Associations between dietary salt, potassium and blood pressure in South African adults: WHO SAGE Wave 2 Salt & Tobacco

Community-level dietary intake of sodium, potassium, and sodium-to-potassium ratio as a global public health problem: a systematic review and meta-analysis

Background

Widespread adoption of a westernized diet represents a major lifestyle change characterized by substantially higher sodium consumption and lower potassium intake, which is related to cardiovascular morbidity.

Methods

We performed a systematic review and meta-analysis over published studies in accordance with quantifying the dietary intake of sodium and potassium of the universal population across the world. The PubMed, EMBASE, Cochrane Library, and Google Scholar databases were used to find research that pronounced 24-hour urinary sodium or potassium excretion (reference period: 2014-2021). The effect size was estimated using the fixed-effect model; sub-group analysis become accomplished to determine urinary sodium and potassium excretion disaggregated by geographical location. Publication bias became evaluated the usage of graphical funnel plot. Data analysis was performed using STATA 16.

Results

Forty-three studies (n= 62,940) qualified the selection criteria. The mean urinary excretion of sodium and potassium was 156.73 mmol/24h [95% confidence interval (CI), 148.98-164.47] and 48.89 mmol/24 h (95% CI, 43.61-54.17), respectively; the mean urinary sodium/potassium ratio was 3.68 (95% CI, 2.96-4.40).

Conclusions

This updated systematic review highlights excessively high dietary intake of sodium and low intake of potassium at the community level in most parts of the world. The urinary Na/K ratio exceeded the level recommended by the WHO guidelines.

Hypertension in sub-Saharan Africa: the current profile, recent advances, gaps, and priorities

Recent global and regional reports consistently confirm the high and increasing prevalence of hypertension in sub-Saharan Africa (SSA), with poor detection, treatment, and control rates. This narrative review summarises the burden of hypertension in SSA and recent findings from community-based hypertension management strategies. We further outline prominent risk factors according to recent data and associated underlying mechanisms for hypertension development. An extensive review of literature showed that most countries have reported on the prevalence of hypertension during 2017-2023, despite limitations linked to the lack of nationally representative studies, heterogeneity of sampling and data collection methods. Task-shifting approaches that assign roles to model patients and community health workers reported improved linkage to healthcare services and adherence to medication, with inconsistent findings on blood pressure (BP)-lowering effects over time. The regularly reported risk factors include unhealthy diet, sedentary lifestyle, increased adiposity and underweight, ageing, level of education, and/or income as well as psychosocial factors. Newer data on the pathophysiological mechanisms leading to hypertension and potential areas of intervention are reported from children and adults and include, among others, salt-handling and volume overload, endothelial function, BP dipping patterns and the role of human immunodeficiency virus . To conclude, significant strides have been made in data reporting from SSA on the burden of hypertension in the region as well as biomarker research to improve understanding and identification of areas of intervention. However, gaps remain on linkage between knowledge generation, translation, and implementation research. Coordinated studies addressing both discovery science and public health are crucial to curb hypertension development and improve management in SSA.

Sociocultural perceptions of physical activity and dietary habits for hypertension control: voices from adults in a rural sub-district of South Africa

BACKGROUND

Over half of adults from rural South Africa are hypertensive. Apart from pharmaceutical treatment, lifestyle changes such as increasing physical activity and reducing dietary salt have been strongly advocated for the control of hypertension. However, the control rates of hypertension for adults in rural South Africa are low. In this paper we explore whether this is due to the recommended lifestyle intervention not aligning with the individual's socio-cultural determinants of behaviour change.

AIM

To explore the social and cultural beliefs, perceptions and practices regarding physical activity and diet as a hypertension control intervention on hypertensive adults living in a rural sub-district in South Africa.

METHODS

Nine focus group discussions were conducted with hypertensive adults aged 40 years and above from Bushbuckridge sub-district in Mpumalanga Province of South Africa using a semi-structured interview guide. Each session began with introductions of the discussion theme followed by a short discussion on what the participants know about hypertension and the normal blood pressure readings. Physical activity and dietary habits were then introduced as the main subject of discussion. Probing questions were used to get more insight on a specific topic. A thematic analysis approach was used to generate codes, categories, and themes. A manual approach to data analysis was chosen and data obtained through transcripts were analysed inductively.

FINDINGS

Participants had a lack of knowledge about blood pressure normal values. Perceived causes of hypertension were alluded to psychosocial factors such as family and emotional-related issues. Physical activity practices were influenced by family and community members' attitudes and gender roles. Factors which influenced dietary practices mainly involved affordability and availability of food. To control their hypertension, participants recommend eating certain foods, emotional control, taking medication, exercising, praying, correct food preparation, and performing house chores.

CONCLUSION

Lifestyle interventions to control hypertension for adults in a rural South African setting using physical activity promotion and dietary control must consider the beliefs related to hypertension control of this population.

Comparing a range of potassium-enriched low sodium salt substitutes to common salt: Results of taste and visual tests in South African adults

BACKGROUND AND AIMS

Potassium-enriched low sodium salt substitutes (LSSS), which replace a proportion of sodium chloride (NaCl) with potassium chloride (KCl), have been shown to reduce blood pressure and offer a potential solution to address the high burden of hypertension in South Africa. However, it is unknown which proportions of KCl in LSSS are acceptable. We compared the taste and visual acceptability of various LSSS in South African adults.

