Sodium intake may be a primary factor in the development of high blood pressure (hypertension), which is a major risk factor for heart attack . Hypertension (a “systolic” blood pressure above 140 and/or a “diastolic” pressure above 90) will develop in nearly everyone who lives into their 80’s, and in many people it occurs long before this age.
About half of the people with hypertension and 30% of the general public are described as "salt sensitive." This means that their blood pressures are likely to increase when they eat a high-sodium diet, and conversely, their blood pressures may be lowered by limiting dietary sodium.
Salt sensitivity is difficult to accurately diagnose. Therefore, appropriate sodium recommendations are a subject of great debate among nutrition experts. Some believe that all people should limit their sodium intakes (to 2,400 mg/day) to either treat or prevent hypertension, regardless of their present blood pressure level. Others, though, advise that only people with hypertension or those who are believed to be salt sensitive need to limit sodium in their diets.
Nutrition researchers are still trying to tease out the exact role of sodium in hypertension. A major study in this area is DASH—Dietary Approaches to Stop Hypertension. This study found that a diet rich in fruits, vegetables, and low-fat dairy products, and low in saturated fat, cholesterol, and saturated fat—now called the DASH diet —helped lower blood pressure.
The second phase of the study found further reductions in blood pressure when the DASH diet was combined with a sodium intake of no more than 2,400 mg/day. The combination of DASH diet and a sodium intake of no more than 1,600 mg/day was as effective in controlling blood pressure as medication involving a single antihypertensive drug. For some people with mild hypertension, diet alone may be an effective means of blood pressure control when the diet includes adequate calcium and potassium (DASH) along with sodium restriction.
Sodium is found in many foods. Some are obvious, but others may surprise you.
Table salt (sodium chloride, NaCl) is the major source of dietary sodium; about 1/3 to ½ of the sodium we consume is added during cooking or at the table.
Fast foods and commercially processed foods—canned, frozen, instant—also add a significant amount of sodium to the typical American diet. These include:
Sodium occurs naturally in:
Other sources of sodium in the diet:
All food products contain a Nutrition Facts label, which states a food's sodium content. The following terms are also used on food packaging:
Food label term | Meaning |
---|---|
Sodium free | Less than 5 mg/serving |
Very low sodium | 35 mg or less/serving |
Low sodium | 145 mg or less/serving |
Reduced sodium | 75% reduction in sodium content from original product |
Unsalted, no salt added, without added salt | Processed without salt when salt normally would be used in processing |
RESOURCES:
American Heart Association
http://www.americanheart.org/
National Heart, Lung, and Blood Institute
http://www.nhlbi.nih.gov/
CANADIAN RESOURCES:
Canadian Council on Food and Nutrition
http://www.ccfn.ca/
Dietitians of Canada
http://www.dietitians.ca/
References:
American Heart Association. Available at: http://www.americanheart.org . Accessed May 3, 2009.
American Heart Association. The American Dietetic Association's Complete Food and Nutrition Guide. New York, NY: Chronimed Publishing; 1998.
Duyff RL. The American Dietetic Association's Complete Food and Nutrition Guide. 3rd ed. Hoboken, NJ: John Wiley & Sons, Inc; 2006.
Last reviewed April 2009 by Maria Adams, MS, MPH, RD
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