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A pair of dueling editorials in the journal Hypertension debate whether our focus should be on sodium or its often neglected partner, potassium.
A meta-analysis of 85 trials showed a consistent and linear. It may also depend on where you live and whether your concern is treating individuals or implementing effective food policy.
The Case for Sodium Restriction
Stephen Juraschek, MD, PhD, of the Beth Israel Deaconess Medical Center, Boston, Massachusetts, co-author of one editorial, told me in a zoom interview that he believes his side of the debate clearly has the stronger argument. Of the two cations in question, there has been infinitely more ink spilled about sodium.
Studies such as INTERSALT, the DASH diet, and TOHP may be the most well-known, but there are many, many intervention studies of sodium restriction’s effect on blood pressure. A meta-analysis of 85 trials of showed a consistent and linear relationship between sodium reduction and blood pressure. In contrast, the evidence base for potassium is more limited and less consistent. There are half as many trials with potassium, and its ability to lower blood pressure may depend on how much sodium is present in the diet.
An outlier in the sodium restriction evidence base is the PURE study, which suggested that extreme sodium restriction could increase cardiovascular mortality, but the trial suffered from two potential issues. First, it used a single spot urine specimen to measure sodium rather than the generally accepted more accurate 24-hour urine collection. A reanalysis of the TOHP study using a spot urine rather than a 24-hour urine collection changed the relationship between sodium intake and mortality and possibly explained the U-shaped association observed in PURE. Second, PURE was an observational cohort and was prone to confounding, or in this case, reverse causation. Why did people who consumed very little salt have an increased risk for cardiovascular disease? It is very possible that people with a high risk for cardiovascular disease were told to consume less salt to begin with. Hence B led to A rather than A leading to B.
The debate on sodium restriction has been bitter at times. Opposing camps formed, and people took sides in the “salt wars.” A group of researchers, termed the Jackson 6, met and decided to end the controversy by running a randomized trial in US prisons (having discounted the options of long-term care homes and military bases). They detailed their plan in an editorial in Hypertension. The study never came to fruition for two reasons: the obvious ethical problems of experimenting on prisoners and the revelation of undisclosed salt industry funding.
More recent studies have mercifully been more conventional. The SSaSS study, a randomized controlled trial of a salt substitute, provided the cardiovascular outcomes data that many were waiting for. And CARDIA-SSBP, a cross-over randomized trial recently presented at the American Heart Association meeting, showed that reducing dietary sodium was on par with medication when it came to lowering blood pressure.
For Dr. Juraschek, the evidence is clear: “If you were going to choose one, I would say the weight of the evidence is still really heavily on the sodium side.”
The Case for Potassium Supplementation
The evidence for salt restriction notwithstanding, Swapnil Hiremath, MD, MPH, from the University of Ottawa, Ontario, Canada, argued in his editorial that potassium supplementation has gotten short shrift. Though he admits the studies for potassium supplementation have been smaller and sometimes rely on observational evidence, the evidence is there. In the distal convoluted tubule, the sodium chloride cotransporter (NCC), aka the potassium switch, is turned on by low potassium levels and leads to sodium reabsorption by the kidney even in settings of high sodium intake (Figure). To nonnephrologists, renal physiology may be a black box. But if you quickly brush up on the mechanism of action of thiazide diuretics, the preceding descriptor will make more sense.
Dr. Hiremath points out that the DASH diet study also got patients to increase their potassium intake by eating more fruits and vegetables. Furthermore, the SSaSS study tested a salt substitute that was 25% potassium (and 75% sodium).
How much blood pressure lowering is due to sodium restriction vs potassium supplementation is a complex question because lowering sodium intake will invariably lead to more potassium intake. “It’s very hard to untangle the relationship,” Dr. Hiremath said in an interview. “It’s sort of synergistic but it’s not completely additive. It’s not as if you add four and four and get eight.” But he maintains there is more evidence regarding the benefit of potassium supplementation than many realize.
Realistic Diets and Taste Issues
“We know that increasing potassium, decreasing sodium is useful. The question is how do we do that?” says Dr. Hiremath. Should we encourage fruit and vegetable consumption in a healthy diet, give potassium supplements, or encourage the use of low-sodium salt substitutes?
Recommending a healthier diet with more fruits and vegetables is a no-brainer. But getting people to do it is hard. In a world where fruit is more expensive than junk food is, economic realities may drive food choice regardless of our best efforts. The 4700 mg of potassium in the DASH eating plan is the equivalent of eleven bananas daily; although not impossible, it would require a substantive shift in eating patterns for most people.
Given that we prescribe iron, vitamin B12, calcium, and vitamin D to patients who need them, why not potassium tablets to help with blood pressure? Granted, there are concerns about inducing hyperkalemia. Also, why not just prescribe a proven anti-hypertensive, such as ramipril, which has the added benefit of helping with renal protection or cardiac remodeling? Dr. Hiremath points out that patients are far less reluctant to take dietary supplements. Medication is something you take when sick. A supplement is seen as “natural” and “healthy” and might be more attractive to people resistant to prescription meds.
