The relationship of salt intake and arterial blood pressure in salted-tea drinking Kashmiris

Hypertension status and its risk factors in highlanders living in Ganzi Tibetan Plateau: a cross-sectional study

BACKGROUND

The updated status of hypertension and its risk factors are poorly evaluated in Tibetan highland areas. We initiated a large-scale cross-sectional survey to provide updated status of hypertension and its risk factors (especially salt intake) in the Ganzi Tibetan Plateau, China.

METHODS

Stratified multistage random sampling was performed to obtain a representative sample of 4,036 adult residents from 4 counties in the Ganzi Tibetan area. The whole survey population was used to present the epidemiology and risk factors of hypertension. The participants with blood and urine biochemistry data were used to analyze the relationship between salt intake parameters and hypertension.

RESULTS

Stratified multistage random sampling was performed to obtain a representative sample of 4,036 adult residents. The overall prevalence rate of hypertension was 33.5% (the age-adjusted prevalence rate was 28.9%). A total of 50.9% of the hypertensive patients knew their conditions; 30.1% of them received antihypertensive treatment; and 11.2% of them had their blood pressure controlled. Age, male sex, living altitude ≥ 3500 m, overweight and abdominal obesity were positively correlated with hypertension. In addition, the adjusted odds ratio (OR) for hypertension was 1.33 (95% CI: 1.01-1.74) for drinking tea with salt, and 1.51 (95% CI: 1.32-1.72) for per SD increase in the estimation of 24-hour urinary sodium excretion (e24hUSE). Furthermore, per 100mmol/day increase in e24hUSE was associated with elevation of blood pressure (+ 10.16, 95% CI: 8.45-11.87 mmHg for SBP; +3.83, 95% CI: 2.74-4.93 mmHg for DBP) in this population.

CONCLUSIONS

Our survey suggests a heavy disease burden of hypertension in the Ganzi Tibetan Plateau. Age, male sex, altitude of residence ≥ 3500 m, overweight, abdominal obesity, and excessive salt intake (shown as drinking tea with adding salt and a higher level of e24hUSE) all increased the risk of hypertension in this highland area.

Sources of Dietary Salt in North and South India Estimated from 24 Hour Dietary Recall

Recent data on salt intake levels in India show consumption is around 11 g per day, higher than the World Health Organization's (WHO) recommended intake of 5 g per day. However, high-quality data on sources of salt in diets to inform a salt reduction strategy are mostly absent. A cross-sectional survey of 1283 participants was undertaken in rural, urban, and slum areas in North (n = 526) and South (n = 757) India using an age-, area-, and sex-stratified sampling strategy. Data from two 24-h dietary recall surveys were transcribed into a purpose-built nutrient database. Weighted salt intake was estimated from the average of the two recall surveys, and major contributors to salt intake were identified. Added salt contributed the most to total salt intake, with proportions of 87.7% in South India and 83.5% in North India (p < 0.001). The main food sources of salt in the south were from meat, poultry, and eggs (6.3%), followed by dairy and dairy products (2.6%), and fish and seafood (1.6%). In the north, the main sources were dairy and dairy products (6.4%), followed by bread and bakery products (3.3%), and fruits and vegetables (2.1%). Salt intake in India is high, and this research confirms it comes mainly from added salt. Urgent action is needed to implement a program to achieve the WHO salt reduction target of a 30% reduction by 2025. The data here suggest the focus needs to be on changing consumer behavior combined with low sodium, salt substitution.

Mean population salt consumption in India: a systematic review

BACKGROUND

Member states of the WHO, including India, have adopted a target 30% reduction in mean population salt consumption by 2025 to prevent noncommunicable diseases. Our aim was to support this initiative by summarizing existing data that describe mean salt consumption in India.

METHOD

Electronic databases - MEDLINE via Ovid, EMBASE, CINAHL and the Cochrane Database of Systematic Reviews - were searched up to November 2015 for studies that reported mean or median dietary salt intake in Indian adults aged 19 years and older. Random effects meta-analysis was used to obtain summary estimates of salt intake.

RESULTS

Of 1201 abstracts identified, 90 were reviewed in full text and 21 were included: 18 cross-sectional surveys (n = 225 024), two randomized trials (n = 255) and one case-control study (n = 270). Data were collected between 1986 and 2014, and reported mean salt consumption levels were between 5.22 and 42.30 g/day. With an extreme outlier excluded, overall mean weighted salt intake was 10.98 g/day (95% confidence interval 8.57-13.40). There was significant heterogeneity between the estimates for contributing studies (I = 99.97%) (P homogeneity ≤0.001), which was likely attributable to the different measurement methods used and the different populations studied. There was no evidence of a change in intake over time (P trend = 0.08).

CONCLUSION

The available data leave some uncertainty about exact mean salt consumption in India but there is little doubt that population salt consumption far exceeds the WHO-recommended maximum of 5 g per person per day.

Protocol for developing the evidence base for a national salt reduction programme for India

INTRODUCTION

The scientific evidence base in support of salt reduction is strong but the data required to translate these insights into reduced population salt intake are mostly absent. The aim of this research project is to develop the evidence base required to formulate and implement a national salt reduction programme for India.

