대한지역사회영양학회지 23(1): 38~47, 2018 https://doi.org/10.5720/kjcn.2018.23.1.38 ISSN 1226-0983 (print) / 2287-1624 (on-line) RESEARCH ARTICLE 광주지역성인의나트륨배설량과비만의관계 조미진 1) 허영란 2) 1) 전남대학교대학원식품영양학과, 2) 전남대학교식품영양과학부및생활과학연구소 Association between Sodium Excretion and Obesity of Adults in Gwangju Mijin Jo 1), Young-Ran Heo 2) 1) Department of Food and Nutrition, Chonnam National University Graduate School, Gwangju, Korea 2) Division of Food and Nutrition, Research Institute for Human Ecology, Chonnam National University, Gwangju, Korea Corresponding author Young-Ran Heo Division of Food and Nutrition, Research Institute for Human Ecology, Chonnam National University, 77 Yongbongro, Buk-gu, Gwangju, Korea Tel: (062) 530-1338 Fax: (062) 530-1339 E-mail: yrhuh@jnu.ac.kr ORCID: 0000-0001-5476-3714 Acknowledgments This research was supported by a grants from National Institute of Food and Drug Safety Evaluation(14162 미래식 136). Received: January 31, 2018 Revised: February 14, 2018 Accepted: February 14, 2018 ABSTRACT Purpose: The aim of this study was to analyze the association between sodium excretion and obesity for healthy adults in the Gwangju area. Methods: The participants included 80 healthy adults aged 19 to 69 years in Gwangju. The dietary intake and sodium excretion were obtained using the 24-hour recall method and 24 hour urine collection. The participants were classified into two groups according to the amount of urinary sodium excretion: ( 141.75 mmol/dl, > 141.75 mmol/dl). Results: After adjusting for sex, age, smoking history, and income, the high excretion of sodium group was significantly higher for weight, body mass index, body fat mass, percent body fat, visceral fat area (VFA), waist circumference, hip circumference, and WHR. The energy and nutrients intake were significant after adjusting for sex, age, smoking history, and income. The LSE group had a significantly higher fat intake and Na/K intake ratio. The HSE group had significantly higher fiber intake, and K intake. As the amount of urinary sodium excretion increased, the risk of obesity before correction was 3.57 (95% CI: 1.13-11.25) times greater, and the risk of obesity of T3 increased significantly by 3.33 times (95% CI: 1.05-10.59). After correcting for sex and age, the obesity risk of T2 increased significantly by 4.23 times (95% CI: 1.11-16.06), and after correcting for sex, age, smoking history, and income, the obesity risk of T2 increased significantly by 6.81 times (95% CI: 1.44-32.19) the risk of obesity. Conclusions: An association exists between sodium excretion and obesity in Korean adults. In this study, the high excretion of sodium group was obese and the risk of obesity was higher than the low excretion of sodium group. Korean J Community Nutr 23(1): 38~47, 2018 KEY WORDS 24 hour urine collection, urinary sodium excretion, obesity, sodium intake This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 38
