An ensemble method based on marginal-effect models (EMM) for estimating usual food intake from single-day dietary data and internal/external two-day dietary data.

BACKGROUND: With collection of repeated 24-hour recalls, there exist challenges in usual intake estimation, including infeasibility of multiple dietary assessments, and shortage of non-zero intakes for episodically consumed foods. OBJECTIVES: We developed an ensemble method based on marginal-effect models (EMM), which estimates usual intake distribution using single-day data with internal or external two-day data. METHODS: The performance of the EMM was evaluated and compared with the National Cancer Institute (NCI) method and NCI 1-d method, via simulations with various scenarios and real data analyses of red meat, fish, and protein from Korea National Health and Nutrition Examination Survey (KNHANES). RESULTS: Simulations indicated the EMM (maximum bias of 1.67, 3.17, 8.57, 11.63 for average, median, 75%-tile, 95%-tile, respectively) provided more accurate estimation than the NCI method (maximum bias of 4.18, 9.43, 7.56, 37.43) across various scenarios on intake probability and within-person variation. The EMM showed robust estimation when an insufficient number of people have positive consumption on two days. In simulations with various external variance ratios, the EMM showed similar or superior performance to the NCI 1-d method. The EMM produced more stable estimates of usual intake distributions for red meat, fish, and protein than the two NCI methods. CONCLUSION: The proposed EMM showed substantial improvement over the NCI methods when data contain a relatively small number of people with positive consumption on two days; is robust when food intake probability is very low or high; and estimates an external variance ratio with relatively low bias.

Migration study of caprolactam from polyamide 6 sheets into food simulants.

Caprolactam, used in manufacturing polyamide (PA) 6, may threaten human health. Here, PA 6 sheets were produced by using a twin-screw extruder to evaluate its safety. Caprolactam migration concentrations from the PA 6 sheets into food simulants were evaluated according to the standard migration test conditions under the Korean Food Standards Codex (KFSC). Concentrations were investigated under various food simulants (distilled water, 4% acetic acid, 20 and 50% ethanol, and heptane) and storage conditions (at 25, 60, and 95 °C). Caprolactam migration concentrations into food simulants were determined as follows: 4% acetic acid (0.982 mg/L), distilled water (0.851 mg/L), 50% ethanol (0.624 mg/L), 20% ethanol (0.328 mg/L), and n-heptane (not detected). Migrations were determined to be under the regulatory concentration (15 mg/L) according to the KFSC test conditions. Taken together, these results verified that the standard migration test conditions by KFSC were reliable to evaluate the safety of PA 6.

Vegetable, fruit, and phytonutrient consumption patterns in Taiwan.

Phytonutrients may play important roles in human health and yet only recently a few studies have described phytonutrient consumption patterns, using data obtained from daily consumption methods. We aimed to estimate the phytonutrient content in Taiwanese diets and analyzed main food sources of 10 major phytonutrients. In this study, food items and dietary data gathered with the 24-hour dietary recall from 2908 participants in the 2005-2008 Nutrition and Health Survey in Taiwan were used to create a food phytonutrient database with 933 plant-based foods through integrating database, literature search, and chemical analysis and to appraise phytonutrient consumption status of participants. SUDAAN (Survey Data Analysis) was used for generating weighted phytonutrient intake estimates and for statistical testing. In Taiwanese adults, ∼20% met the recommended number of servings for fruits and 30% met that for vegetables from the Taiwan Food-Guide recommendations. However, only 7.4% consumed the recommended numbers for both fruits and vegetables. Those meeting the recommendations tended to be older and with more females compared with those who did not. Phytonutrient intake levels were higher in meeters than nonmeeters. More than 60% of α-carotene, lycopene, hesperetin, epigallocatechin 3-gallate, and isoflavones came from a single phytonutrient-specific food source. In addition, sweet potato leaf, spinach, and water spinach were among the top three sources of multiple phytonutrients. Cross-comparison between this study and two previous studies with similar methodology showed higher mean levels of lycopene and quercetin in the United States, anthocyanidins in Korea, and lutein and zeaxanthin in Taiwan. The Taiwanese phytonutrient pattern is different from that of the Korean and American. It would be interesting to relate phytonutrient patterns to health profiles in the future.

