jen1234
Mar 31, 2010
Research Papers / A Look at Sodium and its Effects on Hypertension [2]
Sodium has become a very important component in this world. Sodium helps with major biological functions that include transmitting nerve impulses, contracting and relaxing muscle fibers and maintaining proper fluid balance. The recommended daily intake of salt is about 2,300 milligrams of sodium. But the average amount that Americans consume is two to four times the recommended amount. It has been assumed that sodium has a big impact on the blood pressure. Many studies have shown that blood pressure is related to sodium intake and if people were to reduce the amount of sodium in their diet it would greatly reduce their blood pressure. The purpose of this paper is to determine the effects that sodium has on blood pressure. Blood pressure is referred to the force of blood pushing against blood vessel walls. The hearts main function is to pump blood into the arteries (blood vessels) which carry the blood throughout the body. So when someone has high blood pressure this means that pressure in the arteries is above the normal range.
Hypertension or what is known as high blood pressure affects 50 million people in the United States (7). High blood pressure is characterized as a reading of 140/90 millimeters of mercury (mm Hg) or higher. The higher number of the blood pressure reading is referred to as systolic. This number represents the pressure of the heart contracting and pumping blood to the body. The lower number is diastolic and represents the pressure when the heart relaxes between beats. These numbers are very important because, as the heart pumps the blood into the blood vessels, that can then be sent to all other parts of the body. Blood vessels are like a tree's branches, they travel away from the heart and branch off and get smaller. Each branch then goes to a different part of the body and supplies the cells with oxygen, nutrients and waste matter is removed. High blood pressure can cause many problems in one's life, including damage to an individual's blood vessels. This in turn can raise the risk for other complications in life like stroke, kidney failure, heart disease and heart attacks.
What does sodium exactly do in the body? Sodium's role is crucial in maintaining the health of the every cell in the human body. It allows the fluid between cells, the extracellular fluid to filter or spread throughout the inside of cells or intracellular fluid that consists of potassium. These two minerals work closely together and have to be in constant balance so that nutrients and waste can be taken across cell membranes. If one of these minerals where to be deficient or in excess then the cells health will deplete and the cell suffers in result. Sodium enters the outside of a cell through the sodium-potassium pump or other known as the Na+/K+ -ATPase. This process involves the movement of sodium and potassium ions across the cell membrane by active transport. The energy that is required for this process to happen is the hydrolysis of ATP which transports the ions against a concentration gradient. In this process the sodium binds to the protein channel, the ATP provides the energy for the channel to change its shape that will drive the reaction to take place. Once the channel has changed shape the sodium ions are released to the outside of the cell membrane. The new shape of the channel then enables potassium ions to bind and to be transported to the inside of the cell membrane with the help of a phosphate that stays behind from the ATP. With the binding of the potassium ions changes the shape of the channel and the release of the phosphate allow the channel to go back to its original shape and release the potassium inside the cell. Once this happens it is in its original shape and the process can begin all over to move more sodium to the outside of the cell and bring more potassium inside the cell (2). The kidneys are the main regulator of the body's sodium level by getting rid of the excess. When there is excess sodium in the body the kidneys may not be able to keep up. Due to all the excess sodium in the bloodstream the result can be water pulled out from the cells and as the fluid increases so does the blood volume. This means there will be more work for the heart or increased pressure in the blood vessels which can result to stiffened vessels walls, high blood pressure and increased risks of heart attacks and strokes. With all this increased sodium can cause more fluid to be contained in the blood vessel which requires the heart to work harder in its job of pumping blood to all the tissues in the body. Sodium is necessary to maintain and provide many things for the body but obtaining too much of sodium can be harmful.
