A Longitudinal Investigation on the Effects of Sodium and Potassium Intake on the Development of Hypertension and Abdominal Obesity from Childhood to Young Adulthood amongst Ellisras Rural Population, South Africa.

BACKGROUND: Hypertension (HT) and obesity have both been on the rise in children. Each is associated with an increase in cardiovascular disease risk, and both track into adulthood. OBJECTIVES: This study aimed to identify the association of sodium intake (Na), potassium (K) intake, and sodium-to-potassium (Na/K) ratio with the development of HT and abdominal obesity amongst the Ellisras rural population over time. METHODS: In this longitudinal study, data on dietary intake of Na and K were collected using a 24 h recall questionnaire from a total of 325 participants tracked from 1999 (5-12 years), 2001 (7-14 years), and 2015 (18-30 years). The averages of Na and K intake were analysed using local food tables and the South African Food Composition Database System (SAFOODS). In addition, blood pressure (BP) and anthropometric measurements (waist circumference (WC) and height) were also examined. Parametric (independent t-test) and Chi-square/Fishers exact tests were conducted to determine the difference between the years for numerical data and categorical variables. A generalised estimating equation (GEE) was used to assess the association of Na intake, K intake and their ratio on BP, WC, and waist-to-height ratio (WHtR). RESULTS: Our results indicate a significant positive association between K intake and WHtR, and even though the model was adjusted for age and sex, there was still an association with WHtR. The Na/K ratio was associated with both BP measurements and abdominal obesity, respectively. Furthermore, Na/K was shown to be associated with an increased risk of developing HT and abdominal obesity. CONCLUSIONS: In our study, we observed that an increase in the Na/K ratio is a predictor of HT and abdominal obesity over time compared to Na and K alone. However, more studies are required to further prove this.

Assessing the Association of Sodium, Potassium Intake and Sodium/Potassium Ratio on Blood Pressure and Central Adiposity Measurements amongst Ellisras Undernourished, Rural Children Aged 5-13 Years: South Africa.

BACKGROUND: Numerous studies have shown how diet, such as sodium (Na) and potassium (K) intake, is an important risk factor for non-communicable diseases (NCDs). This study aimed to assess the relationship between sodium intake, potassium intake; and sodium/potassium ratio with blood pressure (BP) and abdominal obesity amongst Ellisras rural children. METHOD: In this cross-sectional study, data on dietary intake of sodium and potassium were collected using a 24-h recall questionnaire from a total of 765 participants, aged 5-13 years. Blood pressure and anthropometric measurements were also collected. Generalised linear models and Pearson correlation were conducted to assess the association of sodium intake, potassium intake; and their ratio with BP, waist circumference (WC), and waist-to-height ratio (WHtR). RESULTS: In both age groups, less than 14.9% of males and 19.8% of females consumed above the recommended adequate intake (AI) of sodium. In addition, both age groups had more than 90% of males and females who consumed below the recommended AI of potassium. Moreover, the sodium/potassium ratio was above the WHO recommended level in more than 30% of males and females. The study found a significant, weak positive correlation of sodium intake with systolic BP (SBP), diastolic BP (DBP), and with WHtR. A significant, weak positive correlation was also found between sodium/potassium ratio and WHtR. In addition, a significant association was found between potassium intake and systolic BP. CONCLUSION: Although our study found a notable low average intake of sodium and potassium as compared to the recommended values. There was positive correlation found between sodium intake and BP. Furthermore, a positive correlation of sodium intake and sodium/potassium ratio with WHtR was also found.

"Selected Papers from the 2nd Ellisras Longitudinal Study and Other Non-Communicable Diseases Studies International Conference" Special Issue Editorial.

