Sodium intake and mmethodological issues in estimating sodium intake in the Korea National Health and Nutrition Examination Survey Hyun Ja Kim, Kyungwon Oh* Division of Health and Nutrition Survey, Korea Centers for Disease Control and Prevention, Cheongju-si, Republic of Korea * Corresponding author: Kyung Won Oh Division of Health and Nutrition Survey, Korea Centers for Disease Control and Prevention, Osongsaengmyeong -ro, Osong-eup, Cheongju-si, Chungcheongbuk-do, -, Republic of Korea. Tel.: + 0; fax: +. E-mail address: kwoh@korea.kr Running title: Sodium intake and mmethodological issues in estimating sodium intake Keywords: sodium, -hr dietary recall, -urine,, overnight urine
Introduction 0 과다한나트륨섭취는고혈압, 심혈관계질환, 신장질환, 위암의발생위험을증가시키며, 간접적으로는비만, 신장결석및골다공증의위험을증가시키는요인으로작용한다. 나트륨섭취량을줄일경우, 관련만성질환의유병률과사망률이크게감소하는것으로보고되었다 []. 우리나라는전통적으로김치, 장류, 젓갈류, 국 찌개등의섭취로나트륨섭취량이높은것으로알려져있어나트륨섭취를줄이기위한정책적인접근이시급하다. 더나아가, 정책적감소목표를설정하고그효과를평가하기위해서는우선우리나라국민의나트륨섭취량을정확하게파악하고그추이를지속적으로모니터링하는것이필요하다. 나트륨섭취량은 시간회상법 (-hour dietary recall) 이나식사일기법 (food record) 을이용한영양조사외에도 시간소변 (-hour urine), -시간야간뇨 (overnight urine) 및단회뇨 () 의나트륨배설량으로도조사될수있는데, 각나라마다나트륨섭취량을조사하는방법은다양하며, 각기장단점을가지고있다 []. 이에본원고에서는우리나라나트륨섭취현황을파악하고각국가별나트륨섭취량조사방법과그 타당성을고찰하고자하며, 이를통해향후우리나라국민의나트륨섭취량과섭취추이를보다 정확하게파악할수있는방법을모색해보고자한다. 한국인나트륨섭취현황 [] 0 0년국민건강영양조사 (Korea National Health and Nutrition Examination Survey) 결과, 한국인의일일나트륨평균섭취량은, mg ( 남자, mg, 여자, mg) 으로세계보건기구 (World health organization, WHO) 의일일나트륨권고상한치인 [],000mg의 배이상을섭취하는것으로나타났다 (Figure. ). 국민건강영양조사가시작된 년이후의평균나트륨섭취량 ( 만 세이상, 연령표준화 ) 추이를살펴보면, 년, mg에서 00년,0 mg으로증가하였으나, 개정식품성분표가적용된 00년에, mg로감소하였다. 동일한식품성분표가적용된 00년부터의추이를살펴보면, 나트륨섭취량은 00년,0 mg, 00년, mg, 00년, mg로다소증가
추세였으나, 0 년, mg, 0 년, mg 으로감소하였다. 남자는식사량이여자보다많기 때문에일일나트륨섭취량이여자보다약,000-,00 mg 정도높았으나, 연도별추이는남녀에서 비슷한양상을보였다. 0년국민건강영양조사에서목표섭취량 (세이상,,000 mg) 이상의나트륨과잉섭취분율을살펴본결과 (Figure. ), 세이상남자의.%, 여자의.% 가목표섭취량이상을섭취하고있는것으로나타났으며, 0-0대의과잉섭취자분율은.%( 남자.%, 여자.%) 로가장높게나타났다. 거주지역이나소득수준에상관없이 % 이상의대상자가나트륨을과잉섭취하고있는것으로나타났다. 0 나트륨섭취량조사방법의장단점과타당도 일일나트륨섭취량은 시간회상법, 식사일기법등의영양조사뿐만아니라, 시간소변, - 시간 야간뇨, 단회뇨등소변의나트륨배설량으로도측정될수있다. 이중, 섭취한나트륨의 ~% 는소변으로배설되고소변나트륨은식품으로부터의나트륨섭취량과의상관관계가크다는점에서 시간소변을이용한나트륨배설량측정법이분석법이나트륨섭취량을측정하는데가장정확하나신뢰성있는방법으로알려져있다 [-]. 그러나, 자유로운생활을하는일반인구집단에서 시간소변을누락없이수집하는것이어렵고참여자부담이크다는단점이있다. 영국의 National Diet and Nutrition Survey와핀란드의 North Karelia Salt Project, FINMONICA Study, National FINRISK Study에서는자국민의평균나트륨섭취량을파악하기위해국민대표표본일부에서 시간소변을수집하여지속적으로모니터링하고있다. 0 시간회상법이나식사일기법을이용한영양조사는대규모인구집단조사에서비교적용이하게수행할수있는방법이나, 지난 일동안섭취한모든음식의종류와그양을정확하게기억하거나조리시첨가한소금의양을정확하게파악하기어렵고, 자료처리시음식의표준식품재료량을적용할경우개인별소금섭취량차이가반영되지않는단점을가진다. 또한, 식품성분표 (food composition table) 가
