Folic acid supplementation prevents high fructose-induced non-alcoholic fatty liver disease by activating the AMPK and LKB1 signaling pathways

BACKGROUND/OBJECTIVES@#The present study aimed to evaluate the effects of folic acid supplementation in high-fructose-induced hepatic steatosis and clarify the underlying mechanism of folic acid supplementation.MATERIALS/METHODS: Male SD rats were fed control, 64% high-fructose diet, or 64% high-fructose diet with folic acid for eight weeks. Plasma glutamate-pyruvate transaminase, glutamate-oxaloacetate transaminase, lipid profiles, hepatic lipid content, S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH) were measured. @*RESULTS@#The HF diet significantly increased hepatic total lipid and triglyceride (TG) and decreased hepatic SAM, SAH, and SAM:SAH ratio. In rats fed a high fructose diet, folic acid supplementation significantly reduced hepatic TG, increased hepatic SAM, and alleviated hepatic steatosis. Moreover, folic acid supplementation in rats fed high fructose enhanced the levels of phosphorylated AMP-activated protein kinase (AMPK) and liver kinase B (LKB1) and inhibited phosphorylation of acetyl coenzyme A carboxylase (ACC) in the liver. @*CONCLUSIONS@#These results suggest that the protective effect of folic acid supplementation in rats fed high fructose may include the activation of LKB1/AMPK/ACC and increased SAM in the liver, which inhibit hepatic lipogenesis, thus ameliorating hepatic steatosis. The present study may provide evidence for the beneficial effects of folic acid supplementation in the treatment of non-alcoholic fatty liver disease.

Comparison of antioxidant activity and prevention of lymphocyte DNA damage by fruit and vegetable juices marketed in Korea / 한국영양학회지

PURPOSE: Fruit and vegetable juices are known to be rich sources of antioxidants, which have beneficial effects on diseases caused by oxidative stress. The purpose of this study was to directly compare the antioxidant activities of fruit and vegetable juices marketed in Korea. METHODS: We analyzed four fruit juices, two vegetable juices, two yellow-green juices, and six mixed vegetable juices. Antioxidant activities were analyzed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) test, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonate) (ABTS) test, and oxygen radical absorbance capacity (ORAC) assay. Protective effects against DNA damage were determined using an ex vivo comet assay with human lymphocytes. RESULTS: DPPH radical scavenging activities were in the following order: blueberry juice > mixed vegetable C juice > kale juice > mixed vegetable P juice > grape juice. ABTS radical scavenging activities were in the following order: blueberry juice > mixed vegetable C juice > grape juice > mixed vegetable P juice > kale juice. Peroxyl radical scavenging activities as assessed by ORAC assay were in the following order: blueberry juice > kale juice > mixed vegetable C juice > grape juice. Grape or blueberry juice showed strong abilities to prevent DNA damage in lymphocytes, and the difference between them was not significant according to the GSTM1/GSTT1 genotype. CONCLUSION: Antioxidant activities of fruit and vegetable juices and ex vivo DNA protective activity increased in the order of blueberry juice, grape juice, and kale juice, although the rankings were slightly different. Therefore, these juices rich in polyphenols and flavonoids deserve more attention for their high antioxidant capacity.

Effects of excessive dietary methionine on oxidative stress and dyslipidemia in chronic ethanol-treated rats

BACKGROUND/OBJECTIVE: The aim of this study was to examine the effect of high dietary methionine (Met) consumption on plasma and hepatic oxidative stress and dyslipidemia in chronic ethanol fed rats. MATERIALS/METHODS: Male Wistar rats were fed control or ethanol-containing liquid diets supplemented without (E group) or with DL-Met at 0.6% (EM1 group) or 0.8% (EM2 group) for five weeks. Plasma aminothiols, lipids, malondialdehyde (MDA), alanine aminotransferase (ALT), and aspartate aminotransferase were measured. Hepatic folate, S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH) were measured. RESULTS: DL-Met supplementation was found to increase plasma levels of homocysteine (Hcy), triglyceride (TG), total cholesterol (TC), and MDA compared to rats fed ethanol alone and decrease plasma ALT. However, DL-Met supplementation did not significantly change plasma levels of HDL-cholesterol, cysteine, cysteinylglycine, and glutathione. In addition, DL-Met supplementation increased hepatic levels of folate, SAM, SAH, and SAM:SAH ratio. Our data showed that DL-Met supplementation can increase plasma oxidative stress and atherogenic effects by elevating plasma Hcy, TG, and TC in ethanol-fed rats. CONCLUSION: The present results demonstrate that Met supplementation increases plasma oxidative stress and atherogenic effects by inducing dyslipidemia and hyperhomocysteinemia in ethanol-fed rats.

