Causal associations between urinary sodium with body mass, shape and composition: a Mendelian randomization study

Ultra-Processed Food Consumption, Poorer Nutritional Quality, and Lower Muscle Mass in Immediate and Late Postkidney Transplant Periods

OBJECTIVE

To assess the consumption of ultra-processed foods (UPFs) in the immediate (2 months after transplantation) and late post-transplant (14 months after transplantation) periods among kidney transplant patients and to examine its correlation with nutritional quality and body composition.

DESIGN AND METHODS

A cross-sectional analysis of 96 kidney transplant recipients divided into 2 groups: immediate post-transplant (n = 71) and late post-transplant (n = 25). Sociodemographic, anthropometric, and laboratory data were collected and grouped in a database. Food intake was evaluated by a validated food frequency questionnaire and foods were divided according to the NOVA classification system. The consumption of UPFs was calculated and statistical analyses were performed to evaluate its correlation with nutritional components and body composition.

RESULTS

The consumption of UPFs was 649.4 [420.0-1061.72] kcal/day, accounting for 33.3 ± 11.9% of the total daily energy intake. The immediate post-transplant group showed higher total daily energy and UPFs intake compared to the late post-transplant group (P = .002 and P = .046, respectively), although the energy contribution of UPFs was similar between both groups. UPFs intake was positively correlated with higher percentages of total fat, trans fat, saturated, monounsaturated fat, polyunsaturated fat, starch, and sodium (P < .05 for all analyses). An inverse correlation was observed between UPFs consumption and the percentage of protein and carbohydrates in the food intake (P = .025 and P = .008, respectively). In the immediate post-transplant group, a higher intake of UPFs was correlated with lower muscle mass (r = -0.250, P = .037).

CONCLUSIONS

The findings of this study reveal a pattern of increased consumption of UPFs among kidney transplant patients in comparison to the national average. This higher intake of UPFs was correlated with lower nutritional quality during both periods. Moreover, a significant correlation was observed between UPFs consumption and adverse body composition parameters, specifically in the immediate post-transplant period.

Dietary salt intake and kidney function in rural Senegalese populations: a cross-sectional study

INTRODUCTION

High salt intake is a major risk factor for hypertension and its complications such as chronic kidney disease (CKD) and cardiovascular diseases. The present study aimed to determine level of sodium consumption and its relation with kidney function in the rural populations of Ferlo (centre of Senegal).

SUBJECTS AND METHODS

We performed a cross-sectional study including 400 volunteers aged > 18 years. Clinical, biological and dietary data were collected during household visits. Daily sodium intake was measured in the 24 h-urine outpout and CKD was defined as eGFR < 60 ml/min. Linear regression analysis was used to assess association between sodium intake and covariates.

RESULTS

Mean age was 46.42 ± 15.60 and sex-ratio was 1.05. Prevalence of hypertension, CKD and overweight were 21.5, 11.7 and 20.5%, respectively. The median daily salt intake was 11.7 g with interquartile range of 14.8 g. Only 11.25% of participants consumed less than 5 g/day. After multivariate analysis, high salt intake was associated with age > 60 years, overweight and CKD. However, gender and hypertension were not significantly associated with salt intake. Industrial broths (91.5%) and bread (85%) represented the main sources of dietary salt.

CONCLUSION

This study revealed high levels of daily salt intake contrasting with low potassium intakes in the majority of participants. Participants with CKD, overweight and age > 60 years presented higher salt consumption. Stategies to reduce salt consumption are urgently needed to reduce burden of CKD in rural Senegalese populations.

Obesity-related indicators and tuberculosis: A Mendelian randomization study

PURPOSE

Obesity is a strong risk factor for many diseases, with controversy regarding the cause(s) of tuberculosis (TB) reflected by contradictory findings. Therefore, a larger sample population is required to determine the relationship between obesity and TB, which may further inform treatment.

METHODS

Obesity-related indicators and TB mutation data were obtained from a genome-wide association study database, while representative instrumental variables (IVs) were obtained by screening and merging. Causal relationships between exposure factors and outcomes were determined using two-sample Mendelian randomization (MR) analysis. Three tests were used to determine the representativeness and stability of the IVs, supported by sensitivity analysis.

