• Journal of Nutrition and Health
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• v.38 no.7
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• pp.586-604
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• 2005

A reliable nutrient database is a prerequisite for accurate calculation of dietary intakes. The folate database currently available in Korea, however, is not reliable because the values were obtained from published data in other countries using ineffective methods to extract folates from the food matrix. The purpose of this study was to complement the folate database by analyzing folate content in foods using a more effective method to extract food folates (trienzyme treatment). Folate content per unit weight was highest in laver, fermented soybeans, soybean, spinach, black soybeans, crown daisy, mung beans, and quail's egg in descending order. Legumes, leafy greens, eggs, and seaweeds were rich in folate, and meats, chicken, fish, and some fruits contained less folate. Some of the analyzed values were 10 times higher than those in the currently available database. Folate values of 423 foodcodes out of 2,932 foodcodes ($14.4\%$) in the database in the 7th revision in the Recommended Dietary Allowances for Koreans can be replaced by those analyzed in this study. Since folate values of rice and Kimchi, which are core dishes of Koreans, in the newly established database are higher than those in the current database, folate intake assessed using our data will be higher than that using the current available database. Folate content in more foods commonly consumed in Korea are needed to update the folate database. Meanwhile, folate values presented here can be used to assess dietary folate intake of the Korean population.

• Journal of Nutrition and Health
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• v.34 no.7
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• pp.797-808
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• 2001

To determine folate intake and food sources in Korea college students, dietary survey was conducted in March, 1999. Dietary data were collected by trained interviewers using the method of 24-hour recalls for 3 consecutive days. The data of 44 male and 62 female students were analyzed with two different nutrient databases in Recommended Dietary Allowances for Korean on the 6th and 7th revisions, and the results were compared. The intakes of energy and nutrients except vitamin A and folate were lower when analyzed with the 7th database than the 6th database. Mean daily folate intakes with the 6th and 7th databases were 172.9$\mu\textrm{g}$, 221.6$\mu\textrm{g}$ for male students while 125.1$\mu\textrm{g}$, 168.0$\mu\textrm{g}$ for female students, respectively. The results showed significantly higher estimates of folate intake with the 7th database, and significantly higher intake in males than females analyzed with both the 6th and 7th databases. Daily folate intake per 1,000kcal (folate density) was 71.1$\mu\textrm{g}$/1000kcal for males and 67.6$\mu\textrm{g}$/1000kcal for females with the 6th database, and 97.9$\mu\textrm{g}$/1000kcal for males and 95.5$\mu\textrm{g}$/1000kcal for females with the 7th database. The differences in folate density between the two databases were signficant, but the differences between the gender were not significant. The proportions of the subjects who consumed more than the RDA of 250$\mu\textrm{g}$ with the 6th and 7th databases were only 4.6%, 29.6% of males and 1.6%, 9.7% of females, respectively. The biggest food source of folate was Kimchi, contributing 17.9% for male and 13.7% for female students with 7th database. Laver, spinach, Ramyon, rice, and Ko Chu Jang together with Kimchi contributed 41.9% for male and 32.4% for females students with the 7th database. These results imply that folate intake reported in the reported inthe previous studies using the 6th database was underestimated. However, the 7th database seems to be still incomplete since 20.5% of 2,932 foods in the database were derived from the other sources, and the rest were imputed from similar foods. Therefore, in order to accurately estimate folate intake of Koreans, folate contents in major contributing foods need to be measured using an appropriate assay method.

• Journal of Nutrition and Health
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• v.48 no.1
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• pp.94-104
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• 2015

Purpose: The purpose of this study was to estimate dietary folate intake and food sources of children and adolescents using a nutrient database revised based on measured folate in selected foods. Methods: Folate content in 51 foods known as folate sources was measured by microbiological assay after trienzyme extraction. Folate intake was estimated from a part of the data of 'Dietary Intake Survey of Infants, Children and Adolescents in 2007~2008' conducted by the Korea Food and Drug Administration (KFDA) and the Korea Health Industry Development Institute (KHIDI). The study subjects were 567 children aged 1~19 years living in the Chungcheong area who completed two 24-hour recalls. Results: Folate values were revised by replacing the values in the current database with the analyzed values except when the value in the current database was between the analytical values or was not different from the mean analytical value by more than 10%. Among the revised values of 40 food items, folate values of 36 foods were lower than the current values. Mean folate intakes estimated with the revised database were approximately 70~80% lower than those estimated with the current database. Mean folate intakes of males aged 12~14 and females aged 12~19 were lower than the 2010 Recommended Nutrient Intakes (RNIs). Chicken's eggs, Kimchi, rice, mandarin, and laver were found to be main food sources of folate. Conclusion: In this study, mean dietary folate intakes were lower than those estimated with the current database. Further analyses for folate content especially in cooked foods commonly consumed in Korea are needed using a reliable assay in order to accurately assess folate intake of the Korean population. In addition, nutrition education should be provided for adolescent females in order to increase consumption of folate-rich foods.

