Trends in nutrient intakes and consumption while eating-out among Korean adults based on Korea National Health and Nutrition Examination Survey (1998-2012) data

BACKGROUND/OBJECTIVES

Eating-out among Korean people has become an important part of modern lifestyle due to tremendous growth of the food service industry and various social and economic changes. This study examined trends in meal patterns and meal sources while eating-out among Korean adults aged 19 years and older.

SUBJECTS/METHODS

Data were from the 1998-2012 KNHNES (Korea National Health and Nutrition Examination Survey) by the 24-hour dietary recall method. This study included 55,718 adults aged 19 years and older. For analysis of eating-out frequency, data were categorized by source of meals and serving place.

RESULTS

Average frequency of meals consumed away from home increased from 1998 to 2012, although it remained lower than that of meals at home. In addition, male, unmarried, employed, higher educated, and high income individuals more frequently consumed meals away from home. Moreover, sodium intake while eating-out significantly increased from 2,370 mg in 1998 to 2,935 mg in 2012. Lastly, percentage contributions of daily total protein intake, fat intake, and sodium intake from eating-out increased to more than half (53-55%) in 2012 compared with 47-48% in 1998.

CONCLUSIONS

As eating-out has grown in popularity, greater recognition of public health and nutritional education aimed at promoting healthy food choices is needed. In addition to developing consumer education for overall healthier eating patterns, individuals who are younger, unmarried, higher educated, and males are especially at risk and require attention.     

Estimation of curcumin intake in Korea based on the Korea National Health and Nutrition Examination Survey (2008-2012)

BACKGROUND/OBJECTIVES

Turmeric and its active component curcumin have received considerable attention due to their many recognized biological activities. Turmeric has been commonly used in food preparation and herbal remedies in South Asia, leading to a high consumption rate of curcumin in this region. However, the amount of curcumin in the Korean diet has not yet been estimated, where turmeric is not a common ingredient.

SUBJECTS/METHODS

This study utilized the combined data sets obtained from the Korea National Health and Nutrition Examination Survey conducted from 2008 to 2012 in order to estimate the curcumin intake in the Korean diet. The mean intake of curcumin was estimated from the amount of curcumin-containing foods (curry powder and ready-made curry) consumed using reported curcumin content in commercial turmeric and curry powders.

RESULTS

Only 0.06% of Koreans responded that they consumed foods containing curcumin in a given day, and 40% of them were younger than 20 years of age. Curcumin-containing foods were largely prepared at home (72.9%) and a significant proportion (20.4%, nearly twice that of all other foods) was consumed as school and workplace meals. The estimated mean turmeric intake was about 0.47 g/day corresponding to 2.7-14.8 mg curcumin, while the average curry powder consumption was about 16.4 g, which gave rise to curcumin intake in the range of 8.2-95.0 mg among individuals who consumed curcumin. The difference in estimated curcumin intake by using the curcumin content in curry powder and turmeric may reflect that curry powder manufactured in Korea might contain higher amounts of other ingredients such as flour, and an estimation based on the curcumin content in the turmeric might be more acceptable.

CONCLUSIONS

Thus, the amount of curcumin that can be obtained from the Korean diet in a day is 2.7-14.8 mg, corresponding to nearly one fourth of the daily curcumin intake in South Asia, although curcumin is rarely consumed in Korea.     

Trends in Alcohol Consumption for Korean Adults from 1998 to 2018: Korea National Health and Nutritional Examination Survey

Drinking culture has been well developed in Korea. This research assessed trends in daily pure alcohol consumption over time and examined its trends regarding socio-demographic variables and alcoholic beverage types. We used data from the 1998–2018 Korea National Health and Nutrition Examination Survey. A total of 87,623 adults aged ≥ 19 years were included. Alcohol intake was assessed via 24-h dietary recall, and pure alcohol content was calculated according to alcoholic beverage type. Daily alcohol consumption increased from 8.37 g in 1998 to 14.98 g in 2016–2018 (p for trend < 0.001). The degree of the increasing trend was higher for women (2.09 g to 5.79 g) than men (14.78 g to 23.94 g) from 1998 to 2016–2018. Alcohol intake was highest in men aged 30–49 years and women aged 19–29 years. Moreover, the change of the rising trend in alcohol consumption according to high socioeconomic factors was more pronounced than the other variables. Lastly, the alcohol intake from soju and beer was dominant in alcohol consumption and escalated over time. The total daily alcohol intake increased about two times during 21 years in Korea, and the trends varied according to socio-demographic status.     