0 0 년주기로개정되므로년도별추이비교에제한점을가진다. 우리나라의국민건강영양조사는 일간 시간회상법, 미국의국가건강영양조사 (National Health and Nutrition Examination Survey) 는 -일간 시간회상법, 일본의국가영양조사 (Japanese National Nutrition Survey) 는 일간 (년이전에는 일간 ) 반실측량식사기록법 (semi-weighted food record method) 을이용하여나트륨섭취량을산출하고있다. 시간식이회상자료를이용하여나트륨섭취량을산출하는방법의타당도는각국가별주요섭취음식과조리특성에따라다른것으로나타났다 (Table )[-]. 서구지역은나트륨섭취의주요공급원이가공식품 ( 미국 %[], 영국 -0%[]) 으로식품섭취량만으로도개인별나트륨섭취의상당량을파악할수있어 시간소변과의상관성이 0.~0. 정도인반면 [,, ], 한국인대상연구결과에서는 시간회상법을이용한나트륨섭취량과 시간소변나트륨간상관성이 0.로매우낮았다 [0]. 이와같이낮은상관성을보이는이유중하나는한국인의소금섭취주요공급원이김치, 국, 찌개등으로개인간소금염미도와조리시첨가량에따라차이가클수있음에도불구하고조리한음식의식품재료량과첨가한조미료량을파악하지못하는경우, 음식의표준식품재료량을적용하여개인의나트륨섭취량차이를파악하기어렵기때문인것으로사료된다. 단회뇨 () 의나트륨농도를이용하여일일나트륨섭취량을추정하는방법은참여자부담이적은장점이있지만, 나트륨농도는수분섭취량에영향을받기쉬우므로개인별정확한나트륨섭취량을파악하기에는한계가있다. 이러한단점에도불구하고, 단회뇨를이용한나트륨섭취의집단평균값은집단간비교및특정집단의연도별추이를파악하는데유용한방법으로제안되었다 []. 국외연구에서단회뇨의나트륨농도는 시간소변나트륨농도와의상관성이 0.-0.[-] 으로, 단회뇨수집시간과횟수에따라차이를보였다 (Table ). 밤사이 -시간야간뇨 (overnight urine) 를이용하는방법은 시간소변보다는수집이용이한장점을가지는반면, 시간을정확하게지켜완전하게수집해야하고낮과밤소변분비의항상성가정이필요하다는제한점을가진다. 야간뇨의경우, 시간소변나트륨배설량과상관성이 0.-0.[0-] 로, 단회뇨보다 시간소변대체방법으로더타당한것으로보고되었다 (Table ). 국민건강영양조사에서나트륨섭취조사방법개선방안
0 국민건강영양조사에서는 시간회상법을이용하여우리나라국민의평균일일나트륨섭취량을추정하고있으나, 앞서기술한바와같이 시간회상법은그조사방법과자료처리방법이가지는고유한특성으로나트륨섭취량을정확하게파악할수없는제한점이있다. 이에, 영양조사의제한점을보완하기위해국민건강영양조사에서는소변을이용한하여나트륨섭취량을추정하는방법의을도입하고자하며, 도입에앞서소변나트륨측정방법의실현가능성과타당성검증이 필요하다. 이에 국민건강영양조사나트륨섭취추정방법연구 (Study on estimation methods of sodium intake in the Korea National Health and Nutrition Examination Survey) 를질병관리본부 (Korea Centers for Disease Control and Prevention) 의정책연구용역과제로현재진행 중이며, 국민건강영양조사참여자중약 00 명의 시간소변, 시간야간뇨, 단회뇨를수집하여우리나라고유의나트륨섭취량추정식을개발하고 시간소변나트륨총배설량과의비교를통해단회뇨와 시간야간뇨를이용한나트륨섭취추정방법의타당성을검증할계획이다. 이연구를통하여우리나라국민의나트륨섭취량추정에가장적절한소변수집방법, 소변수집시간및 수집량에대한지침을마련하여국민건강영양조사에도입할계획이다. 단회뇨나 시간야간뇨로 추정된나트륨섭취량은국민건강영양조사의 시간회상법을이용한영양조사결과를보완할수 있을것으로기대되며, 이를통해추정된우리나라국민의나트륨섭취량은향후나트륨감소정책 추진과보건정책수립및효과평가에필요한기초자료로활용될수있을것으로기대된다. 0 Acknowledgement The KNHANES has been financially supported by the Health Promotion Fund with administrative support by the Ministry of Health and Welfare.
