Does Sodium Intake Induce Systemic Inflammatory Response? A Systemic 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.

Sodium intake, life expectancy, and all-cause mortality

Aims Since dietary sodium intake has been identified as a risk factor for cardiovascular disease and premature death, a high sodium intake can be expected to curtail life span. We tested this hypothesis by analysing the relationship between sodium intake and life expectancy as well as survival in 181 countries worldwide. Methods and results We correlated age-standardized estimates of country-specific average sodium consumption with healthy life expectancy at birth and at age of 60 years, death due to non-communicable diseases and all-cause mortality for the year of 2010, after adjusting for potential confounders such as gross domestic product per capita and body mass index. We considered global health estimates as provided by World Health Organization. Among the 181 countries included in this analysis, we found a positive correlation between sodium intake and healthy life expectancy at birth (β = 2.6 years/g of daily sodium intake,R2 = 0.66,P < 0.001), as well as healthy life expectancy at age 60 (β = 0.3 years/g of daily sodium intake,R2 = 0.60,P = 0.048) but not for death due to non-communicable diseases (β = 17 events/g of daily sodium intake,R2 = 0.43,P = 0.100). Conversely, all-cause mortality correlated inversely with sodium intake (β = −131 events/g of daily sodium intake,R2 = 0.60,P < 0.001). In a sensitivity analysis restricted to 46 countries in the highest income class, sodium intake continued to correlate positively with healthy life expectancy at birth (β = 3.4 years/g of daily sodium intake,R2 = 0.53,P < 0.001) and inversely with all-cause mortality (β = −168 events/g of daily sodium intake,R2 = 0.50,P < 0.001). Conclusion Our observation of sodium intake correlating positively with life expectancy and inversely with all-cause mortality worldwide and in high-income countries argues against dietary sodium intake being a culprit of curtailing life span or a risk factor for premature death. These data are observational and should not be used as a base for nutritional interventions.

Identifying Interactions between Dietary Sodium, Potassium, Sodium–Potassium Ratios, and FGF5 rs16998073 Variants and Their Associated Risk for Hypertension in Korean Adults

Hypertension is affected by both genetic and dietary factors. This study aimed to examine the interaction between dietary sodium/potassium intake, sodium–potassium ratios, and FGF5 rs16998073 and link these with increased risk for developing hypertension. Using data from the Health Examinee (HEXA) Study of the Korean Genome and Epidemiologic Study (KoGES), we were able to identify a total of 17,736 middle-aged Korean adults who could be included in our genome-wide association study (GWAS) to confirm any associations between hypertension and the FGF5 rs16998073 variant. GWAS analysis revealed that the FGF5 rs16698073 variant demonstrated the strongest association with hypertension in this population. Multivariable logistic regression was used to examine the relationship between dietary intake of sodium, potassium, and sodium–potassium ratios and the FGF5 rs16998073 genotypes (AA, AT, TT) and any increased risk of hypertension. Carriers with at least one minor T allele for FGF5 rs16998073 were shown to be at significantly higher risk for developing hypertension. Male TT carriers with a daily sodium intake ≥2000 mg also demonstrated an increased risk for developing hypertension compared to the male AA carriers with daily sodium intake <2000 mg (adjusted odds ratio (AOR) = 2.41, 95% confidence intervals (CIs) = 1.84–3.15, p-interaction < 0.0001). Female AA carriers with a daily potassium intake ≥3500 mg showed a reduced risk for hypertension when compared to female AA carriers with a daily potassium intake <3500 mg (AOR = 0.75. 95% CIs = 0.58–0.95, p-interaction < 0.0001). Male TT carriers in the mid-tertile for sodium–potassium ratio values showed the highest odds ratio for hypertension when compared to male AA carriers in the lowest-tertile for sodium–potassium ratio values (AOR = 3.03, 95% CIs = 2.14–4.29, p-interaction < 0.0001). This study confirmed that FGF5 rs16998073 variants do place their carriers (men and women) at increased risk for developing hypertension. In addition, we showed that high daily intake of sodium exerted a synergistic effect for hypertension when combined with FGF5 rs16998073 variants in both genders and that dietary sodium, potassium, and sodium–potassium ratios all interact with FGF5 rs16998073 and alter the risk of developing hypertension in carriers of either gender among Koreans.