Associations between dietary patterns and hypertension among Korean adults: the Korean National Health and Nutrition Examination Survey (2008-2010)

The objective of this study is to identify the dietary patterns associated with the risk of hypertensions among Korean adults using data from the Korean National Health and Nutrition Examination Survey (KNHANES, 2008-2010). This study analyzes data from 11,883 subjects who participated in the health and nutrition survey, aging from 20 to 64 years. We performed factor analysis based on the weekly mean intake frequencies of 36 food groups to identify major dietary patterns. We identified three major dietary patterns in both sexes, namely "traditional", "western" and "dairy and carbohydrate" patterns. Participants in the highest quartile of western pattern scores had significantly higher blood pressure, serum total cholesterol, and triglyceride levels than those in the lowest quartile. Although not statistically significant, a trend (P for trend = 0.0732) toward a positive association between the western dietary pattern and hypertension risk was observed after adjustments for age, sex, education, income, body mass index (BMI), smoking, physical activity, and energy intake. The dairy and carbohydrate pattern was inversely related with BMI and blood pressures and positively associated with serum high-density lipoprotein (HDL)-cholesterol. After adjusting the age, sex, education, income, BMI, smoking, physical activity and energy intake, the dairy and carbohydrate pattern showed inverse associations with hypertension prevalence (OR = 0.64, 95% CI = 0.55-0.75; P for trend < 0.0001). Intakes of fiber, sodium, and antioxidant vitamins were significantly higher in the top quartile for the traditional pattern than in the lowest quartile for the traditional pattern (P for trend < 0.0001). Intakes of fiber (P for trend < 0.0001), calcium (P for trend < 0.0001), retinol (P for trend = 0.0164), vitamin B₁ (P for trend = 0.001), vitamin B₂ (P for trend < 0.0001), niacin (P for trend = 0.0025), and vitamin C (P for trend < 0.0001) were significantly increased across quartiles for the dairy and carbohydrate pattern whereas sodium (P for trend < 0.0001) intake was decreased for this pattern. In conclusion, the dairy and carbohydrate pattern may be associated with a reduced risk of hypertension whereas the western pattern may be associated with an increased risk of hypertension among Korean adults.     

A study on the trend analysis regarding the rice consumption of Korean adults using Korean National Health and Nutrition Examination Survey data from 1998, 2001 and 2005

The objective of this study was to provide information regarding trends of rice consumption of Korean adults based on different meal types. Respondent reports 24-hour recall data from the Korean National Health and Nutrition Examination Survey were used to assess daily rice consumption and intake ratios of rice for different meal types and places of preparation. Rice intake had gradually decreased from 224.6 g in 1998 to 190 g in 2001 and to 179.4 g in 2005. The rice consumption of Korean adults decreased every year in all ages for all places of meal preparation in 2001 and 2005 compare to 1998. Analysis for each meal type showed that rice intake at breakfast had not considerably changed, but rice intake had decreased at lunch and dinner. While the rice consumption ratio at lunch and dinner decreased, it also decreased or did not change at snack times except for the 19-29 age groups. All the age groups revealed comparable change in the analysis for meal types. There was some diversity between all age divisions in daily rice intake depending on place of meal preparation. The rice consumption by place of meal preparation was generally highest at home, lowest at other places, but it decreased in all places. The rice consumption at home was highest in the over 50 age group, lowest in the 20-30 age group. These changes seem to be related to food intake patterns of rice and substitutional foods in the diets and development regarding socio-economic status. So the need for further study on differences in rice intake based on socioeconomic levels and age group are indicated.     

