Sodium: the newest chapter in the controversy

Sodium: the newest chapter in the controversy

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Two prestigious organizations disagree on sodium reduction amounts

Sodium is once again mired in controversy. The Institute of Medicine recently released a report that questioned the levels to which Americans should reduce their sodium levels in order to reduce chronic ailments, such as cardiovascular disease. Interestingly, the IOM and the American Heart Association disagree. The AHA believes stricter levels are critically important.

The generally accepted guidelines suggest that healthy people reduce their daily sodium intake to less than 2,300 milligrams, or about a teaspoon, and that those in high-risk categories reduce this further to less than 1,500 mg, or just over a half teaspoon. About 70 percent of Americans are at high risk, which includes those over 50, African Americans and patients with chronic kidney disease, heart failure, diabetes, hypertension (high blood pressure) or prehypertension (MMWR Morb Mortal Wkly Rep 2009; 58:281-283).

The IOM was asked to determine whether there was enough information to suggest everyone follow the less-than-1,500-mg sodium levels, regardless of their risk level. However, the IOM did not find enough data to substantiate that level and even questioned whether 2,300 mg may be too low. If the IOM is right and the research does not support less than 1,500 mg of sodium for anyone, should we be more liberal with sodium? The short answer is “No.”

We will discuss an article written by The New York Times, the Center for Science in the Public Interest’s response and the beneficial effects of sodium reduction on dementia.

 

The New York Times

On May 14, NYT published an article on the IOM’s findings. NYT did say that IOM showed inconclusive results as to whether levels less than 1,500 mg daily are beneficial or not. However, NYT went further, suggesting sodium levels less than 1,500 mg may be dangerous to your health.

The author of the article referenced two studies. The first is a small, randomized controlled Italian study of patients with moderate to severe congestive heart failure. It showed those who consumed 1,840 mg of sodium per day were about three times as likely to be readmitted to the hospital and about twice as likely to suffer mortality, compared to those who consumed more sodium, 2,760 mg per day (Clin Sci (Lond). 2008 Feb;114(3):221-30).

In the second study, an observational one, patients with high blood pressure who consumed more than 7,000 mg of sodium or who consumed less than 3,000 mg per day were more likely to have cardiovascular events, such as congestive heart failure, heart attacks and stroke, as well as higher risk of death (JAMA. 2011 Nov 23;306(20):2229-38). The results are what researchers call a J curve, where the patients at the extremes suffer, while those in the middle do better.

 

Center for Science in the Public Interest

What are we to make of the studies? Even though The New York Times is one of the most prominent newspapers in the country, it is not a peer-reviewed medical journal and, in this case, the journalist is not a scientist.

However, there was an intriguing response from Michael F. Jacobson, who has a doctorate in microbiology from MIT and is the executive director of the CSPI, a highly regarded nonprofit organization focused on health and science. In his analysis of the NYT article and the IOM findings, he found several problems. The New York Times did not bring to light the fact that the IOM report found the evidence of a detrimental effect from very low sodium levels in the diet was “insufficient and inconsistent.” In other words, no conclusion could be drawn.

The studies that showed dangerous effects with very low sodium, including those mentioned above, were flawed in their methodology. It also included a strange treatment regimen for the congestive heart failure patients in the Italian study because they were restricted not only with sodium levels but also significantly limiting the amount of water intake, which is not something we typically do in the U.S. In addition, according to “National Health and Nutrition Examination Survey” data from 2003 to 2006, less than 5 percent of Americans actually consume strict sodium levels of less than 1,500 mg (ars.usda.gov). Jacobson points out that the IOM also did not take into account that consuming less sodium results in lower blood pressure.

As we know, high blood pressure leads to cardiovascular disease and potentially increased mortality. This is why the AHA believes that a sodium intake of less than 1.500 mg is so important, not just for high-risk patients, but also for the general population (www.heart.org/sodium). In the Trials of Hypertension Prevention follow-up, the results showed that a 25 percent reduction of sodium from 3,556 mg to 2,286 mg daily results in a 25 to 30 percent reduction in cardiovascular events, including heart attacks and strokes (BMJ 2007;334:885). This was one of the few studies the IOM said was not flawed.

So how are Americans doing? Not very well. We are currently consuming an average of 3,463 mg per day as of 2010 (www.heart.org/sodium). Evidence shows that the restaurant industry is contributing to Americans’ consumption of higher sodium (JAMA Intern Med online 2013;May 13). From 2005 to 2011, the amount of sodium used by the industry increased. Many processed foods are also part of the problem.

 

Preventing cognitive decline in older adults

With sedentary older adults (67 to 84 years old), a relatively recent population study showed that those who consumed less sodium had a lower risk of cognitive decline in a linear relationship (Neurobiol Aging 2012;33(4):829.e21-829.e28). Those who consumed the lowest levels (about 1,800 mg) of sodium saw less decline than those consuming higher levels (approximately 2,600 mg and 3,900 mg). It was an intake-dependent response. Interestingly, those who exercised regularly were not affected by sodium levels.

Sodium reduction may be important for additional diseases, such as osteoporosis and kidney stones. I wrote about the beneficial effects of reduced sodium on May 25, 2011.

The IOM and the CSPI make a strong case that there does not seem to be any downside to lowering sodium especially since we get far too much in our diet. Sodium reduction is a simple way of lowering the risk of cardiovascular disease and events, as well as potentially other chronic diseases. And the good news is that our taste buds usually adapt to lower sodium levels within six weeks, making food taste more vibrant.

 

 

Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website www.medicalcompassmd.com or consult your personal physician.