Another drawback of oral potassium supplementation is taste. In a Consumer Reports taste test, potassium chloride fared poorly. It was bitter and had a metallic aftertaste. At least one tester wouldn’t ever consume it again. Potassium citrate is slightly more palpable.
Salt substitutes, like the 75:25 ratio of sodium to potassium used in SSaSS, may be as high as you can go for potassium in any low-sodium salt alternative. If you go any higher than that, the taste will just turn people off, suggests Dr. Hiremath.
But SsaSS, which was done in China, may not be relevant to North America. In China, most sodium is added during cooking at home, and the consumption of processed foods is low. For the typical North American, roughly three quarters of the sodium eaten is added to their food by someone else; only about 15% is added during cooking at home or at the dinner table. If you aren’t someone who cooks, buying a salt substitute is probably not going to have much impact.
Given that reality, Dr. Juraschek thinks we need to target the sodium in processed foods. “There’s just so much sodium in so many products,” he says. “When you think about public policy, it’s most expeditious for there to be more regulation about how much is added to our food supply vs trying to get people to consume eight to 12 servings of fruit.”
No Salt War Here
Despite their different editorial takes, Dr. Hiremath and Dr. Juraschek largely agree on the broad strokes of the problem. This isn’t X (or Twitter) after all. Potassium supplementation may be useful in some parts of the world but may not address the underlying problem in countries where processed foods are the source of most dietary sodium.
The CARDIA-SSBP trial showed that a very low–sodium diet had the same blood pressure–lowering effect as a first-line antihypertensive, but most people will not be able to limit themselves to 500 mg of dietary sodium per day. In CARDIA-SSBP, just as in DASH, participants were provided with meals from study kitchens. They were not just told to eat less salt, which would almost certainly have failed.
“We should aim for stuff that is practical and doable rather than aim for stuff that cannot be done,” according to Dr. Hiremath. Whether that should be salt substitutes or policy change may depend on which part of the planet you live on.
One recent positive change may herald the beginning of a policy change, at least in the United States. In March 2023, the US Food and Drug Administration proposed a rule change to allow salt substitutes to be labeled as salt. This would make it easier for food manufacturers to swap out sodium chloride for a low-sodium alternative and reduce the amount of sodium in the US diet without having a large impact on taste and consumer uptake. Both Dr. Hiremath and Dr. Juraschek agree that it may not be enough on its own but that it’s a start.
Christopher Labos is a cardiologist with a degree in epidemiology. He spends most of his time doing things that he doesn’t get paid for, like research, teaching, and podcasting. Occasionally, he finds time to practice cardiology to pay the rent. He realizes that half of his research findings will be disproved in 5 years; he just doesn’t know which half. He is a regular contributor to the Montreal Gazette, CJAD radio, and CTV television in Montreal, and is host of the award-winning podcast The Body of Evidence.
A version of this article appeared on Medscape.com.
A pair of dueling editorials in the journal Hypertension debate whether our focus should be on sodium or its often neglected partner, potassium.
A meta-analysis of 85 trials showed a consistent and linear. It may also depend on where you live and whether your concern is treating individuals or implementing effective food policy.
The Case for Sodium Restriction
Stephen Juraschek, MD, PhD, of the Beth Israel Deaconess Medical Center, Boston, Massachusetts, co-author of one editorial, told me in a zoom interview that he believes his side of the debate clearly has the stronger argument. Of the two cations in question, there has been infinitely more ink spilled about sodium.
Studies such as INTERSALT, the DASH diet, and TOHP may be the most well-known, but there are many, many intervention studies of sodium restriction’s effect on blood pressure. A meta-analysis of 85 trials of showed a consistent and linear relationship between sodium reduction and blood pressure. In contrast, the evidence base for potassium is more limited and less consistent. There are half as many trials with potassium, and its ability to lower blood pressure may depend on how much sodium is present in the diet.
An outlier in the sodium restriction evidence base is the PURE study, which suggested that extreme sodium restriction could increase cardiovascular mortality, but the trial suffered from two potential issues. First, it used a single spot urine specimen to measure sodium rather than the generally accepted more accurate 24-hour urine collection. A reanalysis of the TOHP study using a spot urine rather than a 24-hour urine collection changed the relationship between sodium intake and mortality and possibly explained the U-shaped association observed in PURE. Second, PURE was an observational cohort and was prone to confounding, or in this case, reverse causation. Why did people who consumed very little salt have an increased risk for cardiovascular disease? It is very possible that people with a high risk for cardiovascular disease were told to consume less salt to begin with. Hence B led to A rather than A leading to B.