조미진 허영란 39 서 비만은전세계적으로큰관심이있는공중보건문제이며, 전세계성인인구의비만유병률은 2016 년에 13% 로 1975 년에비해 3배가량증가하였다 [1-3]. 우리나라의비만유병률은국민건강영양조사결과만 19세이상의성인에서 1998년에 26.0% 에서 2015년까지 33.2% 로지속적으로증가추세에있다 [4]. 비만은체내에지방조직이과도한상태로체내지방조직과다로혈중지질농도가증가하여고지혈증, 고혈압, 심뇌혈관계질환의발생률과사망률을증가시키고, 당뇨, 생리불순, 암등만성질환의유병률을증가시키는원인으로알려져있다 [5-8]. 이러한비만의원인은유전적, 사회적, 경제적요인이복합적으로결합됨으로써유발되는것으로알려져있다 [9-10]. 또다른이유로과도한 Sodium(Na) 섭취가비만과의상관성이있음을국내외연구를통해제기되고있다 [11-15]. 적절한 Na의섭취는체내에서삼투압조절, 산 / 염기평형유지, 근육의자극반응을조절하며, 신경자극의전달을하는역할을한다 [16]. 하지만과도한 Na 섭취는고혈압을가져올뿐아니라뇌졸중의유발을촉진시키며이로인한사망위험률을 2.33 배나증가시킨다 [17-19]. 또한위암발생에도관여하며 [20], 골다공증을유발하는것으로보고되었다 [21, 22]. 심뇌혈관계질환및만성질환등의위험인자인비만을일으키는원인으로과도한 Na의섭취가거론되고있다. 독일에서진행된연구에서는건강한성장기아동및청소년들을대상으로소변중 Na 배설량을조사한결과 Na 배설량이높을수록체질량지수와체지방률이높게나타났다 [13]. 미국에서 766명의성인을대상으로 24시간소변 Na 배설량과대사증후군요인과의상관성을분석한결과체중, 체질량지수 (Body Mass Index, BMI) 허리둘레수치등에서 Na 배설량이높을수록유의한증가가관찰되는것으로보고되었다 [14]. 또한영국의 National Diet and Nutrition Survey Rolling Program(NDNS RP) 에서 458명의어린이와 785명의성인을대상으로 Na 배설량에따라 3분위수로나누어허리둘레및 BMI를비교한결과 Na 배설량이높은군일수록허리둘레와 BMI가높았으며, 비만유병률또한당첨가음료섭취와에너지섭취를보정한후에도아이들에게서 1.30 배, 성인에서 1.19 배증가하는것으로조사되었다 [15]. Na 과잉섭취가직 간접적으로비만을유발한다는선행연구들이지속적으로보고가되고있으며, Na 섭취가과도하게되면갈증을생겨간접적으로수분섭취및당 론 이첨가된음료나탄산음료섭취를유도한다 [11, 12, 23]. 또한 Na이많이함유된식품의경우에너지밀도가높은경우가많기때문에전체적인에너지섭취량을높여비만을일으킨다는의견이제시되고있으나 [24, 25], 또다른연구에서는 Na이에너지섭취와는독립적으로비만을일으킨다는가설도제기되고있다 [13, 26]. Na 섭취량을추정하는방법은식품섭취빈도조사법, 24시간회상법, 24시간소변수집법등이있다 [27]. 24시간회상법은조사원이조사대상자의 24시간동안의식품섭취를회상하도록하는방법 [28] 으로시간과비용이적게들고, 쉽게조사할수있으나, 하루의식사섭취를조사하므로일반적인식사섭취에대한대표성이떨어지고조사대상자의기억력에의존하므로오차가자주발생한다 [15, 28, 29]. 단회뇨 (Spot urine) 의경우소변수집이간편하여연구대상자에게부담이적다는장점이있으나, 수분섭취량이나 Na 농도및수집시간에의해쉽게영향을받는제한점이있다 [30]. 24시간소변분석법의경우, 대규모의연구가어려우며 24 시간동안소변을수집하는데번거로움과완벽하게수집을확인하기어렵다는단점이있으나, 체내흡수된 Na의 95% 이상을소변으로배출하기때문에기억에의존하는방법들에비해섭취량과대사량을고려하여정확한 Na의섭취량을파악할수있다는장점이있다 [30-32]. 따라서대상자는건강한광주지방의만 19~69세의건강한성인중성별, 연령별로층화추출로모집하여총 80명을대상으로선정하였다. 본연구는 24시간소변수집방법을이용하여 Na의배설량과비만의연관성을살펴보고자한다. 연구대상및방법 1. 연구대상자 2014년 7월부터 2015년 4월까지진행된식품의약품안전처의연구과제인한국인의식습관에따른나트륨적응지수개발의 1세부과제인전국지역별 Na 섭취량분석에참가하는광주지방의성인을대상으로실시하였다. 광주지역에거주하는만 19세 ~69세의성인을대상으로국민건강영양조사방법에따라성별, 연령별로층화하여모집하였다. 연구내용과진행과정등을설명한후참여에동의한대상자들중지원자중고혈압, 심장질환, 당뇨병, 신장질환, 암등의진단을받은경우, 약물을복용중이거나임산부및수유부, 식이조절자등은제외하였으며, 총 80명 (20~60대별남녀각 8명씩 ) 을대상으로분석하였다. Na 배설량에대한참고치가존재하지않기때문에중위수에따라 low 24-urinary sodium excretion group( 141.75 mmol/dl, n=40,
40 광주지역성인의나트륨과비만의관계 이하 LSE) 과 high 24-urinary sodium excretion group (> 141.75 mmol/dl, n=40, 이하 HSE) 으로연구대상자를나누어비교분석하였다. 본연구는경북대학교생명윤리심의위원회의승인 (IRB 승인번호 : IRB 2014-0053) 하에시행되었다. 2. 신체계측연구대상자들의신체계측항목은신장, 체중, 허리둘레, 엉덩이둘레및혈압등을측정하였으며, 신장과체중은자동신장체중계 (BMS370, Biospace, Korea) 와체성분분석기 (InBody720, Biospace, Korea) 를이용하여소수첫째단위까지측정하였다. 신장과체중을이용하여체질량지수 (Body Mass Index, BMI, kg/m 2 ) 를계산하였으며, 골격근량, 체지방량, 체지방률, 내장지방면적 (Visceral Fat Area, VFA, cm 2 ) 은체성분분석기를이용하여소수첫째단위까지측정하였다. 허리둘레와엉덩이둘레는연구대상자가양발을 25~30 cm 간격으로벌리고서서줄자를이용하여직접측정하였다. 허리둘레는가장오목하게들어간부분, 엉덩이둘레는엉덩이의가장볼록한부분을평행하게둘러측정하였다. 허리와엉덩이둘레를이용하여허리둘레 / 엉덩이둘레비 (Waist-Hip Circumference Ratio; WHR) 를구하였다. 비만의기준은 BMI 의경우아시아태평양지침 (2000) 에따라 23.0 kg/m 2 이상의과체중범위부터비만으로판정하였고, 복부비만의기준은대한비만학회기준인성인남성 90 cm 이상, 성인여성 85 cm 이상이면비만으로판정하였다. 3. 인구학적변수설문지를통하여신체활동정도와흡연경력, 소득및교육수준을조사하였다. 운동여부는평소보다몸이매우힘들거나숨이많이가쁜격렬한신체활동정도를 10분이상한날은일주일에며칠인지, 평소보다숨이약간가쁜중등도신체활동을 10분이상한날은일주일에며칠인지, 10분이상걸은날은일주일에며칠인지조사하였으며, 평소보다몸이매우힘들거나숨이많이가쁜격렬한신체활동정도를일주일에 1회이상 10분이상한경우, 평소보다숨이약간가쁜중증도신체활동을일주일에 1회이상 10분이상한경우를운동한것으로정의하였다. 소득은월평균수입을조사하였다. 흡연경력여부는일생동안한번이라도흡연을경험한경우를흡연한경력이있는것으로정의하였다. 4. 혈액분석채혈은최소 8시간공복상태에서채취하였으며, 혈청분리 관 (Serum Separator Tube) 를이용하여 10 ml을채혈하였다. 채혈후 30분가량실온에두어혈병의응고를육안으로확인한후, 1시간이내에냉장원심분리 (4 o C, 3000 rpm, 10분 ) 하고, 혈청분리관을이용해깨끗한상등액만분리하여냉장보관하고, 1~3일이내로분석기관에의뢰하여 Na과 K 농도를분석하였다. 혈중 Na과 K 농도분석은 Ion Selective Electrode(ISE) 법으로분석하였다. 5. 소변수집및분석소변수집은 24시간소변을각 2회수집하였다. 24시간소변은소변수집당일아침첫소변을버리고, 다음소변부터익일아침첫소변까지 24시간동안의모든소변을수집하는것을원칙으로하였으며, 가급적소변수집시작시간을오전 6~9시에채뇨를시작하도록권장하였다. 소변을유실하거나재수집하는경우등소변수집일정의조정이필요한경우 1차 24시간소변수집과최소 3일간의간격을둔후, 2차 24시간소변수집을진행하였다. 24시간소변수집의적합성을판정 [33] 하기위하여 [ 수집한소변량 /( 체중 21)] 으로계산한값이 0.7 이상이면 24시간소변수집이잘수집된것으로하고, 0.7 미만이면 24시간소변중크레아티닌농도가성별, 연령, 체중을이용한추정값과비교하여낮은경우분석대상에서제외하거나재수집하였다. 