Sodium reduction is a public health priority: reflections on the Institute of Medicine's report, sodium intake in populations: assessment of evidence

Socio-economic and racial/ethnic disparities in the nutritional quality of packaged food purchases in the USA, 2008-2018

OBJECTIVE

To determine whether disparities exist in the nutritional quality of packaged foods and beverage purchases by household income, education and race/ethnicity and if they changed over time.

DESIGN

We used Nielsen Homescan, a nationally representative household panel, from 2008 to 2018 (n = 672 821 household-year observations). Multivariate, multilevel regressions were used to model the association between sociodemographic groups and a set of nutritional outcomes of public health interest, including nutrients of concern (sugar, saturated fat and Na) and calories from specific food groups (fruits, non-starchy vegetables, processed meats, sugar-sweetened beverages and junk foods).

SETTING

Household panel survey.

PARTICIPANTS

Approximately 60 000 households each year from the USA.

RESULTS

Disparities were found by income and education for most outcomes and widened for purchases of fruits, vegetables and the percentage of calories from sugar between 2008 and 2018. The magnitude of disparities was largest by education. Disparities between Black and White households include the consumption of processed meats and the percentage of calories from sugar, while no disparities were found between White and Hispanic households. Disparities have been largely persistent, as any significant changes over time have been substantively small.

CONCLUSIONS

Policies to improve the healthfulness of packaged foods must be expanded beyond SSB taxes, and future research should focus on what mediates the relationship between education and diet so as not to exacerbate disparities.

Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride

BACKGROUND

Recent cohort studies show that salt intake below 6 g is associated with increased mortality. These findings have not changed public recommendations to lower salt intake below 6 g, which are based on assumed blood pressure (BP) effects and no side-effects.

OBJECTIVES

To assess the effects of sodium reduction on BP, and on potential side-effects (hormones and lipids) SEARCH METHODS: The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to April 2018 and a top-up search in March 2020: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions. The top-up search articles are recorded under "awaiting assessment."

SELECTION CRITERIA

Studies randomizing persons to low-sodium and high-sodium diets were included if they evaluated at least one of the outcome parameters (BP, renin, aldosterone, noradrenalin, adrenalin, cholesterol, high-density lipoprotein, low-density lipoprotein and triglyceride,.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected data, which were analysed with Review Manager 5.3. Certainty of evidence was assessed using GRADE.

MAIN RESULTS

Since the first review in 2003 the number of included references has increased from 96 to 195 (174 were in white participants). As a previous study found different BP outcomes in black and white study populations, we stratified the BP outcomes by race. The effect of sodium reduction (from 203 to 65 mmol/day) on BP in white participants was as follows: Normal blood pressure: SBP: mean difference (MD) -1.14 mmHg (95% confidence interval (CI): -1.65 to -0.63), 5982 participants, 95 trials; DBP: MD + 0.01 mmHg (95% CI: -0.37 to 0.39), 6276 participants, 96 trials. Hypertension: SBP: MD -5.71 mmHg (95% CI: -6.67 to -4.74), 3998 participants,88 trials; DBP: MD -2.87 mmHg (95% CI: -3.41 to -2.32), 4032 participants, 89 trials (all high-quality evidence). The largest bias contrast across studies was recorded for the detection bias element. A comparison of detection bias low-risk studies versus high/unclear risk studies showed no differences. The effect of sodium reduction (from 195 to 66 mmol/day) on BP in black participants was as follows: Normal blood pressure: SBP: mean difference (MD) -4.02 mmHg (95% CI:-7.37 to -0.68); DBP: MD -2.01 mmHg (95% CI:-4.37, 0.35), 253 participants, 7 trials. Hypertension: SBP: MD -6.64 mmHg (95% CI:-9.00, -4.27); DBP: MD -2.91 mmHg (95% CI:-4.52, -1.30), 398 participants, 8 trials (low-quality evidence). The effect of sodium reduction (from 217 to 103 mmol/day) on BP in Asian participants was as follows: Normal blood pressure: SBP: mean difference (MD) -1.50 mmHg (95% CI: -3.09, 0.10); DBP: MD -1.06 mmHg (95% CI:-2.53 to 0.41), 950 participants, 5 trials. Hypertension: SBP: MD -7.75 mmHg (95% CI:-11.44, -4.07); DBP: MD -2.68 mmHg (95% CI: -4.21 to -1.15), 254 participants, 8 trials (moderate-low-quality evidence).   During sodium reduction renin increased 1.56 ng/mL/hour (95%CI:1.39, 1.73) in 2904 participants (82 trials); aldosterone increased 104 pg/mL (95%CI:88.4,119.7) in 2506 participants (66 trials); noradrenalin increased 62.3 pg/mL: (95%CI: 41.9, 82.8) in 878 participants (35 trials); adrenalin increased 7.55 pg/mL (95%CI: 0.85, 14.26) in 331 participants (15 trials); cholesterol increased 5.19 mg/dL (95%CI:2.1, 8.3) in 917 participants (27 trials); triglyceride increased 7.10 mg/dL (95%CI: 3.1,11.1) in 712 participants (20 trials); LDL tended to increase 2.46 mg/dl (95%CI: -1, 5.9) in 696 participants (18 trials); HDL was unchanged -0.3 mg/dl (95%CI: -1.66,1.05) in 738 participants (20 trials) (All high-quality evidence except the evidence for adrenalin).

