Country	Year	Methodology	Age (years)	N and participants’ characteristics	Na excreted in urine (mmol/day)a
					Mean	SD	95% CI	Median (P50)	IQR (P25–P75)b
Austria (Elmadfa, 2012)	2010–2012	Casual spot urine samples; 24‐h excretion estimated by multiplying Na concentration by an average urine volume of 1.75 L/day from a subsample of 19 people from whom 24‐h urine were collected	18–64 65–80	NA (total sample: 419 men and women aged 18–64 and 196 men and women aged 65–80) Sample stratified by gender, age and geographical areas	18–24 years: 157 25–50 years: 161 51–64 years: 130 65–80 years: 152	N/A	18–24 years: 117–200 25–50 years: 143–178 51–64 years: 104–157 65–80 years: 126–174	N/A	N/A
Belgium (Koppen et al., 2015)	2015	24‐h urine collection; exclusion of samples with Cr excretion levels outside the normal range of 0.133–0.177 mmol/kg per day for women and self‐reported as incomplete	23–64	106; Sampled via an occupational health survey centre (random cluster sampling), spread over the different Belgian provinces	137	56	N/A	122	N/A
Belgium	2007–2008	2 × 24‐h urine collection (1 month interval); completeness of urine collection assessed by PABA recovery (≥ 85%). For samples with a PABA recovery between 50% and 85%, urinary Na excretion was corrected (formula from Johansson et al. (1999))	45–65	60	173b	N/A	161–185	N/A	N/A
Czech Republica				60	182b	56		173	P5‐P95 101–288
Norway (De Keyzer et al., 2015)				62 Subsamples of the European EFCOVAL study; subjects recruited by convenience sampling through advertisements	151b	N/A	141–161	N/A	N/A
Croatia (Premužić et al., 2010)	2009	24‐h urine collection; completeness check not reported	46.3 ± 7.3	N/A (total sample of 93 men and women); From two out‐patient clinics (one urban, one rural); ‘salt‐mapping survey’	177	73	N/A	N/A
Croatia (Dika et al., 2009)	2009	Morning spot urine samples; 24‐h Na excretion was estimated by applying Kawasaki, INTERSALT and Tanaka equations	N/A	N/A (total sample of 1,669 men and women); Random sample (door‐to‐door method) in the continental rural part of Croatia	Kawasaki: 214	78	N/A	N/A
					INTERSALT: 222	56	N/A	N/A
					Tanaka: 178	69	N/A	N/A
Finland (Laatikainen et al., 2006)	2002	24‐h urine collection; exclusion of incomplete samples with Cr levels ≤ 5.0 mmol/day or Cr levels ≤ 6.0 mmol/day together with a urine volume < 1,000 mL	25–64	486 North Karelia, n = 174 Southwestern Finland, n = 156 Helsinki area, n = 156 Sampled as part of the national FINRISK 2002 study; 10‐year age group and sex‐stratified subsample of the population aged 25–64 years drawn in north Karelia, southwestern Finland and in the Helsinki area	North Karelia: 128 Southwestern Finland: 127 Helsinki area: 119	N/A	North Karelia: 120–135 Southwestern Finland: 119–135 Helsinki area: 111–127	N/A
Germany (Johner et al., 2015)	2008–2011	Casual spot urine samples; 24‐h Na excretion estimated from the Na:Cr ratio by multiplication with age‐ and sex‐stratified Cr excretion reference values (Remer et al., 2002)	18–79	3,622 18–29 years, n = 507 30–39 years, n = 403 40–49 years, n = 586 50–59 years, n = 630 60–69 years, n = 671 70–79 years, n = 543 Random sample, as part of the German National Health Interview and Examination Survey 2008–2011, representative for the German adult population	N/A	N/A	Overall: 138–148 18–29 years: 116–136 30–39 years: 129–153 40–49 years: 141–165 50–59 years: 146–167 60–69 years: 134–153 70–79 years: 127–144	Overall: 143 18–29 years: 126 30–39 years: 139 40–49 years: 155 50–59 years: 156 60–69 years: 146 70–79 years: 134	Overall: 92–217 18–29 years: 85–184 30–39 years: 96–205 40–49 years: 103–226 50–59 years: 96–235 60–69 years: 87–212 70–79 years: 90–223
