Commercial table salt consists mainly of sodium chloride, an electrolyte mineral compound that directly affects human blood pressure. When you consume salt, it dissolves in food liquid and stomach fluid, and your body absorbs the minerals when they reach your small intestine. Your digestive time frame depends on what else you have eaten and how quickly your stomach empties its food contents into your colon. At that juncture, the sodium element fulfills its metabolic role in fluid balance, immediately raising your blood pressure as a side effect.
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As soon as sodium enters your bloodstream from the intestine, it changes your electrolyte balance, triggering a shift in body fluids. Fluids leave the cells and intercellular spaces and move into the blood, to help restore the ratio of electrolyte minerals to body fluid required for homeostasis. The additional volume flowing through the blood vessels exerts greater force and pushes blood pressure upward.
At the same time, the cardiovascular system signals the kidneys to eliminate more sodium from the body. It does so by excreting more urine or by increasing the sodium concentration in urine. A healthy body performs this function daily when sodium and potassium intakes stay within a certain range. Potassium, another electrolyte mineral, reduces the effects of sodium on fluid migration.
High Salt Intake
Most Americans do not control their salt intakes to consume lesser amounts of sodium than potassium from their diets. Depending on your age and heart health, the Institute of Medicine considers 1,500 milligrams to 2,300 milligrams of sodium vs. 4,700 milligrams of potassium a proper dietary ratio. Average sodium intakes exceed recommendations at 3,300 milligrams per day, while potassium intakes fall short at 2,600 milligrams per day. This inverted ratio exacerbates the high-sodium effects, which are generated mainly by eating too much salty food. The U.S. Department of Agriculture attributes this overconsumption to the prevalence of processed foods in American diets.
Short-term changes in blood pressure become chronic over time. If you persist in a high-sodium diet, your blood pressure remains high because the kidneys can longer process the excessive amount of minerals. As a result, the heart, arteries and kidneys can sustain damage from the added stress. High blood pressure requires lifelong medical management. It is also a risk factor for heart attack, stroke and kidney failure.
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- National Digestive Diseases Information Clearinghouse; Your Digestive System and How It Works; April 2008
- Merck Manual Home Health Handbook; Sodium; August 2008
- Harvard School of Public Health: Lower Salt and Sodium
- U.S. Department of Agriculture: Dietary Guidelines for Americans 2010
- NIH Research Matters; Sodium-Potassium Ratio Linked to Cardiovascular Disease Risk; January 2009
- National Heart Lung and Blood Institutes; Your Guide to Lowering Your Blood Pressure With DASH; April 2006