Dietary intake of fats and fatty acids in the Korean population: Korea National Health and Nutrition Examination Survey, 2013

BACKGROUND/OBJECTIVESThe aim of this study was to estimate average total fat and fatty acid intakes as well as identify major food sources using data from the Korea National Health and Nutrition Examination Survey (KNHANES) VI-1 (2013).SUBJECTS/METHODSTotal fat and fatty acid intakes were estimated using 24-hour dietary recall data on 7,048 participants aged ≥ 3 years from the KNHANES VI-1 (2013). Data included total fat, saturated fatty acid (SFA), monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA), n-3 fatty acid (n-3 FA), and n-6 fatty acid (n-6 FA) levels. Population means and standard errors of the mean were weighted in order to produce national estimates and separated based on sex, age, income, as well as residential region. Major food sources of fat, SFA, MUFA, PUFA, n-3 FA, and n-6 FA were identified based on mean consumption amounts of fat and fatty acids in each food.RESULTSThe mean intake of total fat was 48.0 g while mean intakes of SFA, MUFA, PUFA, n-3 FA, and n-6 FA were 14.4 g, 15.3 g, 11.6 g, 1.6 g, and 10.1 g, respectively. Intakes of MUFA and SFA were each higher than that of PUFA in all age groups. Pork was the major source of total fat, SFA, and MUFA, and soybean oil was the major source of PUFA. Milk and pork were major sources of SFA in subjects aged 3-11 years and ≥ 12 years, respectively. Perilla seed oil and soybean oil were main sources of n-3 FA in subjects aged ≥ 50 years and aged < 50 years, respectively.CONCLUSIONSEstimation of mean fatty acid intakes of this study using nationally represented samples of the Korean population could be useful for developing and evaluating national nutritional policies.     

Plain water intake of Korean adults according to life style,anthropometric and dietary characteristic: the Korea National Health and Nutrition Examination Surveys 2008-2010

BACKGROUND/OBJECTIVES

The objective of the study was to provide useful insights into plain water intake of Korean adults according to life style, anthropometric, and dietary characteristics.

SUBJECTS/METHODS

The data from the 2008-2010 Korea National Health and Nutrition Examination Survey were used. The subjects were 14,428 aged 20-64 years. Water intake was estimated by asking the question "How much water do you usually consume per day?". Dietary intake was estimated by 24-hour dietary recall. A qualitative food frequency questionnaire including 63 food items was also administered.

RESULTS

The mean plain water intake for men and women were 6.3 cup/day and 4.6 cup/day, respectively. Plain water intake increased as lean body mass, waist circumference, and body mass index levels increased, except for percentage of body fat. As energy and alcohol intakes increased, plain water intake increased. As total weight of food intake and total volume of food intake increased, plain water intake increased. Plain water intake increased as consumption of vegetables increased. Plain water intake increased as frequencies of green tea, alcoholic drink, and all beverages were increased in men. Plain water intake increased with increased frequencies of green tea, milk, soy milk, and alcoholic drink and decreased frequencies of coffee and soda in women.

CONCLUSIONS

Our results suggest that persons who had a higher waist circumference or lean body mass and women with higher BMI consumed more plain water. The persons eating high quality diet, or the persons who had more vegetables, green tea, milk, soy milk, or alcoholic drink consumed more plain water.     

The association of dietary quality and food group intake patterns with bone health status among Korean postmenopausal women: a study using the 2010 Korean National Health and Nutrition Examination Survey Data

BACKGROUND/OBJECTIVES

Osteoporosis and osteoporosis-related disease are drawing a lot of attention in Korea as one of the serious health problems. Bone health status may be influenced by the general dietary quality and dietary pattern.

SUBJECTS/METHODS

To determine the relationship between dietary quality and intake patterns and bone health status, the %RNI, NAR, DDS, and food group intake patterns were assessed according to their bone health status for 847 postmenopausal women using the 2010 KNHANES data after eliminating those of likely changing their diet under the advice of doctors or those taking estrogen.

RESULTS

Bone health became worse as dietary quality deteriorated. All NAR and %RNI values were highly associated with bone health levels and the consumption frequency of Ca sources, DDS and the food group intake patterns also confirmed the findings.

CONCLUSIONS

This study confirmed that dietary quality and dietary patterns were important for bone health. Nutritional education on eating foods from the five basic food groups has to be emphasized to prevent osteoporosis among older women.     