Greece (unpublished data)	2013–2014	For 7 days, the weight and time of each void were recorded and a sample of urine was collected. For each day, a sample of 10 mL was reconstituted from the individual samples based on the ratio of the volume of each void to the total volume of urinary excretion for the day. Exclusion of samples on the basis of Cr excretion (> 3,500 mg/day or < 350 mg/day)	20–60	83 Participants equally divided in each decade of life	130	48	N/A	124
Greece (Vasara et al., 2017)	2015–2016	24‐h urine collection; exclusion of incomplete samples on the basis of (a) urinary volume < 500 mL/24 h, (b) urinary creatinine less than 2 SD from the mean, (c) timing of collection outside the range 23–25 h and (d) self‐reporting of incomplete collection	18–75	138 Salt intake in northern Greece (SING) Study – regional study conducted in Thessaloniki greater metropolitan area. Recruitment was carried out at various sites and venues including churches and workplaces	158.5	64.1	147.7–169.3	151.0
Hungary (unpublished data)	2010	24‐h urine collection; completeness of the samples checked on the basis of participants’ compliance with the protocol	Adults (age not specified)	86 Random sample of the Hungarian adult population recruited through primary care physicians	163	71	N/A	N/A
Ireland (Morgan et al., 2008)	2007	Spot urine samples; daily Na excretion estimated through arithmetic extrapolation (Na concentration (mmol/L) multiplied by 1.67 for women)	≥ 18	611 Random sample of both Irish citizens and non‐Irish national residents sampled as part of the Survey of Lifestyle, Attitudes and Nutrition (SLAN) 2007, representative of the general population in Ireland	≥ 18 years: 128 45–64 years: 132 ≥ 65 years: 116	≥ 18 years: 72 45–64 years: 75 ≥ 65 years: 62	N/A	N/A	N/A
Ireland (Kearney et al., 2013)	2010–2011	Morning urine samples; daily Na excretion estimated through arithmetic extrapolation (Na concentration (mmol/L) multiplied by 1.67 for women)	45–74	1,029 Registered patients attending the Living Health Clinic of Mitchelstown, Ireland, sampled as part of the Cork and Kerry Diabetes and Heart Disease Study Phase II	overall: 129 45–54: 138 55–64: 128 65–74: 125	overall: 64 45–54: 72 55–64: 61 65–74: 59	N/A	N/A	N/A
Italyc (Donfrancesco et al., 2013; Cappuccio et al., 2015)	2009–2012	24‐h urine collection; A sample if 24‐h urine volume < 500 mL or creatinine content referred to body weight < mean minus 2 SD from the population mean	35–79	1,900 Random samples of the Italian adult population from 20 Italian regions, stratified by age and sex (MINISAL‐GIRCSI Programme)	Overall: 142 35–44 years: 142 45–54 years: 147 55–64 years: 143 65–74 years: 140 75–79 years: 135	Overall: 57 35–44 years: 61 45–54 years: 58 55–64 years: 54 65–74 years: 55 75–79 years: 56	Overall: 139–145 35–44 years: 136–148 45–54 years: 141–152 55–64 years: 138–148 65–74 years: 135–145 75–79 years: 126–144	Overall: 136 35–44 years: 135 45–54 years: 141 55–64 years: 138 65–74 years: 132 75–79 years: 129
Slovenia (Ribic et al., 2010)	2005	24‐h urine collection; exclusion of incomplete samples with Cr level < 120 μmol/kg bw per day for men (Osredkar, 1998)	25–65	82 Participants randomly sampled from census data from all regions, representative of the general population in Slovenia	170	74	N/A	N/A	N/A