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Table. Studies that comparing -hour dietary recall method with -hour urine collections for sodium intake estimation in healthy population Sample size No. of days of No. of days of Correlation with Author (year) Country Population (age, years) -hour recall -hr urine -hour urine Espeland et al. U.S.A Elderly men, -days -days r=0.0 (00)[] cohort 0 women participants (0- year) Sasaki et al. Japan Cohort men, -days -days r=0. for men (00)[] participants women r=0. for women Reinivuo et al. Finland Random 0 men, -days -day r=0. (00)[] population women (- year) Shin et al. South Healthy women -days -day r=0. (00)[0] Korea volunteers ( 0 year) Rhodes et al. U.S.A Healthy men, -days --days r=0.-0. according to (0)[] volunteers women BMI (0- year)
Table. Studies that comparing spot or overnight urine with -hour urine collections for sodium intake estimation in healthy population Author Sample size Comparing urine Correlation with Country Population (year) (age, years) samples -hour urine Spot urine Kawasaki et al. Japan Healthy men, r=0. for -day ()[] volunteers women r=0. for -day after discarding outlier (0- year) r=0. for -days Kawasaki et al. Japan Healthy adults r=0. ()[] free-living (0- year) (second morning r=0. for -day ~ 0. for -days individuals urine) Costa et al. Brazil Healthy adults r=0. ()[] individuals (0- year) Tanaka et al. (00)[] Japan INTERSALT participants men, women (0- year) Mann & U.S.A Unselected men Gerber Volunteers (- year) (00)[] Brown et al. Europe INTERSALT, men, (0)[] participants, women ( populations) (0- year) Overnight urine Watson & U.S.A Students Langford (0- year) (0)[0] Liu et al. U.S.A Volunteers men ()[] (0- year) Kamata & Japan Healthy men, Tochikubo individuals women (00)[0] (- year) morning urine evening urine (individual level) (population level) overnight urine overnight urine overnight urine r=0. r=0. r=0. r=0. r=0.0 for men r=0. for women r=0. for men r=0. for women r=0. r=0. r=0. for men r=0. for women
Sodium intake (mg/day) Figure. Trend in the mean daily intake of sodium among Koreans above year old, Korea National Health and Nutrition Examination Survey, -0 000 Total ( yr) Men ( yr) Women ( yr) 000 000 000 000 0 0 0 0 0 0 0 000 WHO guideline for sodium intake (,000 mg/day) 000 0 ' '0 '0 '0 '0 '0 '0 ' ' Year Age-standardized mean was calculated using the estimated population based on the 00 Census Korean population. Since 00, a revised food composition table was used to calculate sodium intake from foods.
Figure. Prevalence of people with excessive sodium intake compared to the Korean Dietary Reference Intake among Koreans above years old, Korea National Health and Nutrition Examination Survey 0 % 00 0.....0...0....... 0 0 0 0 Total Men Women - - - 0-0- Urban Rural Q Q Q Q (lowest) (highest) Sex Age Area of residence Household income Values are percent and confidence interval. The intake goal for sodium was established at,000 mg/day for above years old in the Korean Dietary Reference Intake. Age-standardized prevalence according to the area of residence and household income was calculated using the estimated population based on the 00 Census Korean population.