Elevated levels of short carbon-chain PFCAs in breast milk among Korean women: Current status and potential challenges.

Breast milks can be contaminated with perfluoroalkyl substances (PFASs). Exposure to PFASs during early stages of life may lead to adverse health effects among breastfed infants. To date, perfluorootanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have been most frequently measured PFASs in breast milks worldwide. Information on shorter carbon-chain PFASs in breast milk is scarce. In this study, breast milks were sampled from 264 Korean lactating women, and measured for seventeen PFASs, including ten perfluoroalkyl carboxylates (PFCAs), four perfluoroalkyl sulfonates, and three perfluoroalkyl sulfonamides. PFOA and PFOS were detected in 98.5% of the breast milk samples, with median concentrations of 0.072 and 0.050ng/mL, respectively. Perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), and perfluoroheptanoic acid (PFHpA) were detected in higher frequencies, ranging between 67.4% and 81.8%. The concentrations of short carbon-chain PFCAs in breast milk such as PFPeA and PFHxA were the highest ever reported to date, and were comparable to that of PFOS. Concentrations of shorter chain PFCA in breast milk tended to be higher among the women with longer lactation period, while those of PFOA showed the opposite trend, suggesting a possibility that breastfeeding might be an important route of excretion for PFOA among lactating women. Fish consumption and the use of consumer products, e.g., skin care products, cosmetics and non-stick coated cooking utensils, were identified as significant predictors of PFAS concentrations in breast milk. Health risks associated with PFOA and PFOS exposure through breastfeeding were estimated negligible, however, risks of the short carbon-chain PFCAs could not be assessed because of lack of relevant toxicological information. Further efforts for source identification and exposure management measures for shorter chain PFCAs are necessary.

Association of Dietary Sugars and Sugar-Sweetened Beverage Intake with Obesity in Korean Children and Adolescents.

Few studies have examined the association between dietary sugar intake and obesity in Asian children and adolescents. We evaluated the association of dietary sugar intake and its food source with obesity in Korean children and adolescents. In this cross-sectional analysis, data were obtained from five studies conducted between 2002 and 2011. The study included 2599 children and adolescents who had completed more than three days of dietary records and had anthropometric data. Total sugar intake was higher in girls than in boys (54.3 g for girls and 46.6 g for boys, p < 0.0001). Sugar intake from milk and fruits was inversely associated with overweight or obesity in girls only (OR for overweight, 0.52; 95% CI, 0.32-0.84; p for trend = 0.0246 and OR for obesity, 0.42; 95% CI, 0.23-0.79; p for trend = 0.0113). Sugar-sweetened beverage (SSB) consumption was not associated with obesity in girls, while boys had lower odds ratios for obesity (OR for obesity, 0.52; 95% CI, 0.26-1.05; p for trend = 0.0310). These results suggest that total sugars and SSB intake in Asian children and adolescents remains relatively low and sugar intake from milk and fruits is associated with a decreased risk of overweight or obesity, especially in girls.

Soft drink consumption is positively associated with metabolic syndrome risk factors only in Korean women: Data from the 2007-2011 Korea National Health and Nutrition Examination Survey.

