Associations of urinary sodium levels with overweight and central obesity in a population with a sodium intake

Juyeon Lee; Yunji Hwang; Kyoung-Nam Kim; Choonghyun Ahn; Ho Kyung Sung; Kwang-Pil Ko; Kook-Hwan Oh; Curie Ahn; Young Joo Park; Suhnggwon Kim; Young-Khi Lim; Sue K Park

doi:10.1186/s40795-018-0255-6

Associations of urinary sodium levels with overweight and central obesity in a population with a sodium intake

BMC Nutr. 2018 Nov 21:4:47. doi: 10.1186/s40795-018-0255-6. eCollection 2018.

Authors

Juyeon Lee^{1

2

3}, Yunji Hwang^{1

2

3}, Kyoung-Nam Kim^{1

4}, Choonghyun Ahn^{1

2

3}, Ho Kyung Sung^{1

3}, Kwang-Pil Ko⁵, Kook-Hwan Oh⁶, Curie Ahn⁶, Young Joo Park⁷, Suhnggwon Kim⁸, Young-Khi Lim⁹, Sue K Park^{1

2

3}

Affiliations

¹ 1Department of Preventive Medicine, College of Medicine, Seoul National University, 103 Daehakro, Seoul, Jongnogu 03080 South Korea.
² 2Department of Biomedical Science, College of Medicine, Seoul National University, 103 Daehakro, Seoul, Jongnogu 03080 South Korea.
³ 3Cancer Research Institute, Seoul National University, 103 Daehakro, Seoul, Jongnogu 03080 South Korea.
⁴ 4Division of Public Health and Preventive Medicine, Seoul National University Hospital, 101 Daehakro, Seoul, Jongnogu 03080 South Korea.
⁵ 5Department of Preventive Medicine, Gachon University College of Medicine, 38-13 Dokjeom-ro 3beon-gil, Incheon, Namdong-gu South Korea.
⁶ 6Division of Nephrology, Department of Internal Medicine, Seoul National University Hospital, 101 Daehakro, Seoul, Jongnogu 03080 South Korea.
⁷ 7Division of Endocrinology, Department of Internal Medicine, Seoul National University Hospital, 101 Daehakro, Seoul, Jongnogu 03080 South Korea.
⁸ Seoul K-Clinic, 18-5, Changgyeonggung-ro 34-gil, Seoul, Jongnogu 03077 South Korea.
⁹ 9Department of Radiological Science, Gachon University College of Medicine, 191 Hambangmoe-ro, Incheon, Yeonsu-gu South Korea.

Abstract

Background: Previous studies have reported an association between dietary sodium intake and overweight/central obesity. However, dietary survey methods were prone to underestimate sodium intake. Therefore, this study investigated the associations of calculated 24-h urinary sodium excretion, an index of dietary sodium intake, with various obesity parameters including body mass index (BMI) and waist circumference (WC) in a population with a relatively high sodium intake.

Methods: A total of 16,250 adults (aged ≥19 years) and 1476 adolescents (aged 10-18 years), with available information on spot urine sodium levels and anthropometric measurements from the Korea National Health and Nutrition Examination Survey (KNHANES) were included in this study. We calculated 24-h urine sodium excretion levels from spot urine sodium levels using the Tanaka formula.

Results: In adults, those with high sodium excretion levels (≥ 3200 mg) showed increased odds of overweight and central obesity compared to those with low urinary sodium excretion level (< 2200 mg) (odds ratio [OR] = 2.17, 95% confidence interval [CI] = 1.90-2.49 for overweight; OR = 2.50, 95% CI = 2.13-2.94 for central obesity). These associations were also observed in adolescents (OR = 5.80, 95% CI = 3.17-10.60 for overweight; OR = 4.19, 95% CI = 1.78-9.89 for central obesity).

Conclusions: The present study suggests that reducing salt intake might be important for preventing overweight and central obesity, especially in adolescents. However, because the present study was conducted with cross-sectional study design, further longitudinal studies are warranted to confirm the causal relationship between urinary sodium excretion and overweight/central obesity.

Keywords: Body mass index; Korean National Health and nutrition examination survey; Obesity; Sodium excretion; Waist circumference.