Table 1.
Characteristics of included studies and results
| First author (Year) Country |
Study design | Participants | Intervention description | Study duration | Study findings |
|---|---|---|---|---|---|
| Health education | |||||
| Ferrara (2012) [36] Italy |
RCT | Risk group—hypertensive patients from an outpatient clinic (I: 94, C: 94) | Patients were educated by doctors and dietitians on the link between salt intake and hypertension, importance of salt reduction and how to reduce salt intake. Delivery setting: clinic |
1 year | Overall, significant net reduction in salt intake by 1.85 g/d (p < 0.001). I: reduction in salt intake from 7.18 g/d (SD 2.42 g/d) to 5.06 g/d (SD 1.75 g/d) after 1 year (p < 0.001). C: reduction in salt intake from 6.58 g/d (SD 2.26 g/d) to 6.31 g/d (SD 2.03 g/d) (p = 0.03). |
| Cotter (2013) [31] Portugal |
RCT (2 intervention groups, 1 control) | General population—school children in their 5th and 6th years of education (I_Practical: 53, I_Theory: 43, C: 31) | Practical group: lecture on the potential dangers of salt intake and school gardening to grow herbs as substitutes of salt in food preparation. Theory group: lectures on the danger of salt intake. Delivery setting: school |
6 months | No significant differences between the 3 groups (practical, theory and control). I_Practical: significant reduction in salt intake by 1.1 g/d (SD 2.5 g/d) pre post intervention. I_Theory: non-significant reduction in salt intake by 0.6 g/d (SD 3.2 g/d). C: non-significant reduction in salt intake by 0.4 g/d (SD 2.4 g/d). |
| Veroff (2012) [23] United States |
RCT | Risk group—adults with heart failure (I: 246, C: 234) | Participants were mailed education materials and medical decision aid (evidence-based DVD and booklet) to help manage heart failure. Delivery setting: community |
4 weeks | No significant difference in the percentage of participants that reported following a low-sodium diet every day or most days between groups. I: 83%. C: 77%. |
| Cappuccio (2006) [33] Ghana |
Community cluster RCT | General population—aged 40–75 (I: 399, C: 402) | Sessions led by community health workers on not adding salt to food and in cooking, salty foods to limit, low salt cooking practices (open to all in community). Delivery setting: community |
6 months | No significant change in salt intake between intervention and control group. I: reduction in salt intake by 0.52 g/d from baseline to follow up. C: reduction in salt intake by 0.84 g/d. |
| Lin (2013) [24], Svetkey (2009) [56] United States |
Nested 2x2 RCT [Only included patient intervention] | Risk group—hypertensive patients (I: 256, C: 269) | Behavioural interventionists delivered education to reduce salt intake through promoting self-monitoring, goal setting and motivational interviewing techniques. Delivery setting: clinic |
18 months | No significant difference in 24- h urinary sodium excretion between groups at 6 months. Salt intake based on FFQ showed that intervention patients significantly decreased intakes compared to controls (p < 0.05). |
| Chen (2008) [15] China | Non-randomised CT | General population—110,000 workplace employees | Education and promotion on reducing salt intake and health professional training. Delivery setting: workplace |
6 years | Significant net reduction of 3.9 g/d (p < 0.05). I: reduction in salt intake from 16 to 10.6 g/d from baseline in 1987 to follow up in 1995. C: reduction in salt intake from 16.9 to 15.5 g/d. |
| Kitaoka (2013) [28] Japan | Non-randomised CT | Risk group—men aged 40–75 years with SBP of 130–180 mmHg and DBP of 85–110 mmHg (I: 38, C: 26) | Dietitian led lectures on diet for reducing BP, self-monitoring and cooking instructions on how to prepare low salt meals and measure seasoning. Delivery setting: community |
5 months | Based on spot urine, I: salt intake decreased from 12.3 g/d at baseline to 10.6 g/d at follow-up (p = 0.025). C: salt intake decreased from 15.5 g/d to 13.3 g/d (p = 0.014). Based on FFQ, intervention patients significantly reduced consumption of preserved vegetables compared to control (p = 0.039). Based on dietary habits questionnaire, intervention group significantly reduced consumption of noodle soup compared to control. |
| Ireland (2010) [26] Australia |
Parallel group RT (2 treatment groups) | Population—healthy adults (I_FSANZ: 21 I_Tick: 22) |
Nutritionist educated groups to choose low-salt foods using the Tick symbol or the FSANZ guideline of <120 mg/100 g sodium. Both groups were also provided with a list of low-sodium foods. Delivery setting: community |
