Salt is an essential part of the human diet. It is especially important to replenish electrolytes lost during exercise. The intake of salt needs to be balanced with the intake of other nutrients as is hopefully done in sports drinks. However consuming more sodium than the body can handle is often a severe, but unnoticed problem for many people. Sodium makes the body hold on to fluid. Also, too much salt can worsen symptoms like swelling and shortness of breath and cause weight gain. If those symptoms become severe, the person may need to be admitted to the hospital.
Physicians often recommend keeping salt intake below 2,300 milligrams (mg) per day for most people. However, for people with heart failure, recommended sodium intake is no more than 2,000 mg per day.
To estimate the benefit of making small reductions in salt intake, investigators use the Coronary Heart Disease Policy Model, a computer simulation of heart disease in the U.S. adult population. The model can be used to evaluate the impact of policy changes on the health of the nation, and has previously been used to project the future of heart disease in the United States given the current rate of childhood obesity.
Researchers used the model to estimate the impact of an immediate reduction of daily salt intake by 0 to 6 grams on the incidence of cardiovascular disease and deaths between 2010 and 2019. In that period, the model suggests that more than 800,000 life-years could be saved for each gram of salt lowered. Larger reductions would have greater benefits, with a 6 gram reduction resulting in 1.4 million fewer heart disease cases, 1.1 million fewer deaths and over 4 million life-years saved.
Salt is also a risk factor in some cases of essential hypertension. Approximately one third of the cases of essential hypertension respond to a reduction of sodium intake. Obesity may be an even larger risk factor in essential hypertension. Hypertension also contributes to kidney failure and dementia, according to the World Health Organization.