| [Background]Low-sodium and high-potassium salt substitute, also known as low-sodium salt, salt substitute, is based on iodized salts and added a certain amount of potassium chloride and magnesium sulfate. Thereby it can improve the body equilibrium state of sodium (Na+), potassium (K+) and magnesium (Mg2+). The main compositions of commercial low-sodium salt are65%sodium chloride,25%potassium chloride,9%8-hydrated magnesium sulfate and a little of calcium.Hypertension is a sustained increase in systemic arterial blood pressure. It is a common clinical syndrome in adults. It usually can be estimated by the systolic blood pressure≥140mmHg and (or) the diastolic blood pressure≥90mmHg. Hypertension and related diseases are a global public health problem; its prevalence rises year by year.Hypertension and related diseases are a global public health problem, the occurrence of about54%of stroke and47%of ischemic heart disease is associated with hypertension. Hypertension is an independent disease, it is also an important risk factor for cardiovascular and cerebrovascular diseases. It has brought a heavy burden of disease to the whole society.A number of epidemiological studies have shown that salt intake was positively associated with blood pressure levels, and reducing the intake of salt is an effective method to control the blood pressure by changing lifestyle.Compared with the dietary habits in China, the intake of sodium is mainly from processed foods in developed countries. So their many studies are about the relationship among reducing sodium, increasing potassium and blood pressure. The policy is tending to reduce the salt of processed foods, implement food label about salt, which is used for reducing the intake of sodium. And ultimately control the incidence of hypertension.However, in China the intake of sodium comes mainly from cooking salt, and the quantity is higher than the other countries. There are geographical differences. Generally, the North is more than the South in intake of salt. Shandong is the largest province of production of salt. Meanwhile, it is the largest province of consumption of salt. In2002National Nutrition and Health Survey showed that residents in Shandong Province, the average daily-salt-intake of cook is up to13.1grams, more than2times as many as Chinese dietary guidelines recommended, and the prevalence of adult high blood pressure (29.2%) is higher than the national average of18.8%.Many studies of low-sodium, based on small samples, special populations or special conditions, have proven its ability to reduce blood pressure. However, large population-based studies of low sodium salt are few; especially field studies which take the family as the observed unit and do not interfere with their normal eating habits are scarce.Shandong Province will start the projects of prevention and control of hypertension in2011by reducing intake of salt. On this basis, it is necessary to evaluate the effect of low sodium salt on blood pressure and compared with the effect of health education. It is also more objective and comprehensive to explore an effective non-medical method to prevent and control the high blood pressure. Therefore, to carry out this low-sodium study on the blood pressure is consistent with the reality and research requirements.[Objectives]The major purpose of this study as follow:(1) To investigate the effect of low-sodium salt and health education on blood pressure in the rural community-based population.(2) To evaluate the difference of the two measures on blood pressure in rural community-based population.(3) To understand the change of the rural community-based population’s relevant knowledge, attitude and behavior of low sodium-salt and low-salt diet.(4) To investigate the tast of low sodium salt and the willingness to buy the low sodium salt in rural community.[Methods]This study used the epidemiology quasi-experimental design. Two villages which had similar socio-economic level and the populations were about2,000people were selected as the research sites in Laicheng district of Laiwu. Subjects aged from30to60, choose from the families. Referring to the "Chinese Hypertension Prevention Guide", that is, twice every other day for blood pressure measurement, the average systolic blood pressure (SBP)≥140mmHg and (or) the average diastolic blood pressure (DBP)≥90mmHg can be diagnosed as hypertension combined with the status of taking medicine.The subjects were divided into2groups:high blood pressure (HBP) and non-HBP (NHBP) according to inclusion and exclusion criteria.Firstly all the common salt of the family of subjects was collected, then, both groups and their family members took a low-sodium salt for3months to replace the normal salt in their bodies. Each family was given the low-sodium salt monthly and enough. We did not interfere with the dosage of low-sodium salt during the research.Contents of baseline/end-stage investigation:(1) General state, health status, and relevant KAP of salt and HBP;(2) Physical examination (PE):BP was measured through mercury-column-sphygmomanometer;(3) Laboratory examination:sodium and potassium in urine were examined in laboratory up to24hr.Besides, BP was measured at the first month and second month after intervention. Through self-control, we investigate the effect of low-sodium salt on blood pressure in the rural community-based population and the changes of KAP about low-salt diet and HBP.One year after the end of the combined intervention, all the subjects were followed up again.Contents of the follow-up:(1) Physical examination (PE):BP was measured through mercury-column-sphygmomanometer;(2) Laboratory examination:sodium and potassium in urine were examined in laboratory up to24hr.