Salt has played a prominent role in the evolution of life on Earth. The earliest occurrence of life is thought to have been in the marine environment, about 3.5–4 billion years ago.1 The history of salt as a commodity is interwoven with human history, dating back to at least 6050 BCE. It is an essential element in the diets of not only humans but also animals and many plants. Salt consumption in animals is necessary for proper bodily function. In fact, all mammals need salt in their diet to survive. Salt is present in sweat, tears, and blood, making it a vital component. It is one of the most effective and widely used food preservatives. It is also used extensively in various industrial processes.2 In earlier centuries, salt was an important commodity, and its trade was facilitated by the establishment of salt routes.3 Yet, owing to its importance, it has precipitated numerous wars and conflicts throughout global history.3 In pre-independence India, salt became a symbol of the freedom struggle through the iconic Salt March. In 1930, Gandhi protested against the draconian Salt Tax imposed by the British colonial government by leading the countrymen in a nonviolent civil disobedience movement, the Salt Satyagraha. The march, which began on the 12th March with 78 followers, ended on April 5 at Dandi village, with a sea of humanity accompanying him. On the 6th of April, Gandhiji and his selected followers went to the sea and violated the Salt Law by picking up a lump of salt from the shore. This simple act of resistance escalated into a nationwide movement and is regarded as an important event in the lead-up to India’s independence.4 When asked to explain his choice of salt as the focus for the protest, Gandhi is said to have remarked, “Next to air and water, salt is perhaps the greatest necessity of life.” However, circumstances have changed dramatically, and India has undergone significant transformations in its sociopolitical fabric since independence, with substantial growth in infrastructure, education, and industry. Today, India is the world’s third-largest producer of salt, with an annual production of 39 million tonnes.5 The average consumption has also increased considerably. It is estimated that average consumption is between 8 and 11 g/day, nearly double the recommended intake of approximately 5 g per person per day proposed by the World Health Organization (WHO).6 In India, most salt is added during cooking or at the table, unlike in Western countries, where most salt is in processed foods.7 However, there is a gradual shift in eating habits, and urbanization and the fragmentation of family structure into nuclear families are leading to increased salt consumption through packaged and convenience foods, which generally contain high levels of salt. BURDEN OF NONCOMMUNICABLE DISEASES IN INDIA In tandem with its rapid social and economic development, India is undergoing a major epidemiological transition. The India Health of the Nation’s States 2017 report showed the difference in the prevalence of various health conditions from 1990 to 2016. Over the last 26 years, the country’s disease patterns have shifted: mortality from communicable, maternal, neonatal, and nutritional diseases (CMNNDs) has declined substantially, whereas the burden of non-communicable diseases (NCDs) has increased.8 There has been a 2.3-fold increase in the prevalence of both ischemic heart disease and stroke in the country between 1990 and 2016. The study also reports a greater than two-fold increase in the number of prevalent cases of cardiovascular diseases (CVDs), from 25.7 million in 1990 to 54.5 million in 2016. NCD is the top contributor to mortality (49.1%), whereas CMNND accounts for 38.4% deaths.9 As of 2017, CVD accounted for 26.6% of total deaths and 13.6% of total disability-adjusted life years (DALYs) in India, compared with 15.2% and 6.9%, respectively, in 1990.10 The prevalence of chronic kidney disease (CKD) is also on the rise. Epidemiologic studies have indicated that the prevalence has increased from 0.89% to 1.39% in the 1990s to 17.2% in 2013, but the studies lack uniform defining criteria, have methodologic differences, which makes objective comparison difficult.11 Moreover, studies indicate that the Indians suffer from cardiometabolic diseases at a younger age.10 SALT CONSUMPTION AND RISE IN NCD PREVALENCE – WHAT IS THE EVIDENCE? There is epidemiologic evidence suggesting that salt consumption is associated with the rising prevalence of NCDs. The Global Burden of Disease Study 2021 estimates that excessive sodium intake is associated with ~1.86 million deaths annually. High dietary sodium consumption significantly increases the risk of various chronic NCDs, including hypertension, cardiovascular disease (CVD), stroke, and gastric cancer.12 Studies indicate that a high-sodium diet could contribute 70 million DALYs and 3 million deaths globally. In cohort