METHODS AND RESULTS

Fifty-six adults underwent double-blind taste and visual tests of four LSSS (35%KCl/65%NaCl; 50%KCl/50%NaCl; 66%KCl/34%NaCl; 100%KCl) in comparison to 100%NaCl (common salt). Participants scored each product by taste ranking, taste perception and likeliness to use. Participants then visually inspected the five products and attempted to identify which was which. Almost half (45 %) of participants ranked the taste of 50%KCl/50 %NaCl as fantastic or really good. Furthermore, 62 % of participants liked and would be happy to use the 50 %KCl/50 %NaCl or felt this tasted like common salt. Only 12 % rated the 100%KCl highly for taste, and over half reported being unlikely to use this. Most participants (57.3 % and 36.4 %) were able to visually identify 100%NaCl and 100%KCl, while identification of other blends was generally poor. Responses were similar for 35%KCl/65%NaCl and 66%KCl/34%NaCl throughout.

CONCLUSION

Our findings suggest that the taste of the 50%KCl salt substitute would be well tolerated by South African adults, most of which could not visually differentiate between this salt substitute and common salt.

Sodium, potassium food intake and global cardiovascular risks in Togo

Objectives

To assess urinary sodium/potassium intake and identify its links with global cardiovascular risk (GCVR) according to the WHOPEN approach to WHO/ISH (International High Blood Pressure Society).

Methods

It was a cross-sectional and analytical study that took place from July 6, 2020, to September 17, 2021, in Togo, in the Aneho, Notse and Dapaong localities. It focused on 400 adults selected by sampling. The analysis of two urine samples was done. Cardiovascular risk scores were determined from specific graphs that take into account age, gender, systolic blood pressure, diabetes status, and smoking behavior.

Results

Among the 400 respondents, 49% lived in rural areas. The average age was 41 (30; 51) years. The average sodium and potassium intakes were respectively 3.2 g (1.04-5.99) or 7.95 g of salt and 1.4 g (1.89-5.62) per day. The risk of excessive sodium intake was 2.39 times higher in urban areas than in rural ones (P=0.049). Residing in rural areas was associated with high potassium intakes compared to urban ones [OR=3,2 IC (1.89-5.62)]. Thirteen percent (13%) of respondents were likely to develop at least a deadly or non-deadly cardiovascular disease in the next 10 years 'time, of whom 5% present a high risk. Excessive sodium intake increases by 2.10 times the risk of a deadly cardiovascular disease occurrence.

Conclusions

Sodium intakes are high while potassium intakes are low with a subsequent GCVR in the three cities. Sodium intakes were associated with GCVR. It is necessary to take steps to reduce excessive sodium intake and improve potassium intake.

Estimated 24-Hour urinary sodium and potassium excretion in adults in the Northwest Region of Morocco, 2017

BACKGROUND

Excessive sodium (Na) and insufficient potassium (K) intake contribute to a high risk of cardiovascular events. Morocco lacks data on actual Na and K intake in adults. We estimated mean Na and K intake in a Moroccan population of adults residing in the Northwest region using 24-h urinary excretion and examined their association with blood pressure (BP).

METHODS

A total of 371 adults from this region, who were recruited for the STEPs Survey Morocco 2017, completed demographic, anthropometric as well as BP data and provided a valid 24-h urine collection according to the standard World Health Organization (WHO) protocol. Multiple Linear Regression analysis was used to examine the association between 24-h urinary sodium (24-hUNa) and 24-h potassium excretion (24-hUK) with BP.

RESULTS

Mean Na excretion was 2794 mg/day and mean K excretion was 1898 mg/day. Overall, only 114 (30.7%) adults met the WHO recommendation for Na intake (< 2000 mg/d) and 31 (8.4%) met the adequate level for K intake (⩾3510 mg/d). There was no association between 24-hUNa and 24-hUK with BP (P > 0.05 for all).

CONCLUSION

Na intake was higher and K intake was lower than WHO recommendations in the study population. There was no association between estimated Na and K intake levels with BP in this population.

Early evidence for the effectiveness of South Africa's legislation on salt restriction in foods: the African-PREDICT study

South Africa was among the first countries to adopt mandatory regulation in 2016 to lower the salt content in processed foods, aiming to reduce population salt intake to <5 g/day. To assess the effectiveness of this regulation in 20-30 year-old adults, we determined the change in salt intake over a mean follow-up time of 4.56-years spanning the implementation of the regulation. This observational study included baseline (2013-2016; N = 668; 24.9 ± 3 years; 47.8% black; 40.7% men) and follow-up data (2018-ongoing; N = 311; 25.4 ± 3.05 years; 51.1% black; 43.4% men) for participants of the African-PREDICT study. Salt intake was estimated from 24-h urinary sodium excretion. Median salt intake at baseline (N = 668) was 7.88 g/day (IQR: 5.67). In those followed (N = 311), salt intake reduced from baseline [median (IQR): 7.91 g/day (5.83)] to follow-up [7.26 g/day (5.30)] [unadjusted median: -0.82 g/day]. After adjusting for baseline salt intake to address regression to the mean, the mean salt reduction was -1.2 g/day. The greatest reductions were in men [mean difference: -1.47 g/day], black adults [mean difference: -2.04 g/day], and participants from low [mean difference: -1.89 g/day] or middle [mean difference: -1.84 g/day] socio-economic status groups, adjusting for baseline salt intake. Our preliminary findings suggest that South Africa's salt regulation has been effective in lowering salt intake in young adults by ~1.2 g salt/day. Our study supports the effectiveness of upstream interventions to lower population salt intake, particularly for vulnerable groups who may typically consume more processed foods. It needs to be determined if the legislation has the anticipated population health gains.

