Country (reference)	Year	Methodology	Age (years)	N and participants’ characteristics	Na excreted in urine (mmol/day)a
					Mean	SD	95% CI	Median (P50)	IQR (P25–P75)d
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	N/A (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: 187 25–50 years: 191 51–64 years: 204 65–80 years: 183	N/A	18–24 years: 152–226 25–50 years: 178–204 51–64 years: 174–235 65–80 years: 139–204	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 0.177–0.230 mmol/kg per day for men and self‐reported as incomplete	23–64	99 Sampled via an occupational health survey centre (random cluster sampling), spread over the different Belgian provinces	179	63	N/A	172	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	63	209b	N/A	195–223	N/A	N/A
Czech Republicc				58	252b	78	N/A	241	P5–P95 149–395
Norway (De Keyzer et al., 2015)				62 Subsamples of the European EFCOVAL study; subjects recruited by convenience sampling through advertisements	204b	N/A	191–218	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’	231	74	N/A	N/A	N/A
Croatia (Dika et al., 2009)	2009	Morning spot urine samples; 24‐h Na excretion 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: 229	80	N/A	N/A	N/A
					INTERSALT: 194	40	N/A	N/A	N/A
					Tanaka: 186	49	N/A	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	423 North Karelia, n = 168 Southwestern Finland, n = 128 Helsinki area, n = 127 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: 163 Southwestern Finland: 170 Helsinki area: 148	N/A	North Karelia: 153–173 Southwestern Finland: 156–183 Helsinki area: 132–164	N/A	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	3,340 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: 165–177 18–29 years: 148–173 30–39 years: 163–197 40–49 years: 148–173 50–59 years: 167–189 60–69 years: 165–194 70–79 years: 158–178	Overall: 170 18–29 years: 160 30–39 years: 180 40–49 years: 163 50–59 years: 177 60–69 years: 177 70–79 years: 167	Overall: 117–252 18–29 years: 113–263 30–39 years: 123–264 40–49 years: 110–231 50–59 years: 115–261 60–69 years: 117–252 70–79 years: 118–245
Greece (unpublished data)	2013–2014	For 7 days, the weight and time of each void was 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 with Cr levels > 3,500 mg/day or < 350 mg/day	20–60	89 Participants equally divided in each decade of life.	159	51	N/A	148
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, (d) self‐reporting of incomplete collection	18–74	114 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	194.3	76.8	180.1–208.6	181.9	N/A
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)	67 Random sample of the Hungarian adult population recruited through primary care physicians	190	73	N/A	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 1.97 for men)	≥ 18	484 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: 176 45–64 years: 188 ≥ 65 years: 158	≥ 18 years: 85 45–64 years: 88 ≥ 65 years: 78	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 1.97 for men)	45–74	999 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: 211 45–54 years: 218 55–64 years: 211 65–74 years: 201	Overall: 89 45–54 years: 92 55–64 years: 87 55–74 years: 89	N/A	N/A	N/A
Italye (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	1,962 Random samples of the Italian adult population from 20 Italian regions, stratified by age and sex (MINISAL‐GIRCSI Programme)	Overall: 183 35–44 years: 184 45–54 years: 190 55–64 years: 182 65–74 years: 180 75–79 years: 176	Overall: 70 35–44 years: 72 45–54 years: 70 55–64 years: 70 65–74 years: 70 75–79 years: 60	Overall: 180–187 35–44 years: 178–191 45–54 years: 184–197 55–64 years: 176–188 65–74 years: 173–187 75–79 years: 166–185	Overall: 175 35–44 years: 174 45–54 years: 182 55–64 years: 173 65–74 years: 170 75–79 years: 172	N/A
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	61 Participants randomly sampled from census data from all regions, representative of the general population in Slovenia	221	86	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	196 Selected as a representative sample of the Spanish young and middle‐aged adult population (from 15 randomly selected provinces; stratified by age and sex)	196	82	N/A	196	140–250
Sweden (Hulthen et al., 2010)	2005	24‐h urine collection; completeness of urine collection assessed by PABA recovery (≥ 85%)	18−20	79 Participants recruited in the city of Gothenburg, as part of the Gothenburg Obesity and Osteoporosis Determinants (GOOD) study	198	69	N/A	N/A
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 ≤ 0.121 mmol/kg bw per day in men	≥ 15	706 Age‐ and sex‐ stratified sample in various cantons of Switzerland, randomly selected. The low participation rate was compensated by recruiting volunteers	Overall: 185 15–29 years: 171 30–44 years: 190 45–59 years: 194 ≥ 60 years: 180	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))	174	63	N/A	163	126–212
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	135 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: 153 19–49 years: 146 50–70 years: 174	Overall: 125–202 19–49 years: 110–195 50–70 years: 138–214
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 and 25 h	19–64	250 Participants from the England National Diet and Nutrition Survey sample and from a ‘Na boost’ study; stratified sample randomly selected in various regions of England	19–34 years: 162 35–49 years: 171 50–64 years: 141	19–34 years: 69 35–49 years: 66 50–64 years: 82	N/A	19–34 years: 159 35–49 years: 165 50–64 years: 133	P2.5–P97.5 19–34 years: 72–296 35–49 years: 73–321 50–64 years: 54–308

bw: body weight; 95% CI: 95% confidence interval; Cr: creatinine; EFCOVAL: European Food Consumption Validation; FFM: fat‐free mass; INTERSALT: International Cooperative Study on Salt, Other Factors and Blood Pressure; IQR: interquartile range; N: number; Na: sodium; N/A: not available; PABA: para‐aminobenzoic acid; SD: standard deviation.

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

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

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

^dUnless indicated otherwise.

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