Effects of excessive dietary methionine on oxidative stress and dyslipidemia in chronic ethanol-treated rats

BACKGROUND/OBJECTIVE: The aim of this study was to examine the effect of high dietary methionine (Met) consumption on plasma and hepatic oxidative stress and dyslipidemia in chronic ethanol fed rats. MATERIALS/METHODS: Male Wistar rats were fed control or ethanol-containing liquid diets supplemented without (E group) or with DL-Met at 0.6% (EM1 group) or 0.8% (EM2 group) for five weeks. Plasma aminothiols, lipids, malondialdehyde (MDA), alanine aminotransferase (ALT), and aspartate aminotransferase were measured. Hepatic folate, S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH) were measured. RESULTS: DL-Met supplementation was found to increase plasma levels of homocysteine (Hcy), triglyceride (TG), total cholesterol (TC), and MDA compared to rats fed ethanol alone and decrease plasma ALT. However, DL-Met supplementation did not significantly change plasma levels of HDL-cholesterol, cysteine, cysteinylglycine, and glutathione. In addition, DL-Met supplementation increased hepatic levels of folate, SAM, SAH, and SAM:SAH ratio. Our data showed that DL-Met supplementation can increase plasma oxidative stress and atherogenic effects by elevating plasma Hcy, TG, and TC in ethanol-fed rats. CONCLUSION: The present results demonstrate that Met supplementation increases plasma oxidative stress and atherogenic effects by inducing dyslipidemia and hyperhomocysteinemia in ethanol-fed rats.

Effects of vitamin C and E supplementation on oxidative stress and liver toxicity in rats fed a low-fat ethanol diet

We compared the preventive capacity of high intakes of vitamin C (VC) and vitamin E (VE) on oxidative stress and liver toxicity in rats fed a low-fat ethanol diet. Thirty-two Wistar rats received the low fat (10% of total calories) Lieber-DeCarli liquid diet as follows: either ethanol alone (Alc group, 36% of total calories) or ethanol in combination with VC (Alc + VC group, 40 mg VC/100 g body weight) or VE (Alc + VE group, 0.8 mg VE/100 g body weight). Control rats were pair-fed a liquid diet with the Alc group. Ethanol administration induced a modest increase in alanine aminotransferase (ALT), aspartate aminotransferase (AST), conjugated dienes (CD), and triglycerides but decreased total radical-trapping antioxidant potential (TRAP) in plasma. VE supplementation to alcohol-fed rats restored the plasma levels of AST, CD, and TRAP to control levels. However, VC supplementation did not significantly influence plasma ALT, AST, or CD. In addition, a significant increase in plasma aminothiols such as homocysteine and cysteine was observed in the Alc group, but cysteinylglycine and glutathione (GSH) did not change by ethanol feeding. Supplementing alcohol-fed rats with VC increased plasma GSH and hepatic S-adenosylmethionine, but plasma levels of aminothiols, except GSH, were not influenced by either VC or VE supplementation in ethanol-fed rats. These results indicate that a low-fat ethanol diet induces oxidative stress and consequent liver toxicity similar to a high-fat ethanol diet and that VE supplementation has a protective effect on ethanol-induced oxidative stress and liver toxicity.