The debate on sodium restriction has been bitter at times. Opposing camps formed, and people took sides in the “salt wars.” A group of researchers, termed the Jackson 6, met and decided to end the controversy by running a randomized trial in US prisons (having discounted the options of long-term care homes and military bases). They detailed their plan in an editorial in Hypertension. The study never came to fruition for two reasons: the obvious ethical problems of experimenting on prisoners and the revelation of undisclosed salt industry funding.
More recent studies have mercifully been more conventional. The SSaSS study, a randomized controlled trial of a salt substitute, provided the cardiovascular outcomes data that many were waiting for. And CARDIA-SSBP, a cross-over randomized trial recently presented at the American Heart Association meeting, showed that reducing dietary sodium was on par with medication when it came to lowering blood pressure.
For Dr. Juraschek, the evidence is clear: “If you were going to choose one, I would say the weight of the evidence is still really heavily on the sodium side.”
The Case for Potassium Supplementation
The evidence for salt restriction notwithstanding, Swapnil Hiremath, MD, MPH, from the University of Ottawa, Ontario, Canada, argued in his editorial that potassium supplementation has gotten short shrift. Though he admits the studies for potassium supplementation have been smaller and sometimes rely on observational evidence, the evidence is there. In the distal convoluted tubule, the sodium chloride cotransporter (NCC), aka the potassium switch, is turned on by low potassium levels and leads to sodium reabsorption by the kidney even in settings of high sodium intake (Figure). To nonnephrologists, renal physiology may be a black box. But if you quickly brush up on the mechanism of action of thiazide diuretics, the preceding descriptor will make more sense.
Dr. Hiremath points out that the DASH diet study also got patients to increase their potassium intake by eating more fruits and vegetables. Furthermore, the SSaSS study tested a salt substitute that was 25% potassium (and 75% sodium).
How much blood pressure lowering is due to sodium restriction vs potassium supplementation is a complex question because lowering sodium intake will invariably lead to more potassium intake. “It’s very hard to untangle the relationship,” Dr. Hiremath said in an interview. “It’s sort of synergistic but it’s not completely additive. It’s not as if you add four and four and get eight.” But he maintains there is more evidence regarding the benefit of potassium supplementation than many realize.
Realistic Diets and Taste Issues
“We know that increasing potassium, decreasing sodium is useful. The question is how do we do that?” says Dr. Hiremath. Should we encourage fruit and vegetable consumption in a healthy diet, give potassium supplements, or encourage the use of low-sodium salt substitutes?
Recommending a healthier diet with more fruits and vegetables is a no-brainer. But getting people to do it is hard. In a world where fruit is more expensive than junk food is, economic realities may drive food choice regardless of our best efforts. The 4700 mg of potassium in the DASH eating plan is the equivalent of eleven bananas daily; although not impossible, it would require a substantive shift in eating patterns for most people.
Given that we prescribe iron, vitamin B12, calcium, and vitamin D to patients who need them, why not potassium tablets to help with blood pressure? Granted, there are concerns about inducing hyperkalemia. Also, why not just prescribe a proven anti-hypertensive, such as ramipril, which has the added benefit of helping with renal protection or cardiac remodeling? Dr. Hiremath points out that patients are far less reluctant to take dietary supplements. Medication is something you take when sick. A supplement is seen as “natural” and “healthy” and might be more attractive to people resistant to prescription meds.
Another drawback of oral potassium supplementation is taste. In a Consumer Reports taste test, potassium chloride fared poorly. It was bitter and had a metallic aftertaste. At least one tester wouldn’t ever consume it again. Potassium citrate is slightly more palpable.
Salt substitutes, like the 75:25 ratio of sodium to potassium used in SSaSS, may be as high as you can go for potassium in any low-sodium salt alternative. If you go any higher than that, the taste will just turn people off, suggests Dr. Hiremath.
But SsaSS, which was done in China, may not be relevant to North America. In China, most sodium is added during cooking at home, and the consumption of processed foods is low. For the typical North American, roughly three quarters of the sodium eaten is added to their food by someone else; only about 15% is added during cooking at home or at the dinner table. If you aren’t someone who cooks, buying a salt substitute is probably not going to have much impact.
Given that reality, Dr. Juraschek thinks we need to target the sodium in processed foods. “There’s just so much sodium in so many products,” he says. “When you think about public policy, it’s most expeditious for there to be more regulation about how much is added to our food supply vs trying to get people to consume eight to 12 servings of fruit.”
No Salt War Here
Despite their different editorial takes, Dr. Hiremath and Dr. Juraschek largely agree on the broad strokes of the problem. This isn’t X (or Twitter) after all. Potassium supplementation may be useful in some parts of the world but may not address the underlying problem in countries where processed foods are the source of most dietary sodium.
The CARDIA-SSBP trial showed that a very low–sodium diet had the same blood pressure–lowering effect as a first-line antihypertensive, but most people will not be able to limit themselves to 500 mg of dietary sodium per day. In CARDIA-SSBP, just as in DASH, participants were provided with meals from study kitchens. They were not just told to eat less salt, which would almost certainly have failed.
