Salt is necessary for human health and life itself, but at levels very much lower than those typically consumed.
In countries where the consumption of processed foods is high and where traditional diets are high in salt, total salt intake is too high . We recommend that the population average consumption of salt from all sources should be less than 6g a day .
Latest figures however indicate that average salt intake varies across the world, from 4g in Kenya to 15g in Kazakhstan per person per day . Many of the countries with the greatest salt consumption are in Eastern Europe and Asia (see table).
Today, because of refrigeration and canning processes, the need to add salt as a preservative is greatly reduced. However, high levels are still being added in processed food and in food consumed out of the home.
How does this relate to cancer?
The strongest evidence on methods of food preservation, processing, and preparation show that salt and salt-preserved foods are probably a cause of stomach cancer .
There are two main types of stomach cancer. Stomach cardia cancer occurs in the upper portion of the stomach near the junction with the oesophagus and stomach non-cardia cancer is found in the rest of the stomach.
Infection with the bacterium Helicobacter pylori interacts with salt in a way that can cause stomach non-cardia cancer, the more common form globally, particularly in Asia. The relationship with stomach cardia cancer is less clear.
Cancer of the stomach is the fifth most common type of cancer worldwide. Around 952,000 cases of stomach cancer were recorded in 2012, accounting for about 7 per cent of all new cancer cases . Incidence rates are about twice as high in men as in women .
Republic of Korea, Mongolia and Japan have the highest rates of stomach cancer and are also high consumers of salt.
High salt consumption raises blood pressure, a major risk factor for cardiovascular disease .
Table: Top 20 countries with highest consumption of salt in 2010 
Salt consumption (g per person per day)*
Korea (Republic of)
Lao People's Democratic Republic
*Sodium intakes have been computed to equivalent salt intakes by multiplying by 2.54.
 Ferlay J, Soerjomataram I, Ervik M, Dikshit R, Eser S, Mathers C, Rebelo M, Parkin DM, Forman D, Bray, F. GLOBOCAN 2012 v1.1, Cancer Incidence and Mortality Worldwide: IARC CancerBase No. 11 [Internet]. Lyon, France: International Agency for Research on Cancer; 2014. Available from: http://globocan.iarc.fr, accessed on 17/02/2016.