Correlation Between Spot Urine Sodium, 24 Hour Urinary Sodium and Food Frequency Questionnairein Estimation of Salt Intake in Healthy Individuals

Background:Salt intake is a known contributor to increased blood pressure. However, it is rarely monitored in clinical practice. 24-hr urinary sodium (24-HrNa) is the gold standard method to estimate salt intake but this method is rather burdensome.Objective: The objective of this study is to correlate between spot urine sodium (SUNa), 24-HrNa and Na intake estimation by food frequency questionnaire (FFQ) (FFQNa).Methods : 430 healthy participants aged between 20-40 years old were recruited. Second morning voided urine samples were obtained from all participants to estimate SUNa. 24-HrNa samples were obtained from 77 out of 430 participants. All participants were required to answer a validated FFQ. Urine samples were analysed for Na using indirect ion-selective electrode (ISE) method. Daily sodium intake was calculated from the FFQ.Results:The mean daily sodium intake from 24-hrNa (n=77) was 155 mmol/day, SUNa (n=430) was 158 mmol/L and FFQNa (n=430) was 271 mmol/day. There was a moderate correlation between SUNa and 24-hrNa (ρ = 0.62, P < 0.000). No correlation was seen between both 24-hrNa and SUNa with FFQNa (ρ = 0.035, P = 0.768 and ρ = 0.026, P = 0.597 respectively).Conclusion: Spot urine Na is a simple cost-effective method to estimate daily Na intake and has the potential to replace 24-hour urinary Na.International Journal of Human and Health Sciences Vol. 05 No. 01 January’21 Page: 74-80

Dietary Sources and Sodium/Salt Intake in Youngsters of Costa Rica

Objectives To describe major dietary sources of sodium/salt and estimate its intake among children and adolescents of Costa Rica. Methods Cross-sectional study of a nationally representative sample of 2677 youngsters aged 7 to 18 years who completed an intake food frequency. Wald F and t tests were used to examine differences between groups. Results Average daily sodium intake was highest among adolescents aged 12 to 18 years (3965 ± 920 mg). The lowest average daily sodium intake was particularly among girls under 12 years of age (2999 ± 94 mg). Twelve food categories contributed to more than half (58%) of Costa Rican youngsters sodium/salt which include: pizza, snacks, hamburger, hot dog, sausage, soups, puff pastry snacks, cheese, fried chicken, sauces/dressings, salted seeds and popcorn. Conclusions Costa Rican youngsters consume almost more than twice of recommended dietary sodium/salt, increasing their risk of high blood pressure and cardiovascular diseases. Funding Sources None.

Dietary Daily Sodium Intake Lower than 1500 mg Is Associated with Inadequately Low Intake of Calorie, Protein, Iron, Zinc and Vitamin B1 in Patients on Chronic Hemodialysis