“We should aim for stuff that is practical and doable rather than aim for stuff that cannot be done,” according to Dr. Hiremath. Whether that should be salt substitutes or policy change may depend on which part of the planet you live on.
One recent positive change may herald the beginning of a policy change, at least in the United States. In March 2023, the US Food and Drug Administration proposed a rule change to allow salt substitutes to be labeled as salt. This would make it easier for food manufacturers to swap out sodium chloride for a low-sodium alternative and reduce the amount of sodium in the US diet without having a large impact on taste and consumer uptake. Both Dr. Hiremath and Dr. Juraschek agree that it may not be enough on its own but that it’s a start.
Christopher Labos is a cardiologist with a degree in epidemiology. He spends most of his time doing things that he doesn’t get paid for, like research, teaching, and podcasting. Occasionally, he finds time to practice cardiology to pay the rent. He realizes that half of his research findings will be disproved in 5 years; he just doesn’t know which half. He is a regular contributor to the Montreal Gazette, CJAD radio, and CTV television in Montreal, and is host of the award-winning podcast The Body of Evidence.
A version of this article appeared on Medscape.com.
A pair of dueling editorials in the journal Hypertension debate whether our focus should be on sodium or its often neglected partner, potassium.
A meta-analysis of 85 trials showed a consistent and linear. It may also depend on where you live and whether your concern is treating individuals or implementing effective food policy.
The Case for Sodium Restriction
Stephen Juraschek, MD, PhD, of the Beth Israel Deaconess Medical Center, Boston, Massachusetts, co-author of one editorial, told me in a zoom interview that he believes his side of the debate clearly has the stronger argument. Of the two cations in question, there has been infinitely more ink spilled about sodium.
Studies such as INTERSALT, the DASH diet, and TOHP may be the most well-known, but there are many, many intervention studies of sodium restriction’s effect on blood pressure. A meta-analysis of 85 trials of showed a consistent and linear relationship between sodium reduction and blood pressure. In contrast, the evidence base for potassium is more limited and less consistent. There are half as many trials with potassium, and its ability to lower blood pressure may depend on how much sodium is present in the diet.
An outlier in the sodium restriction evidence base is the PURE study, which suggested that extreme sodium restriction could increase cardiovascular mortality, but the trial suffered from two potential issues. First, it used a single spot urine specimen to measure sodium rather than the generally accepted more accurate 24-hour urine collection. A reanalysis of the TOHP study using a spot urine rather than a 24-hour urine collection changed the relationship between sodium intake and mortality and possibly explained the U-shaped association observed in PURE. Second, PURE was an observational cohort and was prone to confounding, or in this case, reverse causation. Why did people who consumed very little salt have an increased risk for cardiovascular disease? It is very possible that people with a high risk for cardiovascular disease were told to consume less salt to begin with. Hence B led to A rather than A leading to B.
The debate on sodium restriction has been bitter at times. Opposing camps formed, and people took sides in the “salt wars.” A group of researchers, termed the Jackson 6, met and decided to end the controversy by running a randomized trial in US prisons (having discounted the options of long-term care homes and military bases). They detailed their plan in an editorial in Hypertension. The study never came to fruition for two reasons: the obvious ethical problems of experimenting on prisoners and the revelation of undisclosed salt industry funding.
More recent studies have mercifully been more conventional. The SSaSS study, a randomized controlled trial of a salt substitute, provided the cardiovascular outcomes data that many were waiting for. And CARDIA-SSBP, a cross-over randomized trial recently presented at the American Heart Association meeting, showed that reducing dietary sodium was on par with medication when it came to lowering blood pressure.
For Dr. Juraschek, the evidence is clear: “If you were going to choose one, I would say the weight of the evidence is still really heavily on the sodium side.”
The Case for Potassium Supplementation
The evidence for salt restriction notwithstanding, Swapnil Hiremath, MD, MPH, from the University of Ottawa, Ontario, Canada, argued in his editorial that potassium supplementation has gotten short shrift. Though he admits the studies for potassium supplementation have been smaller and sometimes rely on observational evidence, the evidence is there. In the distal convoluted tubule, the sodium chloride cotransporter (NCC), aka the potassium switch, is turned on by low potassium levels and leads to sodium reabsorption by the kidney even in settings of high sodium intake (Figure). To nonnephrologists, renal physiology may be a black box. But if you quickly brush up on the mechanism of action of thiazide diuretics, the preceding descriptor will make more sense.
Dr. Hiremath points out that the DASH diet study also got patients to increase their potassium intake by eating more fruits and vegetables. Furthermore, the SSaSS study tested a salt substitute that was 25% potassium (and 75% sodium).
