Background
Methods
Sample size
Participant recruitment
Survey data collection
24-h urine collection
24-h dietary recall data
Data management and statistical analysis
Demographic and survey data
Urine collection data
Dietary recall data
Ethical approval
Results
Response rates and final participant sample
Impact of Covid-19 on follow-up data collection
Demographic characteristics of the sample
Urine collection completers | 24-h diet recall completers | Victorian population (%) 49% males, 51% femalesa | |||||
---|---|---|---|---|---|---|---|
Baseline n = 339 | Follow-up n = 211 | p value | Baseline n = 144 | Follow-up n = 90 | p value | ||
Percentage or mean (SD) | Percentage or mean (SD) | Percentage or mean (SD) | Percentage or mean (SD) | ||||
Age (years)* | 47.6 (13.4) | 45.6 (13.9) | 0.034 | 45.2 (13.1) | 38.1 (13.1) | 0.004 | 37 (median)a |
Age group (years) | 0.021 | 0.004 | |||||
18–24 | 13.0 | 12.4 | 7.7 | 22.3 | 13.3b | ||
25–34 | 15.4 | 28.5 | 15.3 | 26.6 | 15.7 | ||
35–44 | 22.8 | 17.2 | 23.5 | 17.1 | 13.4 | ||
45–54 | 23.7 | 20.0 | 27.9 | 17.1 | 12.8 | ||
55–65 | 25.1 | 21.9 | 25.6 | 16.9 | 11.2 | ||
Sex (female) | 53.6 | 49.7 | 0.414 | 56.4 | 46.2 | 0.159 | 51.0 |
BMI*c | 25.3 (4.2) | 25.3 (4.4) | 0.947 | 24.7 (4.2) | 24.3 (3.7) | 0.499 | |
BMI categoryd | 0.781 | 0.286 | |||||
Underweight | 3.1 | 2.2 | 4.3 | 5.6 | 2.3c | ||
Healthy weight | 48.6 | 54.4 | 46.7 | 58.9 | 37.7 | ||
Overweight | 37.8 | 30.8 | 39.7 | 27.0 | 30.6 | ||
Obese | 10.5 | 12.6 | 9.3 | 8.5 | 19.1 | ||
Socioeconomic disadvantage (quintiles) | 0.669 | 0.409 | |||||
1st quintile (greatest disadvantage) | 6.7 | 6.2 | 7.3 | 3.3 | |||
2nd quintile | 6.3 | 9.4 | 5.3 | 10.6 | |||
3rd quintile | 10.4 | 11.4 | 14.2 | 10.7 | |||
4th quintile | 32.6 | 28.2 | 22.9 | 25.1 | |||
5th quintile (least disadvantage) | 44.0 | 44.8 | 50.3 | 50.3 | |||
Day of data collection (weekday) | 66.7 | 68.8 | 0.624 | 72.7 | 88.9 | 0.003 |
Analysis of urinary excretion data over time
Urinary excretion data | Total mean (95% CI) | Baseline mean (95% CI) | Follow-up mean (95% CI) | Regression analysis to test for differences baseline and follow-up | ||
---|---|---|---|---|---|---|
Unadjusted Model 1 N = 550 | Adjusted Model 2 N = 529 | Adjusted Model 3 N = 529 | ||||
n = 550 | n = 339 | n = 211 | Coef (95% CI) p value | Coef (95% CI) p value | Coef (95% CI) p value | |
Sodium (mmol/24-h) | 133 (128–138) | 134 (127–142) | 131 (124–139) | − 2.68 (− 11.29–5.93) 0.541 | − 4.95 (− 13.74–3.83) 0.269 | − 5.05 (− 13.82–3.73) 0.260 |