studies, a 5 g per day higher salt intake (2000 mg of sodium) is associated with a 17% greater risk of total CVD and a 23% greater risk of stroke.13 Chronic high salt consumption is linked to the progression of CKD and an increased risk of end-stage kidney disease and has been substantiated by findings from the GBD study 2019.12 Excessive sodium intake can induce glomerular hyperfiltration, worsen proteinuria and accelerate the decline of kidney function over time, particularly in individuals with pre-existing renal conditions.14 High salt intake, by increasing urinary calcium losses, enhances the risk of urolithiasis. REDUCTION IN SALT – LOWER NCD PREVALENCE Strong evidence indicates that reducing salt intake lowers blood pressure (BP) and reduces the risk of CVD. Clinical studies, such as the Dietary Approaches to Stop Hypertension study, have shown that reducing sodium intake can significantly lower BP and reduce the risk of CVD. A meta-analysis by Filippini et al., also confirmed the linear relationship between sodium intake and BP.15 Pooled data from RCTs with long-term follow-up for CVD suggest that salt reduction reduces CVD incidence. Long‐term experience with salt reduction in Finland, Japan, and the United Kingdom has shown an association between salt reduction and reduced BP and CVD at the population level.16 Importantly, there is a dose‐response relationship and, within the range of 12 g/d to 3 g/d, the greater the reduction in salt intake, the greater the fall in BP.17 Still, controversies abound, with some studies such as the PURE study showing a J-shaped relationship of salt consumption with CV events and mortality, lending support to the debate about public health measures to reduce salt consumption at the population level.18 SALT-LOWERING STRATEGIES – EAT RIGHT INDIA Curtailing salt consumption requires implementation strategies at both the community and individual levels Figure 1. The WHO recommends several sodium-related policies as practical steps for countries to prevent CVD and its associated costs. These include reducing sodium content in foods; implementing front-of-pack labeling, including traffic-light labelling; and mass media campaigns.19 The Food Safety and Standards Authority of India has initiated a large-scale effort to transform the country’s food system to ensure safe, healthy and sustainable food for all Indians through the “Eat Right India” movement.20 There is an emphasis on the reformulation of food products by major food companies to reduce the content of sugar and salt in packaged food, provision of healthier food options by the food services sector and introduction of menu labelling on nutrition information, promotion of healthier food options and responsible retail practices by food retailers and e-commerce players. However, India has not yet adopted mandatory sodium-restriction measures; sodium-content declarations on all prepackaged food are still voluntary and are not yet made mandatory.21 There is a paucity of nationwide data on salt intake, and the last large-scale study was conducted by the Indian Council of Medical Research was in 1988. An accurate measurement of sodium intake levels in India would be critical in our enforcement of salt reduction strategies.18Figure 1: Strategies to reduce consumption of salt at multiple levelsOn the individual front, there is a compelling need for citizens to follow ‘Eating Right’ practices. Several individual-level practices are recommended for adoption Table 1.19 Salt is addictive, and it is difficult to overcome salt habits. Gradual reduction of salt by 10%–20% every week to ensure a reduction to 50% by 4 weeks is a good strategy. The use of herbs and other spices to add flavour is advocated. The addition of salt at the table must be strictly avoided. Schools are encouraged to implement Eat Right activities within the school curriculum and during extracurricular activities under the themes of ‘Eat Healthy’, ‘Eat Safe’ and ‘Eat Sustainable’.Table 1: Individual-level strategies to cut down salt intakeThis year, World Kidney Day falls on 12th March, which also marks the 96th anniversary of the iconic Salt Satyagraha (Dandi March). Just as Gandhiji’s Salt March led us to freedom, we need a ‘new salt satyagraha’ to free us from kidney disease and other NCDs. We should educate our patients to recognise the threat to the kidneys from uncontrolled salt consumption. The kidneys, as the body’s scavengers, face a formidable task of maintaining the body’s internal homeostasis, and the high salt diet stretches their work, especially in the presence of diseased kidneys. Furthermore, drugs such as renin-angiotensin inhibitors and sodium-glucose cotransporter inhibitors are most effective when patients adhere to a low-salt diet. Our patients must realise that salt reduction is not merely about BP; it is about preserving kidney function and life itself.
Y. J. Anupama (Thu,) studied this question.