Tension Over Hypertension: To Salt or Not?
Print This Post
Once again, the American public is confused as to whether they should cut back on salt in an effort to reduce the risk of cardiovascular disease. The uncertainty this time is due to a recent meta-analysis suggesting that reducing dietary consumption of sodium resulted in lowered blood pressure but had no effect on cardiovascular morbidity or mortality. According to the authors, the meta-analysis—which included seven studies—produced no strong evidence that sodium reduction was associated with lower mortality in people with high or normal blood pressure. One study even suggested that restricting salt in patients with congestive heart failure might potentially increase mortality.
Overall, the review’s authors concluded that although sodium did reduce blood pressure in many patients, there were not enough data in the pooled studies to make a conclusion about the impact of salt reduction on the risk of major cardiovascular events. They also believe that the purported relationship between sodium restriction and decreased cardiovascular mortality is due in large part to the relationship of sodium intake to blood pressure.
A closer look at the article reveals some interesting points about the findings and may help you answer patients’ questions about this controversial issue.
Generalizability: The pooled studies included in the meta-analysis included mostly middle-aged white or Asian participants; in the United States, hypertension disproportionately affects African Americans and older Americans. In addition, the results of the seven studies may not apply to the U.S. population because some of the studies were conducted in Taiwan, Australia, and Italy.
Length of follow-up: The meta-analysis reached its conclusions based on results ranging from six to 71 months of study. However, this follow-up is probably not long enough to draw definitive conclusions, as hypertension, heart disease, and stroke risk develop slowly over time.
Data source: All of the studies analyzed participants’ sodium intake using food diaries, which may not be as reliable as measuring urinary salt excretion to quantitatively assess sodium intake.
Sodium levels: The 2010 Dietary Recommendations for Americans say those with heart failure, high blood pressure, and kidney problems—as well as anyone older than 50 and all African Americans—should get no more than 1,500 mg per day and that the rest of us should aim for no more than 2,300 mg. Most of the patients in the meta-analysis who had hypertension or heart failure had a goal of 1,800 mg a day; perhaps the results might have been more conclusive if researchers had been able to lower sodium intakes to currently recommended levels.
So, what’s the bottom line?
The American Heart Association strongly recommends that all people—whether or not they have high blood pressure—limit the amount of sodium consumed daily to no more than 1,500 mg. While there may not be conclusive evidence that salt consumption can decrease the risk of dying from cardiovascular disease, there is likely no disadvantage to recommending that patients cut back on the sodium they consume from processed foods. Most experts still concur that consuming too much salt is undesirable and that cutting salt intake can reduce hypertension in people with normal and high blood pressure.
However, there is also strong evidence for other lifestyle factors when it comes to preventing or reversing hypertension. In most overweight or obese people, even a small amount of weight loss can lower blood pressure more effectively than just reducing salt. In fact, research suggests that overweight people who lose just 5% of their body weight can cut their risk of developing hypertension by almost 50%.
The second most powerful way to lower blood pressure is also through diet—eating mainly fruits, vegetables, whole grains, and low-fat dairy foods, and cutting back on animal fats, sweets, and sugary beverages in addition to salt. Exercise and lowering alcohol intake also may slightly lower blood pressure.
Nine out of 10 Americans will develop hypertension in their lifetime. Helping patients develop an array of healthy behaviors—including sodium reduction—can reap enormous long-term benefits by reducing the risk for developing hypertension and helping those with high blood pressure manage their condition more effectively.
Jill Shuman, MS, ELS
Published on July 19, 2011
- Taylor RS, Ashton KE, Moxham T, et al. Reduced dietary salt for the prevention of cardiovascular disease: A meta-analysis of randomized controlled trials (Cochrane Review) [published online ahead of print July 6, 2011]. Am J Hypertens. doi: 10.1038/ajh2011.115.