• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.2
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• pp.286-290
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• 1998

The effects of cooking methods and storage time on folate content in spinach were determined by boiling for 1, 2, 3, 4, 5, 10 and 20min in distilled water or by microwave blanching for 20, 40, 60, 80, 100 sec. The folate content of cooked spinach was decreased to 80.7% after 1min boiling, and to 5.5% after 20min boiling. The folate recovered from the cooked spinach and cooking water was 101.1% after 1min, 68.0% after 2min and 51.3% after 3min. The relative folate content leached out of the cooked spinach into the cooking water varied from 20.2% after 1min boiling to 88.8% after 20min boiling. Total folate content of spinach was decreased to 45% by microwave heating for 40sec. However, the spinach cooked by microwave heating retained more folate due to the minimal loss of folate into cooking water. More than 90% of folate content of spinach was retained during 1 to 2 weeks of storage at 4$^{\circ}C$.

• Nutrition Research and Practice
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• v.5 no.2
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• pp.112-116
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• 2011

We investigated the effect of paternal folate status on folate content and expression of the folate transporter folate receptor ${\alpha}$ ($FR{\alpha}$) in rat placental tissues. Rats were mated after males were fed a diet containing 0 mg of folic acid/kg of diet (paternal folate-deficient, PD) or 8 mg folic acid/kg of diet (paternal folate-supplemented, PS) for 4 weeks. At 20 days of gestation, the litter size, placental weight, and fetal weight were measured, and placental folate content (n=8/group) and expression of $FR{\alpha}$ (n=10/group) were analyzed by microbiological assay and Western blot analysis, respectively. Although there was no difference observed in litter size or fetal weight, but significant reduction (10%) in the weight of the placenta was observed in the PD group compared to that in the PS group. In the PD group, placental folate content was significantly lower (by 35%), whereas $FR{\alpha}$ expression was higher (by 130%) compared to the PS group. Our results suggest that paternal folate status plays a critical role in regulating placental folate metabolism and transport.

• Nutrition Research and Practice
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• v.7 no.4
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• pp.281-286
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• 2013

We examined the effect of parental folate deficiency on the folate content, global DNA methylation, folate receptor-alpha (FR${\alpha}$), insulin-like-growth factor-2 (IGF-2) and -1 receptor (IGF-1R) in the liver and plasma homocysteine in the postnatal rat. Male and female rats were randomly fed a folic acid-deficient (paternal folate-deficient, PD and maternal folate-deficient, MD), or folic acid-supplemented diet (paternal folate-supplemented, PS and maternal-folate-supplemented, MS) for four weeks. They were mated and grouped accordingly: $PS{\times}MS$, $PS{\times}MD$, $PD{\times}MS$, and $PD{\times}MD$. Pups were killed on day 21 of lactation. The hepatic folate content was markedly reduced in the $PD{\times}MD$ and $PS{\times}MD$ and $PD{\times}MS$ as compared with the $PS{\times}MS$ group. The hepatic global DNA methylation was decreased in the $PD{\times}MS$ and $PS{\times}MD$ groups as much as in the $PD{\times}MD$ group, and all the three groups were significantly lower as compared to the $PS{\times}MS$ group. There were no significant differences in the hepatic FR${\alpha}$, IGF-2 and IGF-1R expressions among the groups. Positive correlations were found between the hepatic folate content and global DNA methylation and protein expressions of FR${\alpha}$, IGF-2 and IGF-1R, whereas an inverse correlation was found between hepatic folate content and plasma homocysteine level in the 3-week-old rat pup. The results of this study show that both paternal and maternal folate deficiency at mating can influence the folate content and global DNA methylation in the postnatal rat liver.

• Journal of Nutrition and Health
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• v.41 no.6
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• pp.518-529
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• 2008

Lactating women have an increased need of folate in the breastfeeding period and, as a consequence, may be in risk of folate deficiency. Folate content of breast milk, furthermore, is important for infants to support exponential growth. However, little is known about the folate content of breast milk from Korean lactating women and their folate nutritional status. In this study, therefore, we investigated the folate status of Korean lactating women and the folate content of their breast milk during extended lactation. A total of 10 subjects who delivered full-term infants participated this study voluntarily. Dietary folate intakes were measured and blood and breast milk were collected at 1, 2, 3, and 6 months postpartum. The women who did not take folic acid supplements failed to meet the recommended intake(RI) of folate for lactating women during all the study periods but those who did met the RI. The unsupplemented women showed lower plasma folate concentrations compared to the supplemented women and all the women were in suboptimal folate status determined by plasma folate concentration throughout the study periods. But the supplemented women showed lower prevalence of suboptimal folate status only at 3 or 6 months postpartum. Plasma folate concentrations of both groups decreased with the progression of lactation. Erythrocyte folate concentrations were not different between the two groups, however, that of the unsupplemented reduced further as time progressed. Plasma homocysteine levels were not different between the two groups. Concentrations of erythrocyte folate and plasma homocysteine were not changed throughout the study periods. Folate contents of their breast milk through the study periods were not different between the two groups and it decreased as lactation progressed in both groups. The results of this study suggest that the folate nutritional status of Korean lactating women might be deteriorated with the progression of lactation without folic acid supplements.

• 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.