Folic acid supplementation reduces oxidative stress and hepatic toxicity in rats treated chronically with ethanol

Folate deficiency and hyperhomocysteinemia are found in most patients with alcoholic liver disease. Oxidative stress is one of the most important mechanisms contributing to homocysteine (Hcy)-induced tissue injury. However it has not been examined whether exogenous administration of folic acid attenuates oxidative stress and hepatic toxicity. The aim of this study was to investigate the in vivo effect of folic acid supplementation on oxidative stress and hepatic toxicity induced by chronic ethanol consumption. Wistar rats (n = 32) were divided into four groups and fed 0%, 12%, 36% ethanol, or 36% ethanol plus folic acid (10 mg folic acid/L) diets. After 5 weeks, chronic consumption of the 36% ethanol diet significantly increased plasma alanine transaminase (ALT) (P < 0.05) and aspartate transaminase (AST) (P < 0.05), triglycerides (TG) (P < 0.05), Hcy (P < 0.001), and low density lipoprotein conjugated dienes (CD) (P < 0.05) but decreased total radical-trapping antioxidant potential (TRAP) (P < 0.001). These changes were prevented partially by folic acid supplementation. The 12% ethanol diet had no apparent effect on most parameters. Plasma Hcy concentration was well correlated with plasma ALT (r = 0.612**), AST (r = 0.652*), CD (r = 0.495*), and TRAP (r = -0.486*). The results indicate that moderately elevated Hcy is associated with increased oxidative stress and liver injury in alcohol-fed rats, and suggests that folic acid supplementation appears to attenuate hepatic toxicity induced by chronic ethanol consumption possibly by decreasing oxidative stress.

Iodine Intake and Tolerable Upper Intake Level of Iodine for Koreans

The present study reviewed the effects of excess iodine intake on thyroid function and the incidence of thyroid disease and discussed the scientific basis for establishing a tolerable upper intake level (UL) of iodine for Koreans. ULs are defined as "the highest level of daily nutrient intake that is likely to pose no risk of adverse effects to almost all individuals in the general population." Koreans consume excess iodine from seaweed, and iodine intake is strongly influenced by seaweed consumption. However, no dose-response data derived from subjects consuming excess iodine frequently but not continuously during a lifetime are available. Therefore, the Korean DRI committee set the iodine UL to reduce the risk of adverse health effects by excess iodine intake for Koreans with distinctive seaweed-eating habits.

Relationships of Plasma Homocysteine Concentration and Oxidative Stress Markers in Korean Collage Students

Elevated plasma concentration of total homocysteine (ptHcy) is known as an independent risk factor of cardiovascular disease (CVD) and oxidative stress is also commonly implicated in CVD. An association between ptHcy and oxidative stress has recently been suggested. The study objective is to examine the relationship between ptHcy and oxidative stress markers in 103 healthy college students (62 males and 41 females). Plasma levels of ptHcy, oxidative stress markers (conjugated diene, erythrocyte catalase, TRAP, lymphocyte DNA damage), antioxidant vitamins (alpha-tocopherol, gamma-tocopherol, carotenoids), and lipid parameters (total cholesterol, triglyceride, HDL cholesterol) were determined. The results show that the concentration of ptHcy was significantly higher in male subjects (22.17 +/- 2.14 micromole/L) than in female subjects (12.28 +/- 0.45 micromole/L). There was a negative association between ptHcy and plasma beta-carotene in male subjects (p or = 15 micromol/L), as compared to those with lower plasma homocysteine. These study results confirmed the views on the association between plasma homocysteine and oxidative stress markers in humans and support the hypothesis that homocysteine promotes the oxidative environment by counteracting the antioxidant defense mechanism.

Effects of dietary supplementation of high-dose folic acid on biomarkers of methylating reaction in vitamin B12-deficient rats

Folate is generally considered as a safe water-soluble vitamin for supplementation. However, we do not have enough information to confirm the potential effects and safety of folate supplementation and the interaction with vitamin B12 deficiency. It has been hypothesized that a greater methyl group supply could lead to compensation for vitamin B12 deficiency. On this basis, the present study was conducted to examine the effects of high-dose folic acid (FA) supplementation on biomarkers involved in the methionine cycle in vitamin B12-deficient rats. Sprague-Dawley rats were fed diets containing either 0 or 100 microg (daily dietary requirement) vitamin B12/kg diet with either 2 mg (daily dietary requirement) or 100 mg FA/kg diet for six weeks. Vitamin B12-deficiency resulted in increased plasma homocysteine (p<0.01), which was normalized by dietary supplementation of high-dose FA (p<0.01). However, FA supplementation and vitamin B12 deficiency did not alter hepatic and brain S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) concentrations and hepatic DNA methylation. These results indicated that supplementation of high-dose FA improved homocysteinemia in vitamin B12-deficiency but did not change SAM and SAH, the main biomarkers of methylating reaction.