The impact of the COVID-19 pandemic on the diet, training habits and fitness of Masters cyclists

Background: The number of Masters-level athletes (≥ 35 years of age) taking part in cycling has increased in the past years which may have beneficial effects on their health. The restrictions brought on by the COVID-19 pandemic has the potential to negatively impact the diet, training and fitness of these individuals due to restrictions in place to slow the spread of the virus. Aim: To investigate how the COVID-19 pandemic impacted the diet, training and fitness of Masters-level cyclists. Methods: 32 Masters cyclists (12 males, 20 females; mean age 47 ± 10 years) completed two incremental exercise tests one month apart during the pandemic to assess sport-specific fitness. Participants also completed online questionnaires to report their sedentary behavior and dietary intake before and during the pandemic, and their training volume and intensity for a specified week in February (before the pandemic) and each of March, April and May (during the pandemic). Results: No differences were seen in fitness (p = 0.6), training volume (p = 0.24) or intensity (p = 0.79) and sedentary behavior (p = 0.14) during the pandemic. Energy intake was unchanged (p = 1.0) during the pandemic, but participants consumed lower amounts of key nutrients such as fiber, vitamin A, omega-3 fatty acids and potassium (p < 0.05) while consuming more alcohol (p = 0.008) and vitamin C (p = 0.03). Conclusions: Our data shows that the COVID-19 pandemic has undesirable effects on nutrient and alcohol intake of Masters cyclists without impacting their training regimes, which may have adverse effects on their overall health and fitness in the long term.

Estimating the changing burden of disease attributable to high sodium intake in South Africa for 2000, 2006 and 2012

Background. Elevated sodium consumption is associated with increased blood pressure, a major risk factor for cardiovascular and chronic kidney disease.Objectives. To quantify the deaths and disability-adjusted life years (DALYs) attributed to high sodium intake in persons aged ≥25 years in South Africa (SA) for 2000, 2006 and 2012.Methods. Comparative risk assessment (CRA) methodology was used and population attributable fractions (PAFs) of high sodium intake, mediated through high blood pressure (BP), for cardiovascular and chronic kidney disease were estimated. This was done by taking the difference between the PAF for elevated systolic BP (SBP) based on the estimated SBP level in the population and the PAF based on the estimated SBP that would result if sodium intake levels were reduced to the theoretical minimum risk exposure level (1 g/day) according to population group and hypertension categories. A meta-regression based on data from nine national surveys conducted between 1998 and 2017 was used to estimate the prevalence of hypertension by age, sex and population group. Relative risks identified from international literature were used and the difference in PAFs was applied to local burden estimates from the second South African National Burden of Disease Study. Age-standardised rates were calculated using World Health Organization (WHO) standard population weights. The attributable burden was also estimated for 2012 using an alternative target of 2 g/day proposed in the National Strategic Plan for the Prevention and Control of Non-communicable Diseases (NSP).Results. High sodium intake as mediated through high SBP was estimated to cause 8 071 (95% uncertainty interval (UI) 6 542 - 15 474) deaths in 2012, a drop from 9 574 (95% UI 8 158 - 16 526) in 2006 and 8 431 (95% UI 6 972 - 14 511) in 2000. In 2012, ischaemic heart disease caused the highest number of deaths in persons (n=1 832), followed by haemorrhagic stroke (n=1 771), ischaemic stroke (n=1 484) and then hypertensive heart disease (n=1 230). Ischaemic heart disease was the highest contributor to deaths for males (27%), whereas for females it was haemorrhagic stroke (23%). In 2012, 1.5% (95% UI 1.3 - 2.9) of total deaths and 0.7% (95% UI 0.6 - 1.2) of total DALYs were attributed to high sodium intake. If the NSP target of <2 g/day sodium intake had been achieved in 2012, ~2 943 deaths and 48 870 DALYs would have been averted.Conclusion. Despite a slight decreasing trend since 2006, high sodium intake mediated through raised BP accounted for a sizeable burden of disease in 2012. Realising SA’s target to reduce sodium intake remains a priority, and progress requires systematic monitoring and evaluation.

Implementing effective salt reduction programs and policies in low- and middle-income countries: learning from retrospective policy analysis in Argentina, Mongolia, South Africa and Vietnam

OBJECTIVE

To understand the factors influencing the implementation of salt reduction interventions in low- and middle-income countries (LMIC).

DESIGN

Retrospective policy analysis based on desk reviews of existing reports and semi-structured stakeholder interviews in four countries, using Walt and Gilson's 'Health Policy Triangle' to assess the role of context, content, process and actors on the implementation of salt policy.

SETTING

Argentina, Mongolia, South Africa and Vietnam.

PARTICIPANTS

Representatives from government, non-government, health, research and food industry organisations with the potential to influence salt reduction programmes.

RESULTS

Global targets and regional consultations were viewed as important drivers of salt reduction interventions in Mongolia and Vietnam in contrast to local research and advocacy, and support from international experts, in Argentina and South Africa. All countries had population-level targets and written strategies with multiple interventions to reduce salt consumption. Engaging industry to reduce salt in foods was a priority in all countries: Mongolia and Vietnam were establishing voluntary programs, while Argentina and South Africa opted for legislation on salt levels in foods. Ministries of Health, the WHO and researchers were identified as critical players in all countries. Lack of funding and technical capacity/support, absence of reliable local data and changes in leadership were identified as barriers to effective implementation. No country had a comprehensive approach to surveillance or regulation for labelling, and mixed views were expressed about the potential benefits of low sodium salts.

CONCLUSIONS

Effective scale-up of salt reduction programs in LMIC requires: (1) reliable local data about the main sources of salt; (2) collaborative multi-sectoral implementation; (3) stronger government leadership and regulatory processes and (4) adequate resources for implementation and monitoring.

Serum potassium concentration and its association with hypertension among Ghanaian migrants and non-migrants: The RODAM study

BACKGROUND AND AIMS

Low serum potassium concentration is associated with hypertension, but whether the same association can be found in African origin populations, is unknown. We assessed serum potassium concentration, and its association with hypertension among Ghanaians living in different geographical locations.

METHODS

Baseline data of 962 rural, 1420 urban, and 2947 migrant Ghanaians from the Research on Obesity and Diabetes among African Migrants study were analysed. Mean serum potassium concentration was compared between the groups, and the association between serum potassium and hypertension was assessed using multivariate regression analyses.

