Hypertension is simply defined as high blood pressure. Blood pressure is a measurement of the force against the walls of your arteries by the circulating blood. Hypertension is a symptom not a disease, but it is a strong risk factor for cardiovascular and kidney diseases. For this reason, it is important to control hypertension, to prevent the development of these conditions. Well-established dietary modifications that lower blood pressure are reduced salt intake, weight loss and moderation of alcohol consumption. A low-sodium diet with restricted calories and saturated fats, supplemented with anti-hypertensive drugs, is the most effective treatment for hypertension.
Sodium and Water Regulation
The kidneys regulate the water and sodium balance in the body. The fundamental idea is if sodium is retained, water is retained and conversely, if sodium is excreted, water will be excreted. If there is excess sodium it signals the kidneys to reabsorb water. It also makes you feel very thirsty, so you drink more water until equilibrium is achieved. This increase in the plasma volume, increases cardiac output, and puts burden on the heart, kidneys and blood vessels, thereby increasing blood pressure.
Sodium Recommendations
Sodium is essential for body functioning but the amount required by the body is relatively low, as little as 0.5 to 1 g daily. The main source of sodium in your diet is table salt. Salt is about 40 percent sodium by weight. One g of salt is 400 mg sodium, 1 tsp. or 5 g of salt is 2,000 mg sodium. An average American consumes about 10 to 12 g of salt per day, which is much higher than the required amounts. Routinely consuming such high amounts, over the years, plays a role in the underlying cause of hypertension. The Dietary Guidelines for Americans currently is 2,300 mg sodium per day for people who are 2 or older. This amounts to about 1 tsp. of salt per day, while the average American consumes about 50 percent more than that--more than 3,400 mg of sodium per day.
Salt and Hypertension
According to "The Textbook of Medicine," salt restriction and weight loss should always be the first steps in hypertension management. Cutting down sodium intake to 2,300 mg per day has an effect similar to that of anti-hypertensive drugs, in hypertensive patients, but without the side effects. This will also bring down blood pressure immediately by 10 percent for normal people and sticking to this sodium intake would prevent a rise in blood pressure for many years. The book '"Understanding Normal and Clinical Nutrition," notes that salt has a greater effect on blood pressure than either sodium or chloride alone or in combination with other ions. Some people have salt sensitivity, where blood pressure increases in response to excessive salt intake. Individuals likely to develop salt sensitivity are obese, those whose parents had high blood pressure, those who have kidney disease or diabetes, African Americans, and people older than 50. For them, a high salt intake correlates strongly with heart disease, and salt restriction helps to lower their blood pressure.
Diet for Hypertension
The dietary approaches to stop hypertension, or DASH, diet when combined with a low-sodium diet, significantly lowers blood pressure in people with stage 1 hypertension and in those with higher than normal blood pressure. The DASH diet also lowers blood pressure in those with isolated systolic hypertension--a very common symptom among older Americans, where only systolic pressure is higher. The DASH diet is high in fruits, vegetables, whole grains and low-fat dairy products and low in total fat, saturated fat and cholesterol. It will also provide an ample amount of fiber, potassium, magnesium and calcium, some other dietary factors needed to lower the risk of blood pressure and cardiovascular diseases. The DASH diet pattern when combined with low sodium intake is more effective in lowering blood pressure then either diet alone.
References
- ''Nutrition and Diet Therapy''; Peggy Stanfield, Y. H. Hui; 2009
- American Heart Association: Individual Blood Pressure Responses to Changes in Salt Intake
- ''Textbook of Medicine''; Robert L. Souhami, John Moxham; 2002
- ''Understanding Normal and Clinical Nutrition''; Sharon Rady Rolfes, Kathryn Pinna, Ellie Whitney; 2008