Spain (Ortega et al., 2011)	2009	24‐h urine collection; completeness of the samples assessed by considering the correlation between urinary Cr and FFM of each subject; FFM estimated from 24‐h Cr excretion and result compared with measured FFM obtained by electrical bioimpedance method (Lopez‐Sobaler and Quintas et al., 2006)	18–60	222 Selected as a representative sample of the Spanish young and middle‐aged adult population (from 15 randomly selected provinces; stratified by age and sex)	143	66	N/A	131	97–178
Switzerland (Chappuis et al., 2011)	2010–2011	24‐h urine collection; exclusion of incomplete samples on the basis of: (1) urinary volume < 300 mL/24 h, (2) self‐reporting of incomplete collection, or (3) Cr level ≤ 0.082 mmol/kg bw per day in women	≥ 15	742 Age‐ and sex‐ stratified sample in various cantons of Switzerland, randomly selected. The low participation rate was compensated by recruiting volunteers	Overall: 137 15–29 years: 135 30–44 years: 140 45–59 years: 144 ≥ 60 years: 125	N/A	N/A	N/A	N/A
Netherlands (Hendriksen et al., 2014)	2010	24‐h urine collection; exclusion of incomplete samples on the basis of (1) Cr excretion ≤ 5 mmol/day, or ≤ 6 mmol/day together with a urine volume < 1,000 mL or (2) missing or overcollection of more than one urine void	19–70	180 Individuals participating in an ongoing long‐term monitoring study on chronic disease risk factors (the Doetinchem Cohort Study (DCS)) or randomly drawn from the municipal register of Doetinchem (General Doetinchem Population Sample (GDPS))	128	43	N/A	122	96–154
Netherlands (Hendriksen et al., 2016)	2015	24‐h urine collection; Start and end time of the urine collection were recorded. Participants had to report urine losses Based on this data, the researchers determined whether participants had an incomplete urine collection	19–70	154 Participants aged 50–70 recruited from an ongoing long‐term monitoring study on chronic disease risk factors (the Doetinchem Cohort Study (DCS)); Participants aged 19–49 randomly drawn from the municipal register of Doetinchem (General Doetinchem Population Sample (GDPS)); Exclusion of individuals had participated in the 24‐h urine test in 2006 and 2010 in the study of Hendriksen et al. (2014), kidney patients and pregnant women	N/A	N/A	N/A	Overall: 120 19–49 years: 122 50–70 years: 113	Overall: 93–146 19–49 years: 103–148 50–70 years: 85–140
United Kingdom (Sadler et al., 2011)	2011	24‐h urine collection; exclusion of samples on the basis of PABA recovery (< 70% (incomplete) or > 104% (unfeasibly high); individuals who elected not to take PABA, or did not take all PABA tablets, but recorded they had completed a 24‐h urine collection were included if recorded collection time was collected between 23–25 h	19–64	297 Participants from the England National Diet and Nutrition Survey sample and from a ‘sodium boost’ study; stratified sample randomly selected in various regions of England	19–34 years: 122 35–49 years: 116 50–64 years: 112	19–34 years: 55 35–49 years: 52 50–64 years: 59	N/A	19–34 years: 120 35–49 years: 104 50–64 years: 108	P2.5–P97.5 19–34 years: 47–261 35–49 years: 57–206 50–64 years: 44–218

bw: body weight; 95% CI: 95% confidence interval; Cr: creatinine; EFCOVAL: European Food Consumption Validation; FFM: fat‐free mass; IQR: interquartile range; N: number; Na: sodium; N/A: not available; PABA: para‐aminobenzoic acid, SD: standard deviation.

For comparison purposes, results provided in g NaCl/day were converted back in mmol/day by multiplying by 0.4 and dividing by 23.

Geometric means; based on two 24‐h collection per subject.

^aThe values reported are unpublished data provided by the National Institute of Public Health of the Czech Republic.

^bUnless indicated otherwise.

^cThe values reported are unpublished data provided by the Italian Instituto Superiore di Sanità.