estimation of sodium availability in food in slovenia: results from household food purchase data from 2000 to 2009 OCENA RAZPOLOŽLJIVOSTI NATRIJA V ŽIVILIH V SLOVENIJI: REZULTATI IZ RAZISKAVE O PORABI ŽIVIL V GOSPODINJSTVIH OD LETA 2000 DO LETA 2009 Cirila Hlastan Ribič1-4, Jožica Maučec Zakotnik1, Barbara Koroušic Seljak2, Rok Poličnik1, Urška Blaznik1, Nataša Fidler Mis3, Ivan Eržen1, Chen Ji5, Francesco P. Cappucio5 Prispelo: 2. 8. 2013 - Sprejeto: 4. 3. 2014 Original scientific article UDC 613.27(497.4) Abstract Introduction: The main aim of the study was to estimate average daily sodium availability of Slovenian consumers based on the food purchase data for the period 2000-2009. The secondary aim was to look for food group contributors to sodium availability. Methods: Food purchase records (Household Budget Survey) as well as country-specific reference values and food composition information were used to estimate mean sodium availability of purchased foods (grams of sodium/person/ day - g Na/p/day) as well as food groups and foods with the largest contribution to the total sodium availability. Discussion and results: The mean sodium availability of purchased foods decreased in the period 2000-2009 and was on average 2,104±132 mg Na/p/day, not accounting for ready-made meals, most semi-prepared foods and adding salt during cooking and at the table. The key food group contributors of sodium in Slovenia were breads and bakery products (35.0%), meat products (27.9%), processed vegetables (6.6%) and cheeses (5.3%). Conclusions: Notwithstanding the smaller purchased quantities of higher-sodium foods (e.g. sausages, prosciutto, dry meat, pickled cucumbers) in comparison to larger purchased quantities of the medium-sodium foods (e.g. white bread, mixed bread, brown bread, milk, rolls), both food groups contribute significant amounts of sodium in the diets of Slovenians. Key words: household budget survey, sodium availability, sodium content, food groups Izvirni znanstveni članek UDK 613.27(497.4) Izvleček Uvod: Glavni namen raziskave je bil ugotoviti razpoložljivost natrija v kupljenih živilih v Sloveniji. Osnovo so predstavljali podatki nacionalne raziskave o porabi v gospodinjstvih za obdobje 2000-2009. Sekundarni cilj raziskave je bil ugotoviti, katere skupine živil prispevajo k največji razpoložljivosti natrija v prehrani slovenskih porabnikov. Metode: Za oceno povprečnega vnosa natrija (izraženega v gramih natrijevega klorida/oseba/dan - g osebo/Na/dan) v kupljenih živilih in glavnih skupinah živil so bili uporabljeni podatki o povprečni porabi živil v gospodinjstvih in podatki 0 hranilni sestavi živil. Razprava in rezultati: Povprečna vrednost razpoložljivega natrija v kupljenih živilih se je v obdobju od leta 2000 do leta 2009 znižala in znaša v povprečju 2,104±132 mg natrija/osebo/dan. Pri tem niso bile upoštevane vrednosti vnosa pripravljenih in polpripravljenih obrokov ter dosoljevanje hrane pri mizi. Ugotovljeno je bilo, da so ključne skupine živil, ki prispevajo največje količine natrija v prehrani prebivalcev Slovenije, kruh in pekovski izdelki (35,0%), mesni izdelki (27,9%), konzervirana zelenjava (6,6%) in siri (5,3%). Zaključki: Raziskava je pokazala, da k vnosu natrija v prehrani prebivalcev Slovenije znatno prispevajo živila, ki vsebujejo višje vrednosti natrija (npr. salame, pršut, sušeno meso, vložena zelenjava) in ki se jih v prehrani ljudi zaužije v nižjih količinah, in živila s srednjimi vrednostmi natrija (npr. bele in mešane vrste kruha, črni kruh), ki se jih porabi v večjih količinah. Ključne besede: anketa o porabi v gospodinjstvih, razpoložljivost natrija, vsebnost natrija, skupine živil 1 National Institute of Public Health, Trubarjeva 2, 1000 Ljubljana, Slovenia 2 Jozef Stefan Institute, Computer