Tuesday, October 22, 2019

REtrospective #248: Salt Warnings: Confusing and Contradictory

Here we go again. Another study about salt! It seems that Australians “pay little attention to salt warnings,” according to a 2014 story from Medscape Medical News. But what made this story interesting to me were the stories that ran with and mostly against it. The Reuters Health story about this research study appeared August 13th in Appetite.
The recommended upper limit for salt intake for Australians is 6g/day, the same as the 2010 U. S. Dietary Guidelines recommendation for “healthy people.” That’s 2,300mg of sodium or 1 teaspoon of salt a day. Six grams (6,000mg) of salt x 0.393 (% sodium in NaCL) = 2,358mg of sodium. If you have high blood pressure, the recommendation is 1,500 mg of sodium a day. According to Medscape, Australian men eat more sodium than women (2907 vs. 1962mg/day).
The next day the prestigious New England Journal of Medicine (NEJM) published 3 major papers on the health effects of sodium consumption in 101,945 individuals in 17 countries, all QUESTIONING the science of salt restriction. And back in 2013, the Institute of Medicine (IOM) reviewed the evidence for the suggested guideline for sodium intake and reported that there was NO EVIDENCE to support the 1500mg/d limit. I reported on this “Retrospective #153.”
How does one decipher this confusing and contradictory advice? Well, Eric J Topol, MD, the Editor-in-Chief of Medscape Medical News, thought it was time to bring some clarity to the issue. In an August 26, 2014, post addressed “Dear Medscape Readers,” Dr. Topol said, “This is important stuff that the public wants to know about.”
Even more compelling is a chart which shows what Dr. Topol describes as “the most striking evidence of the relationship of sodium and cardiovascular events.” “Although there was a trend of higher adverse cardiovascular events with sodium excretion greater than 5g/day [vs. 2.358g], this [higher risk] was much more pronounced at levels lower than 2g/day [vis.1.5g]. In other words, consumption of too little sodium is more harmful than consumption of too much sodium. Following AHA guidelines would lead to about a twofold risk for major adverse events.”
Dr. Topol then cites “the real coup de grace, from a Wall Street Journal’s editorial, ‘The Salt Libel’: ‘The illusion that science can provide some objective answer that applies to everyone is a special danger.” He adds, “I believe that adequately sums up all there is to say about sodium.” But, “The AHA isn’t backing off from its 1.5g/d guideline.”
What followed in Dr. Topol’s rather rare editorial to his large, mostly doctor audience was the piece de resistance:
“But I think there’s a big lesson here about guidelines without adequate evidence. They can do harm. Hopefully this lesson will prove to be impactful, because that certainly has not been the case to date (as in cholesterol/LDL, BP, PSA, mammography and a very long list of poorly conceived non-anchored guidelines. Isn’t it about time to recognize that there shouldn’t be rules for populations? (emphases added by me). Some people are exquisitely sensitive to salt intake, while others are remarkably resistant.”
Well, the “average” Australian male’s sodium intake, currently at 2.9g/day of sodium, would then be still low. And the Australian (and American) women, who it appears to me is (are) trying hard to comply with U. S. sodium guidelines, and whose intake is 1.96g/day, do so at their own peril! From my reading of the chart, the optimum intake or sweet spot of sodium intake is between 4g/d and 5g/d. That is between 1.7 and 2.1 tsp (vs. AHA’s 1.0 and 0.64 tsp) of salt.
The second thing that caught my attention in this Medscape piece is that a New York dietician who was not involved in the study but who was interviewed by Medscape about the piece in Appetite, turned the whole discussion away from sodium intake and “hidden sodium in processed food.” She called the study “interesting and consistent with other research,” but moved quickly to say, “…but hidden sodium is only one of many unhealthy aspects of processed foods that have the potential to affect heart health directly and indirectly.” That’s really, really good advice.
“If a diabetic were to choose a low-sodium version of a highly-processed cereal or bread, they’re going to have a false sense of security in terms of doing something good for their health because they should be limiting a lot of those foods for a lot of reasons,” she said. “The focus,” she continued, “should be on shifting to eating real food and less processed food, which will automatically reduce the sodium content…”  And this dietician works for a cardiac wellness program.

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