• Korean Journal of Community Nutrition
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• v.4 no.4
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• pp.512-520
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• 1999

Microbiological method using a 96-well microplate reader for folate assay was established, and folate intake and blood folate concentrations of 23 female college students were assessed. To evaluate folate intake, dietary data were collected by a 3-day weight food record, and serum and RBC folate concentrations were measured by the new method. The coefficient of variation for the new method was less than 10%. Mean daily folate intake of the subjects was 126.7${\mu}g$ which is only 50.7% of the RDA. The mean concentrations of serum and RBC folate were 7.46ng/ml and 294.4ng/ml, respectively, which were within the normal range. These results indicate that folate intake seems to be underestimated due to incomplete food composition database. Therefore, folate database should be appropriately in order to asses folate intake accurately.

• Journal of Nutrition and Health
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• v.55 no.3
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• pp.330-347
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• 2022

Folate, a water-soluble vitamin, acts as a coenzyme for one-carbon metabolism in nucleic acid synthesis and amino acid metabolism. Adequate folate nutritional status during the periconceptional period is known to prevent neural tube defects. In addition, insufficient folate intake is associated with various conditions, such as anemia, hyperhomocysteinemia, cardiovascular disease, cancer, cognitive impairment, and depression. This review discusses the rationale for the revision of the 2020 Korean dietary reference intakes for folate, and suggestions for future revisions. Based on the changes in the standard body weight in 2020, the adequate intake (AI) for infants (5-11 months) and the estimated average requirements (EARs) for 15-18 years of age were revised, but there were no changes in the recommended nutrient intakes (RNIs) and tolerable upper intake levels (ULs) for all age groups. Mean folate intake did not reach RNI in most age groups and was particularly low in women aged 15-29 years, according to the results of the 2016-2018 Korea National Health and Nutrition Examination Survey (KNHANES). The percentages of folate intake to RNI were lower than 60% in pregnant and lactating women, but serum folate concentrations were higher than those in other age groups, presumably due to the use of supplements. Therefore, total folate intake, from both food and supplements, should be evaluated. In addition, the database of folate in raw, cooked, and fortified foods should be further expanded to accurately assess the folate intake of Koreans. Determination of the concentrations of erythrocyte folate and plasma homocysteine as well as serum folate is recommended, and quality control of the analysis is critical.

• Journal of Nutrition and Health
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• v.57 no.4
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• pp.418-434
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• 2024

Purpose: The nutritional status of folate in Korean adults was evaluated using the newly established folate database (DB) and data from the 7th Korea National Health and Nutrition Examination Survey. Methods: This study analyzed the folate intake of 15,054 people (6,278 men and 8,776 women) and the relationship with serum folate concentration of 5,260 people (2,272 men and 2,988 women). Results: The average daily folate intake among Korean adults was lowest in the 19 to 29-year age group and highest in those in their 50s. Folate intake was higher in groups with higher education and household income, non-smokers, participants in aerobic physical activity, and dietary supplement users regardless of sex. Among men, office workers consumed more folate than physical workers. Vegetables and grains were the first and second most contributing food groups to folate intake. The serum folate levels were higher in women than men and lowest in the 19-29 year age group for both sexes. After adjusting for energy intake, age, income, smoking, physical activity, and dietary supplement intake, serum folate concentration increased significantly as intake increased (p < 0.001). The explanatory power (R²) of folate intake on the blood folate concentration was 0.183 and 0.141 in men and women, respectively. Conclusion: The proportion of participants consuming less than the estimated average requirement was 48.1% and 65.3% in men and women, respectively. In particular, the folate intake and serum levels of young men aged 19-29 years were the lowest. Therefore, it is necessary to improve their folate nutritional status through a balanced diet. In addition, the newly established folate DB may be useful for evaluating the folate nutritional status of Koreans.

• Journal of Nutrition and Health
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• v.42 no.4
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• pp.397-405
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• 2009

A trienzyme extraction method (use of ${\alpha}$-amylase, protease and folate conjugase) for food folate assay has been used to release folate from the food matrix. In order to reduce the incubation time with three enzymes, folate values were compared between two incubation protocols; separate incubation (SI, incubated with ${\alpha}$-amylase and conjugase separately for 2 hours after protease treatment) and combined incubation (CI, incubated with ${\alpha}$-amylase and conjugase together for 2 hours after protease treatment) using 88 food items from 12 kinds of fast foods and processed foods. We found that folate values by CI were comparable to or higher than those by SI, indicating that CI might be a better extraction procedure to shorten the entire incubation time. We measured folate contents in 49 fast foods and 26 processed foods by microbiological assay after CI. Mean folate contents of one serving of various burgers ranged from 43.1 to 62.0 ${\mu}g$. One serving of French fries, pizza, sandwich and triangled kimbab contained a mean of 53.3, 28.4, 47.4, and 25.7 ${\mu}g$ of folate, respectively. Folate contents of non-alcoholic beverages were very low, ranging from 1.0 to 5.2 ${\mu}g$/100 g. Some of our values were comparable to the values in the folate database published in Korean Nutrition Society, however, some of the published values were 140 times higher than the measured values in this study. Folate values measured by the more recent modifications here can be used to update Korean folate database to accurately estimate dietary folate intake.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.1
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• pp.21-25
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• 2013

