The association between excess salt (sodium) intake and raised blood pressure is well established. According to the World Health Organisation, 62 per cent of all strokes and 49 per cent of heart disease events can be attributed to high blood pressure. Yet, not much medical literature is available to establish a direct link between salt intake and strokes and cardiovascular disease. A recently published meta-analysis of 13 studies involving more than 175,000 individuals across six countries and followed up for 3.5 years to 19 years has thrown up strong evidence of such a link. An increase of 5 g in daily salt intake was found to be associated with a 23 per cent higher risk of stroke and 17 per cent risk of cardiovascular disease. The average intake in many developed countries is above 9 g., as against the WHO recommended (1985) norm of 5 g. While processed food is the dominant source for salt in the developed countries, discretionary use also contributes, in addition to the processed food, to the higher salt intake in India and other developing countries.
Several studies, including the latest, have shown that a restriction on salt intake is an important and non-pharmacological public health intervention for preventing and controlling hypertension. A 3 g per day reduction can bring down blood pressure by 2.5/1.4 mm Hg, and a 6 g per day reduction by 5/2.8 mm Hg. Many countries have already taken the lead in cutting down on salt consumption. Finland, Japan and the United Kingdom have mandated reductions in salt content in processed food items. The United States requires mandatory labelling of sodium content. Three-decade-long effort by Finland to reduce sodium levels by about 30 per cent has resulted in 75 per cent reduction in cardiovascular disease in those under 65 years; stroke rates have fallen by more than 70 per cent in Japan. As for India, the 24-30 per cent prevalence of hypertension in urban areas, and 12-14 per cent in rural areas, and the rising trend in the consumption of processed food call for urgent steps to limit salt levels in processed food and to build public awareness on the need to take less salt.