Salt (g/day) | 7.8 (7.5–8.1) | 7.8 (7.4–8.3) | 7.7 (7.2–8.1) | − 0.16 (− 0.66–0.34) 0.541 | − 0.29 (− 0.80–0.22) 0.269 | − 0.29 (− 0.81–0.22) 0.260 |
Sodium (mmol/24 h) Median (IQR) | 126 (86–171) | 121 (87–170) | 131 (86–171) |
Diet recall | Total mean (95% CI) | Baseline mean (95% CI) | Follow-up mean (95% CI) | Regression analysis to test for differences baseline and follow-up | ||
---|---|---|---|---|---|---|
Unadjusted Model 1 N = 550 | Adjusted Model 2 N = 529 | Adjusted Model 3 N = 529 | ||||
n = 234 | n = 144 | n = 90 | n = 234 | n = 229 | n = 229 | |
Sodium DR (mmol/24-h) | 119 (111–127) | 115 (106–124) | 125 (111–139) | 5.89 (− 6.51–18.28) 0.352 | 3.51 (− 8.88–15.90) 0.579 | 3.29* (− 8.20–14.78) 0.575 |
Salt DR (g/day) | 7.0 (6.5–7.4) | 6.7 (6.2–7.2) | 7.3 (6.5–8.1) | 0.34 (− 0.38–1.07) 0.354 | 0.20 (− 0.52–0.93) 0.581 | − 0.19* (− 0.48–0.86) 0.577 |
Energy DR (kJ/day) | 10,215 (9748–10,681) | 9932 (9480–10,384) | 10,597 (9707–11,486) | 340.86 (− 428.15–1109.86) 0.385 | 187.52 (− 547.56–922.60) 0.617 | 262.14 (− 468.76–933.04) 0.482 |
Analysis of 24-h dietary recall data over time
Analysis of 24-h dietary recall data over time (continued)
Sub-major food group name | Baseline (n = 143) | Follow-up (n = 90) | p value* | ||||||
---|---|---|---|---|---|---|---|---|---|
Rank | % of daily intake | 95% CI | Rank | % of daily intake | 95% CI | ||||
Regular breads/bread rolls | 1 | 10 | 8.2 | 12.5 | 2 | 8 | 5.8 | 10.8 | 0.262 |
Mixed dishes (cereal major ingredient) | 2 | 8 | 5.1 | 11.3 | 1 | 13 | 8.5 | 17.6 | 0.035 |
Processed meat | 3 | 6 | 3.4 | 7.5 | 7 | 3 | 0.8 | 4.9 | 0.035 |
English-style muffins, flat breads, and savoury and sweet breads | 4 | 5 | 3.1 | 7.5 | 11 | 2 | 0.9 | 3.9 | 0.049 |
Gravies and savoury sauces | 5 | 5 | 2.4 | 7.2 | 3 | 5 | 2.4 | 7.9 | 0.478 |
Cheese | 6 | 4 | 3.1 | 5.5 | 4 | 4 | 2.1 | 5.8 | 0.862 |
Cakes, muffins, scones, cake-type desserts | 7 | 4 | 2.5 | 5.6 | 5 | 4 | 1.9 | 5.5 | 0.644 |
Mixed dishes (beef, sheep, pork or mammalian game major component) | 8 | 3 | 1.7 | 4.7 | 9 | 3 | 0.8 | 4.9 | 0.712 |
Mixed dishes (poultry/feathered game is major component) | 9 | 3 | 1.2 | 4.6 | 8 | 3 | 1.5 | 4.5 | 0.781 |
Dairy milk (cow, sheep and goat) | 10 | 3 | 2.2 | 3.4 | 12 | 2 | 1.0 | 2.6 | 0.495 |
Pastries | 11 | 3 | 1.1 | 4.2 | 6 | 4 | 1.0 | 6.9 | 0.764 |
Waters, municipal and bottled, unflavoured | 12 | 2 | 1.9 | 2.7 | 10 | 3 | 1.9 | 3.1 | 0.189 |
