from Dr. Jason Fung's IDM blog

Salt Scare 9-25-2018 Dr. Jason Fung's IDM blog

The evidence from the United States was not encouraging either. The National Health and Nutrition Examination Survey (NHANES) are large scale surveys of American dietary habits carried out periodically. The first survey found that those eating the least salt died at a rate 18% higher than those eating the most salt. This was a highly significant, and disturbing result.

The second NHANES survey confirmed that a low salt diet was associated with a staggering 15.4% increased risk of death. Other trials found an increased risk of heart attacks of eating a low salt diet in treated hypertensive patients. Those were precisely the patients doctors had been recommending a low salt diet!

In 2003, worried, the Center for Disease Control, part of the US Department of Health and Human Services asked the Institute of Medicine (IOM) to take a fresh look at the available evidence focusing not on blood pressure, but mortality and heart disease.

After an exhaustive search of the medical literature, the IOM made several major conclusions. Although low salt diets could lower blood pressure, “Existing evidence, however, does not support either a positive or negative effect of lowering sodium intake to <2300 mg/d in terms of cardiovascular risk or mortality in the general population.”. That is, lowering the salt intake did not reduce risk of heart attack or death.

However, in heart failure, “The committee concluded that there is sufficient evidence to suggest a negative effect of low sodium intakes”. Oh my. The very patients we were most strenuously recommending to reduce their salt would be harmed the most.

But dogma is hard to change. The 2015 Dietary Guidelines continues to recommend reducing sodium intake to less than 2,300 mg of sodium (about one teaspoon of salt) per day with a recommendation of no more than 1,500 mg of sodium (about two-thirds of a teaspoon of salt) per day in hypertensives, blacks, and middle-aged and older adults.