• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.2
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• pp.331-338
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• 2004

Folate nutrition in early pregnancy is crucial in order to prevent neural tube defects (NTDs) in the fetus and maternal folate deficiency in late pregnancy If the influencing factors on maternal folate status are identified we may be able to detect the women at most risk of folate deficiency. This study intends to determine folate intakes, assess the levels of serum folate, erythrocyte folate, and plasma homocysteine, and reveal theinfluencing factors on maternal folate status in early pregnancy. A total of 151 healthy women in their first trimester volunteered for this study. The average length of gestation period was 9.1$\pm$ 2.3 weeks and seventy subjects were primipara. They consumed 1599$\pm$589 ㎉/day of energy and 230.8$\pm$145.2 $\mu\textrm{g}$/day of folate. This represented 72.5％ and 46.2％ of the Korean RDA respectively for pregnant women in the first half of Pregnancy. Results show that they consume less folate and energy due to morning sickness. Morning sickness correlated negatively with the intakes of energy, folate, ana Kimchi also. Their levels of serum folate, erythrocyte folate, and plasma homocysteine were 5.5$\pm$1.9 ng/mL, 266.6$\pm$75.0 ng/mL, and 7.0$\pm$1.8 $\mu$mol/L, respectively. Results indicate that 7.8% were deficient and 60.3% were borderline deficient in serum folate, 4.3% were deficient in erythrocyte folate, however, all had normal levels of plasma homocysteine. Results indicate that the folate status was not poor Contributing factors influencing serum folate concentrations ($R^2$= 0.724, p = 0.0001) were self-reported health status (+), folate intake (+), age (-), length of gestation (-), and homocysteine levels (-). Factors influencing erythrocyte folate concentrations ($R^2$ = 0.570, p = 0.0029) were the infant birth height of the last pregnancy (+), energy intake (+), age (-), plasma homocysteine concentration (-), and education level (-). Factors influencing plasma homocysteine concentrations ($R^2$= 0.450, p = 0.0051) were income level (+), prepregnancy weight (+), serum folate concentration (-), and the infant birth weight of the last pregnancy (-). These results indicate that pregnant women are likely to have a folate deficiency if they are in poor health status, having a history of delivering small infant and low energy and/or folate intake, and/or are older. And folate status is likely to decline as pregnancy progresses.

• 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.42 no.5
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• pp.423-433
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• 2009

Folate and vitamin $B_{12}$ are essential cofactors for homocysteine (Hcy) metabolism. Homocysteinemia has been related with cardiovascular and neurodegenerative disease. We examined the effect of folate and/or vitamin $B_{12}$ deficiency on biomarkers of one carbon metabolism in blood, liver and brain, and analyzed the correlation between vitamin biomarkers in mild and moderate homocysteinemia. In this study, Sprague-Dawley male rats (5 groups, n = 10) were fed folatesufficient diet (FS), folate-deficient diet (FD) with 0 or 3 g homocystine (FSH and FDH), and folate-/vitamin $B_{12}$-deficient diet with 3 g homocystine (FDHCD) for 8 weeks. The FDH diet induced mild homocysteinemia (plasma Hcy 17.41 ${\pm}$ 1.94 nmol/mL) and the FDHCD diet induced moderate homocysteinemia (plasma Hcy 44.13 ${\pm}$ 2.65 nmol/mL), respectively. Although liver and brain folate levels were significantly lower compared with those values of rats fed FS or FSH (p < 0.001, p < 0.01 respectively), there were no significant differences in folate levels in liver and brain among the rats fed FD, FDH and FDHCD diet. However, rats fed FDHCD showed higher plasma folate levels (126.5 ${\pm}$ 9.6 nmol/L) compared with rats fed FD and FDH (21.1 ${\pm}$ 1.4 nmol/L, 22.0 ${\pm}$ 2.2 nmol/L)(p < 0.001), which is the feature of "ethyl-folate trap"by vitamin $B_{12}$ deficiency. Plasma Hcy was correlated with hepatic folate (r = -0.641, p < 0.01) but not with plasma folate or brain folate in this experimental condition. However, as we eliminated FDHCD group during correlation test, plasma Hcy was correlated with plasma folate (r = -0.581, p < 0.01), hepatic folate (r = -0.684, p < 0.01) and brain folate (r = -0.321, p < 0.05). Hepatic S-adenosylmethionine (SAM) level was lower in rats fed FD, FDH and FDHCD than in rats fed FS and FSH (p < 0.001, p < 0.001 respectively) and hepatic S-adenosylhomocysteine (SAH) level was significantly higher in those groups. The SAH level in brain was also significantly increased in rats fed FDHCD (p < 0.05). However, brain SAM level was not affected by folate and/or vitamin $B_{12}$ deficiency. This result suggests that dietary folate- and vitamin B12-deficiency may inhibit methylation in brain by increasing SAH rather than decreasing SAM level, which may be closely associated with impaired cognitive function in nutritional homocysteinemia.