RESULTS

Initially, 191 single nucleotide polymorphisms were designated as IVs by screening, followed by two-sample MR analysis, which revealed the causal relationship between waist circumference [odds ratio (OR): 2.13 (95% confidence interval (CI): 1.19-3.80); p = 0.011] and TB. Sensitivity analysis verified the credibility of the IVs, none of which were heterogeneous or horizontally pleiotropic.

CONCLUSION

The present study determined the causal effect between waist circumference and TB by two-sample MR analysis and found both to be likely to be potential risk factors.

The Association Between Insulin Use and Asthma: An Epidemiological Observational Analysis and Mendelian Randomization Study

BACKGROUND

Asthma is a common respiratory disease caused by genetic and environmental factors, but the contribution of insulin use to the risk of asthma remains unclear. This study aimed to investigate the association between insulin use and asthma in a large population-based cohort, and further explore their causal relationship by Mendelian randomization (MR) analysis.

METHODS

An epidemiological study including 85,887 participants from the National Health and Nutrition Examination Survey (NHANES) 2001-2018 was performed to evaluate the association between insulin use and asthma. Based on the inverse-variance weighted approach, MR analysis were conducted to estimate the causal effect of insulin use on asthma from the UKB and FinnGen datasets, respectively.

RESULTS

In the NHANES cohort, we found that insulin use was associated with an increased risk of asthma [odd ratio (OR) 1.38; 95% CI 1.16-1.64; p < 0.001]. For the MR analysis, we found a causal relationship between insulin use and a higher risk of asthma in both Finn (OR 1.10; p < 0.001) and UK Biobank cohorts (OR 1.18; p < 0.001). Meanwhile, there was no causal association between diabetes and asthma. After multivariable adjustment for diabetes in UKB cohort, the insulin use remained significantly associated with an increased risk of asthma (OR 1.17, p < 0.001).

CONCLUSIONS

An association between insulin use and an increased risk of asthma was found via the real-world data from the NHANES. In addition, the current study identified a causal effect and provided a genetic evidence of insulin use and asthma. More studies are needed to elucidate the mechanisms underlying the association between insulin use and asthma.

Estimating population level 24-h sodium excretion using spot urine samples in older adults in rural South Africa

BACKGROUND

South Africa has introduced regulations to reduce sodium in processed foods. Assessing salt consumption with 24-h urine collection is logistically challenging and expensive. We assess the accuracy of using spot urine samples to estimate 24-h urine sodium (24hrUNa) excretion at the population level in a cohort of older adults in rural South Africa.

METHODS

24hrUNa excretion was measured and compared to that estimated from matched spot urine samples in 399 individuals, aged 40-75 years, from rural Mpumalanga, South Africa. We used the Tanaka, Kawasaki, International Study of Sodium, Potassium, and Blood Pressure (INTERSALT), and Population Mean Volume (PMV) method to predict 24hrUNa at the individual and population level.

RESULTS

The population median 24hrUNa excretion from our samples collected in 2017 was 2.6 g (interquartile range: 1.53-4.21) equal to an average daily salt intake of 6.6 g, whereas 65.4% of participants had a salt excretion above the WHO recommended 5 g/day. Estimated population median 24hrUNa derived from the INTERSALT, both with and without potassium, showed a nonsignificant difference of 0.25 g (P = 0.59) and 0.21 g (P = 0.67), respectively. In contrast, the Tanaka, Kawasaki, and PMV formulas were markedly higher than the measured 24hrUNa, with a median difference of 0.51 g (P = 0.004), 0.99 g (P = 0.00), and 1.05 g (P = 0.00) respectively. All formulas however performed poorly when predicting an individual's 24hrUNa.

CONCLUSION

In this population, the INTERSALT formulas are a well suited and cost-effective alternative to 24-h urine collection for the evaluation of population median 24hrUNa excretion. This could play an important role for governments and public health agencies in evaluating local salt regulations and identifying at-risk populations.