소변검체의분석은 24시간소변총량을메스실린더로측정한후, 일회용피펫에약 10 ml씩분주하여크레아티닌, Na와 K 농도를분석기관에의뢰하였다. 소변중 Na, K 농도는 Indirect Ion Selective Electrode(ISE) 법으로, Creatinine 농도는 Kinetic Colorimetry Assay으로분석하였다. 6. 식사섭취조사및분석 Na 섭취량은 24시간회상법을이용하여조사하였으며, 식사섭취조사의날짜는 24시간소변수집직전의하루의식사섭취에대하여조사하였다. 24시간회상법은연구자와일대일면담을통해이루어졌으며, 주말및공휴일을제외한평상시기상후부터취침시까지의식사에대하여조사하였다. 섭취량의오차를최소화하기위하여식사기록지를제공하고식사를섭취하는조사당일직접기록하도록하였으며, 식사전과후사진을촬영하도록권장하였다. 또한대표적인식품들의이차원모델예시와계량컵, 계랑스푼등의보조도구를이용하여식사섭취를조사하였다. 24시간회상법일대일면담시연구자는섭취한음식명과섭취량 ( 눈대중량, 부피, 중량 ), 해당음식에들어간재료의명칭과재료량 ( 눈대중량, 부피, 중량 ) 등을기록하였다. 가공식품의경우제품명과제조회사명을기입하도록하였고, 식이보충제및기타건강기능
조미진 허영란 41 식품의종류및섭취량을조사하였다. 영양소섭취량분석은영양평가프로그램 CAN-Pro 4.0(Computer Aided Nutritional Analysis program version 4.0, 한국영양학회 ) 을활용하여분석하였다. 7. 통계분석수집된자료는 SPSS(ver 23.0, IBM) 프로그램을이용하여통계처리및분석하였다. 범주형변수는빈도와백분율로나타내었으며, 연속형변수는평균 ± 표준편차로나타내었다. Na 상태에따른비만지표및혈액, 소변분석결과의평균차이를살펴보고자 24시간소변중 Na 배설량의분포에따라중위치 (141.75 mmol/dl) 를기준으로두군으로분류하였다. 2회에걸쳐조사한소변수집과식사섭취조사의결과는결과값의평균치를사용하였다. 두군의성별, 흡연경력, 학력, 수입, 운동여부는교차분석을실시하였고, 그외의변수들간의평균차이와나이, 성별, 흡연경력, 수입을보정한신체계측치, 혈청과소변중 Na과 K 농도는 Student s t-test 에의해유의성을검증하였다. 나이, 성별, 흡연경력, 수입을보정하여 Na 배설량과신체계측치, 혈청및소변중 Na과 K 농도의상관관계를 Partial correlation coefficient 를이용하여분석하였고, Na 배설량과에너지및영양소섭취량과의상관관계는 Pearson s correlation coefficient 로분석하였다. Na 배설량과비만의연관성은다중로지스틱회귀분석에의해분석하였다. 모든 p값은양측성검정으로하였으며유의수준은 p<0.05 로비교하였다. 결 1. 대상자의특성및신체계측치연구대상자의평균연령은 LSE군은 39.6±14.7세, HSE 군은 47.1±13.3세로 HSE군의평균연령이유의하게높았다 (p=0.019). HSE군의남성비율 (p=0.007), 흡연경력자비율 (p=0.006) 이높았다. 운동여부에서두군간의유의한차이는없었다. 수입은 LSE군은 100만원미만 19명 (47.5%), 100~300만원 20명 (50.0%), 300만원이상인경우 1명 (2.5%) 이었으며, HSE군은 100만원미만 9명 (22.5%), 100~300만원 19명 (47.5%), 300만원이상인경우 12명 (30.0%) 으로두군간의수입에따라대상자의분포가유의하게차이가있었다 (p=0.011)(table 1). 나트륨배설량에따른두군간의신체계측치를비교한결과는 Table 2과같다. 체중은 LSE군은 57.9±8.7 kg, HSE군은 65.8±9.7 kg으로 HSE군의체중이유의하게높았다 (p<0.001). BMI는 LSE군은 21.3±2.7 kg/m 2, HSE 군은 23.6±2.9 kg/m 2 으로 HSE군의 BMI가유의하게높았다 (p<0.001). 내장지방면적 (VFA) 을비교한결과는 LSE 군 68.0±31.1 cm 2, HSE군 87.6±61.5 cm 2 으로 HSE군에서유의하게높았다 (p=0.006). HSE군에서허리둘레 (p<0.001), 엉덩이둘레 (p<0.001), 허리둘레 / 엉덩이둘레비 (WHR)(p=0.007) 가유의하게높았다. 성별, 나이, 흡연경력, 월평균수입을보정하고비교한결과에서는 HSE군에 과 Table 1. General characteristics of the subjects according to 24-hour urinary sodium excretion Characteristics LSE HSE 1) Total (n=80) χ 2 /t p 2) Age 39.6 ± 14.7 3) 47.1 ± 13.3 43.3 ± 14.5 2.41 0.019 Sex Male 14 (35.0) 4) 26 (65.0) 40 (50.0) Female 26 (65.0) 14 (35.0) 40 (50.0) 7.20 0.007 Smoking history Yes 6 (15.0) 17 (42.5) 23 (28.7) No 34 (85.0) 23 (57.5) 57 (71.3) 7.38 0.006 Education Below middle school 5 (12.5) 7 (17.5) 12 (15.0) High school 13 (32.5) 11 (27.5) 24 (30.0) 2.79 0.594 University/College or higher 22 (55.0) 22 (55.0) 44 (55.0) Income <100 5) 19 (47.5) 9 (22.5) 28 (35.0) 100-300 20 (50.0) 19 (47.5) 39 (48.7) 13.69 0.011 300 1 (52.5) 12 (30.0) 13 (16.3) Exercise Yes 6) 26 (65.0) 29 (72.5) 55 (68.8) No 14 (35.0) 11 (27.5) 25 (31.3) 0.52 0.326 1) LSE: low 24-urinary sodium excretion group ( 141.75 mmol/dl), HSE: high 24-urinary sodium excretion group (>141.75 mmol/dl) 2) By t-test and chi-square test. A value of p<0.05 was accepted as significant. 3) Values are presented as mean ± standard deviation. The unit of the value is years. 4) Values are presented as n (%). 5) Salary is a standard (monthly income), and the unit is ten thousand won. 6) "Yes" of exercise is case of moderate activity or intensive activities once a week for more than 10 minutes.