Systems Department, Jamova 39, 1000 Ljubljana, Slovenia 3 University Medical Centre Ljubljana, Division of Peadiatrics, Department of Gastroenterology, Nephrology and Nutrition, Bohoričeva 20, 1000 Ljubljana, Slovenia 4 University of Ljubljana, Medical Faculty, Department of Public Health, Zaloška 4, 1000 Ljubljana, Slovenia 5 WHO Collaborating Centre for Nutrition, University of Warwick, Coventry, United Kingdom Correspondence to: e-mail: cirila.hlastan-ribic@nijz.si 1 INTRODUCTION Sodium is a mineral nutrient essential for life in small quantities. For many years, concerns have been expressed that consumption levels of sodium are well above those needed for nutritional purposes, and that these are having an adverse effect on health, in particular increased high blood pressure leading to higher risk of cardiovascular diseases (1-2). Studies also indicate significant associations between high sodium intake and a variety of chronic conditions including type II diabetes (3), cataract (4), gastric cancer (5), kidney disease (6, 7) and osteoporosis (6, 8). A high salt intake may also be an important contributing factor in the development of obesity (9). The prevalence of hypertension (blood pressure above 140/90 mmHg) in the Slovenian adult population (age 25 to 64 years) is high (39.6%) (10), making a reduction in salt intake a national priority for the prevention of cardiovascular disease. WHO recommends a reduction in sodium intake to reduce blood pressure and risk of cardiovascular disease, stroke and coronary heart disease in adults. WHO recommends a reduction to <2 g/day sodium (5 g/day salt) in adults (11). In 2005, Slovenia adopted the recommendation for nutrients intake from Germany, Switzerland and Austria named The Reference Values for Nutrients Intake (D-A-CH). The Reference Values for Nutrient Intake create the basis on which diets are planned to match nutritional requirements with food intake. The minimum recommended value for daily sodium intake for adults in-line with D-A-CH recommendations amounts to 550 mg/day of sodium (1.4 g/day salt) (12). In developed countries, ingestion of sodium tends to exceed the recommended intake (13), with the largest proportion originating from processed foods: for example, in the United Kingdom and the USA, it has been estimated that 75% of sodium intake comes from processed or restaurant foods, 1012% is naturally occurring in foods and the remaining 10-15% is from the discretionary use of salt in home-cooking or at the table (14). In the British Diet and Nutrition Survey, a number of key food groups were found to be the major contributors to total daily sodium intake from food among British adults. These included cereals and cereal products providing 35%, meat and meat products contributing 26% and milk and milk products 8% of sodium from food (15). In Slovenia, the average salt intake of the population, assessed by 24h urinary sodium excretion, is 11.3±4.9 g salt/d, significantly higher in men than in women (13.0±5.1 vs. 9.9±4.3 g salt/day respectively) (16). The total salt intake of 2,581 Slovenian adolescents (aged 14 to 17 years) was 10.4±0.2 g salt/d, much higher than the upper WHO limit for adults. Moreover, boys ate more salt than girls (11.5±0.3 vs. 9.4±0.2 g salt/d P < 0.001). The main food sources of salt for adolescents were table salt (33%), bread (24%), salty snack products (10%) and meat products (8%) (17, 18). However, there is little information on exposure to sodium-rich foods in the general population of Slovenia (19-21). There are various methods to estimate sodium intake in a population. While measurement of urinary sodium excretion is the most accurate method (22), other methods, i.e. different food consumption surveys (questionnaires or