The study is a small-scale, short-term unblinded feasibility study to explore the acceptability and feasibility of implementing a reduced-sodium iodised salt intervention in Nigeria. This study will be used to inform a large-scale intervention trial comparing the effects of reduced-sodium salt versus regular salt on the rise in blood pressure with age.

Reduced-sodium salts are a proven method for reducing sodium intake and lowering blood pressure. No studies to date have tested the effects of sodium reduction on the rise in blood pressure with age during adulthood or the critical periods of childhood and adolescence. The investigators want to explore whether reducing dietary sodium intake using reduced-sodium salt in comparison to regular salt, will attenuate the rise in blood pressure with age. This feasibility study aims to determine the feasibility of implementing a reduced-sodium iodised salt (66% potassium chloride, 34% sodium chloride) intervention in Nigeria. Specifically, the investigators will explore the feasibility of recruiting households with at least one child or adolescent 6-17 years of age and one adult ≥18 years, the acceptability of the reduced-sodium salt intervention, adherence to study procedures and data collection methods, and the effect of the reduced-sodium salt intervention on blood pressure. Secondary outcomes include household eligibility, household composition, willingness to engage in monthly follow-up visits in a longer-term trial, blood pressure, urinary sodium and potassium concentrations, height and weight. This study will be used to inform a large-scale intervention trial comparing the effects of reduced-sodium salt versus regular salt on the rise in blood pressure with age. The study will be conducted in two rural communities in Nigeria and will recruit 30 households (approximately 150 participants). All participants will be provided with the reduced-sodium salt intervention to replace all regular salt used for cooking, seasoning and food preservation over a 2-month period; there will be no control. Follow-up visits will be at 1 month and 2 months after the baseline visit, conducted either at the home or a local community healthcare centre.

Inclusion Criteria:

• At least one household member is a child or adolescent (6-17 years) and at least one household member is an adult (≥18 years)
• All household members consume greater than half of meals as food prepared in the home (self-report)
• All household members provide signed informed consent/assent (consent obtained from legal guardians for those <18 years of age; assent also obtained from children/adolescents ≥12 years of age)

Exclusion Criteria:

• Any household member has serious renal impairment.
• Any household member uses a potassium-sparing diuretic.
• Any household member uses a potassium supplement.
• Any household member has other reason for concern about the use of reduced-sodium salt.

Data may be used for future research purposes or shared with other researchers. Researchers wishing to obtain data for secondary research purposes must place a request with the Principal Investigator (Prof Bruce Neal) and provide a copy of their ethics approval. If the request is approved, the Principal Investigator will provide remote access to the data to other researchers via a remote data access service. All data will be made available in a de-identified format with unique participant and household Identifier (ID) numbers. Data linking participant and household IDs to identifiable participant information will not be provided.