Association of sodium intake with adverse left atrial function and left atrioventricular coupling in Chinese

OBJECTIVES

High sodium intake is strongly associated with hypertension and obesity. This study aims to investigate the relationship between 24-h urinary sodium (a surrogate measure of sodium intake), ambulatory blood pressure parameters, left atrial function, and left atrioventricular coupling. Further, we intend to examine whether blood pressure and BMI might be mediators of the relationship between 24-h urinary sodium and subclinical cardiac function.

METHODS

Our study had 398 participants, all of whom were subjected to 24-h urine collection, 24-h ambulatory blood pressure measurement, and cardiac magnetic resonance imaging.

RESULTS

The average age of the participants was 55.70 ± 11.30 years old. The mean urinary sodium of the participants was 172.01 ± 80.24 mmol/24 h. After adjusting for age, sex, history of diabetes, smoking status, alcohol consumption, and use of diuretics, 24-h urinary sodium was correlated with multiple ambulatory blood pressure parameters, BMI, left atrial function, and the left atrioventricular coupling index (LACI) (P < 0.05). Mediation analysis showed that BMI explained 16% of the indirect effect of 24-h urinary sodium and left atrial function and 30% of the indirect effect of LACI. Independent of the mediator, 24-h urinary sodium had a significant direct effect on left atrial function and left atrioventricular coupling.

CONCLUSIONS

Higher 24-h urinary sodium was associated with a greater BMI as well as poor left atrial function and left atrioventricular coupling, and the BMI mediated the relationship between 24-h urinary sodium and subclinical left cardiac function. Furthermore, and more importantly, 24-h urinary sodium may have directly affected the left atrial function and left atrioventricular coupling independent of intermediary factors.

The association between salt intake and blood pressure is mediated by body mass index but modified by hypertension: The ELSA-Brasil study

High salt intake has been linked to both obesity and high blood pressure (BP). Part of the variability of BP attributed to salt intake might be BMI-mediated. To investigate whether hypertension would be an effect modifier in the complex network including salt intake, obesity, and BP, we tested the hypothesis that salt intake has direct and BMI-mediated effects on systolic (SBP) and diastolic blood pressure (DBP). Data from 9,028 participants (aged 34-75 years, 53.6% women) were analyzed. A validated formula was used to estimate daily salt intake from the sodium excretion (12 h urine collection). A path model adjusted for covariates was designed in which salt intake has both a direct and a BMI-mediated effect on BP. In normotensives, standardized beta coefficients showed significant direct (Men: 0.058 and 0.052, Women: 0.072 and 0,061, P < 0.05) and BMI-mediated (Men: 0.040 and 0.065, Women: 0.038 and 0.067, P < 0.05) effect of salt intake on the SBP and DBP, respectively. However, in hypertensive individuals, neither the direct (Men: 0.006 and 0.056, Women: 0.048 and 0.017) nor the indirect effect (Men: -0.044 and 0.014, Women: 0.011 and 0.050) of salt intake on the SBP and DBP were significant. These data suggest that cardiovascular risk stratification should consider the complex interaction between salt intake and weight gain, and their effects on BP of normotensive and hypertensive individuals.

The role of body mass index in the association between dietary sodium intake and blood pressure: A mediation analysis with NHANES

BACKGROUND AND AIMS

Recent research demonstrated that obesity and high dietary sodium intake, the two established risk factors for hypertension, were associated with each other. The objective was to investigate the potential indirect effect of sodium intake on blood pressure via body mass index (BMI).

METHODS AND RESULTS

Using ten years data from US NHANES (2007-2016), the study included adult participants (>20 years old) who were not taking antihypertensive medications and without baseline diseases (n = 12,262). BMI was modelled as the mediator of sodium intake on systolic and diastolic blood pressure, adjusted for age, sex, socioeconomic status, smoking, drinking, physical activity, calorie intake, fluid intake and potassium intake. Mediation analysis was performed to evaluate total effect, direct effect and indirect effect via BMI. Subgroup analyses based on three age subgroups (20-40, 41-60 and ≥61 years old) were performed. The mean age was 39.29 (13.4) years and 53.1 (0.45) % were males. The mean BMI was 27.8 (6.20) kg/m². Overall, 1 g/d increase in sodium intake was associated with an increased systolic blood pressure by 0.36 (95% confidence interval 0.14 to 0.58) mmHg, with a direct effect (0.14 (0.09-0.19)) and an indirect effect via BMI (0.23 (0.02-0.44)). The indirect effect was mainly observed in participants ≤60 years old.

