The U.S. Food and Drug Administration (FDA) has announced a proposed rule that could allow food manufacturers to utilize salt substitutes instead of traditional salt, aiming to reduce added sodium levels in foods.
This public health initiative responds to the fact that around 90 percent of Americans aged 2 and above consume excessive salt, contributing to the prevalence of chronic diseases in the nation, according to the Centers for Disease Control and Prevention (CDC).
The proposed substitutes include potassium chloride, also known as potassium salt, which offers a similar flavor to sodium without its adverse effects. However, concerns have been raised by advocates for individuals with kidney disease, cautioning that the addition of potassium to food could pose risks, potentially being dangerous or fatal for those with chronic kidney disease.
Organizations such as the American Association of Kidney Patients (AAKP), the Academy of Nutrition and Dietetics, and the National Kidney Foundation (NKF) expressed their apprehensions about the proposed rule in a statement issued on August 8. Chronic kidney disease affects an estimated 37 million American adults, approximately 15 percent of the population, with a higher impact on people of color.
Despite applauding the FDA’s effort to lessen sodium in packaged foods, the organization wrote, “We must balance population health goals and the acute needs of an already medically complex population.”
Impaired Kidney Function Hinders Potassium Excretion in the Body
Approximately 37 million adults in the United States, according for about 15 percent of the population, are living with chronic kidney disease – a condition that disproportionately effects individuals of color, as per the CDC.
While Black Americans constitute approximately 13 percent of the U.S. population, they make up 35 percent of individuals experiencing kidney failure. Hispanic Americans, at almost 1.3 times the likelihood of developing kidney failure compared to non-Hispanic Americans, have seen a 70 percent increase in the rate of kidney failure within this population since 2000, according to the National Institutes of Health (NIH).
For many individuals dealing with chronic kidney disease, including those with kidney failure, the normal excretion of potassium is compromised. In cases where these individuals consume elevated levels of potassium, the mineral can accumulate in their blood, leading to hyperkalemia – a condition associated with abnormal heart rhythms and even sudden cardiac death.
The AAKP statement said, “Given the very high estimates of those who are unaware they have compromised kidney function and the clinical consequences of hyperkalemia, adding ‘hidden potassium’ in the form of potassium chloride substitutes to the American diet is a risk that should not be taken.”
While some experts, including David Goldfarb, MD, the clinical chief of nephrology at NYU Langone Health, suggest that the proposed changes may primarily affect those being treated for severe kidney disease, there is an acknowledgement that the effects could be modest. Certain medications can prevent increased potassium levels in individuals with decreased kidney function who are taking drugs that complicate potassium excretion.
Individuals with reduced kidney function who are prescribed medications such as angiotensin-converting enzyme (ACE) inhibitors, angiotensin 2 receptor blockers (ARBs), or spironolactone may experience challenges in potassium excretion due to these drugs.
However, there are medications available to counteract this effect. These supplementary medications function by binding to potassium in the intestines, thereby lowering potassium levels in the blood. Dr. Goldfarb notes that such medications are routinely prescribed to individuals with chronic kidney disease who are also on medications that may pose a risk of excessive potassium levels.
“These people also would have their potassium checked on a regular basis regardless of this FDA change,” he says.
Substituting Salt with Alternatives Might Reduce the Risk of Cardiovascular Disease and Mortality
Goldfarb argues that the potential benefits of reducing salt intake through salt substitutes could outweigh the small risk of harm. Excessive salt consumption is known to contribute to kidney disease, says the National Kidney Foundation. Moreover, it causes high blood pressure, stroke, and heart disease, which happens to be the number 1 killer worldwide.
Dr. Goldfarb says, “People recognize that sodium is adverse and that people have to limit their salt intake, and that’s true especially for people with conditions such as chronic kidney disease, bone disease, and high blood pressure.”
Substituting Salt May Reduce the Risk of Cardiovascular Disease and Mortality
A randomized clinical trial published in the New England Journal of Medicine in 2021, tested the effects of salt versus a potassium-based salt substitute in 600 villages located in rural China. The study had 21,000 people all aged 60 and above, almost all with histories of stroke, hypertension or both. Half of the participants used a salt substitute comprising 75 percent sodium chloride (table salt) and 25 percent potassium chloride, while the other half used regular salt.
After approximately five years, the researchers conducted a follow-up and discovered that individuals in the salt substitute group exhibited lower rates of stroke, major cardiovascular events, and overall mortality
However, a significant limitation of the study was its exclusion of individuals with kidney disease on medications that heightened susceptibility to hyperkalemia. Consequently, the study does not provide insights into whether the additional potassium would affect this specific population.
Despite supporting the proposed rule, Goldfarb acknowledges its potential impact and emphasizes the importance of monitoring individuals with chronic kidney disease on medications that increase susceptibility to hyperkalemia.
“There’s a possibility that a modest amount of potassium would be safe for people with kidney disease, but there’s a border to that,” said Dr. Goldfarb, observing that foods incorporating salt alternatives are likely to maintain relatively low potassium levels, given that it usually substitutes some, though not all, of the salt.
“The amount of potassium that could be used as a salt substitute is relatively small and not necessarily dangerous even to people with kidney disease,” he said.
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