RESULTS

Mean serum potassium concentration was higher in rural Ghana (4.28, 95% confidence interval 4.25-4.32 mmol/L) than in Ghanaians living in Amsterdam (3.90, 3.88-3.92 mmol/L) and London (4.11, 4.07-4.14 mmol/L), but lower than in Ghanaians living in urban Ghana (4.38, 4.34-4.42 mmol/L) and Berlin (4.57, 4.51-4.62 mmol/L) in both sexes. In the age-adjusted analyses, serum potassium was associated with hypertension in urban- (odds ratio 0.44, 0.23-0.82), London- (0.34, 0.17-0.64) and Amsterdam-Ghanaian males (0.41, 0.20-0.86), and in rural- (0.49, 0.28-0.84), London- (0.29, 0.17-0.49) and Amsterdam-Ghanaian females (0.33, 0.17-0.64). However, after adjustment for demographic, lifestyle, and health factors, serum potassium was associated with hypertension in Amsterdam-Ghanaian males only (0.12, 0.02-0.59).

CONCLUSIONS

This study shows differences in mean serum potassium among Ghanaian populations living in different locations in Europe and Ghana, and different associations with hypertension between sites. Further research should focus on elucidating the mechanism underlying potassium handling and blood pressure regulation in African populations, in order to mitigate the burden of hypertension among these populations.

Sodium status is associated with type 2 diabetes mellitus: a systematic review and meta-analysis of observational studies

PURPOSE

The relationship between sodium intake and the risk of developing type 2 diabetes mellitus (T2DM) is inconsistent. We, therefore, aimed to summarize the current evidence by conducting a systematic review and meta-analysis of observational studies.

METHODS

We retrieved studies which compared any marker of sodium status between individuals with T2DM and those without diabetes published in any language by searching online databases from inception up to June 2019. Summary effects were derived using random-effects model.

RESULTS

A total of 44 studies with 503,830 participants from 25 countries were included in this study. Sodium status was significantly different between individuals with and without T2DM (Hedges' g = 0.21; 95% CI 0.02, 0.40; P = 0.029). Individuals with T2DM had higher sodium intake compared to non-diabetic controls (WMD = 621.79 mg/day; 95% CI 321.53, 922.06; P < 0.001) and 24-h urinary excretion was associated with likelihood of developing T2DM (OR = 1.27, 95% CI 1.15, 1.41; P < 0.001). Furthermore, salivary, hair, and platelet sodium were higher in patients with T2DM compared to controls (P < 0.05).

CONCLUSION

The findings of the current meta-analysis suggest that sodium levels are higher in patients with T2DM compared to non-diabetic controls; however, given that these studies are observational, it is not possible to infer causality.

Hypertension among South African children in disadvantaged areas and associations with physical activity, fitness, and cardiovascular risk markers: A cross-sectional study

Childhood hypertension drives hypertension in later life; hence, assessing blood pressure in children is an important measure to determine current and future cardiovascular health. There is, however, a paucity of childhood blood pressure data, particularly for sub-Saharan Africa. This study explores blood pressure and associations with age, sex, socioeconomic status, physical activity, fitness, and cardiovascular risk markers. In the 'Disease, Activity and Schoolchildren's Health' (DASH) study, a cross-sectional analysis was conducted in disadvantaged neighbourhoods in the Eastern Cape province of South Africa. Assessments included blood pressure, accelerometer-measured physical activity, physical fitness, and cardiovascular risk markers. The study consisted of 785 children (383 boys, 402 girls, M = 12.4±0.9 years). Overall, 18% of the children were classified as hypertensive, while 20% were either overweight/obese, and almost four out of ten children did not meet global daily physical activity recommendations. Hypertensive children were more likely to be overweight/obese, χ² (2,785) = 14.42, p < 0.01, but only if they did not meet physical activity recommendations, χ² (2,295) = 11.93, p < 0.01. Considering the moderating effect which sufficient activity has on the relationship between hypertension and body weight, more emphasis should be placed on early primary health intervention and education strategies.

Effect of South Africa's interim mandatory salt reduction programme on urinary sodium excretion and blood pressure

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Thirty percent reduction in population salt intake by 2025 is recommended by WHO.

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South Africa introduced mandatory maximum sodium limits in processed foods in 2016.

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A countrywide impact evaluation assessed change in salt intake after two years.

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Salt intake measured using 24hr Na excretion dropped by 1.15 g per day.

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Ongoing evaluation is necessary as more stringent targets were implemented in 2019.

South Africa implemented legislation in June 2016 mandating maximum sodium (Na) levels in processed foods. A pre-post impact evaluation assessed whether the interim legislative approach reduced salt intake and blood pressure. Baseline Na intake was assessed in a nested cohort of the WHO Study on global AGEing and adult health (WHO-SAGE) Wave 2 (Aug-Dec 2015). 24-hour urine samples were collected in a random subsample (n = 1,299; of which n = 750 were considered valid (volume ≥ 300 mL and creatinine ≥ 4 mmol/day (women) or ≥ 6 mmol/day (men))). Follow-up urine samples were collected in Wave 3 (Jun 2018-Jun 2019), with replacements included for those lost to follow-up (n = 1,189; n = 548 valid). In those aged 18 − 49y, median salt intake was 7.8 (4.7, 12.0) g/day in W2 (n = 274), remaining similar in the W3 sample (7.7 (4.9, 11.3) g salt/day (n = 92); P = 0.569). In older adults (50 + y), median salt intake was 5.8 (4.0, 8.5) g/day (n = 467) in W2, and 6.0 (4.0, 8.6) g/day (n = 455) in W3 (P = 0.721). Controlling for differences in background characteristics, overall salt intake dropped by 1.15 g/day (P = 0.028). 24hr urinary Na concentrations from a countrywide South African sample suggest that salt intakes have dropped during the interim phase of mandatory sodium legislation. Further measurement of population level salt intake following stricter Na targets, enforced from June 2019, is necessary.

