This paper describes the background, aim, and design of a prospective birth-cohort study in Korea called the COhort for Childhood Origin of Asthma and allergic diseases (COCOA). COCOA objectives are to investigate the individual and interactive effects of genetics, perinatal environment, maternal lifestyle, and psychosocial stress of mother and child on pediatric susceptibility to allergic diseases. The participants in COCOA represents a Korean inner-city population. Recruitment started on 19 November, 2007 and will continue until 31 December, 2015. Recruitment is performed at five medical centers and eight public-health centers for antenatal care located in Seoul. Participating mother-baby pairs are followed from before birth to adolescents. COCOA investigates whether the following five environmental variables contribute causally to the development and natural course of allergic diseases: (1) perinatal indoor factors (i.e. house-dust mite, bacterial endotoxin, tobacco smoking, and particulate matters 2.5 and 10), (2) perinatal outdoor pollutants, (3) maternal prenatal psychosocial stress and the child’s neurodevelopment, (4) perinatal nutrition, and (5) perinatal microbiome. Cord blood and blood samples from the child are used to assess whether the child’s genes and epigenetic changes influence allergic-disease susceptibility. Thus, COCOA aims to investigate the contributions of genetics, epigenetics, and various environmental factors in early life to allergic-disease susceptibility in later life. How these variables interact to shape allergic-disease susceptibility is also a key aim. The COCOA data collection schedule includes 11 routine standardized follow-up assessments of all children at 6 months and every year until 10 years of age, regardless of allergic-disease development. The mothers will complete multiple questionnaires to assess the baseline characteristics, the child’s exposure to environmental factors, maternal pre- and post-natal psychological stress, and the child’s neurodevelopment, nutritional status, and development of allergic and respiratory illnesses. The child’s microbiome, genes, epigenetics, plasma cytokine levels, and neuropsychological status, the microbiome of the residence, and the levels of indoor and outdoor pollutants are measured by standard procedures. The COCOA study will improve our understanding of how individual genetic or environmental risk factors influence susceptibility to allergic disease and how these variables interact to shape the phenotype of allergic diseases.

To investigate the association of antioxidant nutritional status with the risk of atopic dermatitis (AD) in young children in a case–control, population-based study. Identified from preschools by using the Korean version of the International Study of Asthma and Allergies in Childhood (ISAAC). Final analysis included 180 AD (mean age 5.3±0.9 years) and 242 non-AD (mean age 5.2±1.0 years) children. Diet was assessed using a validated semi-quantitative food frequency questionnaire. Fasting blood samples were used for analyses of fat-soluble vitamins (retinol, α-tocopherol, and β-carotene) and vitamin C. AD was associated negatively with intakes of antioxidant-related nutrients. The adjusted odds ratio (OR) and 95% confidence interval (95% CI) were 0.44 (0.22–0.88) for the highest (vs lowest) quintile of β-carotene. A similar association was observed for dietary vitamin E (OR=0.33, 95% CI=0.16–0.67), folic acid (OR=0.37, 95% CI=0.18–0.73), and iron (OR=0.39, 95% CI=0.19–0.79). Reduced AD risk was found with 1 s.d. increase of serum α-tocopherol [OR=0.64, 95% CI=0.41–0.98) and retinol (OR=0.74, 95% CI=0.58–0.96) concentrations, and marginally with that of serum β-carotene levels (P=0.0749 for trend). There was no relationship of AD risk with dietary and plasma vitamin C as well as nutrient supplement intake regardless of nutrient type. AD was predicted better by the intake measure than the corresponding blood biomarker regarding vitamin E and β-carotene. These findings suggest that higher antioxidant nutritional status reduces the risk of AD and that such risk-reduction effects depend on nutrient type.

Prevailing dietary patterns and their association with nutritional outcomes are poorly understood, particularly for children in Korea. Our purposes were to identify major dietary patterns and to examine their associations with overweight among young children in Korea. For 1441 preschool children, usual diet was assessed by a FFQ, from which thirty-three food groups were created and entered into a factor analysis. We identified three dietary patterns by relative intake frequency of (1) vegetables, seaweeds, beans, fruits, milk and dairy products (Korean healthy pattern); (2) beef, pork, poultry, fish and fast foods (animal foods pattern); and (3) ice cream, soda, chocolate, cookies and candies (sweets pattern). The Korean healthy pattern was associated with better health status. As compared with the lowest quintile, the multivariate-adjusted OR of the highest quintile for health status inferior or similar to their peers was 042, 077 (95 % CI 194)) v. the lowest quintile regarding the animal foods pattern. These findings suggest that major dietary patterns are predictors of overweight and health status in Korean preschool children.

Methylmercury is well known for causing adverse health effects in the brain and nervous system. Estimating the elimination constant derived from the biological half-life of methylmercury in the blood or hair is an important part of calculating guidelines for methylmercury intake. Thus, this study was conducted to estimate the biological half-life of methylmercury in Korean adults. We used a one-compartment model with a direct relationship between methylmercury concentrations in the blood and daily dietary intake of methylmercury. We quantified the between-person variability of the methylmercury half-life in the population, and informative priors were used to estimate the parameters in the model. The population half-life of methylmercury was estimated to be 80.2 ± 8.6 days. The population mean of the methylmercury half-life was 81.6 ± 8.4 days for men and 78.9 ± 8.6 days for women. The standard deviation of the half-life was estimated at 25.0 ± 8.6 days. Using the direct relationship between methylmercury concentrations in blood and methylmercury intake, the biological half-life in this study was estimated to be longer than indicated by the earlier studies that have been used to set guideline values.

Seo JH, et al. Allergy Asthma Immunol Res. 2013 Mar;5(2):81-87. https://doi.org/10.4168/aair.2013.5.2.81