AUTHORS' CONCLUSIONS

In white participants, sodium reduction in accordance with the public recommendations resulted in mean arterial pressure (MAP) decrease of about 0.4 mmHg in participants with normal blood pressure and a MAP decrease of about 4 mmHg in participants with hypertension. Weak evidence indicated that these effects may be a little greater in black and Asian participants. The effects of sodium reduction on potential side effects (hormones and lipids) were more consistent than the effect on BP, especially in people with normal BP.

Dietary Care for ADPKD Patients: Current Status and Future Directions

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic nephropathy, and tolvaptan is the only therapy available. However, tolvaptan slows but does not stop disease progression, is marred by polyuria, and most patients worldwide lack access. This and recent preclinical research findings on the glucose-dependency of cyst-lining cells have renewed interest in the dietary management of ADPKD. We now review the current dietary recommendations for ADPKD patients according to clinical guidelines, the evidence base for those, and the potential impact of preclinical studies addressing the impact of diet on ADPKD progression. The clinical efficacy of tolvaptan has put the focus on water intake and solute ingestion as modifiable factors that may impact tolvaptan tolerance and ADPKD progression. By contrast, dietary modifications suggested to ADPKD patients, such as avoiding caffeine, are not well supported and their impact is unknown. Recent studies have identified a chronic shift in energy production from mitochondrial oxidative phosphorylation to aerobic glycolysis (Warburg effect) as a contributor to cyst growth, rendering cyst cells exquisitely sensitive to glucose availability. Therefore, low calorie or ketogenic diets have delayed preclinical ADPKD progression. Additional preclinical data warn of potential negative impact of excess dietary phosphate or oxalate in ADPKD progression.

Nutritional Needs of the Older Adult

Older adults are particularly vulnerable to compromised nutritional status. With advancing age, the consumption of a high-quality, nutritionally dense diet is increasingly essential to optimize health and well-being. Proportionally, macronutrient needs for older adults are similar to younger adults, however overall calorie requirements tend to decline with age. Unique factors influencing food intake should be considered and individualized guidance should be designed to help overcome medical, physical, and social barriers to a healthy diet. The goal for nutrition intervention should ultimately be to promote health and quality of life across the continuum of the aging process.

Surrogate disease markers as substitutes for chronic disease outcomes in studies of diet and chronic disease relations

Surrogate biomarkers for clinical outcomes afford scientific and economic efficiencies when investigating nutritional interventions in chronic diseases. However, valid scientific results are dependent on the qualification of these disease markers that are intended to be substitutes for a clinical outcome and to accurately predict benefit or harm. In this article, we examine the challenges of evaluating surrogate markers and describe the framework proposed in a 2010 Institute of Medicine report. The components of this framework are presented in the context of nutritional interventions for chronic diseases. We present case studies of 2 well-accepted surrogate markers [blood pressure within sodium intake and cardiovascular disease (CVD) context and low density lipoprotein-cholesterol concentrations within a saturated fat and CVD context]. We also describe additional cases in which the evidence is insufficient to validate their surrogate status. Guidance is offered for future research that evaluates or uses surrogate markers.