Epidemics of non-communicable diseases (NCDs) are presently emerging and on the increase in South Africa. It is increasingly recognized that the occurrence of adult chronic disease are influenced by factors operating from childhood, which are sustained throughout the individual's life course. Increased risk may start in infancy or even before birth and will continue to be influenced by health related behavior during adulthood. The academic level of people in the community influence the level of their health status. Commitment to the promotion of health through prevention, education, and suitable management is the building block for creating a healthy society. The community must make strides to shift from traditional knowledge and medication, and seek new innovative ways of addressing issues facing the population with regard to obesity, overweight, hypertension health, smoking cessation, alcohol abuse, and low physical activity in line with a healthy living lifestyle. The NCDs pose health problems in South Africa and deserve more attention. Poor control of obesity, hypertension, and diabetes, to name just a few, only adds to the current problems. The South African government and the business sector of South Africa should provide safe walking/riding trails in the cities and in rural area to combat emerging NCDs that are killing our community members indiscriminately without considering race, gender, age, and place of residence. Compulsory introduction of physical education lessons to all public schools cannot be over emphasized in the current escalating NCD situation in South Africa.

Body Roundness Index, A Body Shape Index, Conicity Index, and Their Association with Nutritional Status and Cardiovascular Risk Factors in South African Rural Young Adults.

BACKGROUND: The study aimed to investigate the association of Body Roundness Index (BRI), A Body Shape Index (ABSI), and Conicity Index with nutritional status and cardiovascular risk factors in South African rural young adults. METHODS: The study included a total of 624 young adults aged 21-30 years from the Ellisras rural area. Anthropometric indices, blood pressure (BP), and biochemical measurements were measured. RESULTS: BRI was significantly correlated with insulin (0.252 males, females 0.255), homeostatic model assessment (HOMA)-ß (0.250 males, females 0.245), and TG (0.310 males, females 0.216). Conicity Index was significantly associated with pulse rate (PR) (ß 0.099, 95% confidence interval (CI) 0.017, 0.143, p < 0.013; ß 0.081, 95% CI 0.000 0.130, p < 0.048), insulin (ß 0.149, 95% CI 0.286 0.908, p < 0.001; ß 0.110, 95% CI 0.123 0.757, p < 0.007). Conicity Index is associated with insulin resistance (IR) (odds ratio (OR) 7.761, 95% CI 5.783 96.442, p < 0.001; OR 4.646, 95% CI 2.792 74.331, p < 0.007), underweight (OR 0.023, 95% CI 0.251 0.433, p < 0.001; OR 0.031, 95% CI 0.411 0.612, p < 0.001), and obesity (OR 1.058, 95% CI 271.5 4.119, p < 0.001; OR 1.271, 95% CI 0.672 1.099, p < 0.001). CONCLUSION: Conicity Index was positively associated with insulin resistance, hypertension and dyslipidaemia. Further investigation of these indices and their association with nutritional status and cardiovascular diseases (CVDs) could assist in efforts to prevent CVD in the rural South African population.

The Relationship between Under-Nutrition and Hypertension among Ellisras Children and Adolescents Aged 9 to 17 Years.

Background: Globally, under-nutrition and hypertension in children has been associated with the risk of developing cardiovascular disease (CVD) in adulthood. The main objective of this study was to investigate the relationship between under-nutrition and hypertension, furthermore, to determine the risk of developing hypertension due to under-nutrition. Methods: The study comprised of 1701 participants (874 boys and 827 girls) between the ages of 9 and 17 years old. All anthropometric and blood pressure measurements were taken according to standard procedures. Mid-upper arm circumference (MUAC), body mass index (BMI), upper arm fat area (UFA), total upper arm area (TUAA) and upper arm muscle area (UMA) of Ellisras children were compared with the National Health and Nutrition Examination Survey III reference population. The linear regression models were used to determine the relationship between under-nutrition with hypertension for unadjusted and then adjusted for age and gender. The logistic regression model was used to determine the risk of under-nutrition on developing hypertension for unadjusted and adjusted for age and gender. Results: There was a positive significant (p < 0.0001) association between all under-nutrition variables (MUAC, BMI, UFA, TUAA and UMA) and systolic blood pressure (SBP; beta ranges between 0.84 and 2.78), and diastolic blood pressure (DBP; beta ranges between 0.3 and 1.08 before adjusting and after adjusting for age and gender (SBP, beta ranges between 0.59 and 2.00 and DBP (beta ranges between 0.24 and 0.80. Conclusion: The prevalence of under-nutrition was high while the prevalence of hypertension was low in this study. The mean under-nutrition variables (BMI, UFA, UMA and MUAC) of Ellisras children were far lower compared to the NHANES III reference population. Hypertension was significantly associated with under-nutrition in this study.