Educational attainment and differences in fruit and vegetable consumption among middle-aged adults in the Korean National Health and Nutrition Examination Survey IV

We investigated whether socioeconomic differences affect fruit and vegetable (FV) consumption with respect to total intake and intake of various FV subgroups. Our study included 6667 adults aged 40-64 years who completed a dietary survey in the fourth Korean NHANES (2007-2009). FV intake was estimated from 24-hour recalls and food frequency questionnaires. Differences in FV consumption related to educational attainment were analyzed according to different nutritional categories of FV. Both men and women in the low-education group had the lowest intake of total FV and total fruits, and women also had the lowest intake of total vegetables. Also lowest in this group was consumption of mushrooms and vegetables (excluding kimchi) among men, and cruciferous and allium vegetables (excluding Chinese cabbage and radish) among women, while kimchi consumption was the highest in this group. Additionally, an association between educational level and intake of citrus fruits was evident among men. Adults in the low-education group consumed less carotene-rich FV, red fruit and/or vegetables, and dark-green leafy vegetables, fewer total vegetable dishes, and fewer types of fruit than in other groups. Men in this group had the lowest intake of yellow/orange fruit and/or vegetables, and women consumed the least folate-rich FV. There is a clear association between educational attainment and FV intake with regard to total intake, and to specific nutrients, bioactive compounds, colors, and variety.     

Investigation of variations in energy,macronutrients and sodium intake based on the places meals are provided: Using the Korea National Health and Nutrition Examination Survey (KNHANES, 1998-2009)

This study was conducted to investigate nutrient consumption by Korean adults in various places. To accomplish this, we used the 1998-2009 Korea National Health and Nutrition Examination Survey (KNHANES). Subjects of this investigation were over 19 years and the study included 37,160 people. The meals were categorized as breakfast, lunch, dinner, and snacks consumed at home, or while eating-out. Investigation of the rate of consumption at serving places based on daily meals and years showed that eating-out generally increased with time. The consumption of meals prepared at home was higher than that of meals consumed anyplace else in 1998, 2001, 2005, and 2007-2009. However, the rate of consumption of home meals decreased from 1998 to 2007-2009, while the rate of eating-out increased during this period. Annual nutrient intake according to serving places with respect to meals, energy, fat, and sodium were significantly lower in home meals than those consumed elsewhere in 2007-2009 relative to 1998. The sodium intake and energy distribution ratio of fat in meals consumed while eating-out increased significantly from 1998 to 2007-2009. The energy, fat and sodium intake and energy contribution ratio of fat consumed in meals at institutions was significantly higher in 2007-2009 than in 1998. Based on these results, additional research is required to develop guidelines for dietary life improvement at each serving place and to address education and policies for balanced nutrition intake.     

Alcohol consumption and the metabolic syndrome in Korean adults: the 1998 Korean National Health and Nutrition Examination Survey

BACKGROUND: The metabolic syndrome is associated with a high risk of cardiovascular disease morbidity and mortality. Light and moderate alcohol consumption have been associated with reduced cardiovascular disease morbidity and mortality. OBJECTIVE: This study was performed to examine the association between alcohol consumption and the metabolic syndrome. DESIGN: The study sample comprised 7962 Korean adults (3597 men, 4365 women) who had participated in the 1998 Korean National Health and Nutrition Examination Survey. RESULTS: The prevalence of the metabolic syndrome was 20.8% in men and 26.9% in women. The adjusted odds ratio for the metabolic syndrome in the group consuming 1-14.9 g alcohol/d was 0.71 (95% CI: 0.53, 0.95) in men and 0.80 (95% CI: 0.65, 0.98) in women. Alcohol consumption had a significant inverse relation with the odds ratio for low HDL cholesterol in all alcohol groups. Heavy alcohol consumption (> or =30 g/d) was associated with significantly higher odds ratios for high blood pressure and high triacylglycerol in men and high fasting blood glucose and high triacylglycerol in women. Odds ratios for the metabolic syndrome and its components tended to increase with increasing alcohol consumption. The dose-response relation of the odds ratio between alcohol consumption and the clustering of > or =3 risk factors was significant in both the high and low HDL-cholesterol groups. CONCLUSIONS: Although alcohol consumption had a significant inverse relation with the odds ratio for low HDL cholesterol in all alcohol groups, an increasing dose-response relation was found between alcohol consumption and the odds ratio for the metabolic syndrome. This might be due to the opposite relation of alcohol consumption to other components of the metabolic syndrome.     

