Sodium and potassium urinary excretion levels of preschool children: Individual, daily, and seasonal differences

Seasonal fluctuation of total water intake and hydration status among young men and women: a prospective cohort study

Background

Water intake and hydration status have been reported to fluctuate throughout the year. This study investigated seasonal fluctuations of total water intake and hydration status among young adults in Baoding, China.

Methods

This prospective cohort study enrolled 82 young adults aged 18-23 years in Baoding, China. Total drinking fluids consumed and water from food were assessed, and the osmolality and electrolyte concentrations of 24-h urine and fasting blood samples were determined. Differences among the four seasons were compared by mixed linear models, followed by determinations of least-significant differences (LSD), with spring used as the reference.

Results

Seventy-nine participants (43 men and 36 women) completed the study. Total water intake (TWI) was 359 ~ 429 mL higher in spring and summer than in autumn and winter and was 116 mL higher in summer than in winter (all p < 0.05). Chinese recommendations for TWI were met by 13.9% to 22.8% of participants, and recommendations for total fluid intake were met by 10.1% to 16.5%, but these differences were not statistically significant (p > 0.05). Urinary and plasma biomarkers differed significantly among the four seasons (p < 0.05), with osmolality and urine specific gravity (USG) being significantly higher in summer than in other seasons (p < 0.05). The percentage of participants with optimal hydration status increased from 38.0% in summer to 62.0% in spring (p < 0.05). Men had more concentrated urine as well as higher plasma osmolality and solute concentrations than women during each season of the year (p < 0.05).

Conclusion

TWI and urinary and plasma biomarkers of hydration were found to vary seasonally among Chinese young adults, with hydration status being poorer in summer. Men need to pay more attention than women to maintain optimal hydration status.

Clinical trial registration

https://www.chictr.org.cn/showproj.html?proj=124857, ChiCTR2100045268.

The association of schooling, sibling life situation, and dietary habits with the estimated 24-h urinary salt excretion and sodium-to-potassium ratio in 3-year-old children

OBJECTIVES

We examined the association of schooling, sibling life situation, and dietary habits with the estimated 24-h urinary salt excretion and the urinary sodium-to-potassium (Na/K) ratio in 3-year-old children.

METHODS

The subjects were 639 children who underwent a health checkup in four cities and towns in Kyoto Prefecture from January to November 2019. The children's parents answered questionnaires about weekday childcare places, the birth order, and the awareness of reducing the salt intake. The questions on food intake frequency included 10 items. The estimated 24-h salt excretion and Na/K ratio were calculated from the participants' first voiding urine in the morning.

RESULTS

Data were available for 294 children. The median (interquartile range (IQR)) of salt excretion (g/day) was 2.6 (1.7-3.4), and urinary Na/K ratio (mmol ratio) was 2.6 (1.6-4.1). Multinomial logistic regression analysis showed that the group with older siblings was significantly associated with high salt (odds ratio 1.89 (95% confidence interval 1.04 to 3.46)). In the urinary Na/K ratio, the nursery group had a significantly lower Na/K (odds ratio 0.32 (0.17 to 0.60)). High processed meat products intake was associated with a higher Na/K (odds ratio 1.96 (1.05-3.66)), whereas high vegetable intake was associated with a lower Na/K (odds ratio 0.45 (0.23-0.87)). Other factors showed no significant associations.

CONCLUSIONS

In Japanese 3-year-old children, the estimated 24-h urinary salt excretion was associated with older siblings, and the urinary Na/K ratios were associated with schooling situation and the intake of processed meat products and vegetables.

Strategies for improving the treatment and control of hypertension in Japan

Despite the significant advancements in the diagnosis and treatment of hypertension, the burden of hypertension remains a major global health care concern. In Japan, estimates show that more than two-thirds of the population have uncontrolled hypertension, regardless of whether they were taking antihypertensive medication. To improve hypertension management, hypertension guidelines have been developed and updated regularly by hypertension societies across various countries and regions. The Japanese Society of Hypertension (JSH) updated the Guidelines for the Management of Hypertension in 2019 (JSH 2019). The JSH 2019 aims to establish a standard management strategy for hypertension and provide evidence to all health care providers. One of its updated main features is its proposal for multidisciplinary team-based care (TBC) involving physicians, pharmacists, nurses, dietitians, and other health care providers. The TBC will help initiate and intensify the management of hypertension, as well as combat clinical inertia, which is expected to contribute to uncontrolled blood pressure and subsequent development of cardiovascular diseases. This is consistent with the recommendations from recent major guidelines on hypertension management. Moreover, to reduce the evidence-practice gap in hypertension management, it is essential to disseminate the essence of the guidelines and provide hypertension education programs for all health care providers and patients. This review summarizes the points of the JSH 2019-based strategy for improving hypertension management and discusses guidelines for its implementation into actual clinical practice.