The Relationship between Binge Drinking and Metabolic Syndrome Components amongst Young Adults Aged 21 to 31 Years: Ellisras Longitudinal Study.

BACKGROUND: Evidence is lacking on the effects of binge alcohol consumption on metabolic syndrome in the rural South African population. The purpose of this study was to investigate the association between binge drinking and components of metabolic syndrome (MetS) amongst Ellisras rural young adults aged 21 to 31 years who are part of the Ellisras Longitudinal Study. METHODS: Logistic regression analysis was applied to a total of 624 participants (306 males and 318 females) aged 21 to 31 years who took part in the Ellisras Longitudinal Study (ELS). The model was adjusted for covariates, including smoking, age, and gender. Binge alcohol consumption was assessed using a standardised questionnaire that was validated for the Ellisras rural community. A standardised method of determining the components MetS was used after fasting blood samples were collected from all the participants. RESULTS: Binge drinking remained significantly associated with low levels of high-density lipoprotein cholesterol (HDL-C) (OR = 2.64, 95% CI = 1.23-5.65), after being adjusted for smoking, age, and gender. Other MetS components were not predicted. Instead, gender remained significantly associated with all MetS components, except triglycerides, at multivariate analysis. Age retained significance at multivariate analysis with waist girth (OR = 2.13, 95% CI = 1.37-3.34), triglycerides (OR = 2.30, 95% CI = 1.05-5.02), and the MetS composite (OR = 1.65, 95% CI = 1.12-2.41). CONCLUSION: Binge drinking was significantly associated with lower levels of HDL-C. Future studies should investigate the relationship between alcohol abuse and the components of incident MetS in this population.

A Non-Invasive Investigation into the Prevalence of Higher than Normal Blood Pressure, Hypertension and the Association between Blood Pressure and Body Weight in Male and Female Adolescents in the Polokwane Local Municipality, Limpopo-South Africa: A Cross-Sectional Study.

BACKGROUND: Hypertension (HT) is one of the greatest non-communicable diseases affecting both sexes in all human populations; and it is a major cause of death and morbidity across the world. The purpose of this study was to investigate the prevalence of pre-hypertension, hypertension and investigate the association between blood pressure (BP) and body weight (looking into body mass index (BMI) and body surface area (BSA)). METHOD: A cross-sectional study of adolescents aged 13-19 years was conducted at three secondary schools consisting of 121 females and 97 males. Data on height; weight; and blood pressure was collected from all participants. BMI and BP percentiles were calculated for each participant. RESULTS: The prevalence of pre-hypertension and hypertension in males was 28.9% and 10.3% compared to 25.6% and 7.4% in females. The prevalence of pre-hypertension and hypertension in adolescents who are overweight/obese was 7.3% and 2.7%. A weak positive association between BMI; systolic blood pressure (SBP) and diastolic blood pressure (DBP) was found (r = 0.254 and 0.216; p-value = 0.001) for the whole population. A significant, moderate correlation was found between BSA on SBP was found (r = 0.407, p-value = 0.001); and a significant, weak correlation between BSA and DBP was found (r = 0.183, p-value = 0.007. In conclusion, the prevalence of pre-hypertension and hypertension was higher in males as compared to females. Results highlight the need for screening for blood pressure and body weight in adolescents; especially in adolescents who were found to have pre-hypertension as they are at high risk of developing hypertension.

