Hypertension and Sodium... Just Another Scare?

The general concept that sodium causes high blood pressure is quite inaccurate. An excessive amount of sodium may, in susceptible individuals with high blood pressure, aggravate existing hypertension. Some people with existing high blood pressure, perhaps 30%-40%, are sodium sensitive. This means that dietary sodium, in moderate amounts, can increase their blood pressure further. And for these people, sodium intake should be modified.

Salt modification for those whose blood pressures are normal is not necessary, as sodium has never been shown to cause high blood pressure in these individuals. Unfortunately, the public is continually being given erroneous information about sodium and blood pressure.

Sodium is a necessary nutrient, essential for good health. In an average healthy man of 150 pounds, about 90 grams of sodium may exist in his body. One third of this in the bones, and most of the remaining two thirds surrounding the cells throughout the rest of the body. Sodium is a major player in the regulation of all the cells of the body. Balanced with potassium, sodium acts as an "electrochemical pump" in accomplishing this remarkable feat.

Sodium also helps regulate acid/alkaline balance, water balance, the heart beat, normal muscle contractions, sugar regulation, and even in blood pressure balance.

The problem of hypertension should not be taken lightly, as it is a serious health risk. But what is the definition of hypertension?

Experts disagree on the definition of high blood pressure. In Canada, for example, physicians generally do not consider blood pressures of up to 200/110 mm Hg in the elderly a problem requiring medication. In the U.S., pressures of 140/90 are often considered borderline hypertension. In people over the age of about 60, the "normals" tend to be higher, up to 160/95.

One factor does have general acceptance: some individuals, due to some genetic and/or acquired problem in their kidneys, are unable to process sodium normally. This results in an increased blood pressure.

Despite the fact that the American Heart Association and the Surgeon General recommend sodium restriction to prevent hypertension, other equally valid scientific opinions disagree. The American Council on Science and Health states in their literature that "stronger evidence should be available before persons are advised to alter their diets, and further caution that the possibility of harmful effects (of sodium restriction) cannot be totally discounted."

In 1988, the British Medical Journal (297:307) reported on the Intersalt Cooperative Research Group's international study on sodium and hypertension. The group demonstrated that a large reduction in sodium intake would result in an insignificant decrease in blood pressure. Specifically, an average decrease of 2.2 mm Hg systolic and 0.1 mm Hg diastolic pressures.

Almost everyone, however, agrees that hypertensive persons sensitive to sodium should restrict its use. But not as a primary treatment.

Other Factors Associated with Hypertension... Treatment of hypertension should be preceded by an attempt to find its cause. Two common examples of causes of high blood pressure include kidney problems and narrowed or "clogged" arteries. Some doctors indicate that when certain nutrients are low, such as vitamin A and C, and calcium, the blood pressure will rise. In other cases, emotional factors may play a primary role. A lack of activity -exercise - has also been shown to correlate with hypertension.

In the U.S., over 3 billion dollars is spent annually for blood pressure medication. Correcting hypertension without medication is the healthiest approach. When drugs are required, the proper medication and dose, along with careful observation for harmful side effects is vital. Although high blood pressure is dangerous, lowering it too much is not without potential problems. The findings of Dr. Michael Alderman and coworkers of the Albert Einstein College of Medicine show that too much lowering of blood pressure may reduce blood flow to the heart, which can put the heart at risk. The safest approach is a 10% reduction in blood pressure in a person with hypertension.

Many people do not realize that they can often control their own elevated pressures in the following ways:

Activity is a very important factor in high blood pressure. Studies show that unfit (non-exercising) persons are 1.5 times more likely to develop hypertension than fit individuals. Even in children, higher blood pressures are seen in those most inactive. Not only does increased activity in children result in lower blood pressures, but those who are active in sports have a lower incidence of hypertension later in life.

Hypertension has also been associated with dietary fats. Unfortunately, the common belief is that a low fat diet lowers blood pressure. This is untrue. Actually, studies have shown just the opposite. Unsaturated vegetable oils can lower blood pressure in many individuals. In one study (Am J Cardiol 6/88), low levels of substances called prostaglandin E2 (which is de-rived from the fats found in egg yolk, butter, and cream) were related to the inability of the kidney to eliminate salt which causes higher blood pressures.

Another factor associated with high blood pressure is being overweight. The prevalence of high blood pressure is 50% higher in overweight individuals aged 40-64 years of age. The New England Journal of Medicine (1978;298:1) reported a large study which showed that 75% of the hypertensive patients who lost weight (without sodium restriction) reduced their blood pressures to normal. In another study (Journal of the American Medical Association 1985;253:657), 325 patients with high blood pressures who were on medication for at least 5 years were divided into three groups. One group for weight reduction, one for sodium restriction, and one where no change in the diet was made. All were taken off their medication for the one year duration of the test. After that time, 60% from the weight loss group maintained a normal blood pressure without medication.

It is also known that children and adolescents who are overweight are much more likely to have high blood pressure as adults.

Weight loss can easily be maintained when the person is healthy all around. This means a good diet without extreme caloric restriction, including natural carbohydrates, proteins and fats, and regular activity or exercise. Finding a doctor who can help in these areas may be the first step.

Hypertension is a serious health problem. Attempting to find the cause may give a clue as to the most effective treatment. Assuming no emergency exists, following a thorough evaluation, where no cause can be found, conservative measures should be considered first. These include weight control, exercise, diet, and nutrition.