A Critical Evaluation of the Correlation Between Biomarkers of Folate and Vitamin B12 in Nutritional Homocysteinemia

Folate and vitamin B12 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 B12 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 folate-sufficient diet (FS), folate-deficient diet (FD) with 0 or 3 g homocystine (FSH and FDH), and folate-/vitamin B12-deficient diet with 3 g homocystine (FDHCD) for 8 weeks. The FDH diet induced mild homocysteinemia (plasma Hcy 17.41 +/- 1.94 nmol/mL) and the FDHCD diet induced moderate homocysteinemia (plasma Hcy 44.13 +/- 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 +/- 9.6 nmol/L) compared with rats fed FD and FDH (21.1 +/- 1.4 nmol/L, 22.0 +/- 2.2 nmol/L)(p < 0.001), which is the feature of "ethyl-folate trap"by vitamin B12 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 B12 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.

Comparison of Children's Body Weights and Eating Habits by Maternal Parenting Attitudes Perceived by Children / 대한지역사회영양학회지

Effective parenting attitudes have been known to be associated with children's health practices including dietary intake and physical activity. The objective of this study is to compare children's body weights and eating habits by maternal parenting attitudes. Data were collected at school (N = 396; 4th and 5th grade students) using self-administered questionnaires on maternal parenting attitudes, eating habits and physical activity. Parenting attitudes were categorized as 1 of 4 parenting attitudes (overprotective, authoritarian, democratic, and neglectful) using affection and control median cut points. Children's body weights, frequency of breakfast, eating out and fastfood, and physical activity were compared by maternal parenting attitudes. Children's body weights were related with mother's employment status (p < 0.05) and parenting attitudes (p < 0.01). Children of unemployed mothers were more likely to be overweight. Children of neglectful mothers (p < 0.01) were more likely to be underweight, compared with children of mothers with other parenting attitudes. Since, unfortunately, the number of children of neglectful mothers was very limited in this study, we could hardly assess eating habits of children of neglectful mothers. Children of authoritarian mothers ate breakfast more regularly (p < 0.05), but ate snacks less regularly (p < 0.01). Children of democratic mothers ate fastfood less frequently (p < 0.01) and ate snacks more regularly (p < 0.01). Meanwhile, children of overprotective mothers ate breakfast less regularly (p < 0.05) and ate out less frequently (p < 0.01). However, maternal parenting attitudes were not related to children's physical activities. In conclusion, the maternal democratic parenting attitude was associated with healthy eating habits including regular snack time and less fastfood. On the other hand, the maternal neglectful parenting attitude was associated with high risk of children's underweight. Understanding the mechanism through which parenting attitude is related with underweight risk and healthy eating habits may lead to the development of better interventions.

In vitro inhibition of 10-formyltetrahydrofolate dehydrogenase activity by acetaldehyde

Alcoholism has been associated with folate deficiency in humans and laboratory animals. Previous study showed that ethanol feeding reduces the dehydrogenase and hydrolase activity of 10-formyltetrahydrofolate dehydrogenase (FDH) in rat liver. Hepatic ethanol metabolism generates acetaldehyde and acetate. The mechanisms by which ethanol and its metabolites produce toxicity within the liver cells are unknown. We purified FDH from rat liver and investigated the effect of ethanol, acetaldehyde and acetate on the enzyme in vitro. Hepatic FDH activity was not reduced by ethanol or acetate directly. However, acetaldehyde was observed to reduce the dehydrogenase activity of FDH in a dose- and time-dependent manner with an apparent IC50 of 4 mM, while the hydrolase activity of FDH was not affected by acetaldehyde in vitro. These results suggest that the inhibition of hepatic FDH dehydrogenase activity induced by acetadehyde may play a role in ethanol toxicity.