Under-reporting of Energy Intake from 24-hour Dietary Recalls in the Korean National Health and Nutrition Examination Survey

ObjectivesChronic degenerative diseases are closely related to daily eating habits, nutritional status, and, in particular, energy intake. In clarifying these relationships it is very important for dietary surveys to report accurate information about energy intake. This study attempted to identify the prevalence of the under-reporting of energy intake and its related characteristics based on the Korean National Health and Nutrition Examination Survey conducted in the years 2007–2009.MethodsThe present study analyzed dietary intake data from 15,133 adults aged ≥19 years using 24-hour dietary recalls. Basal metabolic rates were calculated from the age- and gender-specific equations of Schofield and under-reporting was defined as an energy intake <0.9, represented by the ratio of energy intake to estimated basal metabolic rate.ResultsUnder-reporters (URs) accounted for 14.4% of men and 23.0% of women and the under-reporting rate was higher in the age group 30–49 years for both men and women. The results from an analysis of the age-specific socioeconomic characteristics of participants classified as URs showed that under-reporting was high in women living alone and in women with only elementary school education or no education. The results from an analysis of the health-specific characteristics of URs showed that a large proportion of URs had poor self-rated health or were obese, or both, compared with non-URs. The proportion of participants who consumed less than the estimated average requirements for nutrients was significantly higher in URs compared with non-URs.ConclusionThe under-reporting of energy intake was associated with age, gender, education level, income level, household status (single-person or multi-person), self-rated health, physical activity, and obesity.     

BMI and metabolic disorders in South Korean adults: 1998 Korea National Health and Nutrition Survey

OBJECTIVE: The prevalence of overweight, obesity, and metabolic disorders and their relationship with BMI were studied in South Korean adults. The appropriate BMI categories for overweight and obesity for Koreans were evaluated. RESEARCH METHODS AND PROCEDURES: The 1998 Korea National Health and Nutrition Examination Survey was the first such survey, to our knowledge, conducted on a cross-sectional and nationally representative population. The survey provided data on body weight; height; fasting serum glucose; triacylglycerol; total, low-density lipoprotein, and high-density lipoprotein cholesterol; blood pressure; and various other questions that were incorporated into this study. A total of 39,060 persons over the age of 1 year from 12,283 households participated in the Health and Nutrition Interview Survey. Of these, 10,876 people over the age of 10 years old participated in the Health Examination. We analyzed data from 7962 adults over the age of 20 years old. RESULTS: The overweight (BMI, >/=25.0 to <30.0) and obesity (BMI, >/=30) rates were low among Korean adults: 23.4% and 1.7% in men and 24.9% and 3.2% in women, respectively. However, the prevalences of diabetes, hypertension, and abnormal concentrations of serum triacylglycerol and total, low-density lipoprotein, and high-density lipoprotein cholesterol were high at 10.5%, 27.1%, 29.0%, 34.5%, 28.4%, and 37.4%, respectively. These disorders were age dependent, and, in general, there was a strong linear relationship between BMI and the disorders. The relative risk of disorders doubled at a BMI of 23.0 to 24.0 and tripled at a BMI of 26.0, compared with a baseline BMI of 18.5 to 22.0. DISCUSSION: High rates of diabetes, hypertension, and dyslipidemia were noted in middle-aged and elderly Koreans even at relatively low BMI. It might be appropriate to lower the BMI classification from the current >/=25.0 for overweight and >/=30.0 for obesity for this group of Koreans.     