The Third Time's a Charm: Psychometric Testing and Update of the Atlanta Heart Failure Knowledge Test

BACKGROUND AND OBJECTIVE

Since first being published in 2009, the Atlanta Heart Failure Knowledge Test (AHFKT) has proven a reliable and valid instrument and has been used in multiple studies. Given advances in heart failure (HF) self-care, we proposed to reevaluate the psychometric properties of the AHFKTv2 across these recent studies and update the instrument.

METHODS

Demographic, clinical, and baseline AHFKTv2 data from 4 intervention studies in persons with HF were combined for this analysis (N = 284). The 30 questions of the AHFKT are focused on 5 HF self-care knowledge domains: pathophysiology, nutrition, behavior, medications, and symptoms. Characteristics of the sample were analyzed using descriptive statistics; validity testing with t tests and Mann-Whitney 2-group tests and Pearson r and Spearman ρ correlations; and reliability calculations and factor analysis were performed based on tetrachoric correlations.

RESULTS

Participants were 22 to 84 years of age, 66% were African American, 63% were male, and 94% had New York Heart Association class II to III HF. Mean AHFKT score was 80.6% (±11%). Hypotheses that higher levels of knowledge would be associated with higher education level (t = -2.7, P < .01) and less sodium consumption (ρ = -0.22, P = .03) were validated. Factor analysis revealed 1 general knowledge factor with good reliability, Cronbach's α was .87. Item response analysis identified individual questions requiring review and revision.

CONCLUSION

Comprehensive psychometric evaluation of the AHFKTv2 confirmed its internal consistency reliability and validity and provided direction for production of the AHFKTv3 available for use in research and clinical practice.

Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride

BACKGROUND

In spite of more than 100 years of investigations the question of whether a reduced sodium intake improves health is still unsolved.

OBJECTIVES

To estimate the effects of low sodium intake versus high sodium intake on systolic and diastolic blood pressure (SBP and DBP), plasma or serum levels of renin, aldosterone, catecholamines, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglycerides.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to March 2016: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 3), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also searched the reference lists of relevant articles.

SELECTION CRITERIA

Studies randomising persons to low-sodium and high-sodium diets were included if they evaluated at least one of the above outcome parameters.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected data, which were analysed with Review Manager 5.3.

MAIN RESULTS

A total of 185 studies were included. The average sodium intake was reduced from 201 mmol/day (corresponding to high usual level) to 66 mmol/day (corresponding to the recommended level).The effect of sodium reduction on blood pressure (BP) was as follows: white people with normotension: SBP: mean difference (MD) -1.09 mmHg (95% confidence interval (CI): -1.63 to -0.56; P = 0.0001); 89 studies, 8569 participants; DBP: + 0.03 mmHg (MD 95% CI: -0.37 to 0.43; P = 0.89); 90 studies, 8833 participants. High-quality evidence. Black people with normotension: SBP: MD -4.02 mmHg (95% CI:-7.37 to -0.68; P = 0.002); seven studies, 506 participants; DBP: MD -2.01 mmHg (95% CI:-4.37 to 0.35; P = 0.09); seven studies, 506 participants. Moderate-quality evidence. Asian people with normotension: SBP: MD -0.72 mmHg (95% CI: -3.86 to 2.41; P = 0.65); DBP: MD -1.63 mmHg (95% CI:-3.35 to 0.08; P =0.06); three studies, 393 participants. Moderate-quality evidence.White people with hypertension: SBP: MD -5.51 mmHg (95% CI: -6.45 to -4.57; P < 0.00001); 84 studies, 5925 participants; DBP: MD -2.88 mmHg (95% CI: -3.44 to -2.32; P < 0.00001); 85 studies, 6001 participants. High-quality evidence. Black people with hypertension: SBP MD -6.64 mmHg (95% CI:-9.00 to -4.27; P = 0.00001); eight studies, 619 participants; DBP -2.91 mmHg (95% CI:-4.52, -1.30; P = 0.0004); eight studies, 619 participants. Moderate-quality evidence. Asian people with hypertension: SBP: MD -7.75 mmHg (95% CI:-11,44 to -4.07; P < 0.0001) nine studies, 501 participants; DBP: MD -2.68 mmHg (95% CI: -4.21 to -1.15; P = 0.0006). Moderate-quality evidence.In plasma or serum, there was a significant increase in renin (P < 0.00001), aldosterone (P < 0.00001), noradrenaline (P < 0.00001), adrenaline (P < 0.03), cholesterol (P < 0.0005) and triglyceride (P < 0.0006) with low sodium intake as compared with high sodium intake. All effects were stable in 125 study populations with a sodium intake below 250 mmol/day and a sodium reduction intervention of at least one week.