Background: To measure daily sodium intake in patients on chronic hemodialysis and to compare the intake of nutrients, minerals, trace elements, and vitamins in patients who had a daily sodium intake below or above the value of 1500 mg recommended by the American Heart Association. Methods: Dietary intake was recorded for 3 days by means of 3-day diet diaries in prevalent patients on chronic hemodialysis. Each patient was instructed by a dietitian on how to fill the diary, which was subsequently signed by a next of kin. Results: We studied 127 patients. Mean sodium intake (mg) was 1295.9 ± 812.3. Eighty-seven (68.5%) patients had a daily sodium intake <1500 mg (group 1) and 40 (31.5%) ≥ 1500 mg (group 2). Correlation between daily sodium intake and daily calorie intake was significant (r = 0.474 [0.327 to 0.599]; p < 0.0001). Daily calorie intake (kcal/kg/day) was lower in group 1 (21.1 ± 6.6; p = 0.0001) than in group 2 (27.1 ± 10.4). Correlation between daily sodium intake and daily protein intake was significant (r = 0.530 [0.392 to 0.644]; p < 0.0001). The daily protein intake (grams/kg/day) was lower in group 1 (0.823 ± 0.275; p = 0.0003) than in group 2 (1.061 ± 0.419). Daily intake of magnesium, copper, iron, zinc, and selenium was significantly lower in group 1 than in group 2. Daily intake of vitamin A, B2, B3, and C did not differ significantly between group 1 and group 2. Daily intake of vitamin B1 was significantly lower in group 1 than in group 2. Significantly lower was, in group 1 than in group 2, the percentage of patients within the target value with regard to intake of calories (11.5% vs. 37.5%; p = 0.001) and proteins (9.2% vs. 27.5%; p = 0.015) as well as of iron (23% vs. 45%; p = 0.020), zinc (13.8% vs. 53.8%; p = 0.008) and vitamin B1 (8.1% vs. 50%; p < 0.001). Conclusion: A low daily intake of sodium is associated with an inadequately low intake of calorie, proteins, minerals, trace elements, and vitamin B1. Nutritional counselling aimed to reduce the intake of sodium in patients on chronic hemodialysis should not disregard an adequate intake of macro- and micronutrients, otherwise the risk of malnutrition is high.

Utility of a 24-Hour Urine Collection in Estimating Daily Sodium and Protein Intakes in Living Kidney Donation (P12-058-19)

Objectives Dietary intake can promote good health including blood pressure control from low sodium intake, slow progression of chronic kidney disease (CKD) from low protein diet. Counseling how to control amount of diet may be unpractical unless there is objective information of consumed nutrient. A 24-hour urine collection can provide information regarding the amount of intake nutrient. We present a case of healthy women comes for a living kidney donor evaluation and 24-hour urine collection showed high daily sodium and protein intake and lowering sodium and protein intake are advice for the patient. Methods A 37-year-old Caucasian woman with a past medical history significant for possible gestational diabetes mellitus comes to pre-living kidney donation clinic. She would like to donate her kidney to her friend who has end-stage renal disease from a lupus nephritis. The patient denies history of kidney diseases, dysuria, gross hematuria, difficulty urination, or history of passing kidney stone. Her weight was 49.4 kg, height was 1.47 m, and body mass index was BMI 22.76 kg/m². Blood pressure was 126/76 mmHg. Serum creatinine was 0.7 mg/dL and blood urea nitrogen was 14 mg/dL. A 24-hour urine collection showed volume of 1.98 L, microalbumin of 0.24 g, creatinine of 0.9 g, urine urea of 10.1 g, and sodium of 174. Results Calculations from the 24-hour urine collection include a daily urinary creatinine excretion of 18.22 mg/kg/day indicating adequately collected urine and creatinine clearance of 89.21 ml/min. Since urine sodium was 174 mmol/day, calculated daily sodium intake was 4 g. Daily protein intake of 16% of daily protein excretion was 11.63 g/day; therefore, daily protein intake was 72.7 g/day or 1.47 g/kg/day. She was advice to decrease amount of daily sodium intake to 62% (2.5 g/day) and protein intake to 68% (1 g/kg/day) of her current daily dietary intake. Conclusions From the 24-hour urine collection, we can estimate 2 important nutrients that our patient took a day. Calculated daily sodium and protein intake were 4 g/day and 1.47 g/kg/day, respectively. These amounts of sodium and protein intake are higher than recommended daily amount for general population. Particularly, for the person who plan to donate their kidney and will have lower than normal renal function after kidney donation, should have more strict diet control. Therefore, calculated amount of daily nutrient intake from a 24-hour urine collection provide practical care and recommendation to person who need dietary guidance with subjective evidence. Funding Sources None.