Trends in salt consumption
In early times people who lived in hot savannah environments, remote from the sea, evolved on a diet that contained less than 1 g of salt per day. In other words, human genetic make-up evolved with a need to conserve salt, achieved through sodium retention by the kidneys and uptake by the gut including the large intestine. When humans became sedentary and made the transition from food gathering to food production, salt was added regularly in order to preserve food. Now, people in many industrialized societies consume as much as 10-12 g per day. The level has been as high as 60 g per day in parts of northern Japan. Insufficient time has elapsed in human evolution for the body to adjust to these new high salt intakes.
There is significant variation between countries in the levels and patterns of salt consumption. Not surprisingly, in industrialized countries about 75% of dietary salt intake is from processed foods (World Health Organization, 2006). In Western Europe, the estimated average salt intake for adults is 8.3-10 g per day (Desmond, 2006). In the USA, Eire and the UK, cured and processed meats contribute just over 20% of the daily sodium intake. An important focus has been on reducing the salt content of bacon, ham, sausages and burgers; between 2007 and 2010 the aim in most developed countries has been to reduce the salt content by between 20 and 35%.
Salt in snack foods can enhance their shelf-life, reducing wastage before retail sale, and their flavour impact, increasing their appeal to the consumer. Adding salt to processed meat products increases their uptake and retention of water, and the additional weight adds cash value to the product. Sales of soft drinks are likely to be high if snack foods are salty and stimulate thirst. On account of all these commercial advantages, some companies in the processed food and soft drinks industries are inclined to understate or deny the health hazards associated with dietary salt. By comparison, regulatory and authorities and 'watchdog' groups which promote low-salt diets have, at most, an indirect interest in salt reduction as they seek to reduce community expenditure on future health care, and they may overstate their case in order to achieve an impact.