AUTHORS' CONCLUSIONS

Sodium reduction from an average high usual sodium intake level (201 mmol/day) to an average level of 66 mmol/day, which is below the recommended upper level of 100 mmol/day (5.8 g salt), resulted in a decrease in SBP/DBP of 1/0 mmHg in white participants with normotension and a decrease in SBP/DBP of 5.5/2.9 mmHg in white participants with hypertension. A few studies showed that these effects in black and Asian populations were greater. The effects on hormones and lipids were similar in people with normotension and hypertension. Renin increased 1.60 ng/mL/hour (55%); aldosterone increased 97.81 pg/mL (127%); adrenalin increased 7.55 pg/mL (14%); noradrenalin increased 63.56 pg/mL: (27%); cholesterol increased 5.59 mg/dL (2.9%); triglyceride increased 7.04 mg/dL (6.3%).

A systematic review of economic evaluations of population-based sodium reduction interventions

OBJECTIVE

To summarise evidence describing the cost-effectiveness of population-based interventions targeting sodium reduction.

METHODS

A systematic search of published and grey literature databases and websites was conducted using specified key words. Characteristics of identified economic evaluations were recorded, and included studies were appraised for reporting quality using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist.

RESULTS

Twenty studies met the study inclusion criteria and received a full paper review. Fourteen studies were identified as full economic evaluations in that they included both costs and benefits associated with an intervention measured against a comparator. Most studies were modelling exercises based on scenarios for achieving salt reduction and assumed effects on health outcomes. All 14 studies concluded that their specified intervention(s) targeting reductions in population sodium consumption were cost-effective, and in the majority of cases, were cost saving. Just over half the studies (8/14) were assessed as being of 'excellent' reporting quality, five studies fell into the 'very good' quality category and one into the 'good' category. All of the identified evaluations were based on modelling, whereby inputs for all the key parameters including the effect size were either drawn from published datasets, existing literature or based on expert advice.

CONCLUSION

Despite a clear increase in evaluations of salt reduction programs in recent years, this review identified relatively few economic evaluations of population salt reduction interventions. None of the studies were based on actual implementation of intervention(s) and the associated collection of new empirical data. The studies universally showed that population-based salt reduction strategies are likely to be cost effective or cost saving. However, given the reliance on modelling, there is a need for the effectiveness of new interventions to be evaluated in the field using strong study designs and parallel economic evaluations.

Trends in racial/ethnic and income disparities in foods and beverages consumed and purchased from stores among US households with children, 2000-2013

BACKGROUND

It is unclear whether racial/ethnic and income differences in foods and beverages obtained from stores contribute to disparities in caloric intake over time.

OBJECTIVE

We sought to determine whether there are disparities in calories obtained from store-bought consumer packaged goods (CPGs), whether brands (name brands compared with private labels) matter, and if disparities have changed over time.

DESIGN

We used NHANES individual dietary intake data among households with children along with the Nielsen Homescan data on CPG purchases among households with children. With NHANES, we compared survey-weighted energy intakes for 2003-2006 and 2009-2012 from store and nonstore sources by race/ethnicity [non-Hispanic whites (NHWs), non-Hispanic blacks (NHBs), and Hispanic Mexican-Americans) and income [≤185% federal poverty line (FPL), 186-400% FPL, and >400% FPL]. With the Nielsen data, we compared 2000-2013 trends in calories purchased from CPGs (obtained from stores) across brands by race/ethnicity (NHW, NHB, and Hispanic) and income. We conducted random-effect models to derive adjusted trends and differences in calories purchased (708,175 observations from 64,709 unique households) and tested whether trends were heterogeneous by race/ethnicity or income.

RESULTS

Store-bought foods and beverages represented the largest component of dietary intake, with greater decreases in energy intakes in nonstore sources for foods and in store sources for beverages. Beverages from stores consistently decreased in all subpopulations. However, in adjusted models, reductions in CPG calories purchased in 2009-2012 were slower for NHB and low-income households than for NHW and high-income households, respectively. The decline in calories from name-brand food purchases was slower among NHB, Hispanic, and lowest-income households. NHW and high-income households had the highest absolute calories purchased in 2000.

