09 May 2010

Sodium: How much is right for you?

Sodium’s association with high blood pressure is well known. However, sodium also plays a large role in keeping you healthy. It’s important to know how to strike the right balance.

Along with potassium, sodium is essential for fluid balance, facilitating the flow of water in and out of cells to bring nutrients in and take wastes away. Sodium also has a role in the regulation of blood pressure and helping muscles and the heart relax. Each sodium ion contains an electrical charge, acting as an electrolyte, which allows transmission of nerve impulses to the brain and throughout the body.

Sodium levels in the body are controlled by the kidneys. If the body doesn’t receive enough sodium daily—a chronic problem for our early ancestors—then the kidneys retain sodium. When the body has a high enough amount, then the excess sodium is excreted in the urine.

At times, sodium levels may fluctuate. If a person has a dysfunctional kidney, then the body may retain too much sodium, which can result in edema, or swelling in the legs and feet because sodium attracts water. In contrast, diarrhea or vomiting may result decreased sodium levels, a condition known as hyponatremia.

How sodium regulates blood pressure is not entirely understood, but there is an established link between high sodium intake and high blood pressure. As expected, there is also a link between sodium reduction and lower blood pressure.

The sodium-hypertension relationship may also have to do with how sodium interplays with other minerals such as potassium and calcium. Potassium, for example, appears to assist the kidneys in shedding excess sodium. Lowering sodium intake also helps to conserve calcium, which may affect blood pressure.

Recommendations for Sodium

The Institute of Medicine is recommending an Adequate Intake of sodium at 1,500 mg per day for adults and children 9-13 as well as 1,000 mg and 1,200 mg per day for children ages 1-3 and 4-8, respectively. These levels are considered appropriate for replacing daily losses via sweat and urine. The need for sodium may be slightly greater if exercise produces excessive sweating or if a person has symptoms of vomiting or diarrhea.

On average, however, most adults in the U.S. consume about 3,200 milligrams or more a day. With these figures, it is easy to understand why high blood pressure affects nearly 75 million Americans. The average intake is well above the Institute of Medicine’s Tolerable Upper Intake Level of 2,300 milligrams per day for adults and 1,500mg, 1,900mg and 2,200 mg for children ages 1-3, 4-8 and 9-13, respectively.

Cutting sodium intake daily tor recommended levels is important and it doesn’t have to be difficult with these three simple strategies:

Sodium Strategy #1: Limit processed or prepared foods high in sodium. Most sodium in the diet doesn’t come from the salt shaker, but from processed and prepared foods. Thus, the best way to lower sodium is to reduce intake of processed foods or replace them with low-sodium alternatives. This includes ready-to-eat packaged foods such as potato chips, fast-food meals such as burritos, and highly salted meals prepared at restaurants.

Sodium Strategy #2: Learn to enjoy food without salt. Taste food before salting it; the food may already be salty enough or it may be enjoyed without salt. In fact, salty is an acquired taste. The body and taste buds can easily adjust to less salt. Studies have shown that as people reduce salt intake and stick to a relatively lower intake of sodium, they will naturally begin to prefer foods with less salt. When eating at home, try not having the salt shaker on the table and, if eating out, simply move salt shakers to another table. When preparing food, try using less salt and seasoning food with spices or salt-substitutes instead. Keep an eye on store-bought spice blends, though, as many may contain high amounts of salt.

Sodium Strategy #3: Balance sodium with potassium-rich fruits and vegetables. A clear association exists between higher potassium intake from fruits and vegetables and lower blood pressure regardless of sodium intake. Potassium helps the kidneys in promoting sodium excretion, reduces urinary calcium and magnesium (which influence blood pressure), supports smooth vascular muscle health, and helps with regulation of blood pressure.

Less Sodium in a DASH

Most people who are interested in maintaining healthy blood pressure levels would do best to follow a DASH (Dietary Approaches to Stop Hypertension)eating plan. In the well-known DASH-sodium study, which was conducted by the National Heart, Lung and Blood Institute, people following the diet lowered blood pressure in just 14 days even without reducing salt intake.

The DASH eating plan includes consuming a diet rich in low-fat, low-sodium dairy products, fish, chicken and lean meats as well as large amount of whole grains, fruits and vegetables.

When a person is concerned about blood pressure, the best advice nutritionists can give is to begin following a DASH eating plan combined with regular exercise and weight management. In fact, according to a recent study in Hypertension, this plan helped people reduce blood pressure, lose weight, improve mental function, and improve cardiovascular health.

Taking the Pressure Off of Sodium

It’s extremely easy to place all of the blame for society’s high blood pressure woes and medical costs on sodium, but the mineral’s role in the body should not be ignored. Sodium is essential for good health and too little could lead to other health issues, including deficiencies in iodine, which is mainly provided in the North American diet from iodized salt.

While lowering sodium consumption can lead to a natural preference for foods with less salt, it’s important not to cut salt out completely. Because the body requires some sodium to function properly, avoiding salt entirely might backfire, and cause cravings for high-sodium foods. As with almost all vitamins and minerals, the key to healthy sodium intake is always balance with other nutrients. A DASH eating plan and strategies for maintaining a healthy intake (such as those given above) can help you achieve this balance of nutrients for healthy blood pressure levels and optimal health.


Dyuff RL, American Dietitic Association. American Dietetic Association Complete Food and Nutrition Guide, 3rd edition. 2006. Wiley.

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