• 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.10 no.4
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• pp.84-91
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• 1977

엽산의 결핍은 대혈구성 빈혈(macrocytic and/or megaloblastic anemia)을 일으킨다. 체내에서 엽산은 합성될 수 없는 것으로 알려져, 식품을 통하여 섭취하여야 한다. 이에, 한국인 식생활의 기본을 이루고 있는 쌀, 콩 및 채소류의 식품에 포함된 엽산치를 미생물학적인 측정방법에 따라 분석하였다. Streptococcus faecalis보다 Lactobacillus casei미생물을 사용하여 측정한 방법이, 인간에게 이용될 수 있는 보다 정확한 엽산치로 밝혀졌다. 산화되기 쉬운 형태로 된 labile folate를 보호하기 위한 ascorbic acid의 첨가는, 각 식품에 포함된 엽산치를 증가 시켰다. 결합형으로 존재하는 polyglutamates를 유리형으로 하기 위하여 conjugase enzyme을 사용하였으며, 식품에 따른 화학적 조성은 주로 polyglutamyl form이나 각 식품에 따라 큰 차이가 있는 것으로 나타났다. Lactobacillus casei을 사용하여 측정된 각 식품의 엽산치는, 배추 34.5, 당근17.8, 오이 25.3, 가지 24.7, 쑥갓 76.5, 마늘 3.1, 파 40.2, 완두콩 68.7, 풋고추 27.1, 강남콩 66.9, 부추 64.1, 상치 39.3, 양파 4.3, 시금치 150.7, 호박 26.1, 무우 40.3, 백미 29.9 ug으로 각기 식품 100g 중에 함유됨을 보였다.

• Journal of Nutrition and Health
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• v.36 no.8
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• pp.801-810
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• 2003

Chronic alcoholism is considered a common cause of malnutrition. Especially, micronutrient deficiency may playa critical role in the incidence of alcoholic liver diseases. This study was conducted to investigate the effect of folate deficiency and ethanol consumption on cholesterol metabolism and the antioxidative system in rats. Plasma concentration of total cholesterol was increased by ethanol administration in folate-fed rats. HDL-cholesterol tended to be higher in the folate-fed group, but it was not significant. The plasma and hepatic levels of malondialdehyde were increased after chronic ethanol feeding, but dietary folate depressed the plasma malondialdehyde content of rats. Ethanol or folate feeding did not significantly change alcohol dehydrogenase activity. But folate feeding increased catalase activity in ethanol-fed rats. There was no significant change in superoxide dismutase activity among the experimental groups. Glutathione peroxidase activity tended to decrease by chronic ethanol feeding, but dietary folate did not affectthe glutathione peroxidase activity of chronic ethanol-fed rats. Glutathionine-S-transferase activity was not affected by ethanol feeding or folate deficiency. The plasma and hepatic levels of retinol decreased after chronic ethanol feeding. The hepatic level of retinol significantly decreased in ethanol-fed rats by folate deficiency. The plasma level of $\alpha$-tocopherol tended to be low in the folate deficient group with ethanol feeding, but there was no difference among the experimental groups in the hepatic level of $\alpha$-tocopherol. These results demonstrate that chronic ethanol consumption changes the plasma cholesterol metabolism and antioxidative system of rats, and optimal folate feeding in ethanol-fed rats exerts protective effects to some extent.

• 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.10 no.4
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• pp.92-96
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• 1977

과실류 식품에 포함된 엽산치를 Lactobacillus casei 미생물을 사용하여 분석하였다. 측정시 결합형으로 존재하는 엽산을 유리형으로 하기 위해서 conjugase효소를 사용했고, 산화되기 쉬운 형해로 된 엽산을 보호하기 위하여 비타민 C를 첨가하였다. 과실류는 일반적으로 엽산을 소량 함유한 식품으로 나타났다. 각 과실에 포함된 엽산 분석치는 사과 7.5, 살구 8.6, 바나나 20.2, 앵두 3.0, 포도 11.2, 귤 26.6, 복숭아 3.5, 배 10.5, 자두(붉은색) 3.7, 자두(노란색) 2.0, 딸기 19.7, 수학 3.8, 감 7.5, 참외 3.7, 토마도 $9.1{\mu}g$으로 각기 식품 100g 중에 함유 되었음을 보였다.

• 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.

• Journal of Nutrition and Health
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• v.24 no.4
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• pp.337-343
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• 1991

The effect of 9-methyl folate on histidine oxidation, the uptake of an injected dose of $[^{3}H]folate$ by the livers and kidneys, the hepatic and blood folate levels were investigated by feeding crude x-methyl folate(XMF) at a level of 5 g per kg diet. 9-Methyl folate is konwn as a major forate antagonist in XMF to produce deficiency signs in rat. Feeding of XMF decreased histidine oxidation and hepatic folate levels significantly, which showed the function of 9-methyl folate as an antifolate in rats. The hepatic uptake of labeled folate in XMF- fed rats was decreased significantly. These data led to conclude that 9-methyl folate inhibited folate uptake and retention by tissue, especially liver, which could explain the low liver folate levels and the decreased histidine oxidation. However, only very low level of 9-methyl folate was detected in liver. It suggested that 9-methyl folate may be metabolized very quickly in the liver after uptaken.