interviews), tend to underestimate sodium intake by approximately 16-22% (17, 18). Information about nutrient availability within a country can be collected using three different means: food balance sheets, household budget surveys (HBSs) and specifically designed individual food consumption surveys. Both food balance sheets and HBSs provide insight into food availability but do not assess food consumption at an individual level. Food consumption data collected in nutrition surveys could be used for estimating sodium intake where accurate data on the sodium content of local foods were available (23). The objective of the present study was to estimate average daily sodium availability in purchased foods per Slovenian consumer based on the food purchase data from the HBSs for the period 2000-2009. The secondary aim was to establish a comprehensive food composition database to monitor the sodium content of foods in Slovenia. 2 METHODS 2.1 The Household Budget Survey sampling design The sample frame is the Central Population register (CRP). The sample stratification was made with regard to 12 statistical regions and six types of settlements. The survey was harmonised with Eurostat's recommendations. By combining data of three consecutive years, more accurate estimates are obtained. Data from three years are calculated to the middle year, which is used as the reference year for the interpretation of published results. The survey is implemented on the basis of the Slovenian National Statistics Act (24) and the Annual Programme of Statistical Surveys. The consumption of goods is collected by diaries that are kept by all household members for two consecutive weeks. HBS data used for calculations in the present survey contains 223 foods purchased in stores, food markets or produced at own garden/farm by an average 3,727 households a year. Average sample in the HBS consisted of 11-12% children (<11 years), 8-9% adolescents (11-18 years) and 78-80% adults (>18 years) from 12 Slovenian geographical regions. The Slovenian representative sample of households was equally distributed throughout the year. A more detailed description of the HBS sampling design is available elsewhere (25). In the study, we used data from nine HBSs from the period 2000-2009. 2.2 Estimation of dietary sodium and salt availability HBS foods were classified according to the international COICOP classification into seven food groups, 19 food categories and 242 food subcategories. Purchasing data and sodium values were provided for all food products within the following categories: grains and grain-based products, fresh and processed vegetables and fruits, starchy roots and tubers, legumes, nuts and seeds, dairy products, eggs and egg products, fresh and processed meats, poultry and fish, food for infants and small children, sugar and confectionary, snack food, edible oils, sauces and spreads, beverages and drinks. Based on the data on annual purchases in kilograms per person, provided by HBSs (25) and the sodium content of foods, we carried out the calculations to estimate the average sodium availability of purchased foods (SAPF) in Slovenian households for the period 2000-2009. There were three sources from which we obtained information about food composition: 1. sodium content of purchased foods were derived from food product labels; 2. for fresh foods and unlabelled products, we applied generic data from national and European food composition tables, and 3. sodium content of purchased meat products and bread and bakery products were analysed at the National Institute of Public Health, in a laboratory accredited according to ISO 17025. Sodium content was calculated from the present and quantified salt in the products (26). Data obtained from the second and last source were screened by the authors (CRH) for plausibility. The results were expressed in milligrams of sodium per person daily. Comparisons on distribution of the largest contributors to the total SAPF were carried out. For the conversion from sodium (Na) to salt (sodium chloride (NaCl)), a factor of 2.54 was used, NaCl (mg) = Na (mg) x 2.54. 