Salt intake in 3-year-old Japanese children

Abstract

Salt restriction is widely recommended for the prevention and management of hypertension. It is very important to reduce salt intake during childhood. This survey was conducted to investigate salt intake in Japanese children. The study subjects, totalling 1424, comprised 3-year-old children who received health checkups conducted by a public health center. Using first-morning urine samples, urinary concentrations of sodium, potassium and creatinine were measured. Additionally, the participants' parents filled out a questionnaire regarding their children's dietary habits. Urinary sodium and potassium concentrations were 140 ± 67 and 67 ± 41 mmol l À1 , respectively. The estimated urinary sodium excretion values had a wide distribution, with a mean value of 75±47 mmol per day (4.4 g per day of salt). Sodium excretion exceeded 100 and 200 mmol per day in 336 (24%) and 32 (2.2%) subjects, respectively. Urinary sodium excretion was significantly higher in children who had older siblings than in firstborn children (78 ± 49 vs. 72 ± 45 mmol per day, Po0.05). The urinary sodium/potassium ratio was also higher in the former group (3.0±2.7 vs. 2.7±2.2, Po0.01). Sodium excretion tended to be higher in children who ate daily snacks than in those who did not (76±48 vs. 71±44 mmol per day, P¼0.07). In contrast, potassium excretion was significantly higher and the sodium/potassium ratio was lower in children who ate fruits daily than those who did not (39 ± 29 vs. 33 ± 23 mmol per day and 2.6 ± 2.0 vs. 3.2 ± 2.7, Po0.01, respectively). These results suggest that excess salt intake occurs in a significant number of 3-year-old Japanese children. The presence of older siblings and dietary habits of eating snacks or fruits influence their sodium and potassium intake.

Association between daily salt intake of 3‐year‐old children and that of their mothers: A cross‐sectional study

“…We hypothesized that living with grandparents could result in higher salt intake of the children, as elderly people in Japan tend to consume more salt than young people do, and their taste preference for salt might influence salt consumption in their grandchildren. Moreover, it has been suggested that having older siblings might be related to increased salt intake in children, though this was based only on univariate analysis . It is possible that older siblings who enjoy salty snacks are likely to expose younger siblings to them early, but our analysis found no significant associations between the daily salt intake of the children and family structure.…”

“…Although the ideal method for estimating daily salt excretion is 24‐hour urine collection, it is very difficult to collect 24‐hour urine from a 3‐year‐old child; according to a previous study, only about half of such attempts are successful . We therefore used a formula developed by Morinaga and colleagues that estimates daily salt excretion based on a first morning urine sample. The formula, which assumes a 24‐hour urinary creatinine excretion in 3‐year‐old children of 300 mg, is as follows: 24‐hour salt excretion (g/d) = 0.0585 × 300 × (NaM/CrM), where NaM is the sodium concentration in the first morning urine (mEq/L) and CrM is the creatinine concentration in the first morning urine (mg/L).…”

“…This effect is modifiable, and trials of salt‐reduced diets in children have led to lower blood pressures and even prevention of subsequent hypertension . In Japan, one of the countries with the highest salt intake, the mean salt intake in 3‐year‐old children is quite high at 4.4 g/d . According to the Japanese Ministry of Health, Labour and Welfare, the recommended daily salt intake for 3‐year‐old children is less than 4.5 g for girls and less than 4.0 g for boys .…”

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

“…In a study of 79 children aged 3 to 5 years, Haga and colleagues used a 24‐hour urine collection method and reported that the urinary sodium excretion level was 79 mmol/d (salt: 4.6 g/d). Morinaga and colleagues estimated the urinary sodium excretion of 1424 children aged 3 years using spot urine samples, and reported the mean value as 75 mmol/d (salt: 4.4 g/d). However, these results for sodium intake and excretion are from 1‐ to 2‐day studies, which may not reflect the average intake/excretion levels of sodium and potassium because these fluctuate within and between children .…”

Urinary Sodium and Potassium excretion among Year 4 pupils in Choshi city, Japan

“…All participants (358 participants; boys 193, girls 165) underwent anthropometric measurement (weight, height, obesity index) and the measurement of Systolic blood pressure (SBP) and diastolic blood pressures (DBP) by an automatic sphygmomanometer. Urinary sodium, potassium and creatinine concentrations using the first morning urine specimen were measured, and the 24hr intake of sodium and potassium were estimated (2,3) . Continuous variables were expressed as the mean ± standard deviation.…”