OBJECTIVE: To examine the association between sugar-sweetened beverage consumption and metabolic syndrome risk factors in Korean adults. METHODS: We used data from 13,972 participants (5432 men and 8540 women) aged ≥30 years, from the 2007-2011 Korea National Health and Nutrition Examination Survey. The subjects were divided into six groups based on their soft drink consumption levels from a food frequency questionnaire. Dietary sugar intake was compared among groups using 24-hour dietary recall data. RESULTS: The highest soft drink consumption frequency category was ≥4 times per week, observed in 4.6% of men and 1.7% of women. The percentage of energy from total sugar and sugar in processed foods increased with increased soft drink consumption in both men and women. In the highest consumption group, the percentage of energy from sugar in processed foods was 8.9% in men and 11.0% in women. After adjusting for potential confounding variables, greater consumption of soft drinks was positively associated with all of the components of metabolic syndrome, except the high density lipoprotein (HDL) cholesterol level, in women only. Women who consumed soft drinks ≥4 times per week had a 74% higher risk of metabolic syndrome compared to those who consumed soft drinks infrequently (OR: 1.74; 95% CI: 1.00-3.03; P for trend <0.0001). CONCLUSION: High levels of soft drink consumption might constitute an important determinant of metabolic syndrome and its components only in Korean adult women.

Association between High Blood Pressure and Intakes of Sodium and Potassium among Korean Adults: Korean National Health and Nutrition Examination Survey, 2007-2012.

BACKGROUND: The association between dietary sodium and potassium, the ratio of sodium to potassium, and blood pressure remains unclear. OBJECTIVE: We evaluated the associations between blood pressure and dietary sodium and potassium intake in terms of the amount and ratio in Korean adults. DESIGN: This cross-sectional study was based on data from the fourth and fifth Korean National Health and Nutrition Examination Survey, 2007-2012. PARTICIPANTS/SETTING: A total of 24,096 adults (aged ≥19 years) without history of antihypertensive medication use were selected. The 24-hour recall method was used for dietary assessment. We categorized the subjects into four groups using median intakes of sodium and potassium, and defined the low sodium/high potassium intake group as the reference group. MAIN OUTCOME MEASURES: High blood pressure (HBP) was defined as mean systolic or diastolic blood pressures of ≥140 or ≥90 mm Hg, respectively. STATISTICAL ANALYSES PERFORMED: Multivariate logistic regression was performed to estimate the odds ratio and 95% CI to investigate the association between the four groups of sodium and potassium intakes and HBP. RESULTS: Sodium intake was positively associated with diastolic blood pressure, with an increase of 0.21 mm Hg per 1 mg/kcal increase in sodium (P<0.001). In contrast, potassium intake was negatively associated with systolic blood pressure, with a decrease of 1.01 mm Hg per 1 mg/kcal increase in potassium (P<0.001). After adjusting for confounders, the high sodium/low potassium (odds ratio 1.21, 95% CI 1.02 to 1.44) and low sodium/low potassium intake groups (odds ratio 1.19, 95% CI 1.01 to 1.40) were at higher risk of HBP than the reference group. The risk of HBP in the high sodium/high potassium group did not differ from that in the reference group. CONCLUSIONS: Low potassium intake was associated with an increased risk of hypertension. These results suggest that increasing potassium intake might be beneficial for hypertension control among populations with low-potassium diets.

Cross-continental comparison of national food consumption survey methods--a narrative review.

Food consumption surveys are performed in many countries. Comparison of results from those surveys across nations is difficult because of differences in methodological approaches. While consensus about the preferred methodology associated with national food consumption surveys is increasing, no inventory of methodological aspects across continents is available. The aims of the present review are (1) to develop a framework of key methodological elements related to national food consumption surveys, (2) to create an inventory of these properties of surveys performed in the continents North-America, South-America, Asia and Australasia, and (3) to discuss and compare these methodological properties cross-continentally. A literature search was performed using a fixed set of search terms in different databases. The inventory was completed with all accessible information from all retrieved publications and corresponding authors were requested to provide additional information where missing. Surveys from ten individual countries, originating from four continents are listed in the inventory. The results are presented according to six major aspects of food consumption surveys. The most common dietary intake assessment method used in food consumption surveys worldwide is the 24-HDR (24 h dietary recall), occasionally administered repeatedly, mostly using interview software. Only three countries have incorporated their national food consumption surveys into continuous national health and nutrition examination surveys.