2.3 Statistical analysis Statistical analyses were performed using SPSS for Windows (16.0). Descriptive statistics were calculated for continuous variables and expressed as mean, standard error of mean and standard deviation. 3 RESULTS 3.1 Sodium availability from purchased foods in Slovene households for the period 20002009 Based on the HBS data, sodium contained in salt added at cooking/preparing meals and at the table, salt from ready-made meals and most semi-prepared foods were excluded from this survey. Table 1 represents estimated household SAPF and salt availability (SA) based on household food purchases in Slovenia for the period 2000-2009. Sodium availability of purchased foods (SAPF) in Slovenian households decreased from 2,289 mg/p/day (year 2000) to 1,860 mg/p/day (year 2009). Thus, the average SAPF for the period 2000-2009 was 2,104±132 mg/p/day. 2000 2001 2002 2003 2004 2005 2006 2007 2009 Mean/ Povprečje Sodium/Natrij (mg/person/day)/ (mg/osebo/dan) 2,289 2,254 2,168 2,127 2,103 2,103 2,042 1,988 1,860 2,104 Salt*/Sol* (mg/person/day)/ (mg/osebo/dan) 5,814 5,725 5,508 5,405 5,343 5,340 5,186 5,049 4,723 5,343 Table 1. Household SAPF and SA based on food purchases in Slovenian households for the period 2000-2009. Tabela 1. Razpoložljivost natrija in soli v kupljenih živilih v Sloveniji, v obdobju od 2000 do 2009. * 1 mmol of sodium (Na) corresponds to 23.0 mg; NaCl (mg) = Na (mg) x 2.54/ 1 mmol Natrija (Na) ustreza 23.0 mg; NaCl (mg) = Na (mg) x 2.54 3.2 Sodium and salt availability by food groups In Table 2, a distribution (mg sodium/person/day and % to total daily SAPF) of household SA between food groups with the largest contribution to SAPF is presented. The key food groups contributing to dietary sodium intake were breads and bakery products (761 mg Na/p/day; 35.0% of SAPF) and meat products (597 mg Na/p/day; 27.9% of SAPF), while processed vegetables (136 mg Na/p/day; 6.6%) and cheeses (110 mg Na/p/day; 5.3%) also contributed to the household SAPF. Table 2. Food groups with largesta contribution to total daily SAPF in Slovenian households for the period 2000-2009. Tabela 2. Skupine živil, ki prispevajo največjea količine natrija v gospodinjstvih v Sloveniji, v obdobju od 2000 do 2009. Year/Leto ^ i= aa "O "O "ÎS "ÎS u. z z Çt o> o> ^ E E Contribution to SAPF/Količina natrija v kupljeni hrani Bread and bakery products/ Kruh in pekovsko pecivo Meat productsc / Mesni izdelkic Processed vegetablesd / Konzervirana zelenjavad Cheeses/ Siri 2000 2,289 mg Na/p/day/ mg Na/o/dan 947 599 115 97 % 41.14 26.19 4.89 4.14 2001 2,254 mg Na/p/day/ mg Na/o/dan 883 622 115 103 % 39.16 27.59 5.01 4.47 2002 2,168 mg Na/p/day/ mg Na/o/dan 826 594 119 103 % 38.10 27.40 5.41 4.67 2003 2,127 mg Na/p/day/ mg Na/o/dan 763 608 126 110 % 35.87 28.57 5.86 5.12 2004 2,103 mg Na/p/day/ mg Na/o/dan 728 593 135 114 % 34.59 28.20 6.33 5.36 2005 2,103 mg Na/p/day/ mg Na/o/dan 673 618 153 120 % 32.02 29.41 7.21 5.64 2006 2,042 mg Na/p/day/ mg Na/o/dan 624 611 162 116 % 30.59 29.94 7.85 5.63 2007 1,988 mg Na/p/day/ mg Na/o/dan 648 532 162 114 % 32.59 26.75 8.13 5.72 2009 1,860 mg Na/p/day/ mg Na/o/dan 570 496 155 123 % 30.65 26.69 8.33 6.63 Mean/ Povprečje 2,104 mg Na/p/day/ mg Na/o/dan 761 597 136 110 % 34.97 27.86 6.63 5.32 Estimated 5,343* mg NaCl/p/dan/ 1,933 1,517 345 278 average salt mg Na/o/dan availability/ Povprečna ocenjena razpoložljivost soli a Only food subcategories with