42 광주지역성인의나트륨과비만의관계 서신장 (p<0.001), 체중 (p<0.001), 체질량지수 (Body Mass Index)(p<0.001), 골격근량 (p<0.001), 체지방량 (p<0.001), 체지방률 (p<0.001), 내장지방면적 (VFA)(p< 0.001), 허리둘레 (p<0.001) 와엉덩이둘레 (p=0.003), 허리둘레 / 엉덩이둘레비 (WHR)(p<0.001) 가유의하게높았다. 2. 나트륨배설량에따른혈액및소변분석결과 LSE군과 HSE군의혈청 Na과 K 농도는 Table 3과같다. LSE군과 HSE군의혈청 Na 농도 (141.2±1.3 mmol/ dl vs 141.2±1.9 mmol/dl), K 농도 (4.4±0.4 mmol/ dl vs 4.4±0.3 mmol/dl), 혈청 Na/K ratio(32.5±2.9 mmol/dl vs 32.3±2.4 mmol/dl) 는두간의유의한차이는없었다. 성별, 나이, 흡연경력, 수입을보정한결과에서도두군간의유의한차이는없었다. LSE군과 HSE군의소변중 Na, K 농도는 Table 4와같다. 소변중 Na 농도 (p<0.001), K 농도 (p=0.004) 와 Na/ K ratio(p=0.039) 는 HSE군에서유의하게높았다. 성별, 나이, 흡연경력, 수입을보정한결과에서도소변중 Na 농도 (p<0.001), K 농도 (p<0.001) 와 Na/K ratio(p<0.001) 가 LSE군에비해 HSE군에서유의하게높았다. Table 2. Anthropometric assessments and obesity index according to 24-hour urinary sodium excretion LSE HSE 1) Total (n=80) p 2) Adjusted p 3) Height (cm) 164.8 ± 58.1 4) 167.0 ±5 7.8 165.9 ± 57.9 0.224 <0.001 Weight (kg) 57.9 ± 58.7 65.8 ±5 9.7 61.9 ± 10.0 <0.001 <0.001 BMI (kg/m 2 ) 21.3 ± 52.7 23.6 ± 52.9 22.4 ± 53.0 <0.001 <0.001 Skeletal muscle mass (kg) 23.3 ± 54.8 27.0 ±5 4.8 25.2 ± 55.1 0.001 <0.001 Body fat mass (kg) 15.0 ± 55.7 17.1 ± 55.8 16.0 ±5 5.8 0.118 <0.001 Percent body fat (%) 25.9 ±5 8.3 25.8 ± 57.4 25.7 ±5 8.2 0.920 <0.001 Visceral fat area (cm 2 ) 68.0 ± 31.1 87.6 ± 61.5 77.8 ± 32.6 0.006 <0.001 Waist circumference (cm) 77.6 ± 58.6 84.0 ± 57.6 80.8 ± 58.7 <0.001 <0.001 Hip circumference (cm) 93.1 ±5 4.9 97.0 ± 55.5 95.0 ±5 5.5 <0.001 0.003 WHR 0.8 ± 50.1 0.9 ± 50.1 0.8 ±5 0.1 0.007 <0.001 1) LSE: low 24-urinary sodium excretion group ( 141.75 mmol/dl), HSE: high 24-urinary sodium excretion group (>141.75 mmol/dl) 2) By t-test analysis. A value of p<0.05 was accepted as significant. 3) By t-test analysis adjusted for age, sex, smoking history and income. A value of p<0.05 was accepted as significant. 4) Values are presented as mean ± standard deviation. BMI: Body Mass Index, WHR: Waist-Hip Circumference Ratio Table 3. Na level, K level and Na/K ratio in serum according to 24-hour urinary sodium excretion LSE HSE 1) Total Adjusted p 2) (n=80) p 3) Serum Na (mmol/l) 141.2 ± 1.3 4) 141.2 ± 1.9 141.2 ± 1.6 0.840 0.067 Serum K (mmol/l) 4.4 ± 0.4 4.4 ± 0.3 4.3 ± 0.4 0.877 0.160 Serum Na/K Ratio 32.5 ± 2.9 32.3 ± 2.4 32.4 ± 2.7 0.810 0.098 1) LSE: low 24-urinary sodium excretion group ( 141.75 mmol/dl), HSE: high 24-urinary sodium excretion group (>141.75 mmol/dl) 2) By t-test analysis. A value of p<0.05 was accepted as significant. 3) By t-test analysis adjusted for age, sex, smoking history and income. A value of p<0.05 was accepted as significant. 4) Values are presented as mean ± standard deviation. Table 4. Na level, K level and Na/K ratio in urine according to 24-hour urinary sodium excretion LSE HSE 1) Total (n=80) p 2) Adjusted p 3) Na (mmol/dl) 108.8 ± 23.0 3) 198.6 ± 41.2 153.7 ± 56.0 <0.001 <0.001 K (mmol/dl) 52.6 ± 28.3 69.0 ± 20.0 60.8 ± 25.7 0.004 <0.001 Na/K Ratio 2.6 ± 51.2 3.1 ±5 0.9 2.8 ± 51.1 0.039 <0.001 1) LSE: low 24-urinary sodium excretion group ( 141.75 mmol/dl), HSE: high 24-urinary sodium excretion group (>141.75 mmol/dl) 2) By t-test analysis. A value of p<0.05 was accepted as significant. 3) By t-test analysis adjusted for age, sex, smoking history and income. A value of p<0.05 was accepted as significant. 4) Values are presented as mean ± standard deviation.