8 weeks | I_FSANZ: significant reduction in salt intake by 1.99 g/d based on 24- h urine at week 8 (p < 0.05). Also significant reduction by 3.27 g/d of salt based on multiple 24- h diet recall (p = 0.003). I_Tick: significant reduction in salt intake based on 24-h urine by 0.88 g/d at week 8 (p < 0.05). Non-significant reduction in salt intake based on multiple 24 h diet. |
| Lu (2015) [17] China |
Parallel group RT (3 treatment groups) | Risk group—hypertensive patients (Group 1: 116, Group 2: 114, Group 3: 117) | Group 1: reading materials for self-learning. Group 2: lectures on hypertension. Group 3: interactive workshop using visual health education tools such as animation, food models, salt spoons, and CVD models. Delivery setting: community |
2 years | Based on monthly salt weighing, all three groups demonstrated significant increases in the number of people with salt intake <6 g/d between baseline and post-intervention, but it was progressively greater from group 1 (self-learning) to group 2 (regular lecture) and group 3 (interactive education). |
| Resnick (2014) [25] USA | Before and after study | Population—29 low income residents living in the senior housing facility | Nurses led lectures on heart healthy diets and medication adherence. Remaining 11 weeks included provision of health tips to avoid high salt foods led by a lay trainer. Delivery setting: community |
3 months | Significant reduction in mean salt intake from 13.49 g/d (SE 1.58) at baseline to 9.08 g/d (SE 1.30) post intervention (p = 0.01) based on FFQs. |
| White (2013) [27] Australia |
Before and after pilot study (Mixed methods) | Risk group—21 patients with diagnosis of stroke in community | A multi-professional community based team led education session on various topics such as stroke risk factors, nutrition and diet. Delivery setting: community |
1 year | Statistically significant reduction in salt intake from 10.62 g/d (SD 2.62 g/d) in baseline to 8.62 g/d (SD 2.36 g/d) in the post program based on questionnaires (p = 0.01). At 3 months follow-up, mean salt intake of 8.6 g/d (SD 1.68 g/d) was sustained. |
| Bogle (2008) [19] UK | Before and after study | Population—African-Caribbean, Black African, Asian, Irish and Turkish ethnic groups (Shop tours: 23; Cook and eat sessions: 37) | “Cook and Eat” programmes and grocery shopping tours were delivered by dietitians/nutritionists to provide advice on risks of high salt intake, cooking low-salt meals and low-salt practices interpreting food labels. Delivery setting: community |
4 weeks | Self-reported behaviour about adding salt in cooking significantly decreased (p = 0.04). Significant increase in participants checking sodium label of foods when shopping. At 3 months post intervention, 65% reported reducing salt by ‘a lot’ in their diet and 21.6% ‘somewhat’ reduced salt intake. |
| Chen (2013) [16] China | RCT | Population—adults responsible for home cooking (I: 141, C: 107) | Education about the amount of salt that should be eaten, provision of a salt-restriction spoon and how to correctly use the salt restriction spoon. Delivery setting: community |
7 months | No significant difference in salt intake between intervention and control group based on 24-h urine. Based on salt weighing after 6 months, there was a significant difference between groups by time, with 1.42 g/d reduction in intervention compared to 0.28 g/d in control group (p = 0.041). |
| Fujii (2009) [29] Japan |
Before and after study | Population—185 workplace employees | Participants were provided lifestyle advice (including advice to reduce salt) through a computer-based lifestyle modification support tool. Delivery setting: workplace |
4 months | Significant increase in the proportion of women practicing low salt intake behaviours post intervention (63.3 to 75%, p = 0.039). No significant increase in men practicing low salt intake behaviours. |
| Public awareness campaigns | |||||
| Papadakis (2010) [32] Canada | Before and after controlled trial | Population—adults aged 35–50 living in Champlain District of Ontario (I: 1565, C: 1565) |
Bilingual mass media campaign to reduce consumption of high sodium processed foods delivered through TV, radio, print and web advertisements, and 100 editorial stories. Delivery setting: community |
2 years | At 6 months there was a significant reduction in salt added to foods in the intervention community compared to control. Intervention participants at follow-up were 1.27 (95% CI:1.09,1.49) times more likely to check nutrition labels for sodium content in foods compared to baseline. |
| Wyness (2012) [20], Millett (2012) [38], He (2014) [54] UK |