Association between the Urinary Sodium to Potassium Ratio and Blood Pressure in Adults: A Systematic Review and Meta-Analysis

While sodium and potassium are individually important for blood pressure (BP) regulation, the relative contribution of sodium to potassium intake has not been sufficiently investigated. This study aimed to evaluate the association between urinary sodium to potassium ratio (UNa: K) and systolic and diastolic BP in adults. A systematic review (PROSPERO; CRD42016035296) was conducted and was reported according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Three scientific databases (MEDLINE, Scopus, Web of Science) were searched to March 2020 while reference lists of included articles were further hand-searched. Randomized controlled trials (RCT), cohort and cross-sectional studies that assessed 24-h urinary excretion in adults were included. Data from eligible studies were extracted and summarized. Random effects meta-analysis was conducted on RCT data to assess standardized mean differences (SMD) in systolic and diastolic BP according to 24-h UNa: K. Thirty-nine studies were included. Meta-analysis of 5 RCTs found a lower UNa: K ratio to be associated with a significantly greater reduction in systolic and diastolic BP compared with a higher UNa: K ratio [SMD: -1.09 (95% CI: -1.91, -0.28) mmHg and -1.42 (95% CI: -2.24, -0.59) mmHg, respectively]. Heterogeneity between RCTs was observed in systolic and diastolic BP (I2 = 97%, P < 0.0001 and I2 = 98%, P < 0.0001, respectively). The current body of evidence demonstrates that a lower 24-h UNa: K ratio is associated with lower BP in adults. Dietary strategies to achieve an increase in potassium while at the same time lowering sodium would be beneficial in lowering BP.

Identifying co-occurrence and clustering of chronic diseases using latent class analysis: cross-sectional findings from SAGE South Africa Wave 2

OBJECTIVES

To classify South African adults with chronic health conditions for multimorbidity (MM) risk, and to determine sociodemographic, anthropometric and behavioural factors associated with identified patterns of MM, using data from the WHO's Study on global AGEing and adult health South Africa Wave 2.

DESIGN

Nationally representative (for ≥50-year-old adults) cross-sectional study.

SETTING

Adults in South Africa between 2014 and 2015.

PARTICIPANTS

1967 individuals (men: 623 and women: 1344) aged ≥45 years for whom data on all seven health conditions and socioeconomic, demographic, behavioural, and anthropological information were available.

MEASURES

MM latent classes.

RESULTS

The prevalence of MM (coexistence of two or more non-communicable diseases (NCDs)) was 21%. The latent class analysis identified three groups namely: minimal MM risk (83%), concordant (hypertension and diabetes) MM (11%) and discordant (angina, asthma, chronic lung disease, arthritis and depression) MM (6%). Using the minimal MM risk group as the reference, female (relative risk ratio (RRR)=4.57; 95% CI (1.64 to 12.75); p =0.004) and older (RRR=1.08; 95% CI (1.04 to 1.12); p<0.001) participants were more likely to belong to the concordant MM group, while tobacco users (RRR=8.41; 95% CI (1.93 to 36.69); p=0.005) and older (RRR=1.09; 95% CI (1.03 to 1.15); p=0.002) participants had a high likelihood of belonging to the discordant MM group.

CONCLUSION

NCDs with similar pathophysiological risk profiles tend to cluster together in older people. Risk factors for MM in South African adults include sex, age and tobacco use.

Bivariate Joint Spatial Modeling to Identify Shared Risk Patterns of Hypertension and Diabetes in South Africa: Evidence from WHO SAGE South Africa Wave 2

Recent studies have suggested the common co-occurrence of hypertension and diabetes in South Africa. Given that hypertension and diabetes are known to share common socio-demographic, anthropometric and lifestyle risk factors, the aim of this study was to jointly model the shared and disease-specific geographical variation of hypertension and diabetes. The current analysis used the Study on Global Ageing and Adult Health (SAGE) South Africa Wave 2 (2014/15) data collected from 2761 participants. Of the 2761 adults (median age = 56 years), 641 (23.2%) had high blood pressure on measurement and 338 (12.3%) reported being diagnosed with diabetes. The shared component has distinct spatial patterns with higher values of odds in the eastern districts of Kwa-Zulu Natal and central Gauteng province. The shared component may represent unmeasured health behavior characteristics or the social determinants of health in our population. Our study further showed how a shared component (latent and unmeasured health behavior characteristics or the social determinants of health) is distributed across South Africa among the older adult population. Further research using similar shared joint models may focus on extending these models for multiple diseases with ecological factors and also incorporating sampling weights in the spatial analyses.

Salt-reduction strategies may compromise salt iodization programs: Learnings from South Africa and Ghana

OBJECTIVES

Universal salt iodization has been adopted by many countries to address iodine deficiency. More recently, salt-reduction strategies have been widely implemented to meet global salt intake targets of <5 g/d. Compatibility of the two policies has yet to be demonstrated. This study compares urinary iodine excretion (UIE) according to 24-h urinary sodium excretion, between South Africa (SA) and Ghana; both countries have implemented universal salt iodization, but in Ghana no salt-reduction legislation has been implemented.

METHODS

Participants from the World Health Organization's Study on Global Ageing and Adult Health Wave 3, with survey and valid 24-h urinary data (Ghana, n = 495; SA, n = 707), comprised the sample. Median 24-h UIE was compared across salt intake categories of <5, 5-9 and >9 g/d.