• Korean journal of food and cookery science
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• v.33 no.2
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• pp.162-173
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• 2017

Purpose: The purpose of this study was to evaluate the folate contents and quality characteristics of commercial and fermented Kimchi and compare the correlation between folic acid and quality characteristics. Methods: The contents of total folate and quality characteristics were evaluated in 10 kinds of industrial and local Kimchi and nine kinds of other commonly consumed Kimchi. Changes in folate content and quality characteristics of Kimchi during 14 days of fermentation at $15^{\circ}C$ were compared. Results: Chungnam (L4) Kimchi had the lowest pH of 4.62, and acidity (0.57%) and salinity (3.26%) were highest compared to other areas. The content of total folate of D company (A) was the highest at $73.66{\mu}g/100g$. The content of total folate was significantly higher than those of Sesame leaf Kimchi (O9) and Young leafy radish Kimchi (O5) containing 65.77 and $62.82{\mu}g/100g$, respectively. The pH of fermented Kimchi decreased from 6.09 to 4.11 (p<0.05), and the acidity significantly increased (p<0.001) to 0.32-0.66%. Reducing sugar content decreased rapidly by 4 days and then slowly decreased (p<0.001). Total bacteria and lactic acid bacteria counts significantly increased (p<0.05) with fermentation period. Content of total folate was highest at $69.82{\mu}g/100g$ and $68.16{\mu}g/100g$ on days 0 and 2 of fermentation, after which it decreased to 77.6% at $15.61{\mu}g/100g$ on day 10 of fermentation. Conclusion: As a result, there was no definite trend regarding folate content in commercial Kimchi and other Kimchi. Young leafy radish, Chives, and Welsh onion Kimchi, which are rich in green leaves, are excellent folate source foods. The highest folate content of fermented Kimchi was identified on day 2 of fermentation. Therefore, it is recommended to use raw or immature Kimchi when using Kimchi as a folate source food.

• Journal of Nutrition and Health
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• v.31 no.3
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• pp.271-278
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• 1998

Folate coenzymes are involved in one-carbon transfer reactions needed for the synthesis of nucleic acids, amino acids, and proteins which are very important for cell proliferation and differentiation. To investigate the effects of dietary folate content on plasma and tissue folate concentrations and on folate excretions in urine and feces, male Sprague-Dawley rats were raised for 4-10 weeks on semi-purified experimental diets containing 0mg, 2 mg, 8mg folate/kg diet. Folate concentrations were determined microbiologically using Lactobacillius casei (ATCC 7469). When compared to the folate adequate diet, the folate deficient diet decreased folate levels in plasma, liver and kidney , and the values were further decreased with experimental period. In rats reviving folate supplemented diets, plasma , liver and kidney folate adequate or supplemented diets, folate concentrations weer increased compared to animals on the folate adequate diet. In the folate adequate or supplemented diets, folate concentrations in the plasma and kidney were maintained at essentially the same level for 10 weeks . Folate concentrations in the liver, however, continued to increase with experimental period. Dietary folate intake seems to influence plasma and liver folate concentrations more than kidney folate concentrations. Folate excretions unrine and feces were significantly increased with dietary foalte intakes and experimental period. Folate excreted via urine was consideerably greater than that via feces. These resutls indicated that the foate supplemented diet improved plasma and tissue foalte status. Whether folate supplmentation improves foalte-dependent reactions remains to be researched.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.152-158
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• 2001

In this study, we determined major foods and food groups which contributed to the intake of folate in korean child-bearing women. Folate content of the major foods was also analyzed. A total of 91 healthy women with childbearing potential participated. They were divided into one of three groups by age; A (15∼24 yrs), B(25∼34 yrs) and C (35∼49 yrs). Food consumption data of the subjects were obtained by the 24-hr recall method. The rate of contribution of each food to the total intake of dietary folate was determined. Seventy major foods for folate were selected from the 178 foods they consumed. Two sets of the 70 foods were collected from different markets. After extracting folates from the foods by heating with a HEPES-CHES buffer, the samples were treated with α-amylase, protease and folate intakes was Korean cabbage kimchi followed by laver, soybean sprout, rice, yolmu kimchi, eggs, lettuce, perilla leaves, sea mustard and radish root. Food items that contributed to folate intake were slightly different among the age groups. Although the folate content of Korean cabbage kimchi was 51.6 ㎍/100g, but due to the high amount of intake, it was ranked the first major food prviding folate. High folate foods containing over 100㎍/100g were laver, corn flakes, spinach, mungbean, sesame, quail's eggs, small radish kimchi, kidney beans, leeks and peanuts. However, based on the serving size, spinach, corn flakes, leeks, sweet potato, pepper leaves, quail's eggs, crown daisy, small radish kimchi and perilla leaves contributed above 50㎍ of folate per serving size.

• 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.

• Journal of Nutrition and Health
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• v.32 no.6
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• pp.654-660
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• 1999

Folate, a precursor of the coenzyme tetrahydrofolate, plays an important role in DNA replication and cell proliferation, and thus could influence rapidly proliferating immune cells such as leukocytes and splenocytes. The effects of dietary folate on folate concentrations of plasma, thymus, spleen and leukocytes were investigated in rats. The animals were raised for 6 weeks on semipurifed experimental diets containing 0mg, 2mg, 4mg, 8mg folate/kg diet. Folate concentrations were determined microbiologically using Lactobacillus casei(ATCC 7469), and DNA strand breaks produced by alkaline treatment were analyzed fluorometrically. When compared to folate adequate diet, the folate deficient diet(0mg folate/kg diet) resulted in lowest folate levels in plasma, thymus, spleen and leukocytes, and the highest DNA strand breaks in spleen cells and leukocytes. Dietary folate levels significantly increased folate concentrations of immune tissues, leukocytes, and the plasma in a dose dependent manner, folate concentrations being highest with a diet providing 8mg folate/kg diet. The percentages of the double strand DNA remaining in the splenocytes and leukocytes after alkaline treatment were significantly increased with higher amounts of dietary folate in a dose dependent manner. Folate intakes of 8mg than 4mg/kg diet was found to be more effective in the prevention of DNA strand breaks. The results of this study suggest that increased folate above the requirement level could improve DNA stabilities in immune cells.