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.

Doenjang, a Korean fermented soy food, exerts antiobesity and antioxidative activities in overweight subjects with the PPAR-γ2 C1431T polymorphism: 12-week, double-blind randomized clinical trial.

We examined the antiobesity and antioxidant effects of supplementation with doenjang, a fermented soybean paste, in overweight Koreans with the PPAR-γ2 C1431T polymorphism. Sixty overweight subjects were randomly assigned to consume either 9.8 g/day of doenjang or placebo for 12 weeks. Before and after the intervention, anthropometric and metabolic parameters, along with abdominal fat distribution and PPAR-γ2 polymorphisms, were measured. Fifty-one subjects completed the study, doenjang (n=26) and placebo (n=25) groups. Relative frequencies of the PPAR-γ2 genotypes CC, TC, and TT were 70% (n=41), 25.9% (15), and 3.4% (2), whereas those of the PPAR-γ2 alleles C and T were 81.6% and 18.4%. Visceral fat area (VFA) was significantly decreased by doenjang supplementation in subjects with a mutant T allele of PPAR-γ2 compared to those with a C allele after adjusting for age, sex, and body mass index. Plasma free fatty acid, insulin, and homeostatic model assessment insulin resistance (HOMA-IR) levels were also significantly increased in the doenjang group. Doenjang pills significantly activated radical clearance capacity (ORAC and DNA tail length) in subjects with the C allele. The catalase (CAT) activity was increased twofold in the doenjang-treated group with the C allele, but this phenomenon was reversed in those with the T allele. Doenjang-treated subjects tended to have low dietary carbohydrate and sodium intakes compared with those given placebo. We found that doenjang supplementation decreased visceral fat accumulation and aging most effectively in subjects with PPAR-γ polymorphisms. This study suggests that doenjang has antiobesity and antioxidative effects in overweight individuals with mutant alleles of PPAR-γ2.

Weight Status and Dietary Factors Associated with Sugar-Sweetened Beverage Intake among Korean Children and Adolescents - Korea National Health and Nutrition Examination Survey, 2008-2011.

There has been growing concern about the role of sugar-sweetened beverages (SSBs) in the development of obesity. This study investigated factors associated with SSB intake among Korean children (7-12 years) and adolescents (13-18 years). We examined associations between SSB intake and demographic and dietary factors using nationally representative data from the 2008-2011 Korea National Health and Nutrition Examination Survey, and 3,179 children and 2,242 adolescents were included in the final analysis. We calculated adjusted odds ratios (ORs) for factors associated with high SSB intake (≥ 300 ml/day) by multivariable logistic regression. The mean daily SSB intake of school children was 98.7 ml/day, with a mean of 64.7 ml/day for those aged 7-12 years and 120.2 ml/day for those aged 13-18 years. SSB intake of ≥ 300 ml/day was found in 12.0% of the children and adolescents. Factors associated with a greater OR for high SSB intake were high energy intake (≥ 125% of EER; OR = 3.17 for boys aged 7-12 years, OR = 2.74 for girls aged 7-12 years, OR = 3.0 for girls aged 13-18 years), low milk consumption (< 1 cup/day; OR = 1.93 for boys aged 7-12 years; OR = 2.53 for girls aged 7-12 years; OR = 1.83 for boys aged 13-18 years), and not meeting the recommended fruit and vegetable intake (< 400 g/day; OR = 1.71 for boys aged 7-12 years). Being overweight and obese was significantly associated with greater ORs for high SSB intake among boys aged 7-12 years (OR = 1.72). These findings may be used to develop targeted education programs for reducing SSB intake and encouraging healthier food choices.

Dietary intake of phytonutrients in relation to fruit and vegetable consumption in Korea.