RESULTS

In Ghana, median sodium excretion indicated a salt intake of 10.7 g/d (interquartile range [IQR] = 7.6), and median UIE was 182.4 µg/L (IQR = 162.5). In SA, both values were lower: median salt = 5.6 g/d (IQR = 5.0), median UIE = 100.2 µg/L (IQR = 129.6). UIE differed significantly across salt intake categories (P < 0.001) in both countries, with positive correlations observed in both-Ghana: r = 0.1501, P < 0.0011; South Africa: r = 0.4050, P < 0.0001. Participants with salt intakes <9 g/d in SA did not meet the World Health Organization's recommended iodine intake of 150 µg/d, but this was not the case in Ghana.

CONCLUSIONS

Monitoring and surveillance of iodine status is recommended in countries that have introduced salt-reduction strategies, in order to prevent reemergence of iodine deficiency.

Salt and potassium intake among adult Ghanaians: WHO-SAGE Ghana Wave 3

Though Ghana has high hypertension prevalence, the country lacks current national salt consumption data required to build and enhance advocacy for salt reduction. We explored the characteristics of a randomly selected sub sample that had valid urine collection, along with matched survey, anthropometric and BP data (n = 839, mean age = 60y), from the World Health Organization's Study on global AGEing and adult health (WHO-SAGE), Ghana Wave 3, n = 3053). We also investigated the relationship between salt intake and blood pressure (BP) among the cohort. BP was measured in triplicate and 24 h urine was collected for the determination of urinary sodium (Na), potassium (K), creatinine (Cr) and iodine levels. Hypertension prevalence was 44.3%. Median salt intake was 8.3 g/day, higher in women compared to men (8.6, interquartile range (IQR) 7.5 g/day vs 7.5, IQR 7.4 g/day, p <  0.01), younger participants (18-49 y) compared to older ones (50+ y) (9.7, IQR 7.9 g/day vs 8.1, IQR 7.1 g/day, p <  0.01) and those with higher Body Mass Index (BMI) (> 30 kg/m2) compared to a healthy BMI (18.5-24.9 kg/m2) (10.04, IQR 5.1 g/day vs 6.2, IQR 5.6 g/day, p <  0.01). More than three quarters (77%, n = 647) of participants had salt intakes above the WHO maximum recommendation of 5 g/d, and nearly two thirds (65%, n = 548) had daily K intakes below the recommended level of 90 mmol. Dietary sodium to potassium (Na: K) ratios above 2 mmol/mmol were positively associated with increasing BP with age. Population-based interventions to reduce salt intake and increase K consumption are needed.

Monitoring and implementation of salt reduction initiatives in Africa: A systematic review

This systematic review aims to document salt consumption patterns and the implementation status and potential impact of salt reduction initiatives in Africa, from studies published between January 2009 and November 2019. Studies were sourced using MEDLINE, Embase, Cochrane Library electronic databases, and gray literature. Of the 887 records retrieved, 38 studies conducted in 18 African countries were included. Twelve studies measured population salt intake, 11 examined salt level in foods, 11 assessed consumer knowledge, attitudes, and behaviors, 1 study evaluated a behavior change intervention, and 3 studies modeled potential health gains and cost savings of salt reduction interventions. The population salt intake studies determined by 24‐hour urine collections showed that the mean (SD) salt intake in African adults ranged from 6.8 (2.2) g to 11.3 (5.4) g/d. Salt levels in foods were generally high, and consumer knowledge was fairly high but did not seem to translate into salt lowering behaviors. Modeling studies showed that interventions for reducing dietary sodium would generate large health gains and cost savings for the health system. Despite this evidence, adoption of population salt reduction strategies in Africa has been slow, and dietary consumption of sodium remains high. Only South Africa adopted legislation in 2016 to reduce population salt intake, but success of this intervention has not yet been fully evaluated. Thus, rigorous evaluation of the salt reduction legislation in South Africa and initiation of salt reduction programs in other African countries will be vital to achieving the targeted 30% reduction in salt intake by 2025.

Towards Population Salt Reduction to Control High Blood Pressure in Ghana: A Policy Direction

Although population salt reduction is considered a "best buy" in addressing hypertension and cardiovascular disease, Ghana shares a high hypertension burden with a seemingly high salt consumption. This article discusses best practices in reducing population salt intake and provides preliminary data on salt and potassium intake, as well as the process to develop a road map and identification of actions needed to support the development of a strategic national document towards salt reduction in Ghana. In February 2019, a 2-d stakeholder meeting was held with government agencies, researchers, nongovernmental organizations, civil society organizations, and international partners to deliberate on salt reduction strategies and interventions needed in the face of rising hypertension and other noncommunicable diseases (NCDs) in Ghana. Recommendations were developed from the stakeholder meeting and are being considered for inclusion in the revision of Ghana's national NCD policy.

Correcting for Intra-Individual Variability in Sodium Excretion in Spot Urine Samples Does Not Improve the Ability to Predict 24 h Urinary Sodium Excretion