조미진 허영란 43 Table 5. Energy and nutrients intake according to 24-hour urinary sodium excretion LSE HSE 1) Total Adjusted p 2) (n=80) p 3) Energy (kcal) 1872.6 ± 1,459.2 4) 1856.8 ± 1,487.2 1,864.7 ± 1,470.5 0.882 0.127 Carbohydrate (g) 280.4 ± 15,75.8 279.2 ± 15,77.2 279.8 ± 15,76.0 0.945 0.446 Fiber (g) 21.9 ± 15,10.3 23.0 ± 155,7.4 22.4 ± 155,8.9 0.599 0.001 Protein (g) 72.5 ± 15,22.1 71.6 ± 15,20.7 72.0 ± 15,21.3 0.845 0.363 Fat (g) 49.4 ± 15,20.8 47.2 ± 15,22.9 48.4 ± 15,21.7 0.694 0.001 Cholesterol (mg) 391.0 ± 1,238.2 334.9 ±1, 174.4 362.9 ±1, 209.3 0.233 0.071 Water (g) 2,251.0 ±1, 712.8 2,214.6 ± 1,766.5 2,101.5 ± 1,222.3 0.645 0.802 Na (mg) 3,776.2 ± 1,890.4 3,906.2 ± 1,786.0 3,841.2 ± 1,828.4 0.753 0.634 K (mg) 2,680.1 ± 1,031.5 2,712.3 ±1, 879.1 2,696.2 ±1, 952.4 0.881 0.011 Na/k intake ratio 1.6 ± 155,1.1 1.4 ± 155,0.5 1.5 ± 155,0.8 0.570 0.008 Na density (mg/1000 kcal) 2,003.0 ± 1,842.3 2,064.9 ± 1,606.0 2,034.0 ± 1,729.8 0.707 0.503 1) LSE: low 24-urinary sodium excretion group ( 141.75 mmol/dl), HSE: high 24-urinary sodium excretion group (>141.75 mmol/dl) 2) By t-test analysis. A value of p<0.05 was accepted as significant. 3) By t-test analysis adjusted for age, sex, smoking history and income. A value of p<0.05 was accepted as significant. 4) Values are presented as mean ± standard deviation. 3. 나트륨배설량에따른에너지및영양소섭취량연구대상자의에너지및영양소의섭취량은 Table 5와같다. 두군간의에너지섭취량, 탄수화물섭취량, 식이섬유섭취량, 단백질섭취량, 지방섭취량, 콜레스테롤섭취량, 수분섭취량, Na 섭취량, 칼륨섭취량, Na/K intake ratio, 섭취량중 Na 밀도는두군간의유의한차이가없었다. 성별, 나이, 흡연경력, 수입을보정한결과 LSE군이 HSE군에비해지방섭취량 (p=0.001), Na/K intake ratio(p=0.008) 이유의하게높았으며, HSE군이 LSE군에비해식이섬유섭취량 (p=0.001), 칼륨섭취량 (p=0.011) 이유의하게높았다. 4. 나트륨배설량과변수들의연관성연구대상자의 24시간소변중 Na 배설량과변수들간의상관관계를분석한결과는 Table 6과같다. 상관관계는에너지및영양소섭취량을제외한연속형변수들은성별, 나이, 흡연경력, 수입을보정하고분석하였다. 그결과체중 (r=0.286, p=0.013), 허리둘레 (r=0.249, p=0.031), 엉덩이둘레 (r=0.351, p=0.002), BMI(r=0.301, p= 0.009), 체지방량 (r=0.279, p=0.015), 체지방률 (r= 0.244, p=0.035), 24시간소변중 K 배설량 (r=0.432, p<0.001) 과양의상관관계를보여주었다. 5. 나트륨배설량과비만의연관성연구대상자의 Na 배설량과비만의연관성을분석한결과는 Table 7과같다. Na 배설량에따라 3분위 (Lower tertile; T1, Middle tertile; T2, Upper tertile; T3) 로나누었고, 비만판정은아시아태평양지침 (2000) 의 BMI를기준으로과체중과비만을분류하였다. 보정하지않은 Table 6. Correlation between 24-hour urinary sodium excretion and variables Variables Coefficients p 1) Height (cm) 0.001 0.995 Weight (kg) 0.286 0.013 Waist circumference (cm) 0.249 0.031 Hip circumference (cm) 0.351 0.002 WHR 0.076 0.519 BMI (kg/m 2 ) 0.301 0.009 Skeletal muscle mass (kg) 0.178 0.127 Body fat mass (kg) 0.279 0.015 Percent body fat (%) 0.244 0.035 Visceral fat area (cm 2 ) 0.148 0.204 Serum Na (mmol/dl) 0.099 0.397 Serum K (mmol/dl) 0.103 0.378 Serum Na/K (mmol/dl) 0.081 0.492 Energy intake (kcal) 0.072 0.523 Carbohydrate intake (g) 0.023 0.841 Fat intake (g) 0.009 0.936 Cholesterol intake (mg) 0.059 0.601 Protein intake (g) 0.114 0.313 Fiber intake (g) 0.071 0.531 Water intake (g) 0.071 0.534 Na intake (mg) 0.138 0.223 K intake (mg) 0.056 0.624 Na/k intake ratio 0.008 0.994 Na density (mg/1000 kcal) 0.104 0.358 Urine K (mmol/dl) 0.447 <0.001 Urine Na/K Ratio 0.084 0.472 1) Anthropometric, Na and K level in serum and urine were adjusted for age, sex, smoking history and income by Partial correlation coefficients. Energy and nutrients intake by Pearson's correlation coefficients. A value of P<0.05 was accepted as significant. BMI: Body Mass Index, WHR: Waist-Hip Circumference Ratio
