Posted on 06/23/2012 at 12:47:23 PM by Student BloggerBy Sarah Gold
Low-sodium diets are a common recommendation for people with hypertension (HTN) and cardiovascular disease (CVD). Dietitians and other health professionals push patients to cut sodium, and many are urging food companies to work to reduce sodium levels in processed foods. But is the message that the general public should decrease sodium intake really necessary? This was the first topic of four “controversies” debated at the opening day of Advances and Controversies in Clinical Nutrition here in Chicago.
While most studies show a positive relationship between sodium intake and blood pressure, there are some that show no relationship and some that even show more of a J-shaped curve, which Andrew Mente, PhD says indicates that diets too low in sodium may be risky. However, Paul K. Whelton, MB, MD, MSc noted that we should look at this data with caution – suggesting a possible reverse causality issue here. People with coronary heart failure, HTN, and cardiovascular disease are often told to reduce sodium intake, or they may eat less overall due to illness.
Dr. Whelton presented a slew of evidence supporting small reductions in sodium intake for improving one's blood pressure. However, as with most areas of scientific research, there are challenges to analyzing the data. For one, there is a large degree of interaction between sodium intake and other foods that are related to HTN and CVD, particularly calorie intake.
In addition, a Cochrane meta-analysis showed that these benefits are not universal. One particular group that did not benefit was Caucasians with normal blood pressure. He also suggests that an overall healthy diet, one much like the DASH (dietary approaches to stop hypertension) diet, is more effective at improving blood pressure and overall heart health than just reducing sodium. And of course, as both men agreed, sodium cannot truly be discussed without its partner in crime, potassium.
In the end, both men agreed that the field is lacking a large randomized control trial looking at this relationship. But, as Dr. Whelton said, we likely won't ever see that – it's too difficult and too expensive to get thousands of people to reduce sodium intake for many years.
For now, practitioners should follow the sodium guidelines as put forth by the Institute of Medicine and 2010 Dietary Guidelines. Dr. Mente thinks we urge people to improve overall diet instead as focusing on sodium. Dr. Whelton thinks the answer lies in the hands of food companies. After all, about 77% of sodium in Americans' diets comes from packaged foods. He believes it's more feasible to get manufacturers to slowly reduce sodium in foods than it is to get people to reduce calories and increase activity. Sounds like the opening for another debate between food scientists and weight-management specialists.