Chronic high blood pressure or hypertension is a major health threat in the United States. It can result in heart disease, kidney failure and stroke. The causes of hypertension are not completely understood yet, but they appear to be related to a number of factors, including diet. While it is recognized that serum electrolytes have a profound effect on the heart's physiology, it is not yet known how some electrolytes obtained from the diet relate to long term blood pressure changes.
What are Electrolytes?
The Encyclopedia of Surgery states that electrolytes are ions or charged particles in water that can conduct electricity. They begin as elements found in nature in one of many forms. For example, potassium can exist in a salt form, such as potassium chloride. It can also exist in a chelated form, which means it is held by a large molecule, as occurs with potassium citrate. When food is processed by the body, the molecules are dissociated and atoms are freed. When certain atoms become ions in water, and thus form electrolytes, the body uses them in a variety of cell processes.
Sodium Electrolyte
The Encyclopedia of Surgery says normal serum sodium is 135 to 145 mEq per liter. This is a laboratory value, and within this range the heart and other organs should function normally. Higher or lower sodium in the blood is called hypernatremia or hyponatremia, respectively. The kidneys control the amount of sodium and other electrolytes in the blood. If there is too much serum sodium, the kidneys excrete it in the urine. If the blood contains too little sodium then it is conserved by the kidneys.
Other Electrolytes
Sodium is one of several electrolytes important to cell function, especially the function of the heart. Potassium, calcium and magnesium are also required to maintain normal physiological function. According to the Textbook of Physiology, these four electrolytes act together through complex mechanisms to help control a great variety of cell processes throughout the body. Examples of these processes include maintaining water balance within cells, exchange of nutrients across cell membranes and communication between cells.
Effect on the Heart
The heart is an organ with high energy and oxygen demands. It also requires a fine balance of electrolytes inside and outside cardiac cells to operate normally. Any imbalance between electrolytes can produce heart dysfunctions which can manifest as irregularities in heart beat or heart muscle contraction. This is because electrolytes help control these functions at the most basic level of the cardiac cell. Intake of foods high in sodium may produce high levels of serum sodium. This is correlated with high blood pressure. The elevated sodium also can produce fibrillation, which is an irregular heart rhythm. If the blood pressure remains high for a long time it is called hypertension. The correlation of high sodium intake and hypertension increases with age, blood pressure level and family history, says the American Heart Association. The heart is also affected by other electrolytes that also come from the diet. The relationship between potassium, calcium and magnesium is complex when it comes to heart function. However, the American Heart Association says that regular consumption of fruits, vegetables and low fat dairy products, which are high in potassium, magnesium and calcium can lower blood pressure over time. However, it is not yet certain whether blood pressure is reduced by eating these foods based entirely on their electrolyte contents alone.
References
- Encyclopedia of Surgery: Electrolyte tests
- "Textbook of Medical Physiology"; Arthur C. Guyton and John E. Hall; 2006
- American Heart Association: Circulation: Dietary Electrolytes and Blood Pressure
