Salt - Public Enemy Number 1?

Popular press articles and self appointed gurus who claim to protect our health, are converging on sodium as the next public enemy. Is it really that bad for one? Try Googling "Salt is bad for you", and you will see a variety of opinions. We take the position that research and facts rather than hype and hysteria should determine whether a war against salt is warranted! We also consider the impact of diet on hypertension, regardless of salt intake - a tasty diet that includes salt, might be more acceptable and easy to adhere to for many people, if it improves their condition.

It is well documented that hypertension is an important risk factor that shoud be mitigated to reduce the risk of stroke and heart disease. Often, the first attempt at mitigation involves diet modification, and in particular, a reduction in salt (sodium) intake. Salt is a compound composed of two elements - sodium and chlorine. When people talk about the impact of salt on humans, they are really referring to the impact of sodium. Consequently, we will use the words "salt" and "sodium" interchangeably in this series.

The relationship between sodium intake, diet and hypertension (high blood pressure) has been studied for decades. The first study we address, (Reference 1), dates back to 1997, and deals with the effects of diet (only) on hypertension. This study involved 459 adults with systolic (the higher number in blood pressure readings) blood pressures of less than 160 mm Hg and diastolic (the lower number) blood pressures of 80 to 95 mm Hg. For the first three weeks, the subjects were fed a "control" diet. It was low in fruits, vegetables, and dairy products, with a fat content typical of the average diet in the United States at that time. They were then randomly split into three groups for eight weeks. The first group stayed on the control diet; a second group had a diet rich in fruits and vegetables; the third group had a “combination” diet rich in fruits, vegetables, and low-fat dairy products and with reduced saturated and total fat. After three weeks, the following results were obtained:

The second group (relative to the control diet), had reduced their systolic blood pressure by an average of 2.8 (Margin of Error 0.9 to 4.7). However, hypertensive people had a much larger reduction: 7.2 (Margin of Error 3 to 11.4). A similar reduction was observed for the diastolic pressure: average reduction of 1.1 (Margin of Error 0.3 to 2.4) for the general population, and 2.8 (Margin of Error 0.3 to 5.4) for hypertensive people.

The third group (relative to the control diet), had reduced their systolic blood pressure by an average of 5.5 (Margin of Error 3.7 to 7.4). However, hypertensive people had a much larger reduction: 11.4 (Margin of Error 6.9 to 15.9). A similar reduction was observed for the diastolic pressure: average reduction of 1.1 (Margin of Error 0.3 to 2.4) for the general population, and 5.5 (Margin of Error 2.7 to 8.2) for hypertensive people.

In this diet, sodium intake was identical for all diet groups. We conclude that a diet rich in fruits, vegetables, and low-fat dairy foods and with reduced saturated and total fat can substantially lower blood pressure, especially for hypertensive people. What, then, will the role of reducing sodium play in enhancing this effect?

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Last Modification - September 1, 2008