Many studies that have been conducted have used the Dietary Approaches to Stop Hypertension (DASH) diet, which is composed of rich fruits, vegetables, low fat dairy products, whole grains, nuts, fish, lean meats and poultry (3). In many of these trials the participants were involved in diets that were divided into three levels of sodium, high which was 3,500 mg/day, moderate of 2, 400 mg/day and low which consisted of 1,500 mg/day. The results showed that less sodium did lower many of their blood pressures. In the study that was performed by Frank Sacks, the participants ate a diet that was high in sodium for two weeks and then were randomly selected to follow one of the two diets, the control diet and the DASH diet. The researchers looked at three sodium levels that the participants had to follow in their diet as well. The first level was defined as high and consisted of 150 mmol per day of sodium that resembled the typically consumption in the United States, the second level was intermediate with 100 mmol per day and resembled the upper limit of the current national recommendations and the last level was low which consisted of 50 mmol per day and resembled what the researchers thought would produce an additional lowering of blood pressure. Researchers found that the reduction of sodium intake lowered the systolic and diastolic blood pressure in both diets but the DASH diet resulted in a significantly (P<0.001 for the interaction) lower systolic and diastolic blood pressure in the high and intermediate levels of sodium. The researchers were able to see a lower blood pressure in the participants that did not have hypertension as well. The results showed that people with hypertension that participated in the DASH diet and a low level of sodium reduced their systolic blood pressure by 11.5 mm Hg. This trial was able to provide several key findings that are important to the prevention and treatment of hypertension. First, by following the DASH diet it does lower blood pressure at the high, intermediate and low sodium levels. The trial has proven the benefits of the DASH diet can be applied to different ranges of sodium intake. Second this trial proves that blood pressure can be lowered in either a diet that is typical in the United States or the DASH diet by reducing their sodium intake to 100 mmol per day. Finally this study shows that with the combination of the DASH diet and lower sodium in the diet will result in lower blood pressure (7).
Due to the early epidemiologic studies, that show that there was a strong positive correlation between salt intake and blood pressure, and due to some earlier studies that have since shown a diffident decrease in blood pressure with the restriction of sodium has left this topic very controversial due to the inconsistencies in the studies. This next study that will be discussed conducted a study on the concept of salt sensitivity. Salt sensitivity is referred to "an increase in blood pressure in response to an increased or a decreased blood pressure in response to a reduction in dietary sodium intake" (4). Myron H. Weinberger conducted a study involving 74 individuals that had normal blood pressure had them on a restricted diet of sodium for four months. To be diagnosed as salt sensitive there needed to be a decrease in blood pressure by 3 mm Hg and an increase by 3 mm Hg would indicate salt resistance. The results of the study showed that 31 of the 74 individuals were salt sensitive. This concept of salt sensitivity is very important because reduction in sodium intake can reduce both blood pressure and possibly the need of drug treatment (4).
Many things affect individual's health or how their blood pressure is affected by salt, including their genes, age, race and medical conditions. The studies have proven that a diet with a lower intake of 2,300 mg/day of sodium will lower blood pressure and will result in 11 million fewer cases of high blood pressure. Based on consistent research that has been done regarding blood pressure and the relation with sodium has proven that avoidance of excessive sodium intake can lower blood pressure.
Sodium has become a very important component in this world. Sodium helps with major biological functions that include transmitting nerve impulses, contracting and relaxing muscle fibers and maintaining proper fluid balance. The recommended daily intake of salt is about 2,300 milligrams of sodium. But the average amount that Americans consume is two to four times the recommended amount. It has been assumed that sodium has a big impact on the blood pressure. Many studies have shown that blood pressure is related to sodium intake and if people were to reduce the amount of sodium in their diet it would greatly reduce their blood pressure. The purpose of this paper is to determine the effects that sodium has on blood pressure. Blood pressure is referred to the force of blood pushing against blood vessel walls. The hearts main function is to pump blood into the arteries (blood vessels) which carry the blood throughout the body. So when someone has high blood pressure this means that pressure in the arteries is above the normal range.
Hypertension or what is known as high blood pressure affects 50 million people in the United States (7). High blood pressure is characterized as a reading of 140/90 millimeters of mercury (mm Hg) or higher. The higher number of the blood pressure reading is referred to as systolic. This number represents the pressure of the heart contracting and pumping blood to the body. The lower number is diastolic and represents the pressure when the heart relaxes between beats. These numbers are very important because, as the heart pumps the blood into the blood vessels, that can then be sent to all other parts of the body. Blood vessels are like a tree's branches, they travel away from the heart and branch off and get smaller. Each branch then goes to a different part of the body and supplies the cells with oxygen, nutrients and waste matter is removed. High blood pressure can cause many problems in one's life, including damage to an individual's blood vessels. This in turn can raise the risk for other complications in life like stroke, kidney failure, heart disease and heart attacks.
