Original Article Clin Nutr Res 2015;4:182-189 http://dx.doi.org/10.7762/cnr.2015.4.3.182 pISSN 2287-3732 ∙ eISSN 2287-3740
Dietary Very Long Chain Saturated Fatty Acids and Metabolic Factors: Findings from the Korea National Health and Nutrition Examination Survey 2013 Youn Sue Lee1,2, Yoonsu Cho1,2, Min-Jeong Shin1,2,3* 1
Department of Food and Nutrition, Korea University, Seoul 136-701, Korea Department of Public Health Science, BK21PLUS Program in Embodiment: Health-Society Interaction, Graduate School of Korea University, Seoul 136-701, Korea 3 Korea University Guro Hospital, Korea University College of Medicine, Seoul 152-703, Korea
2
The present study was aim to evaluate the association between very long chain saturated fatty acids (VLSFAs) and metabolic syndrome (MetS) in Korean population. The study population were recruited from the Korea National Health and Nutrition Examination Survey VI (2013). Using the cross-sectional study design, socio-demographic factors, medical history, and clinical measurements were investigated according to quartiles of VLSFAs intake. The associations between each and sum of VLSFAs intake and MetS were assessed by logistic regression. The result indicated that higher intake of VLSFAs was significantly associated with favorable metabolic status, including lower levels of circulating triglyceride (TG) (p < 0.05). Additionally, subjects with higher intake of arachidic acid and total VLSFAs were negatively associated with MetS risk compared to subjects with lower intake of those fatty acids (p < 0.05). In conclusion, dietary VLSFAs intake was associated with metabolic risk factors and lower risk of MetS in Korean population. Key Words: Fatty acid, Metabolic syndrome, Arachidic acid, Behenic acid, Lignoceric acid
*Corresponding author Min-Jeong Shin Address Department of Food and Nutrition, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 136-701, Korea Tel +82-2-3290-5643 Fax +82-2-940-2849 E-mail
[email protected] Received June 14, 2015 Revised June 30, 2015 Accepted July 2, 2015
© 2015 The Korean Society of Clinical Nutrition 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.
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Introduction Metabolic syndrome (MetS) is a clustering of metabolic disorders such as abdominal obesity, dyslipidemia, elevated blood pressure, and high levels of blood glucose [1]. According to the world reports, the age-adjusted MetS prevalence has been estimated 34.2% between 1999 and 2006 in the US [2] and 31.3% in 2007 in Korea [3]. Although MetS accelerates the risk of developing chronic diseases such as atherosclerosis, cardiovascular disease, and diabetes [4], the exact pathologic mechanisms of MetS have not been identified. Previous studies, across the observational [5-7], prospective [8,9], and meta-analysis study designs [10], have speculated that type of dietary fat and plasma fatty acid (FA) composition contribute to development of insulin resistance and MetS. Furthermore, the intervention studies reported that a change of fat composition in diet affects on a composition of plasma FA as well as metabolic dysfunction [11,12]. While polyunsatu-
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Dietary Fatty Acids and Metabolic Factors rated FA (PUFA) intake has been reported by its inverse association with the risk of metabolic dysfunction [13,14], the intake of saturated FA (SFA) has been associated with its adverse effects on the risk of MetS [15,16]. It is a well established fact that palmitic acid (16:0) and stearic acid (18:0) have atherogenic and cardiovascular effects [17,18]. However, recent studies have suggested that each SFAs have different effects on metabolic conditions according to their chain length [19]. SFAs with 20 or more carbon atoms such as arachidic acid (20:0), behenic acid (22:0), and lignoceric acid (24:0), were classified as very long chain SFAs (VLSFAs). Previous studies on that VLSFAs reported that intakes of VLSFA have beneficial effects on the metabolic abnormalities, including diabetes and cardiovascular diseases [1, 20-22]. However, the association between dietary VLSFAs and MetS has not been fully understood. With respect to nutrition transition the intake of saturated fat has been considerably increased in the Korea. Therefore, we aimed to evaluate the effect of VLSFAs intake on metabolic parameters. Additionally, we also examined the association between dietary VLSFAs intake and MetS prevalence in Korean population.
hormonal status. Finally, 4,232 subjects were included in the statistical analysis. The institutional review board of the Centers for Disease Control and Prevention in Korea approved the KNHANES. All participants in the survey provided informed consent form.