The purpose of this study was to provide baseline data for health policy creation by estimating phytonutrient intake and identifying major food sources of phytonutrients. Dietary recall data collected in the 2008 Korea National Health and Nutrition Examination Survey and phytonutrient database of the Korea National Academy of Agricultural Science were used in this study. The proportions of the population satisfying recommended dietary guidelines for fruits and vegetables were estimated, and phytonutrient intake was compared between populations who consumed the recommended intake and those who did not. The study found that 5.3% of subjects satisfied the recommended fruit and vegetable intake. In particular, the proportions of adolescents (13 to 18 years of age) and young adults (19 to 39 years of age) meeting the recommended fruit and vegetable intake were lower than other age groups (P<0.001). Intakes of major carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin, and lycopene), flavonoids (anthocyanidins, hesperitin, quercetin, catechin, and isoflavones), and one phenolic compound (gallic acid) were significantly higher (P<0.001) among subjects who met the recommendations for fruit and vegetable consumption compared with those who did not. Carrots, sweet potatoes, squash, tomatoes, and watermelons were found to be major sources of carotenoids. Flavonoids were mainly obtained from persimmons, mandarins, apples, grapes, onions, soybeans, and chestnuts. However, one or two food items contributed to nearly all intake of each phytonutrient, suggesting a lack of variety. In conclusion, the Korean population needs to consume a larger quantity and variety of fruits and vegetables.

South Korea's entry to the global food economy: shifts in consumption of food between 1998 and 2009.

Korea has undergone a major opening of its food markets and economy in the past decade. Little is understood about the impact of these shifts on the diet of Koreans. This analysis studies the shifts in consumption of foods between 1998 and 2009 to provide a thorough understanding of the transition and insights into directions in the next decades in Korea. Data are from the Korea National Health and Nutrition Examination Survey (KNHANES). The sample used was a nationally representative sample of individuals age ≥2 in 1998 and 2009 (n=10,267 and 9,264, respectively). The data was corrected for seasonality, and the original raw food data was regrouped into 53 food groups. SAS was used to adjust for design effects and weight. Despite a decade of efforts to increase whole grains intake, and fruit and vegetable intake, the mean intake of whole grains increased only a small amount (16 kcal/person/day); however, the proportion consuming any whole grains doubled from 24% to 46.3%. Rice declined significantly, and several important less healthful food trends emerged: total alcohol intake increased from 39 kcal/person/day to 82 kcal/person/day. Also, energy from sugar-sweetened beverages increased among teens and energy from tea and coffee increased among adults. Remarkably, compared to other Asian countries and a general worldwide trend, vegetable intake remained relative high in South Korea during this last decade while fat energy increased modestly from relative low levels. Dynamic causes of these trends and the government's response are discussed.

Development of supplemental nutrition care program for women, infants and children in Korea: NutriPlus.

Onto the world-fastest ageing of society, the world-lowest fertility rate prompted a development of various policies and programs for a betterment of the population in Korea. Since the vulnerability of young children of low socio-economic class to malnutrition was clearly shown at the in-depth analysis of the 2001 Korea National Health and Nutrition Examination Survey data, an effort to devise supplemental nutrition care program for pregnant/breastfeeding women, infants and preschool children was initiated. The program was designed to offer nutrition education tailored to fit the needs of the participants and special supplementary foods, using USDA WIC program as a benchmark. Based on the dietary intake of those age groups, target nutrients were selected and their major food sources were searched through nutrient content of foods and dietary pattern analysis. As a result, we developed 6 kinds of food packages using combinations of 11 different food items. The amount of each item in a food package was determined to supplement the intake deficit in target nutrients. Nutrition education in NutriPlus(+) aims to improve the nutrition knowledge, attitude, and dietary behaviors of the participants, and is provided through group lessons, individual counseling sessions and home visits. Breastfeeding is promoted with top priority in education for the health of both mother and baby. The eligibility guidelines were set for residency, household income, age, pregnancy/breastfeeding and nutritional risk such as anemia, stunting, underweight, and/or inadequate nutrient intake. Income eligibility was defined as household income less than 200 percent of the Korean poverty guidelines. A pilot study to examine the feasibility of program implementation was run in 3 public health centers in 2005 and expanded to 15 and 20 in the following 2 years. The result of 3-year pilot study will be reported separately along with the ultimate nationwide implementation of the NutriPlus(+) in 2008.

