Strict dietary guidelines for daily sodium consumption have been around for more than 30 years. The 2015 USDA dietary guidelines recently reaffirmed that we limit salt intake to approximately one teaspoon or 2,300 mg per day, and those with high blood pressure should consume even less. However, when it comes to nutrition advice, once again we find ourselves on “shaky” ground. The average American consumes closer to 3,500 mg daily, much of which can be attributed to high sodium levels in processed and restaurant foods. According to Elliott Antman, President of the American Heart association, “Everyone agrees that current sodium intake is too high.” Everyone, that is, except a group of researchers led by Dr. Andrew Mente, Associate Professor of Clinical Epidemiology and Biostatistics at McMaster’s Michael G. DeGroote School of Medicine and lead author of a major worldwide study recently published in the Lancet. According to Mente, “There is no longer any valid basis for the current salt guidelines.” Suzanne Oparil, former President of the American Heart Association, now a Professor of Medicine at the University of Alabama concurs, “The current salt guidelines are based on almost nothing.”
Why the controversy? The long established view of reduced sodium consumption is based on the observation that reducing salt intake can lower blood pressure for some people. Additionally, it was assumed that since high blood pressure is a fairly common condition, recommendations for limited salt intake would benefit everyone, even those with normal blood pressure. The study suggests that only those with high blood pressure who have a high salt consumption should conform to a reduced sodium diet. The study, which involved more than 130,000 people from 49 countries, found that regardless of whether people have high blood pressure, low-sodium intake is associated with more, not less, heart attacks, strokes and deaths compared to average intake. These findings may be very important for people who do not have high blood pressure, as elevated sodium levels were not linked to poor health outcomes.
The American Heart Association was quick to condemn the study, stating that ample research supports the link between low sodium consumption and more optimal health. Dr. Walter Willet, Professor of Epidemiology and Nutrition and Chair of the Department of Nutrition at Harvard School of Public Health, cheekily recommends the study be taken “with a grain of salt.” According to Willet, the U.S. Dietary Guidelines that advise a maximum of 2,300 mg of sodium per day is robustly supported by evidence, and efforts being made to reduce sodium in our food supply are strongly justified. Dr. Willet contends that the American Heart Association, based upon “meticulously reviewed scientific research,” recommends all Americans limit their daily sodium consumption to 1,500 mg daily, the amount currently viewed as more appropriate for those with hypertension.
Yet, for decades, these policy guidelines have failed to convince Americans to eat less salt. Other studies, published in the American Journal of Hypertension and the Journal of the American Medical Association, found no strong evidence that cutting back on salt reduced the risk of heart attacks, and also found a greater the risk of dying from heart disease with the presence of low urinary sodium excretion. But then, evidence linking salt to heart disease has always been tenuous at best. In fact, for every study that suggests too much salt is unhealthy, there’s another that suggests it isn’t. Although these findings run counter to advice recommended for years by the World Health Organization and the Heart and Stroke Foundation, there remains a small but vocal group of researchers who challenge the idea that large decreases in sodium consumption support better overall health for everyone, and contend that for people with normal blood pressure, elevated sodium levels are not linked to poor health outcomes.
Along with the differing opinions on the low-fat versus higher fat diet, the low-salt and higher salt intake may remain controversial for many more years. Although the findings suggest that only people with hypertension and high sodium intake should reduce their salt intake, this study will not change the public health message that we all continue to monitor and reduce salt intake in order to achieve optimal health. According to the New England Journal of Medicine, hypertension is the most common modifiable risk factor for cardiovascular disease and death. In an effort to reduce sodium consumption, the FDA has just issued draft guidance to the food industry for voluntarily reducing sodium in processed and commercially prepared foods. Even so, it may take many more years of sustained effort to get even close to the recommended 2,300 mg of daily dietary sodium. Getting individuals to the 1,500 mg range may be a lofty goal indeed.
References:
It’s Time to End the War on Salt. http://www.scientificamerican.com/article/its-time-to-end-the-war-on-salt/
The New Salt Controversy. http://www.hsph.harvard.edu/nutritionsource/the-new-salt-controversy/
Is the American diet too salty? Scientists challenge the longstanding government warning. https://www.washingtonpost.com/news/wonk/wp/2015/04/06/more-scientists-doubt-salt-is-as-bad-for-you-as-the-government-says/
Low-salt diets may not be beneficial for all, study suggests. https://www.sciencedaily.com/releases/2016/05/160521071410.htm
Low Sodium Intake – Cardiovascular Health Benefit or Risk? http://www.nejm.org/doi/full/10.1056/NEJMe1407695
Salt Intake Not Associated with Mortality or Risk of Cardiovascular Disease, Heart Failure in Older Adults. http://media.jamanetwork.com/news-item/salt-intake-not-associated-with-mortality-or-risk-of-cardiovascular-disease-heart-failure-in-older-adults/
Low-sodium diets don’t benefit health? A closer look at the maddening debate over salt. www.theglobeandmail.com/life/health-and-fitness/health/low-sodium-diets-dont-benefit-health-a-closer-look-at-the-maddening-debate-over-salt/article30189988/
FDA issues draft guidance to food industry for voluntarily reducing sodium in processed and commercially prepared food. http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm503874.htm
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