Rationale: Increased salt intake may pose health risk and may lead to hypertension and heart disease
Salt is an essential ingredient of food and enhances its taste. From time immemorial, it has been used as a preservative. All food substances contain sodium, but added salt (sodium 40%, chloride 60%) is the major source of sodium in our diet. Sodium is primarily involved in the maintenance of water balance and equilibrium. It also plays an important role in electro-physiological functions of the cell. Humans have powerful in-built mechanisms for maintaining blood pressure even on minimal sodium intake.
Sodium is rapidly absorbed from the gastrointestinal tract and a positive balance is achieved on intakes just above minimal requirements. Sodium requirements depend on its losses through urine, faeces and sweat. The sweat loss varies according to climatic conditions. High ambient temperatures and vigorous physical exercise increase sodium loss through sweat. Even after 6 hours of hard physical labor, which may generate 3 litres of sweat, the requirement of sodium chloride may not be more than 6 g/day.
Natural diets, in general, provide about 300-400 mg of sodium a day. Cereals, pulses, vegetables, milk, animal and sea foods are the major sources of sodium. Indian data indicate that per capita consumption of salt ranges from less than 5g to 30g/day in different States with almost 40% of population consuming about 10g/day. Since, the taste for salt is acquired, its consumption could be restricted right from an early age.
Preserved foods such as pickles, sun dried foods such as papads, sauces/ ketch up and canned foods contribute to higher intakes of salt.
There is a strong association between salt intake and blood pressure. Prevalence of hypertension is low in populations consuming less than 3 g salt per day. The usual increase in blood pressure with age is also not seen with such intakes. The amount of salt consumed is reflected in urinary sodium. Drastic restriction of dietary salt decreases the risk of hypertension. However, this effect is not uniform as only 20-30% of population is salt sensitive. Potassium-rich foods such as fresh vegetables and fruits decrease blood pressure. In fact, it is the ratio of sodium to potassium in the diet which is important. Salt intake higher than 8 g/day is considered as a risk factor for hypertension.
Besides increasing blood pressure, excessive salt may also affect stomach mucosa and result in atrophic gastritis and gastric cancer.
Higher sodium intake leads to greater calcium excretion which may result in reduction in bone density. Existing evidence reveals a deleterious impact of high salt intake on blood vessels, blood pressure, bones and gastrointestinal tract. Salt intake in our population generally exceeds the requirement. It should not be more than 6 g per day. Salt is used as a vehicle for food fortification since, it is commonly used in food preparation.