44 광주지역성인의나트륨과비만의관계 Table 7. Association between obesity and sodium excretion according to 24-hour urinary sodium excretion 24-hour urinary sodium excretion T1 1) T2 T3 Reference Odds ratio (95% CI) p 5) Odds ratio (95% CI) p overweight/obesity Model-1 2) 1.00 3.57 (1.13 11.25) 0.030 3.33 (1.05 10.59) 0.041 Model-2 3) 1.00 4.23 (1.11 16.06) 0.034 2.41 (0.64 9.08) 0.195 Model-3 4) 1.00 6.81 (1.44 32.19) 0.015 1.47 (0.33 6.63) 0.613 1) T1: Lower tertile of 24-hour urinary sodium excretion, T2: Middle tertile of 24-hour urinary sodium excretion, T3: Upper tertile of 24-hour urinary sodium excretion 2) Model-1: unadjusted 3) Model-2: adjusted for age and sex 4) Model-3: adjusted for age, sex, smoking history and income 5) By multiple logistic regression analysis. A value of p<0.05 was accepted as significant Model-1, 성별과나이를보정한 Model-2, 성별, 나이, 흡연경력, 수입을보정한 Model-3 으로분석하였다. Na 배설량이증가함에따라 Na 배설량낮은분위인 T1 을기준으로보정하지않은 Model-1에서 T2의비만위험률은 3.57배 (95% CI: 1.13-11.25, p=0.030), T3의비만위험률은 3.33배 (95% CI: 1.05-10.59 p=0.041) 로유의하게위험률이증가하였다. 성별과나이를보정한 Model-2에서 T2의비만위험률은 4.23배 (95% CI: 1.11-16.06 p=0.034) 로유의하게증가하였다. 성별, 나이, 흡연경력, 수입을보정한 Model-3 에서 T2의비만위험률은 6.81배 (95% CI: 1.44-32.19 p=0.015) 로비만위험률이유의하게증가하였다. 고 Na 배설량의참고치가존재하지않기때문에중위수에따라 LSE군 ( 141.75 mmol/dl, n=40) 과 HSE군 (> 141.75 mmol/dl, n=40) 으로연구대상자를나누어비교분석하였다. 두군을비교한결과 HSE군의평균연령이높았고, 남성의비율과흡연경력자의비율이높았다. Na 배설량을조사한선행연구에서 Na 배설량이높은분위일수록평균연령이높았고, 남성의비율이높은것으로나타났으며, 흡연경력자의비율도높은것으로나타났다 [34]. 한국인중장년층을대상으로진행한연구에서흡연하는사람이짠맛을선호하고 Na 섭취량이높다고보고되었다 [35]. 이는나이가들수록미각의감도가감소하여짠맛에대한기호가증가하는경향을보이며 [36-40], 흡연이미각의예민도를저하시켜식품선택에영향을주기때문인것으로사료된다 [40]. HSE군에서체중, BMI, 골격근량, 내장지방면적 (VFA), 허리둘레와엉덩이둘레, 허리둘레 / 엉덩이둘레비 (WHR) 가유의하게높았다. 성별, 나이, 흡연경력, 월평균수입을보정하고비교한결과, HSE군이신장, 체중, BMI, 골격근량, 체 찰 지방량, 체지방률, 내장지방면적 (VFA), 허리둘레와엉덩이둘레, 허리둘레 / 엉덩이둘레비 (WHR) 가유의하게높았다. 우리나라성인을대상으로조사한선행연구 [41] 에서는 Na 배설량이가장높은군이나트륨배설량이낮은다른군에비해허리둘레수치가유의하게높았고, 국외에서보고된선행연구 [42] 에서도 Na 배설량이많을수록 BMI, 허리둘레, 엉덩이둘레, 엉덩이둘레, 허리둘레 / 엉덩이둘레비 (WHR), 허리 / 신장비 (Waist to height ratio; WHtR) 가증가하는경향을보여주었다. 독일과미국에서보고된결과에서도 Na 배설량이많을수록체중, BMI, 체지방률과허리둘레가높았다 [13, 14]. 혈청 Na, K 농도, Na/K ratio는두간의유의한차이는없었으며, 성별, 나이, 흡연경력, 수입을보정한결과에서도두군간의유의한차이는없었다. 소변중 Na, K 농도, Na/ K ratio는 HSE군이유의하게높았으며, 성별, 나이, 흡연경력, 수입을보정한결과에서도소변중 Na과 K 농도, Na/K ratio가 HSE군에서유의하게높았다. 건강한성인을대상으로한선행연구에서는혈중 Na과 K 농도는두군간의차이가없으나, 체외로배설되는 Na과 K 농도에유의한차이를보이는것은체내항상성유지를위한조절이적절하게이루어진결과로보고하였다 [43]. 체내 Na 농도의조절및배설은 K이부신피질호르몬의분비를감소시켜 Na의재흡수를저해하고, Na/K 프를펌활성화하여혈관을확장시켜 Na을체외로배설되도록하는역할을한다 [44]. 건강한성인에서 Na 섭취량이많은경우신장에서여과한 Na의 99.9% 가배설되어 Na 섭취량이많을수록배설량이증가하고 [22, 45], 체내항상성유지를위해 Na의배설과함께 K의배설이발생하기때문에 Na 배설량이높을수록 K의배설량이증가하게된다 [44]. 에너지및영양소섭취량은두군간의유의한차이는없었다. 성별, 나이, 흡연경력, 수입을보정한결과 LSE군이 HSE군에비해지방섭취량, Na/K의섭취비율이유의하게