How much blood pressure lowering is due to sodium restriction vs potassium supplementation is a complex question because lowering sodium intake will invariably lead to more potassium intake. “It’s very hard to untangle the relationship,” Dr. Hiremath said in an interview. “It’s sort of synergistic but it’s not completely additive. It’s not as if you add four and four and get eight.” But he maintains there is more evidence regarding the benefit of potassium supplementation than many realize.
Realistic Diets and Taste Issues
“We know that increasing potassium, decreasing sodium is useful. The question is how do we do that?” says Dr. Hiremath. Should we encourage fruit and vegetable consumption in a healthy diet, give potassium supplements, or encourage the use of low-sodium salt substitutes?
Recommending a healthier diet with more fruits and vegetables is a no-brainer. But getting people to do it is hard. In a world where fruit is more expensive than junk food is, economic realities may drive food choice regardless of our best efforts. The 4700 mg of potassium in the DASH eating plan is the equivalent of eleven bananas daily; although not impossible, it would require a substantive shift in eating patterns for most people.
Given that we prescribe iron, vitamin B12, calcium, and vitamin D to patients who need them, why not potassium tablets to help with blood pressure? Granted, there are concerns about inducing hyperkalemia. Also, why not just prescribe a proven anti-hypertensive, such as ramipril, which has the added benefit of helping with renal protection or cardiac remodeling? Dr. Hiremath points out that patients are far less reluctant to take dietary supplements. Medication is something you take when sick. A supplement is seen as “natural” and “healthy” and might be more attractive to people resistant to prescription meds.
Another drawback of oral potassium supplementation is taste. In a Consumer Reports taste test, potassium chloride fared poorly. It was bitter and had a metallic aftertaste. At least one tester wouldn’t ever consume it again. Potassium citrate is slightly more palpable.
Salt substitutes, like the 75:25 ratio of sodium to potassium used in SSaSS, may be as high as you can go for potassium in any low-sodium salt alternative. If you go any higher than that, the taste will just turn people off, suggests Dr. Hiremath.
But SsaSS, which was done in China, may not be relevant to North America. In China, most sodium is added during cooking at home, and the consumption of processed foods is low. For the typical North American, roughly three quarters of the sodium eaten is added to their food by someone else; only about 15% is added during cooking at home or at the dinner table. If you aren’t someone who cooks, buying a salt substitute is probably not going to have much impact.
Given that reality, Dr. Juraschek thinks we need to target the sodium in processed foods. “There’s just so much sodium in so many products,” he says. “When you think about public policy, it’s most expeditious for there to be more regulation about how much is added to our food supply vs trying to get people to consume eight to 12 servings of fruit.”
No Salt War Here
Despite their different editorial takes, Dr. Hiremath and Dr. Juraschek largely agree on the broad strokes of the problem. This isn’t X (or Twitter) after all. Potassium supplementation may be useful in some parts of the world but may not address the underlying problem in countries where processed foods are the source of most dietary sodium.
The CARDIA-SSBP trial showed that a very low–sodium diet had the same blood pressure–lowering effect as a first-line antihypertensive, but most people will not be able to limit themselves to 500 mg of dietary sodium per day. In CARDIA-SSBP, just as in DASH, participants were provided with meals from study kitchens. They were not just told to eat less salt, which would almost certainly have failed.
“We should aim for stuff that is practical and doable rather than aim for stuff that cannot be done,” according to Dr. Hiremath. Whether that should be salt substitutes or policy change may depend on which part of the planet you live on.
One recent positive change may herald the beginning of a policy change, at least in the United States. In March 2023, the US Food and Drug Administration proposed a rule change to allow salt substitutes to be labeled as salt. This would make it easier for food manufacturers to swap out sodium chloride for a low-sodium alternative and reduce the amount of sodium in the US diet without having a large impact on taste and consumer uptake. Both Dr. Hiremath and Dr. Juraschek agree that it may not be enough on its own but that it’s a start.
Christopher Labos is a cardiologist with a degree in epidemiology. He spends most of his time doing things that he doesn’t get paid for, like research, teaching, and podcasting. Occasionally, he finds time to practice cardiology to pay the rent. He realizes that half of his research findings will be disproved in 5 years; he just doesn’t know which half. He is a regular contributor to the Montreal Gazette, CJAD radio, and CTV television in Montreal, and is host of the award-winning podcast The Body of Evidence.
A version of this article appeared on Medscape.com.
