The efficacy of a low-sodium salt substitute enriched with potassium to improve sodium-to-potassium ratio and reduce blood pressure in adolescents and their families in Soweto, South Africa: study protocol for randomised controlled trial

INTRODUCTION: The burden of cardiovascular disease in Sub-Saharan Africa has increased in recent years, and high blood pressure is the leading cause. One established risk factor for hypertension and cardiovascular disease is dietary salt intake. The World Health Organisation has highlighted low-sodium salt substitutes (LSSS) as a potential method to lower sodium intake. LSSS enriched with potassium may additionally support improving sodium-potassium balance. Studies in India and China have investigated the impact of LSSS on reducing sodium intake and the risk of stroke and hypertension in adults. However, evidence in African populations, and in particular youth, is lacking. As such, this protocol describes a phase 1 double-blinded randomised controlled trial to assess the efficacy of a potassium-enriched LSSS compared to traditional salt to improve urinary sodium-to-potassium ratio and blood pressure in African adolescents and their families. METHODS: We will enrol 600 adolescents (13-19 years old) and their primary caregivers living in Soweto, South Africa. Adolescents and their households will be randomised to receive a LSSS or traditional table salt (NaCl) for a 16-week period. All other household salt products will be removed. Anthropometrics and questionnaire data will be collected at 0 and 16 weeks. Spot urine samples and blood pressure will be collected at 0, 4, 12 and 16 weeks. Safety screening for kidney function will be conducted on household members at baseline. The trial protocol received ethics approval from the University of Witwatersrand Medical Human Research Ethics Committee (M221056). DISCUSSION: The obtained results will, to the best of our knowledge, be the first in an African population to provide insights into the efficacy of a potassium-enriched LSSS in improving urinary sodium-to-potassium ratio and blood pressure. TRIAL REGISTRATION: This trial is registered with the Pan African Clinical Trials Registry ( https://pactr.samrc.ac.za ); identifier: PACTR202306727520808 (09 June 2023).