Food nutrition labels help you buy and eat healthy foods. The U.S. Food and Drug Administration, or FDA, designed these labels to help you better understand a specific food's nutritional value compared to a consistent standard. Most labels compare the nutrition of the food to a standard 2,000-calorie diet. The recommendation of some nutrients, such as fat, are linked to a percentage of this caloric intake, while other, such as sodium are not.
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The 2010 Dietary Guidelines for Americans as well as the Institute of Medicine and the National High Blood Pressure Education Program recommend that healthy adults limit their sodium intake to about 1,500 mg to 2,300 mg per day. Typical American diets far exceed this recommended limit, averaging between 3,100 and 4,700 mg of sodium per day for men; the average for women is slightly lower, between 2,300 mg and 3,100, due to their lower calorie intake. Children ages 2 to 8 should limit their intake even further, to between 1,000 mg and 1,900 mg per day. The limitation on sodium intake does not depend upon the amount of calories consumed.
Why Sodium Is Needed
Sodium helps transmits nerve impulses and influences the contraction and relaxation of muscle cells, including your heart. Sodium also helps maintain an appropriate balance of fluids within your cells. In processed foods, sodium preserves foods by preventing the growth of bacteria, yeast and mold, thereby increasing the shelf life of the product. Sodium also enhances flavors in food, accentuating the sweetness of cakes and cookies, disguising metallic or chemical aftertastes in products such as soft drinks, and reducing the perception of dryness in foods such as crackers and pretzels. When you consume sodium in excess of your body's needs, your kidneys function to excrete it. However, over time, continued excess sodium intake can lead to decreased kidney function, causing you to experience swelling or water retention, and eventual kidney damage.
Blood pressure measures the force of blood against your artery walls. Sodium chloride, or table salt, increases blood pressure, causing your heart to work harder, contributing to atherosclerosis and increasing the risk of heart disease and stroke, heart failure, kidney disease and blindness. Some individuals have greater blood pressure responses to sodium intake than others. According to the National Institutes of Health, controlled research trials and observational studies support reducing sodium intake as a way to prevent and treat hypertension, especially in sodium-sensitive individuals. Studies cannot yet distinguish which individuals are more sodium-sensitive than others, but a lower-sodium diet does no harm and has the potential for much good.
According to a 2006 article in the Journal of the American College of Nutrition, excess sodium intake can lead to osteoporosis, a condition characterized by low bone density and frequent bone breakage. The study reports that excess sodium excretion due to excess sodium intake is associated with elevated urinary calcium excretion. This loss of calcium evokes a response in your body that could eventually lead to significant bone loss. Three factors help control this loss of calcium: adequate calcium intake, adequate potassium intake and decreased sodium intake.
While high levels of sodium can cause significant health problems, low levels of sodium, known as hyponatremia, are also bad. When athletes and heavy laborers exercise, especially in excess heat, they can lose a significant amount of sodium through perspiration. Other conditions causing hyponatremia include kidney, heart or liver problems; diuretics or certain chemotherapy drugs; steroid, hormone or other metabolic defects; or water intoxication, a condition where water consumption occurs in the absence of other electrolytes. Symptoms of hyponatremia include disorientation, confusion or even coma, and symptoms can come on suddenly. For athletes and hard laborers, where excess perspiration is the cause, salt tablets are not recommended for treatment because they increase dehydration and exacerbate the condition. Instead, replace sodium loss by consumption of sports drinks or simply eating a regular meal. For more serious conditions, consult a health care professional.