To Salt or Not to Salt
Most doctors advise a strict limitation of salt and recently the American Heart Association (AHA) announced goals to achieve “ideal cardiovascular health” by 2020, the mainstay of which is a daily sodium intake of 1500mg/day or less. The Center for Nutrition Policy and Promotion recommends a daily sodium intake of less than 2300 mg/day for the general population and 1500 mg/day for those with greater risk of cardiovascular disease. Healthcare providers constantly advise no added salt to anyone’s regular diet and to be very careful reading labels for salt content in foods. The reasoning behind salt limitation has typically followed the basic tenet that too much sodium intake causes the body to retain extra water and fluid. Any added burden for the heart and blood vessels to pump this around the body overloads the system and can cause heart failure. Too much sodium causes high blood pressure, and puts people at risk for stroke and heart attack. The AHA advises everyone, not just those with chronic disease, to restrict their sodium intake.
However, newer committees such as the Institute of Medicine and the Centers for Disease Control are casting doubt on this theory. Recent evidence demonstrates that low sodium diets have not been shown to reduce cardiovascular events such as heart attack and stroke or in those with prehypertension or nonmalignant high blood pressure. Moreover, there is evidence that a low sodium diet may lead to a worse cardiovascular outcome in those with cardiometabolic risk and heart disease.
The latest of the NHANES studies (NHANES 3) showed an inverse association between dietary sodium intake and all-cause cardiovascular mortality. Other evidence showed that low salt diets may adversely affect insulin resistance, serum lipids, and neurohormonal pathways in the body, actually increasing both cardiac and all-cause mortality. Plunging sodium levels can actually increase the activity of the sympathetic nervous system and increase the risk of heart disease. With conflicting evidence and studies, as well as scientists on both sides of the debate, how much salt should a health conscious person consume?
The bottom line is that limiting sodium in cases where there is heart failure, edema and water retention, and where the heart is limited as a pump is still quite important. Likewise, in those whose increased fluid status worsens their blood pressure or when cardiac valves are limited and need to do less work in order to function properly, limited salt intake is of great value. However, the healthy body also regulates sodium in such a tight physiologic range that normal human biology is its own regulatory system, and that while attempts at either consuming too much or too little sodium can tax the body’s own maintenance system, our physiologic systems do a good job of regulating and controlling what the body needs for optimal function.
The debate on salt is only getting more heated amongst scientists on both sides. In the meantime, moderation appears the best rule of thumb as well as following your doctor’s advice.