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All rights reserved. This material may not be published, broadcast, copied, or otherwise reproduced or distributed without the prior written permission of Frontline Medical Communications Inc.</copyrightNotice> </rightsInfo> </provider> <abstract/> <metaDescription>Should we cut sodium from our diet or eat more potassium to lower blood pressure? The answer requires an intricate understanding of renal physiology that is fas</metaDescription> <articlePDF/> <teaserImage>300110</teaserImage> <teaser>Nephrologist discusses benefits of reducing salt in diet and eating more potassium to reduce BP.</teaser> <title>Sodium vs Potassium for Lowering Blood Pressure?</title> <deck/> <disclaimer/> <AuthorList/> <articleURL/> <doi/> <pubMedID/> <publishXMLStatus/> <publishXMLVersion>1</publishXMLVersion> <useEISSN>0</useEISSN> <urgency/> <pubPubdateYear/> <pubPubdateMonth/> <pubPubdateDay/> <pubVolume/> <pubNumber/> <wireChannels/> <primaryCMSID/> <CMSIDs/> <keywords/> <seeAlsos/> <publications_g> <publicationData> <publicationCode>fp</publicationCode> <pubIssueName/> <pubArticleType/> <pubTopics/> <pubCategories/> <pubSections/> </publicationData> <publicationData> <publicationCode>im</publicationCode> <pubIssueName/> <pubArticleType/> <pubTopics/> <pubCategories/> <pubSections/> </publicationData> </publications_g> <publications> <term>15</term> <term canonical="true">21</term> </publications> <sections> <term canonical="true">52</term> </sections> <topics> <term canonical="true">255</term> </topics> <links> <link> <itemClass qcode="ninat:picture"/> <altRep contenttype="image/jpeg">images/24012603.jpg</altRep> <description role="drol:caption"/> <description role="drol:credit">Medscape</description> </link> </links> </header> <itemSet> <newsItem> <itemMeta> <itemRole>Main</itemRole> <itemClass>text</itemClass> <title>Sodium vs Potassium for Lowering Blood Pressure?</title> <deck/> </itemMeta> <itemContent> <p>A pair of dueling editorials in the journal <em><a href="https://emedicine.medscape.com/article/241381-overview">Hypertension</a> </em>debate whether our focus should be on <span class="Hyperlink"><a href="https://doi.org/10.1161/HYPERTENSIONAHA.123.20544">sodium</a></span> or its often neglected partner, <span class="Hyperlink"><a href="https://doi.org/10.1161/HYPERTENSIONAHA.123.20545">potassium</a></span>.</p> <p><span class="tag metaDescription">Should we cut sodium from our diet or eat more potassium to lower blood pressure? The answer requires an intricate understanding of renal physiology that is fascinating. To nephrologists.</span> A <span class="Hyperlink"><a href="https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.120.050371">meta-analysis</a></span> of 85 trials showed a consistent and linear. It may also depend on where you live and whether your concern is treating individuals or implementing effective food policy.</p> <h2>The Case for Sodium Restriction</h2> <p>Stephen Juraschek, MD, PhD, of the Beth Israel Deaconess Medical Center, Boston, Massachusetts, co-author of one editorial, told me in a zoom interview that he believes his side of the debate clearly has the stronger argument. Of the two cations in question, there has been infinitely more ink spilled about sodium.<br/><br/>Studies such as <span class="Hyperlink"><a href="https://doi.org/10.1136/bmj.297.6644.319">INTERSALT</a></span>, the <span class="Hyperlink"><a href="https://doi.org/10.1056/NEJM200101043440101">DASH diet</a></span>, and <span class="Hyperlink"><a href="https://doi.org/10.1136/bmj.39147.604896.55">TOHP</a></span> may be the most well-known, but there are many, many intervention studies of sodium restriction’s effect on blood pressure. A <span class="Hyperlink"><a href="https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.120.050371">meta-analysis</a></span> of 85 trials of showed a consistent and linear relationship between sodium reduction and blood pressure. In contrast, the <span class="Hyperlink"><a href="https://doi.org/10.1161/jaha.119.015719">evidence base</a></span> for potassium is more limited and less consistent. There are half as many trials with potassium, and its ability to lower blood pressure may depend on how much sodium is present in the diet.<br/><br/>An outlier in the sodium restriction evidence base is the <span class="Hyperlink"><a href="https://doi.org/10.1056/NEJMoa1311989">PURE study</a></span>, which suggested that extreme sodium restriction could increase cardiovascular mortality, but the trial suffered from two potential issues. First, it used a single spot urine specimen to measure sodium rather than the <span class="Hyperlink"><a href="https://doi.org/10.1136/bmj.m2440">generally accepted</a></span> more accurate 24-hour urine collection. A <span class="Hyperlink"><a href="https://doi.org/10.1093/ije/dyy114">reanalysis</a></span> of the TOHP study using a spot urine rather than a 24-hour urine collection changed the relationship between sodium intake and mortality and possibly explained the U-shaped association observed in PURE. Second, PURE was an observational cohort and was prone to confounding, or in this case, reverse causation. Why did people who consumed very little salt have an increased risk for cardiovascular disease? It is very possible that people with a high risk for cardiovascular disease were told to consume less salt to begin with. Hence B led to A rather than A leading to B.