Poultry and feathered game | 13 | 2 | 0.9 | 3.3 | 28 | 0 | 0.1 | 0.7 | 0.059 |
Fin fish (excluding commercially sterile) | 14 | 2 | 0.9 | 3.3 | 23 | 1 | 0.2 | 1.6 | 0.094 |
Breakfast cereals, ready to eat | 15 | 2 | 0.9 | 2.5 | 24 | 1 | 0.3 | 1.3 | 0.150 |
Sausages, frankfurts and saveloys | 16 | 2 | 0.5 | 2.9 | 25 | 1 | − 0.2 | 1.7 | 0.270 |
Coffee and coffee substitutes | 17 | 1 | 0.9 | 1.9 | 13 | 2 | 1.5 | 3.1 | 0.008 |
Packed (commercially sterile) fish and seafood | 18 | 1 | 0.5 | 2.4 | 14 | 2 | 0.4 | 3.0 | 0.687 |
Pickles, chutneys and relishes | 19 | 1 | 0.5 | 2.1 | 17 | 1 | 0.2 | 2.2 | 0.717 |
Sweet biscuits | 20 | 1 | 0.5 | 1.9 | 15 | 2 | 0.2 | 3.0 | 0.028 |
Savoury biscuits | 21 | 1 | 0.6 | 1.6 | 18 | 1 | 0.2 | 1.9 | 0.298 |
Yoghurt | 22 | 1 | 0.5 | 1.5 | 26 | 1 | 0.2 | 1.2 | 0.974 |
Eggs | 23 | 1 | 0.5 | 1.3 | 29 | 0 | 0.0 | 0.8 | 0.018 |
Beef, sheep and pork, unprocessed | 24 | 1 | 0.5 | 1.3 | 27 | 0 | 0.1 | 0.8 | 0.050 |
Salad dressings | 25 | 1 | 0.0 | 1.6 | 19 | 1 | 0.2 | 2.7 | 0.160 |
Batter-based products | 26 | 1 | 0.0 | 1.4 | 22 | 1 | 0.0 | 2.0 | 0.742 |
Pasta and pasta products (without sauce) | 27 | 1 | − 0.1 | 1.5 | 20 | 1 | 0.3 | 2.4 | 0.260 |
Dips | 28 | 1 | 0.3 | 1.1 | 16 | 2 | 0.0 | 3.6 | 0.091 |
Nuts and nut products | 29 | 1 | 0.2 | 1.0 | 21 | 1 | 0.3 | 2.0 | 0.139 |
Origin of purchase | Baseline (n = 143) | Follow-up (n = 90) | p value* | ||||
---|---|---|---|---|---|---|---|
% of daily intake | 95% CI | % of daily intake | 95% CI | ||||
Store-grocery/supermarket | 57 | 50.9 | 62.7 | 77 | 70.6 | 84.2 | < 0.001 |
Quick service/take-out/delivery | 9 | 4.3 | 13.0 | 12 | 5.9 | 17.0 | 0.433 |
Full service restaurant | 9 | 4.7 | 12.3 | 5 | 1.7 | 8.5 | 0.235 |
Water from tap | 1 | 1.4 | 2.0 | 2 | 1.6 | 2.7 | 0.036 |
Fresh food market | 13 | 8.7 | 16.2 | 2 | 0.4 | 3.4 | < 0.001 |
From someone else/gift | 3 | 1.3 | 4.6 | 1 | 0.1 | 1.2 | 0.021 |
Bar or tavern | 1 | 0.0 | 1.2 | 1 | − 0.1 | 1.7 | 0.117 |
Grown or caught | 3 | 1.3 | 4.9 | 0 | − 0.1 | 0.4 | 0.004 |
Analysis of discretionary salt use behaviours over time
Discretionary salt use | Baseline n = 339 | Follow-up n = 211 | p value |
---|---|---|---|
% 95% CI | % 95% CI | ||
Add salt during cooking (yes) | 63 57–68 | 68 61–74 | 0.244 |
Place a shaker on the table at meal times (yes) | 34 28–39 | 37 30–44 | 0.400 |
Doing anything on a regular basis to control salt or sodium (yes) | 22 18–27 | 21 15–27 | 0.793 |