Last month we discussed a study on twins that found that when identical twins have very different blood pressure (BP) measurements, the one with the higher BP consumed significantly more salt/sodium than the twin with the lower BP. The twin with the higher BP also tended to have a bigger waist and BMI than their more normotensive sibling. However, the impact of dietary sodium intake appeared significantly greater than the impact of central adiposity and so remains significant after correcting for BMI and waist circumference or waist/hip ratio. However, it would be wrong to conclude that other factors besides excessive salt intake also contribute to the development of hypertension (HTN). Indeed, a second study presented at this same conference, showed that 85% of obese subjects with an initially elevated BP of 130-159/80-99mmHg (but not taking BP-drugs) could sufficiently control their HTN and avoid the need for anti-HTN drugs simply by changing their diets and lifestyles.
The study was conducted by Dr. Alan Hinderliter, MD, an associate professor of medicine at University of North Carolina in Chapel Hill. The subjects in this study were men and women with elevated BP. Dr. Hinderliter and associates studied 129 overweight or obese men and women between ages 40 and 80 years who had been diagnosed with HTN. These patients’ BPs were between 130-160/80-99 mmHg, but they were not taking medications to lower BP at the time of the study. Most were candidates for antihypertensive medication at the study’s start, according to the most recent medical guidelines. Researchers randomly assigned each patient to one of three 16-week intervention groups. Participants in one group changed the content of their diets and took part in a weight management program that included behavioral counseling and three times weekly supervised exercise programs. They also changed their eating habits to that of the DASH diet plan, a nutritional approach proven to help lower BP. The DASH diet emphasizes fruits, vegetables, and low-fat dairy or nonfat dairy, and minimizes the consumption of red meats, added salt, and foods rich in added sugars. Participants in the second group changed diet only, focusing on the DASH diet with the help of a nutritionist. The third control group didn’t change either their exercise or dietary habits.
The results showed the need for antihypertensive medications was markedly reduced within 16 weeks after making most of the recommended diet and lifestyle changes. The results were presented at the American Heart Association's Joint Hypertension 2018 Scientific Sessions, which is an annual conference focused on recent advances in hypertension research. Lifestyle changes are already the first step physicians are told to emphasize for reducing elevated BP, according to the most recent 2017 American College of Cardiology/American Heart Association Hypertension Guideline, but all too often rushed physicians put too little emphasis on these changes, perhaps because they believe they really are not nearly as effective as the anti-hypertensive drugs that the vast majority of patients end up on in America after being diagnosed with HTN.
“Lifestyle modifications, including healthier eating and regular exercise, can greatly decrease the number of patients who need blood pressure-lowering medicine. That’s particularly the case in folks who have blood pressures in the range of 130 to 160 mmHg systolic and between 80 and 99 mmHg diastolic,” said study author Alan Hinderliter, MD. Dr. Hindliter informed me that the sodium content of the DASH diet he used was 1.2mg of sodium per kcal or about 2400mg sodium for 2000kcal diet. So while the diet used in his study was a bit lower than than what is average for Americans it was not nearly as low as what is now recommended for optimal reduction of BP in those diagnosed with HTN.
The researchers found:
- Those eating the DASH diet and participating in the weight management group lost an average of 19 lbs and had reduced their BP by an average 16 mmHg systolic and 10 mmHg diastolic BP after 16 weeks.
- Those following only the DASH eating plan without the exercise program also saw a similar drop in BP with an average decline of 11mmHg systolic 8mmHg diastolic BP after 16 weeks.
- By contrast, the subjects in the control group who didn’t change their eating or exercise habits experienced a minimal BP decline with an average drop of only 3mmHg systolic and 4mmHg diastolic BP after 16 weeks.
- By the study’s end, only 15 percent of those who had changed both their diet and their exercise habits needed antihypertensive medications, as recommended by the 2017 AHA/ACC guideline, compared to 23 percent in the group that only changed their diet. However, there was no change in the need for medications among those who didn’t change their diet or exercise habits. For the control group, about half continued to meet current criteria for starting on drug treatment for their elevated BP.
Dr. Hinderliter said that he suspects diet and lifestyle modifications would be just as helpful to people with an even higher risk of cardiovascular disease than those in his study. He still felt more research was needed to confirm what the optimal criteria would be and how best to wean patients off their BP medications as their BP declined. Indeed, research published more than 35 years ago found that among 216 adults who entered the Pritikin Center taking anti-hypertension medications, after 3 weeks 83% finished the Pritikin Program off all their BP medications and yet still maintained their BP at levels as low or even lower than at the start of this residential diet and exercise program. Most of the remaining 17% also had their BP-medications dosages reduced (1). The Pritikin Diet, like the DASH diet, emphasizes plenty of fruits and vegetables, whole grains, and nonfat dairy products with limited amounts of mostly low-saturated-fat animal products such as fish, skinless white meat poultry, and egg whites. Sodium on the Pritikin Diet is limited to no more than 1200 to 1500mg daily.
Bottom Line: The results of the recent twin study showing the strong association between high sodium intake and elevated BP that is independent of central adiposity coupled with Dr. Hinderliter’s study of the DASH diet and exercise program described here confirm research conducted at the Pritikin Center 35+ years ago. Overall, it seems clear that most patients diagnosed with elevated BP could lower their BP sufficiently to avoid the need for BP-drugs. Indeed, most patients taking BP-medications could get off all or certainly most of those drugs and still lower their BP with a healthy DASH-style diet and exercise program. The ideal approach to preventing and treating HTN is a DASH-style diet with no more than 1500mg of sodium. It is also important for overweight subjects to lose some of that excess weight and become more active. Those consuming alcohol should limit their intake to no more than ½ to one drink per day. Those already on BP drugs may need medical guidance to wean themselves off of all or most of their medications. Diuretics should be the first to go if a low sodium diet is adopted.
By James J. Kenney, PhD, FACN
- Barnard RJ, et. al. Effects of a high-complex carbohydrate diet and daily walking on blood pressure and medication status of hypertensive patients. J Cardiac Rehab, 3: 839-846, 1983.
Stephanie Ronco has been editing in a professional capacity for the past 10 years. In addition to her work as an editor, Ronco has also served as a ghostwriter and writing tutor. A voracious reader, Ronco loves watching language evolve and change. When she’s not delving into her latest project, Ronco can be found teaching acting classes, performing in community theater, or sailing with her husband.