<br/><br/>The debate on sodium restriction has been bitter at times. Opposing camps formed, and people took sides in the “<span class="Hyperlink"><a href="https://doi.org/10.1093/ije/dyw015">salt wars</a></span>.” A group of researchers, termed the Jackson 6, met and decided to end the controversy by running a randomized trial in US prisons (having discounted the options of long-term care homes and military bases). They detailed their plan in an <span class="Hyperlink"><a href="https://doi.org/10.1161/HYPERTENSIONAHA.118.11103">editorial</a></span> in Hypertension. The study never came to fruition for two reasons: the obvious ethical problems of experimenting on prisoners and the <span class="Hyperlink"><a href="https://www.buzzfeednews.com/article/stephaniemlee/salt-institute-sodium-study-prison-funding">revelation of undisclosed salt industry funding</a></span>.<br/><br/>More recent studies have mercifully been more conventional. The <span class="Hyperlink"><a href="https://doi.org/10.1056/NEJMoa2105675">SSaSS study</a></span>, a randomized controlled trial of a salt substitute, provided the cardiovascular outcomes data that many were waiting for. And <span class="Hyperlink"><a href="https://doi.org/10.1001/jama.2023.23651">CARDIA-SSBP</a></span>, a cross-over randomized trial recently presented at the American Heart Association meeting, showed that reducing dietary sodium was on par with medication when it came to lowering blood pressure.<br/><br/>For Dr. Juraschek, the evidence is clear: “If you were going to choose one, I would say the weight of the evidence is still really heavily on the sodium side.”</p> <h2>The Case for Potassium Supplementation</h2> <p>The evidence for salt restriction notwithstanding, Swapnil Hiremath, MD, MPH, from the University of Ottawa, Ontario, Canada, argued in his editorial that potassium supplementation has gotten short shrift. Though he admits the <span class="Hyperlink"><a href="https://doi.org/10.1136/bmj.f1378">studies for potassium supplementation</a></span> have been smaller and sometimes rely on observational evidence, the evidence is there. In the distal convoluted tubule, the sodium chloride cotransporter (NCC), aka the <span class="Hyperlink"><a href="https://doi.org/10.1056/nejmra2030212">potassium switch</a></span>, is turned on by low potassium levels and leads to sodium reabsorption by the kidney even in settings of high sodium intake (Figure). To nonnephrologists, renal physiology may be a black box. But if you quickly brush up on the mechanism of action of thiazide diuretics, the preceding descriptor will make more sense.<br/><br/>[[{"fid":"300110","view_mode":"medstat_image_full_text","fields":{"format":"medstat_image_full_text","field_file_image_alt_text[und][0][value]":"Effects of High K+ on the Sodium Chloride Cotransporter (NCC)","field_file_image_credit[und][0][value]":"Medscape","field_file_image_caption[und][0][value]":""},"type":"media","attributes":{"class":"media-element file-medstat_image_full_text"}}]]<br/><br/>Dr. Hiremath points out that the <span class="Hyperlink"><a href="https://doi.org/10.1056/NEJM200101043440101">DASH diet</a></span> study also got patients to increase their potassium intake by eating more fruits and vegetables. Furthermore, the <span class="Hyperlink"><a href="https://doi.org/10.1056/NEJMoa2105675">SSaSS study</a></span> tested a salt substitute that was 25% potassium (and 75% sodium).<br/><br/>How much blood pressure lowering is due to sodium restriction vs potassium supplementation is a complex question because lowering sodium intake will invariably lead to more potassium intake. “It’s very hard to untangle the relationship,” Dr. Hiremath said in an interview. “It’s sort of synergistic but it’s not completely additive. It’s not as if you add four and four and get eight.” But he maintains there is more evidence regarding the benefit of potassium supplementation than many realize.<br/><br/></p> <h2>Realistic Diets and Taste Issues</h2> <p>“We know that increasing potassium, decreasing sodium is useful. The question is how do we do that?” says Dr. Hiremath. Should we encourage fruit and vegetable consumption in a healthy diet, give potassium supplements, or encourage the use of low-sodium salt substitutes?<br/><br/>Recommending a healthier diet with more fruits and vegetables is a no-brainer. But getting people to do it is hard. In a world where fruit is more expensive than junk food is, economic realities may drive food choice regardless of our best efforts. The <span class="Hyperlink"><a href="https://www.nhlbi.nih.gov/sites/default/files/publications/WES09-DASH-Potassium.pdf">4700 mg of potassium</a></span> in the DASH eating plan is the equivalent of eleven bananas daily; although not impossible, it would require a substantive shift in eating patterns for most people.