Given a global focus on salt reduction efforts to reduce cardiovascular risk, it is important to obtain accurate measures of salt intake on a population level. This study determined firstly whether adjustment for intra-individual variation in urinary sodium (Na) excretion using three repeated 24 h collections affects daily estimates and whether the use of repeated spot urine samples results in better prediction of 24 h Na compared to a single collection. Twenty three community-dwelling men and women from South Africa (mean age 59.7 years (SD = 15.6)) participating in the World Health Organization Study on global AGEing and adult health (WHO-SAGE) Wave 3 study collected 24 h and spot early morning urine samples over three consecutive days to assess urinary Na excretion. INTERSALT, Tanaka, and Kawasaki prediction equations, with either average or adjusted spot Na values, were used to estimate 24 h Na and compared these against measured 24 h urinary Na. Adjustment was performed by using the ratio of between-person (sb) and total (sobs) variability obtained from repeated measures analysis of variance. Sensitivity of the equations to predict daily urinary Na values below 5 g salt equivalent was calculated. The sb/sobs for urinary Na using three repeated samples for spot and 24 h samples were 0.706 and 0.798, respectively. Correction using analysis of variance for 3 × 24 h collections resulted in contraction of the upper end of the distribution curve (90th centile: 157 to 136 mmoL/day; 95th centile: 220 to 178 mmoL/day). All three prediction equations grossly over-estimated 24 h urinary Na excretion, regardless of whether a single spot urine or repeated collections corrected for intra-individual variation were used. Sensitivity of equations to detect salt intake equivalent values of ≤5 g/day was 13% for INTERSALT, while the other two equations had zero sensitivity. Correcting for intra-individual variability in Na excretion using three 24 h urine collections contracted the distribution curve for high intakes. Repeated collection of spot samples for urinary Na analysis does not improve the accuracy of predicting 24 h Na excretion. Spot urine samples are not appropriate to detect participants with salt intakes below the recommended 5 g/day.

Salt intake among Iranian population: the first national report on salt intake in Iran

OBJECTIVE

In Iran, there has been no national report on salt intake based on laboratory measurements so far. Therefore, this study was conducted to measure salt intake among Iranian population at the national level.

METHODS

In stepwise approach to conduct a surveillance survey 2016, 18 624 Iranian adults (25 years old and above), as a representative sample of Iranian adult population at national and subnational levels, underwent urine sodium measurement and were included in this study. The participants were recruited through a systematic random sampling from 30 provinces of Iran. For each individual, through a computer-assisted interview, a questionnaire on lifestyle risk factors was completed, all anthropometric indices were measured, and data on sodium of spot urine sample for all individuals and 24-h urine sample for a subsample were collected. To estimate the 24-h salt intake, common equations were used.

RESULTS

In total, 97.66% of the population consumed at least 5 g of salt per day. In addition, in 41.20% of the population, the level of salt intake was at least two times higher than the level recommended by the WHO for adults. The mean of salt intake among Iranian population was 9.52 g/day (95% confidence interval: 9.48-9.56).

CONCLUSION

The study showed that the consumption of salt among the Iranian population is higher than the level recommended by WHO. To reduce salt intake, it is necessary to adopt a combination of nationwide policies such as food reformulation and food labelling.

N-acetyl-l-cysteine exacerbates kidney dysfunction caused by a chronic high-sodium diet in renal ischemia and reperfusion rats

AIMS

To investigate the effect of long-term N-acetyl-l-cysteine (NAC) treatment in Wistar rats subjected to renal ischemia and reperfusion (IR) and a chronic high‑sodium diet (HSD).

MAIN METHODS

Adult male Wistar rats received an HSD (8.0% NaCl) or a normal‑sodium diet (NSD; 1.3% NaCl) and NAC (600 mg/L) or normal drinking water starting at 8 weeks of age. At 11 weeks of age, the rats from both diet and NAC or water treatment groups underwent renal IR or Sham surgery and were followed for 10 weeks. The study consisted of six animal groups: NSD + Sham + water; NSD + IR + water; NSD + IR + NAC; HSD + Sham + water; HSD + IR + water; and HSD + IR + NAC.

KEY FINDINGS

Tail blood pressure (tBP) increased with IR and NAC treatment in the NSD group but not in the HSD group. The serum creatinine level was higher after NAC treatment in both diet groups, and creatinine clearance was decreased in only the HSD + IR + NAC group. Albuminuria increased in the HSD + IR + water group and decreased in the HSD + IR + NAC group. Kidney mass was increased in the HSD + IR group and decreased with NAC treatment. Renal fibrosis was prevented with NAC treatment and cardiac fibrosis was decreased with NAC treatment in the HSD + IR group.

SIGNIFICANCE

NAC treatment promoted structural improvements, such as decreased albuminuria and fibrosis, in the kidney and heart. However, NAC could not recover kidney function or blood pressure from the effects of IR associated with an HSD. Therefore, in general, long-term NAC treatment is not effective and is deleterious to recovery of function after kidney injury.

HIV, immune activation and salt-sensitive hypertension (HISH): a research proposal

OBJECTIVE

The objective of this study is to quantify and compare the effect of excess dietary salt on immune cell activation and blood pressure in HIV versus HIV negative individuals.

RESULTS

Salt-sensitivity is associated with increased immune cell activation in animal studies. This concept has not been tested in people living with HIV. This study will therefore add more information in elucidating the interaction between HIV infection and/or anti-retroviral therapy (ART), immune-activation/inflammation and hypertension.

Paucity of high-quality studies reporting on salt and health outcomes from the science of salt: A regularly updated systematic review of salt and health outcomes (April 2017 to March 2018)

The purpose of this review is to identify, summarize, and critically appraise studies on dietary salt and health outcomes that were published from April 2017 to March 2018. The search strategy was adapted from a previous systematic review on dietary salt and health. Identified studies were screened based on a priori defined criteria to identify publications eligible for detailed critical appraisals. Overall, 6747 citations were identified by the search strategy, and 42 health outcome studies were identified. Three of the 42 studies met the criteria for methodological quality and health outcomes and underwent detailed critical appraisals and commentary. In addition, a systematic review and meta-analysis was critically appraised, although it did not strictly meet our methodological criteria. All four of the studies critically appraised found that sodium reduction improved blood pressure, especially in individuals with hypertension. In addition, sodium reduction reduced albuminuria in patients with stage 1-3 chronic kidney disease. Examination of the time course of blood pressure responses to sodium reduction revealed lowering sodium in the context of an average American diet may not produce maximal blood pressure reductions within a 4-week intervention period. This review provides further evidence of the benefit of sodium reduction for blood pressure lowering and gives insights into the subgroups of the population that may derive the greatest benefit from sodium reduction and the time course required to see benefit. Only three high-quality studies were identified during this 12-month review period, highlighting the critical need for more well-conducted rigorous studies in this area.

