientific support to national health strategies to reduce the use of NaCl in bread. For this reason 176 flour samples belonging to 41 soft wheat cvs. currently cultivated in Italy, were analyzed for their protein content, Zeleny sedimentation value, and by means of the Chopin Alveograph and Brabender Farinograph, with no salt and with 1.5% salt addition (average salt content in Italian bread). Three selected cvs. (Aubusson, Bolero, and Blasco) were additionally studied by means of the Rapid Visco Analyzer (RVA) at three levels of salt addition (0%, 1.5% and 3.0%). The fermentation behaviour of the cvs. Aubusson and Blasco was also studied by means of a Rheofermentometer under the same conditions. The results of our study confirmed the role of salt in strengthening the wheat gluten network (up to 86%), and thus the gas retention of dough and in affecting yeast activity. However, it also definitely proved that careful cultivar selection can help in overcoming technical challenges in reduced-salt bread manufacturing and eventually, it opens the path to wheat breeding for reduced-salt bread baking.