<br/><br/>Given that we prescribe iron, vitamin B12, calcium, and <span class="Hyperlink"><a href="https://reference.medscape.com/drug/drisdol-calciferol-vitamind-344417">vitamin D</a></span> to patients who need them, why not potassium tablets to help with blood pressure? Granted, there are concerns about inducing <span class="Hyperlink"><a href="https://emedicine.medscape.com/article/240903-overview">hyperkalemia</a></span>. Also, why not just prescribe a proven anti-hypertensive, such as <span class="Hyperlink"><a href="https://reference.medscape.com/drug/altace-ramipril-342331">ramipril</a></span>, which has the added benefit of helping with renal protection or cardiac remodeling? Dr. Hiremath points out that patients are far less reluctant to take dietary supplements. Medication is something you take when sick. A supplement is seen as “natural” and “healthy” and might be more attractive to people resistant to prescription meds.<br/><br/>Another drawback of oral potassium supplementation is taste. In a <span class="Hyperlink"><a href="https://www.consumerreports.org/health/sodium/how-salt-substitutes-really-taste-a9564762805/">Consumer Reports taste test</a></span>, <span class="Hyperlink"><a href="https://reference.medscape.com/drug/kdur-slow-k-potassium-chloride-344450">potassium chloride</a></span> fared poorly. It was bitter and had a metallic aftertaste. At least one tester wouldn’t ever consume it again. <span class="Hyperlink"><a href="https://reference.medscape.com/drug/urocit-k-potassium-citrate-342853">Potassium citrate</a></span> is slightly more palpable.<br/><br/>Salt substitutes, like the 75:25 ratio of sodium to potassium used in SSaSS, may be as high as you can go for potassium in any low-sodium salt alternative. If you go any higher than that, the taste will just turn people off, suggests Dr. Hiremath.<br/><br/>But SsaSS, which was done in China, may not be relevant to North America. In China, most sodium is added during cooking at home, and the consumption of processed foods is low. For the typical North American, roughly <span class="Hyperlink"><a href="https://doi.org/10.1016/j.pcad.2009.12.006">three quarters of the sodium</a></span> eaten is added to their food by someone else; only about 15% is added during cooking at home or at the dinner table. If you aren’t someone who cooks, buying a salt substitute is probably not going to have much impact.<br/><br/>Given that reality, Dr. Juraschek thinks we need to target the sodium in processed foods. “There’s just so much sodium in so many products,” he says. “When you think about public policy, it’s most expeditious for there to be more regulation about how much is added to our food supply vs trying to get people to consume eight to 12 servings of fruit.”</p> <h2>No Salt War Here</h2> <p>Despite their different editorial takes, Dr. Hiremath and Dr. Juraschek largely agree on the broad strokes of the problem. This isn’t X (or Twitter) after all. Potassium supplementation may be useful in some parts of the world but may not address the underlying problem in countries where processed foods are the source of most dietary sodium.<br/><br/>The <span class="Hyperlink"><a href="https://doi.org/10.1001/jama.2023.23651">CARDIA-SSBP</a></span> trial showed that a very low–sodium diet had the same blood pressure–lowering effect as a first-line antihypertensive, but most people will not be able to limit themselves to 500 mg of dietary sodium per day. In CARDIA-SSBP, just as in DASH, participants were provided with meals from study kitchens. They were not just told to eat less salt, which would almost certainly have failed.<br/><br/>“We should aim for stuff that is practical and doable rather than aim for stuff that cannot be done,” according to Dr. Hiremath. Whether that should be salt substitutes or policy change may depend on which part of the planet you live on.<br/><br/>One recent positive change may herald the beginning of a policy change, at least in the United States. In March 2023, the US Food and Drug Administration <span class="Hyperlink"><a href="https://www.fda.gov/news-events/press-announcements/fda-takes-additional-steps-improve-nutrition-reduce-disease-expanded-use-salt-substitutes-help-lower">proposed a rule change</a></span> to allow salt substitutes to be labeled as salt. This would make it easier for food manufacturers to swap out sodium chloride for a low-sodium alternative and reduce the amount of sodium in the US diet without having a large impact on taste and consumer uptake. Both Dr. Hiremath and Dr. Juraschek agree that it may not be enough on its own but that it’s a start.<span class="end"/></p> <p> <em>Christopher Labos is a cardiologist with a degree in epidemiology. He spends most of his time doing things that he doesn’t get paid for, like research, teaching, and podcasting. Occasionally, he finds time to practice cardiology to pay the rent. He realizes that half of his research findings will be disproved in 5 years; he just doesn’t know which half. He is a regular contributor to the Montreal Gazette, CJAD radio, and CTV television in Montreal, and is host of the award-winning podcast <span class="Hyperlink"><a href="https://www.bodyofevidence.ca/">The Body of Evidence</a></span>.<span class="end"/></em> </p> <p> <em> <span class="Hyperlink">A version of this article appeared on <a href="https://www.medscape.com/viewarticle/999805">Medscape.com</a>.</span> </em> </p> </itemContent> </newsItem> <newsItem> <itemMeta> <itemRole>teaser</itemRole> <itemClass>text</itemClass> <title/> <deck/> </itemMeta> <itemContent> </itemContent> </newsItem> </itemSet></root>
