Sodium reduction in Malawi

High blood pressure (hypertension) and its complications (such stroke and heart disease) cause significant
disability and mortality, particularly in SSA where more than 25% of the adult population have the condition.
Excessive salt intake is a major contributor, and the UN has recognised salt reduction as a “best-buy” intervention to prevent heart disease and stroke. There is much research on reducing salt intake in high-income countries, but little data on how this can be achieved in SSA. Different approaches are necessary, because, unlike developed countries where most salt consumed is from processed food (and interventions have targeted the food industry and policy regulations), in low-income Africa, most salt intake is from cooking at home and added to the plate. This, and profound cultural connotations attached to salt in African societies, will have to be addressed in successful interventions.
Our work in Malawi shows that hypertension is common, and salt consumption very high. In both rural and urban areas; the majority of salt consumption is at home. Building on this information and our research platform, we will partner Ministries of Health and Nutrition to design and test interventions to reduce salt consumption, blood pressure and hypertensive complications. We will conduct preparatory activities to enable us to develop successfully cost-effective interventions that are appropriate for the community and sustainable. Initial steps will
include assessing community acceptability of potential interventions, the size of population required to accurately test the effect of the intervention and what tools will be necessary to evaluate its success.

Hypertension is a major cause of morbidity, disability and mortality, causing 7.5 million deaths worldwide. Globally, approximately 25% of adults are hypertensive, and rates are highest in sub-Saharan Africa(SSA) – up to 40% of adults are affected and blood pressure levels are nearly 10mmHg higher than in high-income countries1. High dietary salt may cause 30% of hypertension. Reducing salt intake would reduce strokes and cardiovascular diseases,2,3 and was nominated a ‘best-buy’ at the UN High-Level non-communicable diseases(NCD) meeting. Wealthy countries have tackled salt reduction through regulations, public education and food industry collaboration, but effective strategies to reduce salt intake in SSA (where most salt intake is from home food preservation or cooking) need development.
We are conducting large urban/rural studies to determine NCD risk factors in Malawi; establishing a platform for interventions (Malawi Epidemiology and Intervention Research Unit/Karonga Prevention Study http://www.lshtm.ac.uk/eph/ide/research/kps/). Preliminary data reveal high salt consumption (11g/day). Engaging with policy-makers and community leaders, we will design and study the acceptability of, novel, cost effective and culturally-acceptable community-based salt reduction interventions. In this early phase we will
1)capitalise on our existing datasets and population-research platforms; calculating the population attributable risk fraction of excessive salt intake for hypertension and planning a cluster-randomised trial (accounting for cluster nature and between-cluster variation); 2)using published data, calculate the effects-size/sample-size; 3)test interventions/evaluation feasibility including salt reduction/substitution acceptability.