조미진 허영란 45 높았으며, HSE군이 LSE군에비해식이섬유섭취량, 칼륨섭취량이유의하게높았다. 부산지역의일부성인을대상으로 Na 배설량에따라 4분위로나누어에너지및영양소섭취량을비교한결과 Na 섭취량, Na/K의섭취비율, 섭취량중 Na 밀도에서유의한차이를보였으나에너지및 Na을제외한다른영양소섭취량에서는차이가없어본연구결과와일부일치하는부분이있었다 [46]. Na의섭취량에대한상반된결과가나온이유는우리나라의주요식사패턴과 Na 섭취의주요공급원은김치, 국, 찌개등으로개인간의소금염미도나조리시첨가량, 조리방법에따라차이가커질수있음에도표준요리법에의한식품재료량을적용하여산출하기때문에파악하기어렵기때문이다 [48]. Na이비만을일으키는기전은아직명확하게밝혀지지않았지만, 선행연구에서는 Na이많이함유된식품의경우에너지밀도가높은경우가많기때문에전체적인에너지섭취량을높여비만하게된다는의견이있다 [24, 25]. 또한 Na의섭취가과도하면갈증을불러일으켜이러한갈증으로당첨가음료 (sugarsweetened beverage) 의섭취가증가하게되어총에너지섭취량이증가하여비만을일으킨다고보고되었다 [11, 12, 44]. 하지만이에대한상반된연구결과도보고되어비만을일으키는기전으로설명하기에역부족하다 [13, 26]. 일각에서는 Na이중독을일으키는물질로작용하여쾌락을느끼는오피오이드수용체를자극하게되어짠맛에대한중독과내성으로인해에너지섭취량을증가시켜비만을일으킨다는의견도제시하였다 [47]. 따라서 Na의섭취가에너지및영양소의섭취와의상관성을밝히기위해서는에너지와영양소섭취량에대한정확한조사가이루어져야한다. Na 배설량과체중, 허리둘레, 엉덩이둘레, BMI, 체지방량, 체지방률, 소변중 K 배설량에서양의상관관계가나타났으며, 로지스틱회귀분석을실시한결과, Na 배설량이증가함에따라 Na 배설량낮은분위인 T1을기준으로보정하지않은 Model-1에서 T2의비만위험률은 3.57배, T3의비만위험률은 3.33 배로유의하게위험률이증가하였다. 성과나이를보정한 Model-2 에서 T2의비만위험률은 4.23 배로유의하게증가하였으며, T3의비만위험률은 2.41배증가하였으나유의한차이는없었다. 성별, 나이, 흡연경력, 수입을보정한 Model-3에서 T2의비만위험률은 6.81배로비만위험률이유의하게증가하였다. 하지만 T3의비만위험률은유의한차이를보이지않았다. 본연구에서 T3의비만위험률이 T2와달리 Model-2와 Model-3에서유의성이없어진것은흥미로운결과이다. 이러한결과는본연구에서보정하지않은다른요인, 즉에너지와당섭취와같은영양소와식이섭취요인및교육수준과신체활동과같은 인자의영향이크게작용했을가능성이있으며이에대한추후연구가필요한것으로생각된다. 선행연구들에따르면영국에서어린이와성인을대상으로 Na 배설량에따라 3분위수로나누어비만위험률이당첨가음료섭취와에너지섭취를보정한후에도아이들에게서 1.30 배, 성인에서 1.19 배증가한다고보고되었다 [15]. 우리나라성인을대상으로 Na 배설량과비만위험률을분석한결과남성의경우 2.68배, 여성의경우 3.60 배증가하였으며, 성별, 흡연상태, 신체활동정도, 월평균수입, 교육수준, 하루에너지섭취량을보정한후의결과에서남성은 2.86 배, 여성은 3.41 배증가하였다 [32]. 우리나라 2010년 ~2014년국민건강영양조사를분석한결과성인남성의경우에너지밀도를보정한모델에서 Na을 2000 mg 이하, 2000~4000 mg 정도섭취한군에비해 4000 mg 이상으로과도하게섭취할수록 BMI가 1.29~1.65 배가증가하는것으로보고되었다 [10]. 위의결과로살펴본바, Na 배설량이많은군에서비만지표의수치가유의하게높았고, 양의상관관계를나타났으며, 비만의위험률또한증가하여 Na 배설량이비만과연관성이있음을유추해볼수있다. 본연구는지역이광주로한정되어있어지역적제한이있으며, 대상자들이모든인간에대한대표성을지니기힘들다는점, 단면연구특성상 Na의섭취와비만과직접적인영향을주는주요인자나기전을규명하기어렵다는한계점이있다. 따라서장기간의추적관찰등추가적인연구가필요할것으로생각된다. 그러나연구대상자를성별, 연령별층화표본추출로대상자를모집하여변수들의영향력을최대한배제하여연구를진행하였고, Na의상태를반영할수있는섭취량, 혈액내함량, 배설량을모두측정하였다. 또한배설량측정에는가장신뢰도가높은 24시간소변수집법을이용하였다. 비만과의정확한연관성을파악하고자본연구과제에서보고된선행연구 [40] 에추가로체지방량, 체지방률, 내장지방면적 (VFA) 를제시하여건강한성인을대상으로 Na 배설량과비만과연관성을분석했다. 우리나라의경우절임류, 김치류, 찌개등전반적인일상적으로섭취하는식사에서 Na 섭취수준이높은점을감안할때, 그로인한비만이다양한관련질환을유발할수있는환경에쉽게노출될수있으므로, 향후지속적인국가적차원의 Na 섭취저감화방안이필요할것으로생각된다. 요약및결론 Na의섭취와비만과의직접적인연관성에대해서는아직논란의여지가많다. 본연구는광주광역시에거주하는건강
46 광주지역성인의나트륨과비만의관계 한성인을대상으로 Na 배설량과비만과의연관성을비교분석하고자하였다. 연구대상자는성별, 연령별로층화표본추출하여선정, 모집하였으며, 고혈압, 신장질환등이없는건강한성인만 19~69세의남녀 80명이참여하였다. 모든대상자의신체계측, 혈액검사, 식사섭취조사, 24시간소변수집을진행하였다. 연구대상자는 Na배설량에따라중위수 (141.75 mmol/dl) 를기준으로나트륨배설량이낮은 LSE 군과나트륨배설량이많은 HSE군, 2군으로나누어비교분석하였다. HSE군이 LSE군에비하여평균연령이높았고, 남성의비율과흡연경력자의비율이높았으며, 두군간의월평균수입에따른대상자의분포가유의하게차이가있었다. HSE군이 LSE군에비하여체중, BMI, 골격근량, 내장지방면적 (VFA), 허리둘레와엉덩이둘레, 허리둘레 / 엉덩이둘레비 (WHR) 가유의하게높았다. 성별, 나이, 흡연경력, 월평균수입을보정한결과에서 HSE군이신장, 체중, BMI, 골격근량, 체지방량, 체지방률, 내장지방면적 (VFA), 허리둘레와엉덩이둘레, 허리둘레 / 엉덩이둘레비 (WHR) 가유의하게높았다. 혈청 Na, K 농도, Na/K ratio는성별, 나이, 흡연경력, 수입을보정한전과후의결과에서두군간의유의한차이는없었다. 소변중 Na 농도, K 농도와 Na/K ratio는성별, 나이, 흡연경력, 수입을보정한전과후의결과에서 LSE 군에비해 HSE군에서유의하게높았다. 에너지및영양소섭취량은성별, 나이, 흡연경력, 수입을보정한결과 LSE군이 HSE군에비해지방섭취량과 Na/K 섭취비율이유의하게높았으며, HSE군이 LSE군에비해식이섬유섭취량과칼륨섭취량이유의하게높았다. 연구대상자의 Na 배설량과 Na 배설량과비만의연관성을 Na 배설량에다라 3분위로나누어비교분석하였다. Na 배설량이증가함에따라 Na 배설량이낮은분위를기준으로보정하지않은 Model-1에서 Na 배설량의중간분위그룹에서비만위험률은 3.57 배, Na 배설량이높은분위그룹에서비만위험률은 3.33 배유의하게위험률이증가하였다. 성별과나이를보정한 Model-2 에서 T2의비만위험률은 4.23 배유의하게증가하였다. 