Getting the Combination Right to Reduce the Risk of High Blood Pressure

We know that high blood pressure is just one of the risk factors for heart disease and stroke, and that having high blood pressure is related to being overweight, not exercising, and not eating right. If that's so, just how many cases of high blood pressure might be avoided with the right combination of diet and lifestyle?

The researchers used data gathered in the second Nurses' Health Study, a prospective study of over 116,000 female nurses which lasted over 15 years (JAMA 2009;302(4):401-411). The nurses focused on for this study, almost 84,000 of them, were those who had normal blood pressure at the start of the study and did not have diabetes, high cholesterol levels, or heart disease.

They began by looking at the common risk factors. To assess the quality of the nurses' eating habits, the scientists compared the participants' dietary questionnaires with the principles of the DASH diet (Dietary Approaches to Stop Hypertension) and assigned a score based on how closely the nurse's diet matched it. The DASH diet is based on eating higher amounts of fruits, vegetables, legumes and nuts, eating low-fat dairy products and whole grains, and eating less sodium (salt), sweetened drinks, and red or processed meats. As an example, those who ate the most fruits and vegetables received a higher score than those who ate the least fruits and vegetables. Similarly, those who ate the least red meat got a higher score than those who ate the most. The nurses with the best overall DASH score were considered to be in the "low risk" category with regard to their diet.

The researchers also looked at the nurses' Body Mass Index (BMI), and those whose BMI was under 25 (normal weight according to the World Health Organization) were also considered to be in the "low risk" category for weight. Another "low risk" factor was spending an average of 30 minutes per day doing vigorous exercise.

Over 12,000 of the nurses in the study developed high blood pressure over the course of the study. Their diet scores, BMI and level of exercise were then compared with those of the women who did not develop hypertension and had "low risk" scores in all three of these risk factors, then just two of the three factors, then just one. For each high-risk factor, the scientists were able to estimate what percentage of cases of high blood pressure might have been avoided if that high risk factor had been a low risk factor.

The results? It shouldn't be too surprising to find that just being in the healthy weight range could have prevented about 40% of all cases of high blood pressure. Having a high DASH score, exercising 30 minutes per day, and maintaining a Body Mass Index under 25 could have prevented 53% - over half – of the cases of high blood pressure.

What this means for you

One of the factors the researchers included in their analysis was a family history of high blood pressure. For those women with a family history of high blood pressure, being in the low-risk groups for the three risk factors meant 51% fewer cases of hypertension. Not having a family history of high blood pressure only added another 6% fewer cases. If you have hypertension in your family, you're not doomed to have it yourself. You can help reduce your risk by eating right, exercising and maintaining a healthy weight.

First posted: July 29, 2009