Dietary Assessment and Factors According to Fruits and Vegetables Intake in Korean Elderly People: Analysis of Data from the Korea National Health and Nutrition Examination Survey, 2013–2018

This study analyzed dietary assessment and factors according to fruits and vegetables intake in Korean elderly people. We enrolled 8336 Korean elderly people aged ≥65 who participated in the dietary intake survey (24-h recall methods) of the 2013–2018 Korea National Health and Nutrition Examination (KNHANES). The intake of fruits and unsalted/non-starchy vegetables was 372.06 g/day. According to age group, the intake in the age group 65–74 years as 422.47 g/day, and the intake in the age group 75 years + was 301.12 g/day. Based on the intake of daily meals and snacks, the intake of fruits and unsalted/non-starchy vegetables was the highest in snack-eating individuals (480.96 g/day). The subjects who consumed more than the World Health Organization (WHO)/World Cancer Research Fund (WCRF)’s plant food intake standards (over 400 g/day of intake of fruits and unsalted/non-starchy vegetables) were 35.47% of the elderly people. These results suggest that it is necessary to develop more fundamental strategies to increase fruits and vegetables intake among elderly people. Furthermore, the study outcomes are expected to provide basic information for developing education programs to improve the dietary life of Korean elderly people.     

Cadmium exposure and cardiovascular disease in the 2005 Korea National Health and Nutrition Examination Survey

Background

Limited epidemiologic data are available concerning the cardiovascular effects of cadmium exposure, although recent studies suggest associations with myocardial infarction and peripheral arterial disease. We examined the associations of cadmium exposure with cardiovascular disease in nationally representative general Korean adults.

Methods

We used cross-sectional data on blood cadmium and self-reported diagnoses of ischemic heart disease (IHD), stroke, and hypertension in a sub-sample of 1908 adults, aged 20 years and older, who participated in the 2005 Korea National Health and Nutrition Examination Survey (KNHANES). We used survey logistic regression models accounting for the complex sampling design to estimate the odds ratios (OR), adjusting for age, education, income, alcohol, smoking, body mass index, waist circumference, family history of hypertension, blood pressure, and blood lead.

Results

The geometric mean of blood cadmium was 1.53 μg/L. After adjusting for potential confounders, an interquartile range (IQR) increase in blood cadmium (0.91 μg/L) was found to be associated with an increased risk for IHD (OR 2.1, 95% confidence interval (CI) 1.3–3.4). An IQR increase in blood cadmium was found to be associated with an elevated risk for hypertension only among men (OR 1.4, 95% CI 1.1–1.8) but not among women. No association was observed with stroke in both genders.

Conclusions

These findings suggest that cadmium in blood may be associated with an increased risk for IHD and hypertension in the general Korean adult population.     

Socioeconomic status,food security,and chewing discomfort of Korean elders: results from the Korea National Health and Nutrition Examination Survey

BACKGROUND/OBJECTIVESThe purpose of this study was to investigate the association between socioeconomic status and chewing discomfort and identify the role of food insecurity in the association''s causal pathway in a representative sample of Korean elders.MATERIALS/METHODSWe conducted cross-sectional analyses of the Korea National Health and Nutrition Examination Survey (2013–2015) data for elders aged ≥ 65 years. Socioeconomic status indicators used included household income and education level. Chewing discomfort was assessed according to the self-reported presence of chewing problems. Food security was surveyed using a questionnaire based on the US Household Food Security Survey Module.RESULTSThe odds ratios of chewing discomfort in the 1st and 2nd income quartiles were 1.55 (95% confidence interval [CI], 1.15–2.10) and 1.40 (95% CI, 1.03–1.90), respectively, compared to participants in the highest income quartile. Participants with the lowest education level were 1.89 (95% CI, 1.30–2.75) times more likely to have chewing discomfort than those without chewing discomfort. After including food security in the final model, the logistic coefficients were attenuated in the income and education quartiles.CONCLUSIONSLow socioeconomic status was associated with chewing discomfort. In addition, the results confirm that food insecurity can mediate the association between socioeconomic inequalities and chewing discomfort among the elderly.     

Prevalence of osteoporosis according to nutrient and food group intake levels in Korean postmenopausal women: using the 2010 Korea National Health and Nutrition Examination Survey Data

BACKGROUND/OBJECTIVES

Women''s bone health status is closely related with environmental factors and lifestyle factors. The purpose of this study is to evaluate the dietary risks of osteoporosis and osteopenia for Korean postmenopausal women.

