Back to Menu

DIET WITH OR WITHOUT SALT RESTRICTION CAN KEEP YOUR BLOOD PRESSURE LOWER OR CAN TREAT MILD HYPERTENSION

(July 2002)

That is the message of an impressive article in the Annals of Internal Medicine of December 18, 2001. Four hundred twelve adults with normal to moderately elevated blood pressures (systolic pressure 120 to 160 millimeters of mercury, diastolic 80 to 95 millimeters) were placed on either the Dietary Approaches to Stop Hypertension (DASH) diet or a normal (control) diet. The DASH diet is high in fruits, vegetables, low fat dairy foods, poultry, fish, and nuts. It is low in both saturated fats and high sugar sweets. Those on each diet had three 30-day trial periods, during which the basic diets (DASH or control) were designed to provide a sodium content close to that in the usual American diet, a moderately reduced sodium content, or a very low sodium content.

The DASH diet significantly reduced both systolic and diastolic blood pressures. So did lowering the salt intake. The greatest effect - and it was quite impressive - was found when the DASH diet was combined with a low salt diet. As expected, the blood pressure lowering with the DASH diet, the lowered sodium diet, or both was more pronounced in subjects with hypertension than it was among those who started with normal blood pressure.

Commentary: This is a very important study. The health risks of elevated, or even high normal, blood pressure are on a continuum. A systolic blood pressure of 120 millimeters of mercury or less and a diastolic of 70 millimeters or less is considered ideal; a systolic of 130 to 139 millimeters and a diastolic of 84 to 89 millimeters are considered high normal. Above that, for either systolic or diastolic pressures, is hypertension. Each 5 millimeters increase above ideal increases the risk of blood pressure-related heart attack or stroke, and each 5 millimeters decrease in high normal or elevated blood pressure reduces the risk. The DASH diet or sodium restriction can be useful for treating mild hypertension, for getting high normal blood pressure into the normal range, and for reducing diastolic pressures of 80 to 84 millimeters of mercury. For those with systolic pressures of between 120 and 129 millimeters and diastolic pressures of between 70 and 79 millimeters, the DASH diet can push the blood pressure closer to the ideal.

It is unlikely that the American public is going to significantly reduce sodium intake. The most that will happen is some restraint in use of the salt shaker. That will almost certainly not be enough to decrease the frequency of hypertension. On the other hand, the DASH diet is really the prudent diet and is not difficult to follow. It is still not entirely certain which components of the DASH diet are the most critical, but the evidence from previous studies indicates that increasing fruits and vegetables can reduce blood pressure significantly in those who are hypertensive, but not in those who have normal blood pressures. In contrast, the full DASH diet with its combination of lots of fruits and vegetables plus low fat dairy products seems to be effective for those with normal, high normal, or high blood pressures. Whether it is the calcium content of the low fat dairy products that is primarily responsible for the blood pressure lowering effect is not yet established.

The study period for each dietary regimen was only thirty days, but there is every reason to believe that the blood pressure effects will persist as long as the diet is followed. This is a reasonable and practical approach to keeping blood pressure in a good range. Of course, an equally effective approach is avoiding overweight. The combination of this diet plus weight control would contribute enormously to the health of the American public.

CLICK HERE for a list of high calcium-low fat dairy products.

Vollmer, W.M., et al. Effects of diet and sodium intake on blood pressure. Annals of Internal Medicine. Vol 135. (December 18) Pgs 1019-1028. 2001.

Supported by