Dietary salt intake in Japan - past, present, and future

Salt reduction is the most important lifestyle modification, especially in Japanese individuals who still consume a significant amount of salt. The Dietary Reference Intakes for Japanese 2020, issued by the Ministry of Health, Labour and Welfare, propose a salt intake goal of <7.5 g/day for men and <6.5 g/day for women. Regarding the goal of salt reduction in hypertensive patients, the hypertension guideline by the Japanese Society of Hypertension 2019 (JSH2019) proposes a goal of <6 g/day. Although the average salt intake in Japan gradually decreased in the early 2000s, the declining trend has not been seen in recent years, and thus, it seems difficult to achieve these target salt intake levels. To overcome this challenge, the JSH announced the 'JSH Tokyo Declaration' and pledged to create a specific action plan to achieve the target salt intake level of <6 g/day. The six strategies to achieve the target salt intake level are as follows: (1) educating citizens on the harms of excessive salt intake and the importance of reducing salt intake; (2) recommending the assessment of the salt intake of individuals or populations and proposing adequate methods to reduce salt intake; (3) promoting salt reduction for children as a part of dietary education at school; (4) promoting salt reduction in takeout food, prepared dishes, canteens, and school lunches; (5) encouraging companies to develop and promote low-salt foods; and (6) encouraging the government to take measures to promote salt reduction. Through these activities, a society with a low salt intake will be expected in the near future.

Association between urinary sodium-to-potassium ratio and home blood pressure and ambulatory blood pressure: the Ohasama study

OBJECTIVE

No studies have demonstrated the association between urinary sodium-to-potassium (Na/K) ratio and all out-of-office blood pressure (BP) [home morning and evening BP (self-measured at home), and 24-h, daytime, and night-time ambulatory BP] in the same cohort. We aimed to assess, which type of out-of-office BP is more strongly associated with urinary Na/K ratio in the general population.

METHODS

This cross-sectional study was conducted in the general population of Ohasama, Japan. Home and ambulatory BP levels were measured, and 24-h urine samples were obtained from 875 participants (men, 25.5%; mean age, 60.1 years). The urinary Na/K ratio in the 24-h urine samples was calculated.

RESULTS

The median (interquartile range) urinary Na/K ratio was 4.19 (3.36-5.26). Significant positive trends of home morning, home evening, 24-h, and daytime SBP were observed across quartiles of urinary Na/K ratio (trend P ≤ 0.041; adjusted mean values between Q1 and Q4 of urinary Na/K ratio: 121.0-125.5 mmHg for home morning, 120.1-123.8 mmHg for home evening, 121.6-123.4 mmHg for 24-h, 127.5-129.5 mmHg for daytime). Urinary Na/K ratio was not significantly associated with office or night-time SBP and nocturnal BP fall (trend P ≥ 0.13). In the model with both home morning or evening SBP and daytime SBP, only home SBP was significantly associated with urinary Na/K ratio (P ≤ 0.048 for home SBP).

CONCLUSION

These findings suggest that urinary Na/K ratio might be more strongly associated with home BP than with 24-h and daytime BP but was not associated with night-time BP.

Analysis of spot urine biomarkers and association with body weight in Japanese elementary schoolchildren

Childhood obesity is rapidly increasing worldwide and is largely the consequence of adoption of unhealthy diets excessive in calories and salt (NaCl) as well as devoid in pivotal micronutrients such as potassium (K) and magnesium (Mg). Education-based programs aiming to encourage healthy food knowledge and behaviors are crucial at a young age, and for this purpose, convenient ways to assess daily dietary intake are warranted. We therefore attempted to evaluate the dietary intake of Okinawan schoolchildren in Japan by analyzing a series of biomarkers in morning spot urine samples and explore whether these biomarkers correlate with body weight and a series of metabolic parameters. We enrolled 98 third-grade elementary schoolchildren in Okinawa, Japan. Morning spot urine samples were collected and analyzed using high-performance liquid chromatography (HPLC) to assess dietary intake. We found that estimated daily NaCl intake was higher in obese/overweight children as compared to healthy-weight children (p = 0.0001). There was also a significant positive correlation between body mass index (BMI) and NaCl intake (Spearman) (ρ = 0.45, p < 0.0001) and a negative correlation between BMI and Mg/Cr (ρ =  -0.27, p = 0.01). Furthermore, Na/K ratio was higher in samples collected on Monday (weekend) as compared to samples collected on Thursday or Friday (weekday) (p < 0.0001).