SUBJECTS/METHODS

The data from 1,433 subjects from the 2010 KNHANES were used and divided into three groups: normal, osteopenia, and osteoporosis group using bone mineral density (BMD). Nutrient intakes and food intake frequency were evaluated. Logistic regression analysis was applied to determine the odds ratios for osteoporosis and osteopenia.

RESULTS

The RNI percentage of each nutrient and food intake frequency from 12 food groups decreased as bone mineral density status deteriorated. Risk for osteoporosis of low calcium (Ca) intake, under the EAR, showed an odds ratio of 2.13(95% CI; 1.26-3.61, P < 0.05). Higher intake frequency showed preventive effect from osteoporosis compared to lower intake frequency in such food group as dairy products (ORs 0.40, CI 0.21-0.75), beans (ORs 0.49, CI 0.29-0.83), seaweeds (ORs 0.55, CI 0.32-0.94), fish (ORs 0.56, CI 0.32-0.98), and fruits (ORs 0.42, CI 0.23-0.79) after adjusting for age.

CONCLUSION

To prevent osteoporosis in later life, sufficient Ca intake and more frequent intakes of foods containing Ca such as dairy products, beans, fish, seaweeds, and fruits, which help in Ca absorption, should be stressed for Korean postmenopausal women.     

Factors associated with low water intake among South Korean adolescents - Korea National Health and Nutrition Examination Survey, 2007-2010

Water is essential for life and plain water instead of sugar-sweetened beverages is one approach for decreasing energy intake. Due to limited data on characteristics associated with water intake among Korean adolescents, this study examined associations of demographic and behavioral characteristics with plain water intake by using nationally representative sample of South Korean adolescents. The data (2007-2010 Korea National Health and Nutrition Examination Survey) for 1,288 high school-aged adolescents (15-18 years) were used. Multivariable logistic regression was used to calculate adjusted odds ratios (OR) for factors associated with low water intake (< 4 cups/day) and very low water intake (< 2.5 cups/day). Nationwide, 38.4% and 19.0% of adolescents reported drinking water < 4.0 cups/day and < 2.5 cups/day, respectively. The mean plain water intake was 5.7 cups/day for males and 4.1 cups/day for females. Females had significantly higher odds for drinking water < 2.5 cups/day (OR = 2.2) than males, whereas adolescents with low milk consumption had significantly lower odds for drinking water < 2.5 cups/day (OR = 0.7). Factors significantly associated with a greater odds for drinking water < 4 cups/daywere being female (OR = 2.8) and not meeting physical activity recommendations (≥ 20 min/day on < 3 days/week) (OR = 1.6). Being underweight, overweight, and obese were significantly associated with reduced odds for drinking water < 4 cups/day (OR = 0.7, 0.4 and 0.5, respectively). However, intake of soda, coffee drinks, fruits, vegetables, and sodium and eating out were not significantly associated with low or very low water intake. These findings may be used to target intervention efforts to increase plain water intake as part of a healty lifestyle.     

Inappropriate Survey Design Analysis of the Korean National Health and Nutrition Examination Survey May Produce Biased Results

Objectives

The inherent nature of the Korean National Health and Nutrition Examination Survey (KNHANES) design requires special analysis by incorporating sample weights, stratification, and clustering not used in ordinary statistical procedures.

Methods

This study investigated the proportion of research papers that have used an appropriate statistical methodology out of the research papers analyzing the KNHANES cited in the PubMed online system from 2007 to 2012. We also compared differences in mean and regression estimates between the ordinary statistical data analyses without sampling weight and design-based data analyses using the KNHANES 2008 to 2010.

Results

Of the 247 research articles cited in PubMed, only 19.8% of all articles used survey design analysis, compared with 80.2% of articles that used ordinary statistical analysis, treating KNHANES data as if it were collected using a simple random sampling method. Means and standard errors differed between the ordinary statistical data analyses and design-based analyses, and the standard errors in the design-based analyses tended to be larger than those in the ordinary statistical data analyses.

Conclusions

Ignoring complex survey design can result in biased estimates and overstated significance levels. Sample weights, stratification, and clustering of the design must be incorporated into analyses to ensure the development of appropriate estimates and standard errors of these estimates.