METHODS AND ANALYSIS

The research will comprise three components: a stakeholder analysis involving government, industry, consumers and civil society organisations; a population survey using an age-stratified and sex-stratified random samples drawn from urban (slum and non-slum) and rural areas of North and South India; and a systematic quantitative evaluation of the nutritional components of processed and restaurant foods. The stakeholder interviews will be analysed using qualitative methods to summarise the main themes and define the broad range of factors influencing the food environment in India. The population survey will estimate the mean daily salt consumption through the collection of 24 h urine samples with concurrent dietary surveys identifying the main sources of dietary sodium/salt. The survey of foods will record the nutritional composition of the chief elements of food supply. The findings from this research will be synthesised and proposals for a national salt reduction strategy for India will be developed in collaboration with key stakeholders.

ETHICS AND DISSEMINATION

This study has been approved by the Human Research Ethics Committees of the University of Sydney and the Centre for Chronic Disease Control in New Delhi, and also by the Indian Health Ministry's Screening Committee. The project began fieldwork in February 2014 and will report the main results in 2016. The findings will be targeted primarily at public health policymakers and advocates, but will be disseminated widely through other mechanisms including conference presentations and peer-reviewed publications, as well as to the participating communities.

Potential roles of high salt intake and maternal malnutrition in the development of hypertension in disadvantaged populations

1. It has been argued that all major risk factors for cardiovascular disease have been identified. Yet, epidemiological studies undertaken to identify risk factors have largely focused on populations in developed nations or on the urban or relatively affluent rural populations of developing countries. Poor rural populations are seldom studied. 2. Somewhat different risk factors may operate in poor rural populations. Evidence for this is provided by the finding that, in disadvantaged rural India, the prevalence of hypertension is greater than would be expected based on established risk factors in these populations. One risk factor to be considered is a poor intrauterine environment. 3. In animals, maternal macro- and micronutrient malnutrition can lead to reduced nephron endowment. Nephron deficiency, in turn, can render blood pressure salt sensitive. The combination of nephron deficiency and excessive salt intake will predispose to hypertension. 4. Human malnutrition may have similar effects, particularly in regions of the world where malnutrition is endemic and where women are disadvantaged by existing social practices. 5. Moreover, high salt intake is endemic in many parts of Asia, including India. Therefore, we propose that maternal malnutrition (leading to reduced nephron endowment), when combined with excessive salt intake postnatally, will account, at least in part, for the unexpectedly high prevalence of hypertension in disadvantaged rural communities in India and elsewhere.

Environmental and occupational determinants of blood pressure in rural communities in China

PURPOSE

To identify and characterize major environmental and occupational determinants of blood pressure in rural communities in China.

METHODS

In 1993 we conducted a large cross-sectional, community-based study of 20,216 residents aged 15 years or older, from the Yijing area of Anhui Province (8022 men, 12,194 women), one of whom were receiving treatment for hypertension. The mean systolic blood pressure was 116.7 +/- 19.5 mmHg for men and 113.2 +/- 19.4 mmHg for women.

RESULTS

The mean diastolic blood pressure was 72.4 +/- 12.1 mmHg for men and 70.4 +/- 11.6 mmHg for women. Age and body mass index were the two most important determinants of blood pressure in this population. With controls for age and body mass index, height and weight remained significant predictors of blood pressure. Multiple linear regression analysis indicated that alcohol consumption, self-reported exposure to noise, drinking of tap water and pond water, occupational exposure to dust/fumes/gases, rice consumption, inferior housing, household crowdedness, and being unmarried were related to increased blood pressure levels. Vegetable intake, frequent consumption of meat at meals, high level of physical activity, exposure to straw-combustion smoke, and pesticide use were negatively associated with blood pressure.

CONCLUSIONS

Our study demonstrated that a broad array of demographic, ergonomic, nutritional, and environmental factors are critical determinants of blood pressure in this rural Chinese population.

Hypertension and determinants of blood pressure with special reference to socioeconomic status in a rural south Indian community

OBJECTIVES

The objective of the study was to establish the prevalence of hypertension and to assess determinants of blood pressure with special reference to socioeconomic status in a rural south Indian community.

DESIGN

This was a door to door, cross sectional survey.

SETTING

A rural south Indian community, KV Kuppam panchayat, North Arcot District, Tamil Nadu.

SUBJECTS

The area has a total population of 3500 people. Those aged over 20 years who were available at the time of measurement were asked to participate (mean age 39.5 years). This convenience sample totalled 1027 (456 men, 571 women). Out of 697 families, 487 were visited; 15 people refused to participate.

MEASUREMENTS AND MAIN RESULTS

The following potential determinants of blood pressure were assessed: age, body weight, pulse rate, salt intake, meat intake, and socioeconomic class. The prevalence of hypertension was 12.5%. Using multiple linear regression analysis, the most important positive determinants of high blood pressure seemed to be age, body weight, and pulse rate. Salt and meat intake were not significantly associated with hypertension. The prevalence of hypertension in the highest socioeconomic group (22.5%) was more than twice that in the lowest socioeconomic group (8.8%). When adjusted for body weight, the mean (SEM) difference in systolic blood pressure between the highest and lowest socioeconomic classes was 5.83 mmHg (1.63).

CONCLUSION

Hypertension is not yet as important a health problem in rural southern India as it is in westernised societies. Those particularly at risk of hypertension, however, are the elderly and overweight people of high socioeconomic class.