Background: Genetic factors and environmental factors play a role in pathogenesis of esophageal squamous cell carcinoma (ESCC). Previous studies regarding the association of folate intake and Methylenetetrahydrofolate reductase C677T polymorphism with ESCC was conflicting. We conducted a meta-analysis to investigate the association of MTHFR C677T and folate intake with esophageal cancer risk. Methods: MEDLINE, EMBASE and the Chinese Biomedical Database were searched in our study. The quality of studies were evaluated by predefined scale, and The association of polymorphisms of MTHFR C677T and folate intake and ESCC risk was estimated by Odds ratio (ORs) with 95% confidence intervals (CIs). Results: 19 studies (4239 cases and 5575 controls) were included for meta-analysis. A significant association was seen between individuals with MTHFR 677 CT [OR(95%)=1.47(1.32-1.63)] and TT [OR(95%)=1.69(1.49-1.91)] genotypes and ESCC risk (p<0.05). Low intake of folate had significantly higher risk of esophageal cancer among individuals with CT/TT genotype [OR(95%)=1.65(1.1-2.49)], while high intake of folate did not find significant high risk of esophageal cancer among individuals with CT/TT genotype [OR(95%)=1.64 (0.82-3.26)]. Conclusions: Our meta-analysis indicated the folate intake and MTHFR 677CT/TT are associated with the risk of ESCC, and folate showed a significant interaction with polymorphism of MTHFR C677T.

• Nutrition Research and Practice
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• v.11 no.5
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• pp.419-429
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• 2017

BACKGROUND/OBJECTIVES: The relationship between folate and colorectal neoplasia remains controversial. We examined the association between serum folate concentrations and colorectal adenomas in a case-control study of Korean adults and conducted a meta-analysis. SUBJECTS/METHODS: Our case-control study included 113 pairs of case and control who underwent colonoscopy and provided blood samples. We used multivariable conditional logistic regression models to obtain the odds ratios and 95% confidence interval (CIs). For meta-analysis, we identified the relevant studies by searching the PubMed database up to February 2017, included our case-control study and combined the study-specific relative risks (RRs) using a random-effects model. RESULTS: In this case-control study, we included 58 men and 55 women with colorectal adenomas and sex and fasting status matched the controls. We did not find any significant association between the serum folate levels and colorectal adenomas in either men or women. For meta-analysis, a total of eleven studies were included in our analysis and classified into two groups; polyp clearance group (PC) for the studies that included participants who underwent endoscopies and had their polyps removed at baseline; and no polyp clearance group (NPC) for the studies that included participants whose histories of endoscopies were unknown or who underwent their first endoscopies. Four PC (1,311 cases and 1,672 non-cases) and eight NPC studies (3,501 cases and 11,347 non-cases) were included. The combined RRs (95% CIs) comparing the bottom with the top categories of circulating folate levels were 1.07 (0.97-1.18) for the NPC group but 1.45 (1.16-1.74) for the PC group. CONCLUSIONS: Low circulating folate levels were associated with new adenoma formation.

• Korean Journal of Food Science and Technology
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• v.52 no.6
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• pp.580-586
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• 2020

Fishery resources have been widely consumed as protein- and vitamin-rich food sources in the Korean diet. However, information regarding their vitamin levels is extremely limited. In this study, trienzyme-Lactobacillus casei method was validated and used to determine the folate contents in fishery foods. The trienzyme-L. casei method for folate analysis showed excellent accuracy (85.2 to 95.3% recovery) and precision (repeatability 1.4% RSD and reproducibility 2.4% RSD). Folate contents of 20 fish foods (4 fish, 3 crustaceans, 3 sea algae, 3 cephalopods, 4 shellfish, and 3 others) ranged from 1.75 to 97.98 ㎍/100 g. Furthermore, we found that the folate content in seaweed fusiforme was the highest, followed by gulfweed (69.73 ㎍/100 g). Folate analysis using the trienzyme-L. casei method was determined excellent based on the z-score of -0.3 in the Food Analysis Performance Assessment Scheme test. Analytical and method validation data generated in this study could be used to update the national food composition table on vitamin B9 in Korean fishery resources.