CONCLUSION

Via the use of morning spot urine analyses, our results show that NaCl intake was associated with obesity, and Mg excretion negatively correlated with BMI in Japanese schoolchildren, highlighting the potential role of these micronutrients in maintaining a healthy body weight.

WHAT IS KNOWN

•Overweight and obesity are largely due to excessive consumption of calories and positively correlated with salt (NaCl) intake. •Spot urine methods are convenient for assessing the nutritional needs and targeting prevention programs in children.

WHAT IS NEW

•Utilizing morning spot urine analyses, estimated NaCl intake is positively correlated and Mg/Cr negatively correlated with BMI in Okinawan schoolchildren. •As estimated via morning spot urine samples, a greater proportion of children likely exceeds the recommended NaCl intake on the weekend as compared to weekday.

Necessity of salt intake reduction education beginning in youth: a cross-sectional survey of sodium-to-potassium ratios in mothers and their preschool children

Urinary sodium-to-potassium ratios are known to be high in preschoolers, but there are no reports comparing these ratios with those of the children's mothers. The aim of this study was to investigate the association between the urinary sodium-to-potassium ratios of mothers and their preschool children under the hypothesis that the ratio is equivalent between the two. We evaluated 297 preschoolers aged four to five attending six kindergartens (four in northern Japan, two in southern Japan), and we also evaluated the children's mothers. We asked the participants to take morning first urine samples for 2 consecutive days in the spring and autumn of the same year (four samples per participant) and to fill out a dietary questionnaire. There was a correlation between the urinary sodium-to-potassium ratios of preschoolers and those of their mothers. However, in a comparison between the preschoolers and their mothers overall, higher values were found in the preschoolers [preschoolers: 4.6 (3.5-6.3) mmol/L/g·Cr; mothers: 4.3 (3.9-4.7) mmol/L/g·Cr, p = 0.003]. These results correlated with the urinary sodium-to-potassium ratios estimated from the dietary questionnaire. The preschoolers showed high sodium and low potassium intake consumption compared to the mothers. Interestingly, these were found to differ by region and gender. In conclusion, the urinary sodium-to-potassium ratio in Japanese preschoolers is related to and higher than that of their mothers. It is important to educate children, their parents, childcare professionals, and society as a whole about proper salt restriction and potassium supplementation, as well as to improve the food environment.

The Development of a Web-Based Program to Reduce Dietary Salt Intake in Schoolchildren: Study Protocol

BACKGROUND

Salt intake of schoolchildren in the Australian state of Victoria is high. To protect future cardiovascular health, interventions that seek to reduce the amount of salt in children's diets are required.

OBJECTIVE

We sought to develop and pilot test a Web-based program (Digital Education to Limit Salt Intake in the Home [DELISH]) that aims to reduce dietary salt intake among schoolchildren and to improve child and parent knowledge, attitudes, and behaviors related to salt intake. This paper presents the DELISH study protocol, along with pilot findings used to inform the development of the program.

METHODS

The DELISH program is a 5-week Web-based intervention that targets schoolchildren aged 7-10 years and their parents. This is a single-arm study with a pretest and posttest design. We will assess change in salt intake through analysis of 24-hour urinary sodium excretion. Children and parents will complete online surveys assessing knowledge, attitudes, and behaviors related to salt intake. We will assess feasibility of the program via process measures, which include metrics to describe intervention uptake (eg, number of children who complete Web-based sessions and of parents who view online newsletters) and evaluation surveys and interviews conducted with children, parents, and schoolteachers. The first 2 Web sessions developed for children were pilot tested in 19 children aged 8-12 years.

RESULTS

Findings from pilot testing indicated that most children (session 1: 18/19, 95%; and session 2: 19/19, 100%) enjoyed completing each session and liked the inclusion of comic strips and interactive games. Commonly reported areas of improvement related to sessions being text and content heavy. Based on these findings, we simplified sessions and developed 3 additional sessions for use in the DELISH program. The DELISH program was implemented during June-December 2016. We expect to have results from this study at the end of 2017.

CONCLUSIONS

To our knowledge, this is the first Australian study to examine the effectiveness of a Web-based program to reduce salt intake among children in primary school. If shown to be acceptable and effective in lowering salt intake, the DELISH program could be tested using a more rigorous randomized controlled trial design.