CONCLUSION

Sodium intake showed both direct effect and indirect effect (via BMI) on systolic blood pressure in US NHANES. The findings provide evidence for combining sodium restriction and weight reduction measures for prevention of hypertension. Cautions should be taken when generalizing the findings to other populations with lower average BMI.

Role of skeletal muscle perfusion and insulin resistance in the effect of dietary sodium on heart function in overweight

Aims

Weight excess and insulin resistance predispose to heart failure. High sodium consumption may contribute to the development of cardiac impairment in insulin‐resistant individuals by promoting inadequate skeletal muscle microvascular perfusion response to insulin. We sought to investigate the association of dietary sodium reduction with muscle perfusion, insulin sensitivity, and cardiac function in overweight/obese insulin‐resistant (O‐IR) normotensive subjects.

Methods and results

Fifty O‐IR individuals with higher than recommended sodium intake were randomized to usual or reduced sodium diet for 8 weeks; 25 lean, healthy subjects served as controls for pre‐intervention measurements. Echocardiography and muscle perfusion were performed during fasting and under stable euglycaemic–hyperinsulinaemic clamp conditions. O‐IR patients demonstrated subclinical cardiac dysfunction as evidenced by lower left ventricular global longitudinal strain (GLS), e′ tissue velocity, and left atrial strain and reduced muscle perfusion. The intervention arm showed improvements in insulin resistance [glucose infusion rate (GIR)], GLS, e′, atrial strain, and muscle perfusion in fasting conditions, as well as improved responses of GLS and muscle perfusion to insulin during clamp. Significant interactions were found between the allocation to low‐salt diet and improvement in muscle perfusion on change in GIR at follow‐up (P = 0.030), and between improvement in muscle perfusion and change in GIR on change in GLS response to insulin at follow‐up (P = 0.026). Mediation analysis revealed that the relationship between the reduction of sodium intake and improvement in GLS was mediated by improvements in muscle perfusion and GIR (decrease in beta coefficient from −0.29 to −0.16 after the inclusion of mediator variables to the model).

Conclusions

The reduction of dietary sodium in the normotensive O‐IR population improves cardiac function, and this effect may be associated with the concomitant improvements in skeletal muscle perfusion and insulin resistance. These findings might contribute to refining heart failure preventive strategies.

Intake of processed meat, but not sodium, is associated with risk of colorectal cancer: Evidence from a large prospective cohort and two-sample Mendelian randomization

BACKGROUND & AIMS

Processed meat and high sodium intake are common in Western diet. The objective was to examine their independent effects on the risk of colorectal cancer (CRC).

METHODS

We performed both observational analysis with UK Biobank and genetic analysis with Mendelian randomization (MR). The 24-h urinary sodium (UNa) and reported intake of processed meat were fitted on incident CRC by multivariable Cox proportional hazard model, adjusted for covariates, such as age, gender, family history, etc. Different sodium measures were used for sensitivity analyses. Two-sample MR analyses were performed using summary data from genome-wide association studies of UNa and CRC. Multivariable MR was adjusted for body mass index.

RESULTS

We included 415 524 eligible participants from UK Biobank. During a median follow-up of 11.1 years, 2663 participants were diagnosed with CRC. High intake of processed meat independently increased risk of CRC by 23% (HR 1.23; 95% CI: 1.03 to 1.46), but 24-h UNa was not significantly associated with CRC (HR 0.96; 95% CI: 0.87 to 1.06). Furthermore, MR also showed little evidence for the effect of UNa on CRC (OR 1.02; 95% CI: 0.11 to 9.42). Sensitivity analyses showed consistent results across different measurements of sodium intake.

CONCLUSIONS

Intake of processed meat had an independent effect on the risk of CRC, but the risk was not associated with sodium level. Reduction of processed meat intake may be an effective strategy for CRC prevention, while sodium reduction should still be recommended to achieve other health benefits.