Longitudinal relationship between screen-based sedentary behavior and nutrient intake in Japanese children: an observational epidemiological cohort study.

BACKGROUND: Concerns regarding the impact of screen-based sedentary behavior on health have been increasing. Therefore, the present study investigated the longitudinal relationship between multiple screen time and nutrient intake in children and adolescents. METHODS: The present study was conducted utilizing 3 years longitudinal data. Study subjects were 740 Japanese children aged between 6 and 12 years at baseline and between 9 and 15 years in the follow-up. Screen-based sedentary behavior was assessed using screen time, including television (TV) viewing, personal computer (PC) use, and mobile phone (MP) use. The main outcomes were the intakes of nutrients. Mixed effect multivariate linear regression analyses were used to examine the longitudinal relationship between screen-based sedentary time and nutrient intake. Covariates included in the multivariable analysis consisted of sex, age, solitary eating, skipping breakfast, staying up late, and body weight status, as confounders, and physical inactivity, as mediator. RESULTS: In boys, a longer total screen time longitudinally correlated with higher intake of energy and lower intakes of protein, dietary fiber, minerals, and vitamins. In girls, longer total screen time longitudinally associated with higher intake of sucrose and lower intakes of protein, minerals, and vitamins. In boys, a longer TV viewing time was associated with higher intake of sucrose and lower intakes of protein, minerals, and vitamins. In girls, a longer TV viewing time was associated with higher intake of carbohydrates and lower intakes of protein, fat, minerals, and vitamins. In boys, relationships were observed between a longer PC use time and higher intakes of energy as well as lower intakes of protein, minerals, and vitamins. Relationship was observed between longer PC use time and lower intakes of minerals in girls. An increased MP use time was associated with higher intakes of energy, and lower intakes of protein, sucrose, dietary fiber, minerals, and vitamins in boys. A longer MP use time was associated with higher intakes of fat, and salt as well as lower intakes of carbohydrates, protein, minerals, and vitamins in girls. CONCLUSIONS: The present results revealed that longer screen-based sedentary behaviors were longitudinally associated with nutrient intake in children and adolescents. Future study is needed to elucidate these relationships.

Dietary Calcium Intake and Hypertension: Importance of Serum Concentrations of 25-Hydroxyvitamin D.

The relationship among dietary calcium, hypertension and vitamin D status currently remains unclear. This population-based cross-sectional study examined the association between dietary calcium intake and hypertension and the influence of serum concentrations of 25-hydroxyvitamin D [25(OH)D] in Japanese subjects. A total of 619 subjects aged from 40 years were recruited. Dietary intake was measured using a validated brief self-administered diet history questionnaire. Hypertension was defined as the use of antihypertensive medication or a blood pressure of 140/90 mmHg. Serum concentrations of 25(OH)D were used as the biomarker of vitamin D status. The prevalence of hypertension and low serum 25(OH)D levels (<20 ng/mL) were 55 and 32%, respectively. Dietary calcium intake inversely correlated with hypertension in subjects with serum 25(OH)D levels higher than 20 ng/mL (OR: 0.995; 95% CI: 0.991, 0.999) but it was not significant in those with serum 25(OH)D levels of 20 ng/mL or lower. Furthermore, dietary vitamin D intake correlated with serum concentrations of 25(OH)D after adjustments for various confounding factors. The present results demonstrate that the regular consumption of calcium may contribute to the prevention and treatment of hypertension in subjects with a non-vitamin D deficiency and also that dietary vitamin D intake may effectively prevents this deficiency.