What does sodium exactly do in the body? Sodium's role is crucial in maintaining the health of the every cell in the human body. It allows the fluid between cells, the extracellular fluid to filter or spread throughout the inside of cells or intracellular fluid that consists of potassium. These two minerals work closely together and have to be in constant balance so that nutrients and waste can be taken across cell membranes. If one of these minerals where to be deficient or in excess then the cells health will deplete and the cell suffers in result. Sodium enters the outside of a cell through the sodium-potassium pump or other known as the Na+/K+ -ATPase. This process involves the movement of sodium and potassium ions across the cell membrane by active transport. The energy that is required for this process to happen is the hydrolysis of ATP which transports the ions against a concentration gradient. In this process the sodium binds to the protein channel, the ATP provides the energy for the channel to change its shape that will drive the reaction to take place. Once the channel has changed shape the sodium ions are released to the outside of the cell membrane. The new shape of the channel then enables potassium ions to bind and to be transported to the inside of the cell membrane with the help of a phosphate that stays behind from the ATP. With the binding of the potassium ions changes the shape of the channel and the release of the phosphate allow the channel to go back to its original shape and release the potassium inside the cell. Once this happens it is in its original shape and the process can begin all over to move more sodium to the outside of the cell and bring more potassium inside the cell (2). The kidneys are the main regulator of the body's sodium level by getting rid of the excess. When there is excess sodium in the body the kidneys may not be able to keep up. Due to all the excess sodium in the bloodstream the result can be water pulled out from the cells and as the fluid increases so does the blood volume. This means there will be more work for the heart or increased pressure in the blood vessels which can result to stiffened vessels walls, high blood pressure and increased risks of heart attacks and strokes. With all this increased sodium can cause more fluid to be contained in the blood vessel which requires the heart to work harder in its job of pumping blood to all the tissues in the body. Sodium is necessary to maintain and provide many things for the body but obtaining too much of sodium can be harmful.
Many studies that have been conducted have used the Dietary Approaches to Stop Hypertension (DASH) diet, which is composed of rich fruits, vegetables, low fat dairy products, whole grains, nuts, fish, lean meats and poultry (3). In many of these trials the participants were involved in diets that were divided into three levels of sodium, high which was 3,500 mg/day, moderate of 2, 400 mg/day and low which consisted of 1,500 mg/day. The results showed that less sodium did lower many of their blood pressures. In the study that was performed by Frank Sacks, the participants ate a diet that was high in sodium for two weeks and then were randomly selected to follow one of the two diets, the control diet and the DASH diet. The researchers looked at three sodium levels that the participants had to follow in their diet as well. The first level was defined as high and consisted of 150 mmol per day of sodium that resembled the typically consumption in the United States, the second level was intermediate with 100 mmol per day and resembled the upper limit of the current national recommendations and the last level was low which consisted of 50 mmol per day and resembled what the researchers thought would produce an additional lowering of blood pressure. Researchers found that the reduction of sodium intake lowered the systolic and diastolic blood pressure in both diets but the DASH diet resulted in a significantly (P<0.001 for the interaction) lower systolic and diastolic blood pressure in the high and intermediate levels of sodium. The researchers were able to see a lower blood pressure in the participants that did not have hypertension as well. The results showed that people with hypertension that participated in the DASH diet and a low level of sodium reduced their systolic blood pressure by 11.5 mm Hg. This trial was able to provide several key findings that are important to the prevention and treatment of hypertension. First, by following the DASH diet it does lower blood pressure at the high, intermediate and low sodium levels. The trial has proven the benefits of the DASH diet can be applied to different ranges of sodium intake. Second this trial proves that blood pressure can be lowered in either a diet that is typical in the United States or the DASH diet by reducing their sodium intake to 100 mmol per day. Finally this study shows that with the combination of the DASH diet and lower sodium in the diet will result in lower blood pressure (7).
Due to the early epidemiologic studies, that show that there was a strong positive correlation between salt intake and blood pressure, and due to some earlier studies that have since shown a diffident decrease in blood pressure with the restriction of sodium has left this topic very controversial due to the inconsistencies in the studies. This next study that will be discussed conducted a study on the concept of salt sensitivity. Salt sensitivity is referred to "an increase in blood pressure in response to an increased or a decreased blood pressure in response to a reduction in dietary sodium intake" (4). Myron H. Weinberger conducted a study involving 74 individuals that had normal blood pressure had them on a restricted diet of sodium for four months. To be diagnosed as salt sensitive there needed to be a decrease in blood pressure by 3 mm Hg and an increase by 3 mm Hg would indicate salt resistance. The results of the study showed that 31 of the 74 individuals were salt sensitive. This concept of salt sensitivity is very important because reduction in sodium intake can reduce both blood pressure and possibly the need of drug treatment (4).
Many things affect individual's health or how their blood pressure is affected by salt, including their genes, age, race and medical conditions. The studies have proven that a diet with a lower intake of 2,300 mg/day of sodium will lower blood pressure and will result in 11 million fewer cases of high blood pressure. Based on consistent research that has been done regarding blood pressure and the relation with sodium has proven that avoidance of excessive sodium intake can lower blood pressure.