Materials and Methods
General characteristics of the subjects We obtained data from KNHANES VI, including demographic, anthropometric, and biochemical measurement data. Demographic variables that were potential confounders including age, education, alcohol use, smoking status, physical activity, nutrient supplementation use, and disease status. Subjects who smoked during the survey period were regarded as current smokers. Subjects who consumed alcohol at least once a month considered as current alcohol consumers. Education level was divided into four categories as elementary school, middle school, high school, or university, according to the subject’s highest achieved level. Physical activity was divided into two categories, exercise or do not exercise as an activity of the following at least 5 days a week: intense physical activity for at least 20 minutes, moderate physical activity for at least 30 minutes, or walking for at least 30 minutes. Nutritional supplement use was divided into two categories as “yes” or “no”.
Study population This study was based on data from the Korea National Health and Nutrition Examination Survey (KNHANES) VI (2013), the cross-sectional survey conducted by a Ministry of Health and Welfare. Details of the KNHANES are available elsewhere [23]. The KNHANES is composed of the three sections such as a health interview, health examination, and nutrition survey. A nationally representative sample was chosen from the Korean population using household records that were provided by the 2010 Population and Housing Census in Korea. In the KNHANES VI, 8,018 participants was selected from each 192 survey section using a stratified, multistage probability cluster sampling method considering each participant’s geographical area, age, and sex (response rate: 79.3% for age ≥1 year). Among the participants, we limited our analyses to adults who is older than 20 years old. We also excluded subjects with missing data for important analytic variables, such as metabolic parameters, and FA intake. Subjects who recorded implausible energy intake (5,000 kcal) were excluded. Additionally, subjects who were diagnosed with severe disease such as cancer were excluded. Pregnant or lactating female subjects were excluded due to their unique changes in
Anthropometric and biochemical measurements Anthropometric measurements were obtained by trained experts following standardized protocols. The body weights and heights of the subjects were measured to the nearest 0.1 kg and 0.1 cm, respectively. Body mass index (BMI) was calculated as weight (kg)/height squared (m2). Waist circumference (WC) was measured on the area between the rib cage and the iliac crest to the nearest 0.1 cm. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured by mercury sphyngmomanometer (Baumanometer, New York, NY, USA) on the right arm. To assess serum levels of biochemical markers, blood samples were collected through an antecubital vein after 10–12 hour of fasting. Serum levels of insulin (μU/mL) were measured by an immunoradiometric assay using a 1,470 Wizard Gamma Counter (PerkinElmer, Turku, Finland). Hemoglobin A1c (HbA1c) level was measured with high performance liquid chromatography-723G7 (Tosoh, Tokyo, Japan). Serum levels of fasting glucose (mg/dL), total cholesterol (TC, mg/dL), triglyceride (TG, mg/dL), high density lipoprotein (HDL) cholesterol (mg/ dL), low density lipoprotein (LDL) cholesterol, aspartate aminotransferase (AST, IU/L), and alanine aminotransferase (ALT, IU/
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Lee YS et al. L) were measured using a Hitachi Automatic Analyzer 7600 (Hitachi, Tokyo, Japan). To compensate the missing data, LDL cholesterol was calculated by Friedewald formula for subjects in less than 400 mg/dL TG: TC (mg/dL) – HDL cholesterol (mg/ dL) – (TG (mg/dL) ÷ 5.0) [24]. Dietary fatty acid measurement Nutrient intake data were obtained from the section of the nutrition survey in the KNHANES (VI). Food content and consumed amounts were obtained by the 24-hour recall method; then, the nutrient intake was analyzed using the database from the food composition table made by the Rural Development Administration [25]. The ratio of energy intake from each macronutrient to total energy was calculated: percentage of energy intake from carbohydrate (%), percentage of energy intake from fat (%) and percentage of energy intake from protein (%). The percentages of energy intake from VLSFAs (%) were also calculated as same method. Definition of metabolic syndrome and other disease According to National Cholesterol Education Program criteria [26], MetS is defined by a co-occurrence of three or more of the following conditions: 1) waist circumference >90 cm in men >80 cm in women using the International Obesity Task Force criteria for the Asian-Pacific population [27]; 2) TG ≥150 mg/dL or medication use; 3) HDL-cholesterol