Using the SITAR Method to Estimate Age at Peak Height Velocity of Children in Rural South Africa: Ellisras Longitudinal Study.

Various studies have been conducted on children using the Ellisras Longitudinal Study Survey in South Africa, but none of these has addressed growth variations of children in this rural location. The aim of this paper is to assess the age at peak height velocity using the superimposition by translation and rotation (SITAR) method for both boys and girls in rural South Africa. The study is part of the on-going Ellisras Longitudinal Study, and has employed secondary data during the period from November 1996 to November 2003. The data was collected biannually in May and November each year. The Ellisras study initially followed a cluster sampling method. All participating children underwent a series of anthropometric measurements of height and weight according to the standard procedures recommended by the International Society for the Advancement of Kinanthropometry. The analysis was done using the SITAR model. Age at peak height velocity for Ellisras rural children was at 14.45 years for boys at 11.82 years for girls. Ellisras rural girls had their age at peak height velocity way earlier than Ellisras rural boys did by an estimated 2.63 years. Ellisras rural children and their growth variations were comparable to other studies.

The Relationship between Physical Activity and Plasma Glucose Level amongst Ellisras Rural Young Adult Males and Females: Ellisras Longitudinal Study.

Unhealthy lifestyle characteristics such as low physical activity (PA) and high plasma glucose levels (PGLs) may lead to the development of type 2 diabetes mellitus in adulthood. The aim of this study was to investigate (i) the level of physical activity; (ii) the prevalence of pre-diabetes and (iii) the relationship between PA and plasma glucose level in a rural Ellisras adult population aged 18 to 28 years. A total of 713 young adults (349 males and 364 females) who took part in the Ellisras Longitudinal Study participated in the study. Fasting plasma glucose levels were analysed using Accutrend glucose meters. Physical activity data was collected using a validated questionnaire. Linear regression was used to assess the relationship between PA and pre-diabetes. The prevalence of pre-diabetes was between 45.7% and 50.2% and that of physical inactivity was 67.3% and 71.0% for males and females, respectively. There was no significant (p > 0.05) relationship between PA and pre-diabetes (beta = 1.016; 95% Confidence Interval from 0.352 to 2.777). The health benefits of PA increased with the increasing frequency, duration and intensity of exercise. The prevalence of pre-diabetes was found to be very high in this population. Our results suggest that greater physical activity is associated with low plasma glucose levels.

The relationships between height and arm span, mid-upper arm and waist circumferences and sum of four skinfolds in Ellisras rural children aged 8-18 years.

OBJECTIVE: Height is required for the assessment of growth and nutritional status, as well as for predictions and standardization of physiological parameters. To determine whether arm span, mid-upper arm and waist circumferences and sum of four skinfolds can be used to predict height, the relationships between these anthropometric variables were assessed among Ellisras rural children aged 8-18 years. DESIGN: The following parameters were measured according to the International Society for the Advancement of Kinathropometry: height, arm span, mid-upper arm circumference, waist circumference and four skinfolds (suprailiac, subscapular, triceps and biceps). Associations between the variables were assessed using Pearson correlation coefficients and linear regression models. SETTING: Ellisras Longitudinal Study (ELS), Limpopo Province, South Africa. SUBJECTS: Boys (n 911) and girls (n 858) aged 8-18 years. RESULTS: Mean height was higher than arm span, with differences ranging from 4 cm to 11·5 cm between boys and girls. The correlation between height and arm span was high (ranging from 0·74 to 0·91) with P<0·001. The correlation between height and mid-upper arm circumference, waist circumference and sum of four skinfolds was low (ranging from 0·15 to 0·47) with P<0·00 among girls in the 15-18 years age group. CONCLUSIONS: Arm span was found to be a good predictor of height. The sum of four skinfolds was significantly associated with height in the older age groups for girls, while waist circumference showed a negative significant association in the same groups.