[Results]1General state of subjectsThere were411persons selected as subjects, including195from HBP group and216from NHBP group The average age was47.3years old (SD=6.7),47.6(SD=6.2)for HBP group and46.9(SD=7.1). The male subjects were221,51.1%of the whole subjects,115(54.8%) of the HBP group subjects and95(45.2%) of the HBP group subjects.2Changes of blood pressure2.1The changes of BP after3monthesThere was a continuously decreasing trend for BP at first month. Three months later, the mean BP decreased by7.4mmHg (1mmHg=0.133kPa, t=10.096, P=0.000) for SBP and3.8mmHg (t=0.817, P=0.000) for DBP in the HBP group, when compared to a1.2mmHg (t=2.507, P=0.007) decrease on SBP and1.0mmHg (t=2.987, P=0.002) on DBP in the NHBP group.The SBP of the two groups decreased largest on the second month,11.6mmHg in the HBP group and6.5mmHg in the NHBP group; however, the DBP decreased largest at the first month, about5.9mmHg in the HBP group and3.9mmHg in the NHBP group.2.2Changes in BP at the end of one year after interventionBesides a significantly decreasing for SBP in HBP group (P<0.05), the SBP and DBP did not have a significantly change in the two groups (P>0.05), compared with the baseline data. In the NHBP group, there was not a significantly change for SBP (P>0.05), but there was significantly change for SBP and DBP in the two groups (P<0.05), compared with the final survey data.3The changes of urinary sodium and potassium3.1Urine sodium and potassium after3monthesThe mean urinary sodium had a decrease of15.5mmol/24h (t=1.803, P=0.037), but urinary potassium increased by4.2mmol/24h (t’=2.132, P=0.018). The result of urinary sodium:potassium ratio potassium (Na+/K+) decreased by1.2(t=2.786, P=0.003) in the HBP group. However, in NHBP group, the mean urinary sodium decreased by1.7mmol/24h (t=0.211, P=0.417) and urinary potassium increased by3.7mmol/24h (t’=2.207, P=0.015), together with the decrease of Na+/K+by0.7(t=1.818, P=0.036).3.2Changes in urine sodium and potassium at the end of one year after interventionCompared with the baseline and final survey data, there was not a significantly change in the urinary sodium (P>0.05). The urinary potassium did not have a significantly change compared with the final survey (P>0.05), but it increased significantly compared with baseline data (P<0.05). The urinary sodium:potassium (Na+/K+) decreased significantly compared with the baseline and final survey data (P<0.05).4The changes of KAPCompared with the baseline, there were significant increase in health awareness and attitude of low-salt diet and hypertension-related knowledge (P<0.05) after three months.5Taste and acceptance of low-sodium215(54.4%) subjects thought that the low sodium salt is a lighter taste than the common salt. About354(89.6%) subjects wanted to continue to buy the low sodium salt if they could have the opportunity to purchase it. [Conclusion]After using low-sodium salt and health education, the mean intake of sodium had reduced while the intake of potassium increased in the subjects. Na+/K+had been improved better. For the person with hypertension, the effect of decrease on blood pressure is significantly, meanwhile for the normal person. It can prevent and control the blood pressure.The health education can increase the intake of potassium and improve the Na+/K+of rural residents.The effect of falling of blood pressure, produced by the low sodium salt, is better than it produced by the health education.The awareness about salt and hypertension of the subject is low and the intake of salt is more than the other place in the rural residents.Health education can significantly improve the KAP about salt and hypertension in rural residents.The acceptance of low sodium salt is well. The rural residents have a high willingness to buy it. The low sodium salt has a good value of marketing.[Suggestions]1. To further strengthen epidemiological investigations and studies of low-sodium salt on blood pressure in Shandong province, particularly in the larger region and long time, observing the possible adverse reactions, to provide theoretical basis for the development of prevention and interventions planning.2. To strengthen the study of salt-sensitive hypertension research, to explain the relationship between sodium and hypertension on molecular level.3. To further survey the market of low-sodium salt, to evaluate the willingness of buying of low-sodium salt.4. Strengthen the education of low-salt diet and raise the public awareness for decreasing the intake of sodium, at last, to reduce the incidence of hypertension.5. Base on the research findings above, to develop particular plan of the projects of prevention and control of hypertension in Shandong Province ", the plan should include general health education for normal populations and specific intervention for special populations. |
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