Trends in Salt Substitute Use Among Adults in the United States, 2003 to 2020

Excessive sodium and inadequate potassium intake are major risk factors for hypertension (HTN).¹ Replacing sodium with salt substitutes reduces blood pressure (BP), stroke, and cardiovascular mortality, with evidence largely coming from trials conducted in China.^2–4 However, the prevalence and predictors of salt substitute use in the US population remain unknown. We examined trends in salt substitute use among US adults.

Methods:

We analyzed National Health and Nutrition Examination Survey (NHANES) data from 2003–2004 through 2017- March 2020. We identified nonpregnant adults aged ≥18 years with complete dietary survey and BP data. Participants were placed into three subgroups based on presence of HTN (BP ≥130/80 mmHg) and antihypertensive treatment: 1)treated HTN, 2)untreated HTN, and 3)normotensive. Participants were asked about the type of discretionary salt they used at the table. Salt type outcomes were categorized by the NHANES survey as 1)ordinary salt, 2)Lite Salt (salt substitute with reduced sodium content), 3)salt substitute (substitute that does not contain sodium), 4)no added salt. The current analysis combines Lite Salt and salt substitute together as they both represent salt flavoring options that limit sodium intake. Eligible participants were defined by estimated glomerular filtration rate (eGFR)≥60 ml/min/1.73m² and not taking medications that reduce potassium excretion or prescribed potassium supplement.¹ Participants were asked about the frequency of foods prepared away from home (FAFH) such as restaurants, fast-food places, food stands, etc. Multinomial logistic regression was used to examine age-adjusted trends and associations between FAFH (<3 vs ≥3 times/week) as exposure and salt type as outcome. All analyses accounted for the complex NHANES sampling design with appropriate sample weights, strata, and primary sampling units. Statistical analyses were conducted using SAS version 9.4 (SAS Institute Inc., Cary, NC) and 2-sided P values <.05 were considered significant.

Results:

Among 37,080 adults in the analytic sample across the NHANES cycles, 37.9% were aged 18–39 years, 36.9% were 40–59 years, and 25.2% were ≥60 years. Half of participants (50.6%) were female, and 10.7% were non-Hispanic Black. Overall, 21.7% had a family income-to-poverty ratio<1.3 (the threshold for Supplemental Nutrition Assistance Program eligibility), 16.0% had less than a high school education, and 28.1% had a college degree or higher. Most participants had health insurance (82.5%) and were married or living with a partner (62.5%). The median (25th-75th percentile) body mass index was 27.7 (24.1–32.2) kg/m².

Salt substitute use ranged from 2.5–5.4% among general adults and 2.3–5.1% among eligible adults (Figure[A]). Prevalence declined significantly from 2003 to 2020 in both groups. Similar trends are observed when Lite Salt use was analyzed separately from the salt substitute category (data not shown). Salt substitute use was higher in treated HTN than in untreated HTN or normotensive adults (Figure[B]). Similar patterns were observed among eligible adults (Figure[C]). Among adults consuming <3 FAFH meals per week, 4.3% reported salt substitute use compared with 3.5% of those consuming ≥3 FAFH meals per week (Figure[D]). In unadjusted analyses, more frequent FAFH meals were associated with lower odds of salt substitute, but this association was not significant after adjusting for age, race/ethnicity, and education (Figure[E]).

Figure.

Trends in salt substitute use from 2003–2020 and associations with frequency of eating FAFH. A) Weighted prevalence of salt substitute use among US general and eligible adults. Multinomial logistic regression was used to examine age-adjusted trends. B) Prevalence by hypertension status among general adults. C) Prevalence by hypertension status among eligible adults. Panels B–C use multinomial logistic regression models with hypertension status as the exposure and salt type as the outcome, adjusting for survey year. *p<.005 for treated hypertensive vs. normotensive within that survey year; †p<.005 for treated hypertensive vs. untreated hypertensive groups within that survey year, after adjusting for multiple comparisons. D) Unadjusted odds ratios for the association between FAFH frequency (<3 vs. ≥3 meals/week) and salt type from multinomial logistic regression. E) Adjusted odds ratios for the association between FAFH frequency and salt type (age, race/ethnicity, education) from multinomial logistic regression. All analyses accounted for the complex survey design and weighting of NHANES. Abbreviations: SS, salt substitute; FAFH, food prepared away from home; OR, odds ratio; GED, General Educational Development; AA, Associate of Arts degree.

Discussion:

In this nationally representative sample of US adults, salt substitutes remained underused over two decades and declined over time. Even among those with treated HTN, fewer than 10% reported using salt substitutes, while most continued to rely on ordinary salt. These findings suggest a persistent underutilization of salt substitutes in the US despite BP-lowering effects and cardiovascular outcome evidence primarily from trials in China, where potassium intake is lower than in the US.^2,3

Several factors may contribute to low use. Limited public awareness, along with possible concerns regarding taste, cost, and perceived safety, may discourage their use among both consumers and clinicians. However, even among participants with preserved kidney function and no potassium-altering medications, use remained below 5%, suggesting underutilization extends beyond safety concerns. More frequent FAFH meals were inversely related to salt substitute use, although this association was not independent of age and race/ethnicity. Given low discretionary use of salt substitutes, industry reformulation programs that replace sodium with potassium in commercially prepared foods might increase potassium and reduce sodium intake at the population level.

Study limitations include reliance on self-reported dietary data and exclusion of non-discretionary salt use. The amount of potassium (if any) in salt substitutes is not captured by the survey. Thus, the prevalence of potassium-containing salt substitute use will be far lower than the overall prevalence.

In conclusion, salt substitute use among US adults remains low despite evidence of benefit in reducing BP via lowering sodium intake and increasing potassium intake which further promotes natriuresis.^2,3,5 As recent guidelines recognize salt substitutes as an effective strategy for hypertension prevention and management, greater efforts are needed to promote their use among eligible adults as a simple, low-cost approach to reduce sodium intake and improve population health.^1–4