The sodium found in salt is a powerful cause of high blood pressure, and most sodium ingested by humans is from their diet. High blood pressure is known to cause heart attacks and strokes, so various public health programs have attempted to find ways for people to reduce their salt intake to avoid these complications. These programs, however, have proven challenging, as asking people to alter their food preparation practices is often met with resistance. As such, we wish to test the blood pressure-lowering effects of low sodium salt substitute (LSSS), a salt substance in which a third of the compound by weight is composed of potassium (which does not increase blood pressure) rather than sodium. Additionally, the best way of supplying LSSS to people is yet unknown. We thus propose to study the effectiveness of an LSSS product by directly providing it via community health workers in 309 households in rural Bangladesh.

The overall objective of this study is to assess the effectiveness of providing access to low-sodium salt substitute (LSSS) (a compound in which a percentage of the sodium chloride (NaCl) is replaced by potassium chloride (KCl) for blood pressure (BP) reduction in a general population of adults (aged 18 years and older) in rural Bangladesh. The intervention will be delivered in the study wing by community health workers to determine if this method is an efficacious approach for blood pressure lowering in this setting.

Inclusion Criteria:

• Our target population is that of adults living in rural Bangladesh, while our study population will be comprised of adults (age ≥18 years old) living in Parbatipur, a rural/semi-rural sub-district in Dinajpur District (Rangpur Division), in the north of the country. Within Parbatipur, BRAC University has assessed 700 households for NCD risk factors as part of a larger Wellcome-trust funded multinational biobank (involving those living in Bangladesh, India, Pakistan, and Sri Lanka) to better understand the patterns and determinants of cardiovascular health in South Asian people in a cross-sectional analysis. All adults living in these surveyed households will be eligible to participate.

Exclusion Criteria:

• Exclusion criteria include subjects taking potassium-sparing diuretics, already taking potassium supplements, or those who have known kidney disease at baseline.
• All adults initially screened for intervention will undergo serum creatinine testing, with those with values >106 mMol/L for males and >97 mMol/L for female excluded from the intervention but kept in the intervention group by intention-to-treat principles to avoid breaking of randomization.
• Although minors will not be involved in the study, to avoid spillover injury to children in the intervention households, all members of intervention households under the age of 18 will also undergo urine dipstick testing. If proteinuria is detected, the household will be excluded from receiving the LSSS intervention (but followed in the intervention arm to avoid breaking randomization).

intervention), participants cannot be blinded. Investigators not involved in the allocation and direct data collection efforts, however, including the analysts, will be blinded to which household received which intervention. Of note, the community health workers responsible for provisioning the intervention and conducting the baseline survey will be a separate team of field workers from those collecting the endline outcomes assessment.