Serial cross sectional survey | Population—United Kingdom (2000 nationally representative adults) | Mass media campaign involved TV, radio, press, poster ads, leaflets and other materials to raise awareness, highlight 6 g/d target and provide tips to reduce salt. Delivery setting: national |
6 years | Increase in proportion of adults self-reporting efforts to reduce salt in their diet from 34% in 2004 to 43% in 2009. Increase in adults checking food labels to find salt content from 29% in 2004 to 50% in 2009. |
| Safefood (2006) [35] Ireland | Before and after study | Population—adults aged 15–74 years in Ireland (Billboard: 172, radio ad: 235) | ‘Already Salted’ campaign on billboard and radio advertisement to raise awareness about level of salt in foods and provide tips on how to reduce salt intake. Delivery setting: national |
6 weeks | Amongst adults who saw the billboard campaign, there was an increase in the proportion reporting that they had changed their salt behaviour (to 37%) from 2003 to 2006. Amongst adults who heard the radio ad, there was an increase in the proportion reporting that they had changed salt behaviour (to 25%) from 2003 to 2005. |
| Martins (2009) [30] Portugal | Before and after study | Population—Portugal | Public education on the harmful consequences of salt and hypertension using mass media (TV, newspapers, radio). Delivery setting: national |
- | Increase in the proportion of adults who reported that they had changed their salt intake (to 44%) and substantially reduced their salt intake (to 25%) from 2007. |
| Multi-component education | |||||
| Zhang (2014) [18] China | Cross sectional study (with intervention vs control counties) | Population—nationally representative sample of residents in provinces and counties in China (I: 17684, C: 13115) | Public awareness campaigns and multisector approach involving health professionals, employers, schools and community organizations to distribute health educational messages through a wide range of channels. Delivery setting: community |
8 years | People living in the intervention counties were 2.16 (95%CI 1.50, 3.12) (unadjusted)/1.98 (95% CI 1.41, 2.76) (adjusted) times more likely to report having reduced salt consumption than people in the control counties. |
| Khosravi (2012) [34] Iran |
Serial cross sectional survey | Population—representative sample of normotensive Iranian adults (Before: 374, After: 806) | Communities received education through mass media and face-to-face education programs by health workers, and educational materials provided in schools and workplaces. Delivery setting: community |
6 years | Statistically significant reduction in salt intake from 12.52 g/d in 2001–02 to 10.66 g/d in 2007 (p < 0.01) based on 24 h urine collection. |
| Drummond (2008) [21] UK | Before and after study | Population—South Asian and Caribbean communities (Before: 100, After: 66) | Distribution of materials to the public including flyers, leaflets and booklet in combination with education sessions on how to read salt content in labels and how it relates to max daily amount, effects of salt on health, practical ways to reduce salt and cook and taste sessions. Delivery setting: community | 1 year | Between baseline and post intervention, there was an increase in the proportion of people who claimed to ‘always’ check the label for salt content of food products when shopping from 12 to 28% and to ‘always’ choose lower salt options when buying food from 23 to 43%. There was also a decrease in those who claimed to ‘always’ add salt to food at the table from 11 to 5%. |
| Surpluss (2008) [22] UK |
Before and after study | Population—workplace employees, men on low income and of an ethnic background (Question 1: Before: 149, After: 91) (Question 2: Before: 272, After: 136) | Distribution of posters, flyers, postcards, ads in the workplace newspapers, information tools for dining tables and health education, healthy cooking and low-salt tasting sessions delivered by experts. Delivery setting: workplace |
1 month | Between baseline and post intervention, there was a reduction in the proportion of men who reported ‘always’ adding salt to food when cooking from 48 to 23% (Question 1) and an increase in the proportion of men who reported checking food labels for salt content prior to purchase or eating from 11 to 26% (Question 2). |
RCT randomized controlled trial, CT controlled trials, RT randomized trial, I intervention group, C control group, FFQ food frequency questionnaire, FSANZ Food Standards Australia New Zealand sodium guideline, Tick Heart Foundation Tick Scheme, CVD cardiovascular disease