Low potassium and high sodium intakes: a double health threat to Cape Verdeans

BACKGROUND

Cape Verde presents a high rate of cardiovascular diseases. Low potassium and high sodium intakes are related to cardiovascular diseases. However, studies regarding these two micronutrients continue to be rare in African urban settings. This work aims to estimate potassium and sodium intakes and to analyse the self-reported salt intake by gender and by type of urban area in the city of Praia - the capital of Cape Verde.

METHODS

In the first stage (n = 1912), an intra-urban study was designed in two types of urban areas (formal and informal), using a sampling strategy based on random selection of geographical coordinates, in order to apply a questionnaire. In a second stage, a 24-h dietary recall and anthropometric measurements were performed by local nutritionists. Potassium and sodium intakes were estimated for 599 participants (149 men and 450 women). Non-parametric methods (including quantile regression) were used in the statistical analysis.

RESULTS

In informal areas, a higher percentage of women reported having hypertension (31.0%) compared to formal areas (19.7%). Based on 24-h dietary recall, median potassium intake for men was 2924.2 mg/day and for women and 2562.6 mg/day. Almost 70.0% of men and 80.0% of women ingested less than the recommended 3510 mg/day of potassium. In informal areas, men and women presented high medians of sodium intakes compared to formal areas (men: 4131.2 vs 3014.6 mg/day and women: 3243.4 vs 2522.4 mg/day). On the other hand, the percentage of participants exceeding 2000 mg/day for sodium was high (≥70.8%), even for participants that self-reported low-salt intake. Quantile regression models revealed effects of the type of urban area and gender in the potassium and sodium intakes, at least, in some quartiles, accounting for age, academic qualifications, and professional situation.

CONCLUSIONS

A low potassium intake and a high sodium intake were found in Praia. Thus, efficient health education campaigns and health promotion are needed and should be tailored considering gender and urban areas.

How will South Africa's mandatory salt reduction policy affect its salt iodisation programme? A cross-sectional analysis from the WHO-SAGE Wave 2 Salt & Tobacco study

OBJECTIVE

The WHO's global targets for non-communicable disease reduction recommend consumption of<5 g salt/day. In 2016, South Africa was the first country to legislate maximum salt levels in processed foods. South Africa's salt iodisation fortification programme has successfully addressed iodine deficiency but information is dated. Simultaneous monitoring of sodium reduction and iodine status is required to ensure compatibility of the two public health interventions.

DESIGN/SETTING/PARTICIPANTS

A nested cohort design within WHO's 2015 Study on global AGEing and adult health (n=2887) including individuals from households across South Africa. Randomly selected adults (n=875) provided 24-hour and spot urine samples for sodium and iodine concentration analysis (the primary and secondary outcome measures, respectively). Median 24-hour urinary iodine excretion (UIE) and spot urinary iodine concentrations (UIC) were compared by salt intakes of <5g/day, 5-9g/dayand >9 g/day.

RESULTS

Median daily sodium excretion was equivalent to 6.3 g salt/day (range 1-43 g/day); 35% had urinary sodium excretion values within the desirable range (<5 g salt/day), 37% had high values (5-9 g salt/day) and 28% had very high values (>9 g salt/day). Median UIC was 130 µg/L (IQR=58-202), indicating population iodine sufficiency (≥100 µg/L). Both UIC and UIE differed across salt intake categories (p<0.001) and were positively correlated with estimated salt intake (r=0.166 and 0.552, respectively; both p<0.001). Participants with salt intakes of <5 g/day were not meeting the Estimated Average Requirement for iodine intake (95 µg/day).

CONCLUSIONS

In a nationally representative sample of South African adults, the association between indicators of population iodine status (UIC and UIE) and salt intake, estimated using 24-hour urinary sodium excretion, indicate that low salt intakes may compromise adequacy of iodine intakes in a country with mandatory iodisation of table salt. The iodine status of populations undergoing salt reduction strategies needs to be closely monitored to prevent re-emergence of iodine deficiency.

Alteration of serum immunoglobins, C-reactive protein, vitamin D, and electrolyte by atenolol and amlodipine in stress-induced hypertensive rats

The present study is designed for the assessment of various pathological changes like immunoglobins, C-reactive protein, vitamin D, sodium, potassium, calcium in stress-induced hypertensive rats. Albino Wistar rats of sex male were grouped into six. Each group consists of six animals. Groups were Group I (normal control), Group II (disease control), Group III (amlodipine control), Group IV (atenolol control), Group V (amlodipine treatment), and Group VI (atenolol treatment). Group II, V, and VI animals exposed to regular stress by placing them in cages individually and giving foot electric shocks (1 mA, 50 ms duration with 0.5-1 min of intervals regulated randomly by a computer) along with forced swimming (30 min) in order to induce hypertension in rats. This stress was given two times daily (morning and evening) for regular 15 days. Induction of hypertension was confirmed by measuring the tail arterial pressure of blood and angiotensin II. For next 1 month, Group III and V animals are treated with amlodipine with 1 mg/kg, s.c. dose while Group IV and VI animals were given 10 mg/kg, s.c. the dose of atenolol once daily. At the end of the experimental work, blood collected, rats sacrificed, and serum separated. Serum sodium, potassium, immunoglobins, C-reactive protein, vitamin D, and calcium were measured by semi-auto-analyzer. Stress-induced hypertension in rats produced altered serum sodium, potassium, immunoglobins, C-reactive protein, vitamin D, and calcium level which is restored by atenolol. Administration of amlodipine in animals without hypertension shows alteration in the level of immunoglobins, calcium, vitamin D, and electrolytes.