성별, 나이, 흡연경력, 수입을보정한 Model-3 에서 T2의비만위험률은 6.81 배로비만위험률이유의하게증가하였다. 본연구는우리나라건강한성인을대상으로 Na 배설량과비만과의연관성을보고자하였다. 위의결과로미루어, 광주광역시건강한성인에서 Na 섭취는비만과상관성이있음을확인할수있었다. 본연구는단면연구로서 Na과비만과의명확한기전을밝히기어려운제한점이있으며, Na과비만의정확한연관성을밝히기위한추후연구가필요하다. References 1. Song HJ, Cho YG, Lee HJ. Dietary sodium intake and prevalence of overweight in adults. Metabolism 2013; 62(5): 703-708. 2. Kang JS, Kim HS. A study on the evaluation of a nutritional education program for the middle aged obese women. Korean J Food Nutr 2004; 17(4): 356-367. 3. WHO. Fact sheets in obesity [Internet]. WHO; 2014 [cited 2017 Oct 15]. Available from: http://www.wpro.who.int/mediacentre/ factsheets/obesity/en/. 4. Prevalence of obesity [Internet]. Ministry of Health & Welfare; 2016 [cited 2017 Oct 15]. Available from: http://www.index. go.kr/potal/main/eachdtlpagedetail.do?idx_cd=2705. 5. Lew EA, AM F. Mortality and weight: insured lives and the American Cancer Society studies. Women 1985; 80(1.20): 1-19. 6. Hida K, Wada J, Eguchi J, Zhang H, Baba M, Seida A et al. Visceral adipose tissue-derived serine protease inhibitor: a unique insulin-sensitizing adipocytokine in obesity. Proc Natl Acad Sci USA 2005; 102(30): 10610-10615. 7. Kunitomi M, Wada J, Takahashi K, Tsuchiyama Y, Mimura Y, Hida K et al. Relationship between reduced serum IGF-I levels and accumulation of visceral fat in Japanese men. Int J Obes 2002; 26(3): 361-369. 8. Flachs P, Mohamed-Ali V, Horakova O, Rossmeisl M, Hosseinzadeh-Attar MJ, Hensler M et al. Polyunsaturated fatty acids of marine origin induce adiponectin in mice fed a high-fat diet. Diabetologia 2006; 49(2): 394-397. 9. Park JA, Yoon JS. Dietary behaviors and status of nutrient intakes by the obesity levels of housewives in Daegu. Korean J Community Nutr 2005; 10(5): 623-632. 10. Cheon SY, Wang HW, Lee HJ, Hwang KM, Yoon HS, Kang YJ. Relationship of sodium consumption with obesity in Korean adults based on Korea National Health and Nutrition Examination Survey 2010~2014. J Nutr Health 2017; 50(1): 64-73. 11. He FJ, Marrero NM, MacGregor GA. Salt intake is related to soft drink consumption in children and adolescents a link to obesity? Hypertension 2008; 51(3): 629-634. 12. Grimes CA, Riddell LJ, Campbell KJ, Nowson CA. Dietary salt intake, sugar-sweetened beverage consumption, and obesity risk. Pediatrics 2013; 131(1): 14-21. 13. Libuda L, Kersting M, Alexy U. Consumption of dietary salt measured by urinary sodium excretion and its association with body weight status in healthy children and adolescents. Public Health Nutr 2012; 15(3): 433-441. 14. Hoffmann IS, Cubeddu LX. Salt and the metabolic syndrome. Nutr Metab Cardiovasc Dis 2009; 19(2): 123-128. 15. Ma Y, He FJ, MacGregor GA. High salt intake independent risk factor for obesity? Hypertension 2015; 66(4): 843-849. 16. Choi HM, Kim JH, Lee JH, Kim CI, Song GH, Jang GJ et al. Nutrition. 4th ed. Paju: Kyomunsa; 2012. p. 316-317. 17. Simon G. Experimental evidence for blood pressure-independent vascular effects of high sodium diet. Am J hypertens 2003; 16(12): 1074-1078.
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