CONCLUSIONS

Across 2 large data sources, we found decreases in intake and purchases of beverages from stores across racial/ethnic and income groups. However, potentially beneficial reductions in calories purchased were more pronounced in some subgroups over others.

A Radical Sodium Reduction Policy is not Supported by Randomized Controlled Trials or Observational Studies: Grading the Evidence

Several health institutions recommend sodium intake be reduced to below 2,300 mg, which means that 6-7 billion individuals should alter their diet to accommodate. Such a radical recommendation should be based on solid evidence. However, this review reveals that (i) there are no randomized controlled trials (RCTs) allocating individuals to below 2,300 mg and measuring health outcomes; (ii) RCTs allocating risk groups such as obese prehypertensive individuals and hypertensive individuals down to (but not below) 2,300 mg show no effect of sodium reduction on all-cause mortality; (iii) RCTs allocating individuals to below 2,300 mg show a minimal effect on blood pressure in the healthy population (less than 1mm Hg) and significant increases in renin, aldosterone, noradrenalin cholesterol, and triglyceride; and (iv) observational studies show that sodium intakes below 2,645 and above 4,945 mg are associated with increased mortality. Given that 90% of the worlds' population currently consumes sodium within the optimal range of 2,645-4,945 mg, there is no scientific basis for a public health recommendation to alter sodium intake.

Estimating Sodium and Potassium Intakes and Their Ratio in the American Diet: Data from the 2011-2012 NHANES

BACKGROUND

The dietary sodium-to-potassium ratio (Na:K) is shown to be more strongly associated with an increased risk of cardiovascular disease (CVD) and CVD-related mortality than either sodium or potassium intake alone.

OBJECTIVE

The aim was to estimate the Na:K in the diet of US adults.

METHODS

Among US adults from the 2011-2012 NHANES (≥20 y; 2393 men and 2337 women), the National Cancer Institute method was used to estimate sodium and potassium intakes, Na:K, and the percentage of individuals with Na:K <1.0 utilizing the complex, stratified, multistage probability cluster sampling design.

RESULTS

Overall, women had a significantly lower Na:K than men (mean ± SE: 1.32 ± 0.02 compared with 1.45 ± 0.02). Non-Hispanic whites had a significantly lower Na:K than non-Hispanic blacks and non-Hispanic Asians (1.34 ± 0.02 compared with 1.54 ± 0.03 and 1.49 ± 0.04, respectively). Only 12.2% ± 1.5% of US adults had a Na:K < 1.0. The Na:K decreased linearly as age increased. Most adults (90% ± 0.8%) had sodium intakes >2300 mg/d, whereas <3% had potassium intakes >4700 mg/d. Grains and vegetables were among the highest contributors to sodium intakes for adults with Na:K < 1.0, compared with protein foods and grains for those with Na:K ≥ 1.0. Vegetables and milk and dairy products constituted the primary dietary sources of potassium for individuals with Na:K < 1.0, whereas mixed dishes and protein foods contributed the most potassium for individuals with ratios ≥1.0. Individuals with a Na:K < 1.0 were less likely to consume mixed dishes and condiments and were more likely to consume vegetables, milk and dairy products, and fruit than those with a Na:K ≥ 1.0.

CONCLUSION

Only about one-tenth of US adults have a Na:K consistent with the WHO guidelines for reduced risk of mortality. Continued efforts to reduce sodium intake in tandem with novel strategies to increase potassium intake are warranted.

The science upon which to base dietary sodium policy

Few nutrient intake recommendations become subjects of heated scientific debate, but sodium is 1 of them. In the absence of sufficient clinical trials focused on sodium intake and health outcomes, studies that used the surrogate marker of blood pressure have been used to support extreme sodium reduction. Under tightly controlled conditions, maximum achievable sodium reduction leads to a 1-6 mm Hg reduction in systolic blood pressure, which presumably leads to reduced cardiovascular disease morbidity and mortality. However, in observational cohort studies that used not blood pressure but actual health conditions as outcomes, the presumed relation between sodium intakes <2500 mg/d was not observed. Thus, the blood pressure effect of sodium restriction can no longer be accepted as a surrogate for health outcomes associated with sodium intake. Evidence that reducing sodium intakes to <2500 mg/d will improve health is needed to justify continuing efforts to modify diet.