the largest contribution to sodium availability are mentioned in the table; the remaining food categories are: pastry, other grain foods, milk and milk products (not cheeses), fresh vegetables, fresh and processed fruit, nuts, sweets, eggs, fresh meat, fresh fish and fish products, etc./ V tabeli so navedene podskupine živil, ki prispevajo k največji razpoložljivosti natrija; ostale kategorije živil so: peciva, ostali žitni izdelki, mleko in mlečni izdelki (razen siri), sveža zelenjava, sveže in konzervirano sadje, oreški, sladka živila, jajca, sveže meso, sveže ribe in ribji izdelki itd. b p = person/o = oseba c Included meat products: bacon, ham, cooked sausages and other sausage meat products, frankfurters (hot-dog)./ Vključeni mesni izdelki: svinjina, šunka, salame in ostali mesni izdelki, hrenovke (hot-dog). d Included processed vegetables: sauerkraut, pickled turnip, canned vegetables (red pepper, mushrooms, olives, "ajvar" (salt based relish made from red pepper, eggplant and garlic), horseradish, corn), prepared potato products (frozen french-fries)/ Vključena konzervirana zelenjava: kislo zelje, kisla repa, konzervirana zelenjava (rdeča paprika, gobe, olive, »ajvar« (zelenjavni izdelek iz rdeče paprike, jajčevcev in česna), hren, koruza), predpripravljeni krompirjevi izdelki (zamrznjen pommes frittes) * 1 mmol of sodium (Na) corresponds to 23.0 mg; NaCl (mg) = Na (mg) x 2.54/ 1 mmol of sodium (Na) ustreza 23.0 mg; NaCl (mg) = Na (mg) x 2.54 In addition, in the examined period the SA in bread and bakery products decreased and the SA in processed vegetables and cheeses increased slightly (Figure 1). 1000 900 800 700 600 500 400 300 200 100 0 Meat products/Mesni izdelki Bread and bakery products/Kruh in pekovsko pecivo Processed vegetables/Konzervirana zelenjava Cheese/Siri 2000 2001 2002 2003 2004 2005 2006 2007 2009 Year/Leto Figure 1. Average annual values in the period 2000-2009 for the SA of food groups with the largest contribution to total SAPF daily in Slovenian households. Slika 1. Povprečne letne vrednosti natrija v živilih z največjo razpoložljivostjo natrija v gospodinjstvih v Sloveniji, v obdobju od 2000 do 2009. 3.3 Sodium and salt availability of foods according to their sodium content and purchased quantity In Table 3 and 4, only foods with the highest contribution to total daily SAPF with confidence intervals are presented. To interpret their high contribution to total SAPF, these foods can be divided into three groups according to the other foods included: 1) foods with high sodium content and high purchased quantity, 2) foods with high sodium content and relatively low purchased quantity and 3) foods with relatively low sodium content and high purchased quantity. Based on this classification, various salamis and cheeses were included in the first group. In the second group with high sodium content, bacon, dry meat, prosciutto and various sausages were included. In the third group with high purchased quantity, foods like cow's milk, brown bread, mixed bread and white bread were included. Table 3. Average SA of foods with the largest contribution to total SAPF in Slovenian households for the period 2000-2009. Tabela 3. Povprečne vrednosti razpoložljivosti soli v skupinah živil, ki prispevajo največ k skupni razpoložljivosti natrija v gospodinjstvih v Sloveniji v obdobju od 2000 do 2009. iv >N e in pi u k /S p/ u o r g d o o la ivi s/ d o o ng .2 o % 0 ntr mg/ 8 g £ 5 »o SPff i s S O o W CT 2 6 ° C S? s E ^ O egn ž E 0 CT* S 3 g o o Ê, CT ~ E e( gi d CS o o CS CS < < SS si dn oe of kup s a en 3 d y 0) a /o t« 5 ra S äE H CT = 3 P > O. S>N b la m w ™ 0) «s I i dq S * es ga ah rc 5 > ea PC C > 'S o 2 p re ? z CT ■pÑ E 73 o B z o J= E B 2 ;Ñ s o) ■Z ^ >N > i. O Ë S5 ßf o 5 C JF .Ü i? oa O ^ C a £