The prevalence of hypertension is high and increasing worldwide [1]. In several recent studies in Western countries the prevalence of high blood pressure among children was found to range from 7 to 19% [2,3,4]. Similar studies in developing countries were rare. The prevalence of hypertension among primary Kuwait students was 5.1% [5], 3.6% among school children in Jordan [6], and 4.30% among preparatory school children in Alexandria [7]. Life-style factors, obesity and positive family history of hypertension are the main causes of primary hypertension [8].
Hypertension in young not only leads to hypertension in adulthood [9], it additionally builds their risk for the early development of cardiovascular disease and death [10, 11].
Overweight/obesity and high sodium consumption are perceived as risk variables for hypertension in adults and also in children. Sugiyama et al. [12], He and MacGregor [13], reported that of 20 observational investigations on sodium consumption and blood pressure in the young, most have demonstrated a positive correlation. Consequences of a meta-investigation from 10 randomized controlled trials demonstrated that modest decrease in young’ sodium consumption was associated with a small but significant reduction in BP [14]. In spite of the fact that several trials among grown-ups and adolescents have stated that decreasing sodium intake might result in reducing BP, however this relationship may be affected by weight status or presence of metabolic disorder [15], in addition analysis the relationship between sodium consumption and BP by weight status or both on the risk for developing hypertension among children and adolescents is constrained.
Kajale et al. [16], stated that low dietary calcium consumption and high adiposity may raise the risk for the development of hypertension. In this context, Mushengezi and Chillo [17] announced higher BMI and WC as indicator for the mean blood pressure. In addition, Skinner et al. [18] reported the association between higher dietary calciumconsumption and lower body and trunk fat in young adult subsequent to adjusting for physical activity. Morikawa et al. [19], reported healthy effect of increased calcium consumption/supplementation with calcium on BP. In this setting, it has been accounted that utilization of low fat and high fat dairy, milk, yogurt and cheese secures against metabolic disorder including hypertension [20].
Multifactorial dyslipideamia, described by raised total cholesterol (TC) or low-density-lipoprotein cholesterol (LDL-C), is linked with atherosclerosis in young adulthood. Screening for dyslipideamia in adolescence could postpone or decrease cardiovascular disease in adulthood [21].
The aim o the work was to assess the association between some dietary factors (sodium, calcium, fat) and cardiovascular risk factors, blood pressure among obese Egyptian children and adolescents.
Subjects and methods
Eighty-three families, shared as volunteers in this cohort prospective study. These families comprised of 83 mothers and 159 offspring, (82 children and 77 adolescents). They were enrolled in a program for nutritional education through a project funded by National Research Centre (NRC) Egypt, 2013-2016: titled “Familiar Overweight and Obesity in Children and Adolescents: Diagnostic Clinical, Behavioral, Genetic and Biochemical Markers and Intervention”, after taking approval from Ethical Committee of NRC (Registration Number is 13/168) and written informed consent from each of them.
All studied adolescents (77); of both sex (35 males and 42 females) aged 12 up to 18 years; shared in this study were subjected to full history taking and physical examination including anthropometric assessment, dietary recalls, measurement of blood pressure, and laboratory investigation.
Anthropometric parameters
Relevant anthropometric measurements were reported including height and weight using standardized method [22]. Body weight was measured using a Seca scale (Seca Balance Beam Scale Model 700, Seca deutschland Medical Scales and Measuring Systems seca gmbh & co. kg. Hamburg, Germany) approximated to the nearest 0.01 kg, and with minimal clothes on, for which no correction was made, and body height without shoes using a Holtain stadiometer (The Harpenden Portable Stadiometer, Wales, UK) approximated to the nearest 0.1 cm. Body mass index (BMI) was calculated as weight in kg/height in meter [2].
Dietary recalls
Information from each adolescent about his usual pattern of food intake was obtained. Data was collected by means of dietary interview consisting of 24 h recall that repeated for 3 days, and a food frequency questionnaire.
Analysis of food items was done using World Food Dietary Assessment System, (WFDAS), 1995, USA, University of California [23].
Blood pressure measurement
Blood pressure was measured using the standardized mercury sphygmomanometer with cuff of suitable size. It was measured on the right arm after the participant was sitting quietly for 5 min. Two readings were obtained, and the average was recorded. Systolic blood pressure (SBP) was determined by the onset of the “tapping” korotkoff sounds (K1), while the fifth korotkoff sound (K5), or the disappearance of korotkoff sounds, as the definition of diastolic blood pressure (DBP). The mean values of blood pressure were measured and corrected for age and sex in the form of centile and compared with US National Childhood Blood Pressure standards [24]. The blood pressure percentiles were determined accordingly.
Blood sampling and biochemical analysis
Venous blood samples were obtained in the morning by venipuncture after 12-h overnight fasting to measure serum lipid profile [triglycerides (TG), total cholesterol (TC) and high density lipoprotein (HDL) by ELIZA technique. The blood samples were left to clot; sera were separated by centrifugation for 10 min at 5000 rpm then stored at –80 °C until assays. Plasma concentrations of total cholesterol [25], triglycerides [26], and high-density lipoprotein-cholesterol (HDL-C) [27], were measured using commercially available kits provided by STANBIO Laboratory Inc. (1261 North Main Street Boerne Texas 78006 USA). LDL-C was calculated according to an equation developed by Friedewald et al. [28] as follows:
$$ \mathrm{LDL}-\mathrm{C}=\mathrm{Total}\ \mathrm{cholesterol}-\mathrm{Triglycerides}/5+\mathrm{HDL}-\mathrm{C} $$
Fasting Plasma Glucose (FPG) on a venous clotted sample type centrifuged and the serum was isolated by the device (Beckman, Synchron chemical system CK5). Fasting was defined as no caloric intake for at least 8 h [29].
Statistical analysis
All values were expressed as mean value ± SD. Two tailed student t-test was used to compare between the groups. Correlation between the different parameters was tested by Pearson test. P values <0.05 were considered statistically significant. SPSS window software version 17.0 (SPSS Inc. Chicago, IL, USA, 2008) was used.
