Patients with cardiovascular or heart disease are frequently told to limit the amount of salt intake in their diets. Unfortunately, this can be a difficult task considering that salt is used as a major flavoring ingredient in many recipes. In addition, most restaurants and ready-to-eat foods contain high amounts of sodium. Dietary salt can have a significant impact on the heart and cardiovascular system.
Sodium and Vasculature
A common rule in biology is that wherever salt goes, water will follow. This is especially true in the case of blood vessels, where water moves in and out mainly through a diffusion process called osmosis. In adults, the sodium chloride concentration in blood is regulated by the body to remain between 136 and 145 mEq/L. The range is slightly wider in people older than 90, at 132 to 146 mEq/L. As more sodium enters the bloodstream, water follows to maintain equilibrium in sodium concentration between the bloodstream and tissue cells. As a result, the volume of fluid contained by the blood stream is increased.
Blood Pressure Calculation
Blood pressure is equal to cardiac output times peripheral resistance, or BP=CO x PR. This equation shows that factors causing cardiac output to increase would also have an increasing effect on blood pressure. Cardiac output can be further broken down into the equation Cardiac Output = Heart Rate x Stroke Volume, or CO=HR x SV. As represented in the equation, stroke volume is the volume of blood pumped out by the heart with each contraction. Since salt intake increases the volume of fluid in blood vessels, stroke volume is also increased. As a result, cardiac output and subsequently blood pressure may also be increased.
Heart Failure
High blood pressure is major risk factor for the development of heart failure. The heart muscle can become weakened from the prolonged burden of pumping larger volumes against higher blood pressures. As the heart becomes less efficient at pumping blood, the kidneys are unable to eliminate excess salt and water from the body. As a result, fluid accumulates in the blood vessels which can then leak into organs causing serious health conditions.
Myocardial Infarction
Higher blood pressures can also irritate and cause damage to the inner lining of arteries. This can lead to a complex process of scarring, as well as platelet and lipid aggregation, which can cause narrowing of the arteries or clot formation. When this occurs in arteries that supply the heart with oxygen, patients can develop angina or have a heart attack.
Low Sodium Diet
According to the American Heart Association, daily intake of sodium should not exceed 1,500 mg per day. Currently, the average American is estimated to have a sodium intake of 3,436 mg per day. By decreasing the amount of dietary salt intake, it is possible to lower blood pressures and reduce the risk of heart disease.