Genomic DNA Methylation Status and Plasma Homocysteine in Choline- and Folate-Deficient Rats

Elevated plasma homocysteine ( Hcy) is a risk factor for cognitive dysfunction and Alzheimer disease, although the mechanism is still unknown. Both folate and betaine, a choline metabolite, play essential roles in the remethylation of Hcy to methionine. Choline deficiency may be associated with low folate status and high plasma Hcy. Alterations in DNA methylation also have established critical roles for methylation in development of the nervous system. This study was un-dertaken to assess the effect of choline and folate deficiency on Hcy metabolism and genomic DNA methylation status of the liver and brain. Groups of adult male Sprague Dawley rats were fed on a control, choline-deficient ( CD) , folate-deficient ( FD) or choline/folate-deficient ( CFD) diets for 8 weeks. FD resulted in a significantly lower hepatic folate ( 23%)(p < 0.001) and brain folate ( 69%)(p < 0.05) compared to the control group. However, plasma and brain folate remained unaltered by CD and hepatic folate reduced to 85% of the control by CD ( p < 0.05) . Plasma Hcy was signi-ficantly increased by FD ( 18.34 +/- 1.62 micrometer) and CFD ( 19.35 +/-3.62 micrometer) compared to the control ( 6.29 +/-0.60 micrometer) ( p < 0.001) , but remained unaltered by CD. FD depressed S-adenosylmethionine ( SAM) by 59% ( p < 0.001) and ele-vated S-adenosylhomocysteine ( SAH) by 47% in liver compared to the control group ( p < 0.001) . In contrast, brain SAM levels remained unaltered in CD, FD and CFD rats. Genomic DNA methylation status was reduced by FD in liver ( p< 0.05) . Genomic DNA hypomethylation was also observed in brain by CD, FD and CFD although it was not signifi-cantly different from the control group. Genomic DNA methylation status was correlated with folate stores in liver ( r = - 0.397, p < 0.05) and brain ( r = - 0.390, p < 0.05) , respectively. In conclusion, our data demonstrated that genomic DNA methylation and SAM level were reduced by folate deficiency in liver, but not in brain, and correlated with folate concentration in the tissue. The fact that folate deficiency had differential effects on SAM, SAH and genomic DNA methylation in liver and brain suggests that the Hcy metabolism and DNA methylation are regulated in tissue-specific ways.

Supplement Dose and Health-Related Life Style of Vitamin-Mineral Supplement User among Korean Middle-Aged / 대한지역사회영양학회지

We studied daily micronutrient intake from vitamin-mineral supplements, health-related life style, clinical case of diseases and food frequency of the Korean middle-aged (40 - 59 yr, n = 404) to compare the characteristics of non-user (n = 270) and user (n = 134) of vitamin-mineral supplements. Rate of supplement use of the middle-aged was 33.2% and there was significant difference in education level (p = 0.0084) and family income (p = 0.0476) of user and nonuser. Smoking habit (p = 0.0844) and drinking frequency (p = 0.0606) tended to be lower in a supplement user than a non-user. The medical history of a case was significantly higher in users (67.9%) than in non-users (44.4%) (p = 0.001), which suggests that medical history is one of the important motivations of supplement use. Supplement users had the medical history of digestive disease (34.1%), anemia (11.0%) and hypertension (9.9%) in order. Vitamin C was the most frequently supplemented nutrient (81.3%) among vitamin-mineral supplement, and the next orders were vitamins E (73.1%), B2 (68.7%) and B6 (60.4%). Mean intakes of vitamin B1, iron, selenium, vitamin E, and vitamin C from supplement was 4,260%, 4,030%, 1,660% and 1,330% of RDA, respectively. The supplement users tended to consume most food items including milk & milk products (p < 0.01), rice (p < 0.01), grains (p < 0.05) and cookies (p < 0.01) less frequently than non-users. Conclusively, nutrient intake of vitamin B1, iron, selenium, vitamin E, and vitamin C from supplement was excessively high compared to RDA. We suggest that the toxic effect of excessive supplementation should be informed to supplement user and nutritional education should be focused on the optimal supplement dose.

The Effect of Folate Defficiency on Plasma Cholesterol and Antioxidative System in Ethanol-fed Rats

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.