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Low Sodium

Low Sodium

What is sodium?

Sodium is an essential nutrient for normal body function. It plays a major role in the regulation of body fluids, in partnership with potassium and chloride. Together, these three maintain proper body water distribution and blood pressure. Researchers have suggested excess sodium in our diet is a contributing factor to the epidemic of high blood pressure in today’s North American population.

How much sodium do I need?

No recommended daily allowance (RDA) has been set for the maximum or minimum levels of sodium intake required by a healthy adult. The Food and Nutrition Board of the National Academy of Sciences suggests a daily minimum of 500 milligrams (mg) is necessary.(2) No more than 2,400 mg should be consumed per day, according to American Heart Association (AHA) recommendations.(3) The Federal Drug Administration (FDA) has adopted the AHA standard and applied it to the FDA’s Daily Value for food labels. This standard equates to only one teaspoon of salt per day.

Today’s North American diet typically contains between 3,000 to 6,000 mg of sodium. This exceeds the AHA standard and suggests there is an excess of sodium in the typical diet. The impact of this excess has been the subject of much study. As a result, two disease states — osteoporosis and hypertension — have been linked to excess dietary sodium. Higher than normal sodium intake may contribute to osteoporosis by increasing calcium loss in the urine. Researchers also believe that a high-sodium diet combined with a genetic predisposition can lead to elevated blood pressure, a condition called hypertension.

What is hypertension?

The pressure of blood against the walls of blood vessels is described as “blood pressure” and is determined by several factors: the pumping action of the heart, blood volume and thickness, the elasticity of arterial walls and the resistance to blood flow in the arteries. When blood pressure rises beyond 140/90 mm Hg, the condition is called hypertension. Untreated, hypertension can lead to heart attack or failure, stroke, kidney failure, and premature death. Hypertension is the most common major health condition in the United States, affecting one-in-four people and half of those over 65.

Is sodium linked to hypertension?

The link between high-sodium diets and hypertension remains controversial. Population studies, however, have shown that people from countries where sodium consumption is high tend to have a higher incidence of hypertension. Conversely, studies of primitive populations where little sodium is consumed shows little or no hypertension. In addition, provided a traditional diet is maintained, blood pressure does not increase amongst these people as they age.(6) While the treatment of hypertension with sodium restriction is hotly debated, research into reducing sodium in the average diet shows that moderate sodium reduction presents no hazard to human health and that there would be a reduction in cardiovascular morbidity and mortality amongst North Americans.(7)

What are food sources of sodium?

The food processing industry is a major user of sodium in several forms, relying upon it as both a flavor enhancer and a natural preservative. It’s estimated that processed foods contribute 75 percent of the sodium in our diet. 10 percent occurs naturally in foods, and the remaining 15% comes from the use of salt in cooking or added at the table.(8)

Sources

1. Oh MS, Uribarri J. Electrolytes, water, and acid-base balance. In: Shils ME, Olson JA, Shike M, Ross AC, eds. Modern Nutrition in Health and Disease, 1999:222, 105-139.
2. Insel P, Turner R, Ross D, Nutrition, 2002:414-415.
3. American Heart Association from www.americanheart.org .
4. Insel P, Turner R, Ross D, Nutrition, 2002:430-432.
6. Zemel MD, Dietary pattern and hypertension: the DASH study. Nutrition Review. 1997;55:303-308
7. USDA Center for Nutrition Policy and Promotion. Dietary guidance on sodium: should we take it with a grain of salt? Nutrition Insights; May, 1997.
8. Insel P, Turner R, Ross D, Nutrition, 2002:414-415.
9. Mayo Clinic, University of California Los Angeles, Dole Co.
Encyclopedia of Foods, A Guide to Healthy Nutrition, 2002:53-57.