Dietary exposure and risk assessment of mercury from the Korean total diet study.

As a national project, obtaining information on the amount of heavy metal exposure of individuals through food intake is an important basic parameter for risk assessment. This study was conducted to evaluate dietary exposure levels and various risks from mercury (Hg) in Korean foods. In total, 342 samples comprising 114 food items were collected and then cooked prior to analysis. As found by Hg analysis, the mean content of metal in the fish and shellfish group was highest among the 15 Korean food groups. The total daily amount of Hg intake from typical Korean foods was 2.40 microg/person/d. The daily amount (microg/person/d) of Hg intake from each food group was 0.155 in grains and cereals, 0.008 potatoes and starch, 0.005 sugars and sweets, 0.0093 pulses, 0.0018 nuts and seeds, 0.203 vegetables, 0.027 fruits, 0.021 meats and poultry, 0.004 eggs, 1.826 fish and shellfish, 0.022 seaweed, 0.043 milk and dairy products, 0.008 oils and fats, 0.042 beverages, and 0.023 seasonings. The fish and shellfish group contributed most to total dietary intake at 76%. For risk assessment, probable daily intake (PDI) was calculated and compared with provisional tolerable weekly intake (PTWI) of the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The level of Hg intake through fish and shellfish of 0.001 mg/kg body weight bw/wk corresponded to 4.54% of the PTWI value of 0.005 mg/kg bw/wk, the safety standard for JECFA. The level of Hg intake through selected foods from the Food list for Koreans was 0.001 mg/kg bw/wk, corresponding to 5.95% of PTWI value. Therefore, overall intake was at levels below the recommended JECFA levels. The relative gender Hg hazard from Korean foods was 6.26% and 5.5% for males and females, respectively. The relative age Hg hazard from Korean foods was, 8.9% in those 3-6 yr old, 6.7% in those 7-12 yr old, 5.2% in those 13-19 yr old, 5.9% in those 20-29 yr old, 6.3% in those 30-49 yr old, 5.6% in those ages 50-64 yr, and 3.7% in the group of those over 65 yr of age. Relative regional Hg hazard from Korean foods was 6.3% in urban versus 5.5% in rural areas. Thus, the amount of Hg intake through consumption of Korean foods was found to be at a relatively safe level. These data may be thus used to establish safety standards for fish and shellfish consumption.

Revised dietary guidelines for Koreans.

With rapidly changing dietary environment, dietary guidelines for Koreans were revised and relevant action guides were developed. First, the Dietary Guidelines Advisory Committee was established with experts and government officials from the fields of nutrition, preventive medicine, health promotion, agriculture, education and environment. The Committee set dietary goals for Koreans aiming for a better nutrition state of all after a thorough review and analysis of recent information related to nutritional status and/or problems of Korean population, changes in food production/supply, disease pattern, health policy and agricultural policy. Then, the revised dietary guidelines were proposed to accomplish these goals in addition to 6 different sets of dietary action guides to accommodate specific nutrition and health problems of respective age groups. Subsequently, these guidelines and guides were subjected to the focus group review, consumer perception surveys, and a public hearing for general and professional comments. Lastly, the language was clarified in terms of public understanding and phraseology. The revised Dietary guidelines for Koreans are as follows: eat a variety of grains, vegetables, fruits, fish, meat, poultry and dairy products; choose salt-preserved foods less, and use less salt when you prepare foods; increase physical activity for a healthy weight, and balance what you eat with your activity; enjoy every meal, and do not skip breakfast; if you drink alcoholic beverages, do so in moderation; prepare foods properly, and order sensible amounts; enjoy our rice-based diet.