The American Heart Association recommends consuming less than 1,500 mg of sodium per day.
If a person's average systolic blood pressure (the top number in the reading, measured when the heart is contracting) increased 5% or more from the low-sodium to the high-sodium regimen, the researchers labeled them as high salt-sensitive.
Casey M. Rebholz, M.P.H., lead author of the study and a medical student at the Tulane School of Medicine and doctoral student at the Tulane University School of Public Health & Tropical Medicine in New Orleans states:
"Patients should be advised to increase their physical activity and eat less sodium. Restricting sodium is particularly important in lowering blood pressure among more sedentary people. In all the analyses we found a dose response relationship with the more activity, the better."
Investigators compared study participants' blood pressure on two one-week diets, one low in sodium (3,000 mg/day) and the other high in sodium (18,000 mg/day). The participants were 1,906 Han Chinese adults (average age 38) in the Genetic Epidemiology Network of Salt Sensitivity (GenSalt), a large project to identify genetic and environmental factors contributing to salt sensitivity. The GenSalt project is located in rural China because the homogeneous population makes it more likely that genes influential to blood pressure control will be identified.
"The study needs to be repeated, but I suspect that the relationship between physical activity and salt-sensitivity will apply to other populations."
Your body needs some sodium to function properly because it helps maintain the right balance of fluids in your body, transmits nerve impulses and influences the contraction and relaxation of muscles.
Kidneys naturally balance the amount of sodium stored in your body for optimal health. When sodium levels are low, kidneys essentially hold on to the sodium. When sodium levels are high, kidneys excrete the excess in urine.
But if for some reason kidneys can't eliminate enough sodium, the sodium starts to accumulate in the bloodstream. Because sodium attracts and holds water, blood volume increases. Increased blood volume makes the heart work harder to move more blood through blood vessels, which increases pressure in arteries. Such diseases as congestive heart failure, cirrhosis and chronic kidney disease can make it hard for kidneys to keep sodium levels balanced.
The vast majority of dietary sodium comes from eating foods that are processed and prepared. These foods are typically high in salt, which is a combination of sodium and chloride, and in additives that contain sodium. While these ingredients have many practical uses, such as preservation and enhanced taste, they can greatly increase your sodium intake.
Like your sushi? Many recipes call for salt, and many people also salt their food at the table. Many other condiments also contain sodium. One tablespoon (15 milliliters) of soy sauce, for example, has about 1,000 mg of sodium.
Sources: The American Heart Association Meeting Report and The Mayo Clinic
Written by Sy Kraft, B.A.