The Healthy Wight Commitment Foundation pledge: calories purchased by U.S. households with children, 2000-2012

CONTEXT

An independent evaluation of the Healthy Weight Commitment Foundation (HWCF) marketplace pledge found that the participating companies met and exceeded their interim 2012 sales reduction pledge.

EVIDENCE ACQUISITION

This follow-up study conducted in 2013 used purchase data from 2000 to 2012 among U.S. households with children and compared trends in calorie purchases of HWCF, non-HWCF name brands, and private label (PL) products in the pre-pledge period (2000-2007) and the post-pledge period (2008-2012); controlled for potential effects of concurrent changes in demographic and economic factors, including the Great Recession and food prices; and assessed whether the HWCF marketplace pledge was associated with reductions in consumer packaged goods (CPG) calorie purchases by households with children.

EVIDENCE SYNTHESIS

There has been a significant per capita decline in average daily CPG caloric purchases between 2000 and 2012 among households with children from all brand categories. Based on pre-pledge trends, declines in CPG caloric purchases were already occurring. However, post-pledge reductions in calories purchased from HWCF brands were less than expected, and reductions in calories purchased from non-HWCF name brands and PLs were greater than expected after economic, sociodemographic, and secular factors were accounted for.

CONCLUSIONS

If the 16 HWCF companies had been able to maintain their pre-pledge trajectory, there should have been an additional 42 kcal/capita/day reduction in calories purchased from HWCF products in 2012 among households with children. A lack of change in total CPG calories purchased between 2011 and 2012 calls into question the sustainability of the decline and a need for continued monitoring.

What determines human sodium intake: policy or physiology?

Past and current U.S. sodium and health policy focused on population-wide reductions in sodium intake. Underlying that policy are a number of assumptions that recent scientific publications challenged. The assumptions include the following: 1) that current intakes are excessive; 2) that the “healthy range” must be below current intakes; 3) that sodium intake can be substantially reduced by public policy; 4) that human intake is dictated by the sodium content of the food supply; and 5) that, unlike all other essential nutrients in which a healthy range is defined by a Gaussian distribution, lower sodium intake is always better. Drawing on the most current published evidence, this review addresses each of these long-standing assumptions. Based on worldwide surveys that assessed sodium intake by 24-h urinary sodium measurements, it is now evident that, across 45 societies and 5 decades, humans consume a reproducible, narrow range of sodium: ∼2600–4800 mg/d. This range is independent of the food supply, verifiable in randomized controlled trials, consistent with the physiologic regulators of sodium intake and is not modifiable by public policy interventions. These findings indicate that human sodium intake is controlled by physiology and cannot be modified by public health policies.

Understanding the patterns and trends of sodium intake, potassium intake, and sodium to potassium ratio and their effect on hypertension in China

BACKGROUND

Recent studies have shown inconsistent effects of sodium reduction, potassium intake, and the ratio of sodium to potassium (Na/K ratio) on hypertension and other cardiovascular diseases. Major gaps exist in knowledge regarding these issues in China.

OBJECTIVE

We analyzed the patterns and trends of dietary sodium intake, potassium intake, and the Na/K ratio and their relations with incident hypertension in China.

DESIGN

The China Health and Nutrition Survey cohort includes 16,869 adults aged 20-60 y from 1991 to 2009. Three consecutive 24-h dietary recalls and condiment and food weights provided detailed dietary data. Multinomial logistic regression models determined trends and patterns of sodium and potassium intake and the Na/K ratio. Models for survival-time data estimated the hazard of incident hypertension.

RESULTS

Sodium intake is decreasing but remains double the Institute of Medicine recommendations. Most sodium comes from added condiments. Adults in the central provinces have the highest sodium intake and the most rapid increase in hypertension. Potassium intake has increased slightly but is below half of the recommended amount. The Na/K ratio is significantly higher than the recommended amounts. Recent measurements of high sodium intake, low potassium intake, and high Na/K ratio have strong independent dose-response associations with incident hypertension.

CONCLUSIONS

Reducing sodium in processed foods, the major public health strategy in Western countries, may be less effective in China, where salt intake remains high. Replacing sodium with potassium in salt to control and prevent hypertension in China should be considered along with other public health and clinical prevention options.