A longitudinal investigation on the effects of sodium and potassium intake have on the development of hypertension and abdominal obesity from childhood to young adulthood amongst Ellisras rural population, South Africa

Thesis (M.Sc. (Physiology)) -- University of Limpopo, 2023

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: Hence, 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 tracking them from 1999 (5–12 years), 2001 (7–14 years) and 2015 (18–30 years). Blood pressure (BP) and anthropometric measurements [waist circumference (WC) and height] 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 generalized estimating equation (GEE) was conducted to assess the association of Na intake, K intake; and their ratio on BP, WC and WHtR. Results: Our results indicate a significant positive association between K intake and WHtR [β= 0.019, (95% CL: 0.004, 0.034) p-value= 0.012], and even the model was adjusted for age and sex there was still an association with WHtR. Na/K ratio was associated with SBP [β= 4.326, (95% CL: 2.056, 6.595) p-value= < 0.001], DBP [β= 2.028, (95% CL: 0.703, 3.353) p-value= 0.003], WC [β= 4.191, (95% CL: 2.080, 6.302) p-value= < 0.001] and WHtR [β= 0.014, (95% CL: 0.003, 0.026) p-value= 0.015], respectively. Furthermore, Na/K was shown to be associated with an increased risk of developing HT [Exp = 1.603, (95% CL: 1.164, 2.207) p-value= 0.004] and abdominal obesity [Exp = 1.797, (95% CL: 1.207, 2.677) p-value= 0.004]. Conclusion: In our study we observed that an increase in Na/K it’s a predictor of HT and abdominal obesity over time compared to Na and K alone. However, more studies are required to further prove this.