• Proceedings of the Korean Nutrition Society Conference
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• 2002.11a
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• pp.54-70
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• 2002

Vitamin C is an essential nutrient involved in many functions. Humans are unable to synthesize vitamin C do novo, because they lack the last enzyme in the biosynthetic pathway. Previous Recommended Dietary Allowances (RDAs) for vitamin C were based on prevention of deficiency with a margin of safety. However preventing deficiency may not be equivalent to ideal nutrient intake. Recommendation should be based on vitamin function in relation to concentration. For this goal, data set of the relationship between wide-range of vitamin C dose and resulting concentrations in plasma and tissues and characterization of functional outcomes in relation to these concentrations should be acquired. This article reviews the current knowledge in these areas and suggest how this knowledge may contribute toward establishing dietary guideline for ideal vitamin C intake.

• Nutrition Research and Practice
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• v.7 no.2
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• pp.109-114
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• 2013

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.

• Nutrition Research and Practice
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• v.5 no.1
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• pp.34-39
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• 2011

The purpose of this study was to assess vitamin $B_6$ intake and status in Korean patients with newly diagnosed type 2 diabetes. Sixty-four patients with newly diagnosed type 2 diabetes and 8-11% glycated hemoglobin (A1C), along with 28 age-matched non-diabetic subjects, participated. Dietary vitamin $B_6$ intake was estimated by the 24 hour recall method and plasma pyridoxal 5'-phosphate (PLP) was measured. There was a significant difference in daily total calorie intake between the diabetic and non-diabetic groups ($1,917{\pm}376$ vs $2,093{\pm}311\;kcal$). There were no differences in intake of total vitamin $B_6$ ($2.51{\pm}0.91$ vs $2.53{\pm}0.81\;mg/d$) or vitamin $B_6$/1,000 kcal ($1.31{\pm}0.42$ vs $1.20{\pm}0.32\;mg$) between the diabetic and non-diabetic groups, and I intakes of total vitamin $B_6$ were above the Korean RDA in both groups ($180.0{\pm}57.9$ vs $179.0{\pm}65.4$). There was a higher percentage of diabetic subjects whose plasma PLP concentration was < 30 nmol/L compared to non-diabetic group. Plasma PLP levels tended to be lower in the diabetic subjects than in the non-diabetic subjects, although the difference was not statistically significant due to a large standard deviation ($80.0{\pm}61.2\;nmol/L$ vs $68.2{\pm}38.5\;nmol/L$). Nevertheless, plasma PLP levels should be monitored in pre-diabetic patients with diabetic risk factors as well as in newly diagnosed diabetic patients for long-term management of diabetes, even though this factor is not a major risk factor that contributes to the development of degenerative complications in certain patients.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.11
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• pp.1482-1489
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• 2010

This study aimed to determine the effects of vitamin C and propolis-supplemented feeds on some blood parameters, lipid peroxidation, and activities of some antioxidant enzymes in broilers exposed to oxidative stress. 360 three-day-old broiler chicks (Ross 308) were randomly divided into four treatment groups each containing 90 animals, including six replicate groups for each treatment. The experimental groups were designated for a 3-42 days period as follows: no supplement to basal ration (Control-Group I); supplement of 500 ppm vitamin C and 200 ppm lead (as lead acetate) to basal ration (Group II); supplement of 1 g/kg propolis and 200 ppm lead (as lead acetate) to basal ration (Group III); and supplement of 200 ppm lead (as lead acetate) to basal ration (Group IV). The highest TG level (86.83 mg/dl) was observed in the lead supplemented group; however, the lowest aspartate aminotransferase (SGOT) level (90.71 IU/L) was observed in the control group (p<0.05). The addition of lead increased the plasma malondialdehyde (MDA) level (p<0.01) compared to other treatments. However, the addition of vitamin C and propolis decreased the plasma MDA level close to control levels. The highest erythrocyte superoxide dismutase (SOD) activity was observed in the lead addition group (p<0.01) while no significant differences were observed for SOD activities of the control, vitamin C +lead, and propolis+lead groups. The plasma reduced glutathione (GSH) activity of the control ($2.30{\mu}mol$/ml) was significantly lower than the lead administered group ($6.20{\mu}mol$/ml) (p<0.01); while this parameter was determined to be similar to other groups. No significant differences were observed between groups for liver GSH activity, but heart GSH activity of the control was significantly higher in comparison to other treatments (p<0.05). To obtain similar antioxidant effects, it is recommend that using propolis (1 g/kg) and vitamin C (500 mg/kg) supplementation in broiler diets may overcome the adverse effects of oxidative stress originating from dietary lead.

• Journal of Nutrition and Health
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• v.40 no.8
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• pp.708-718
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• 2007

The purpose of this project was to evaluate whether vitamin E supplementation could improve the antioxidant status and lymphocyte DNA damage in Korean postmenopausal women. This was double blinded, placebo-controlled trial. Thirty-five subject were randomized to receive either placebo 400 mg/capsule or natural $\alpha$-tocopherol 400 IU/capsule, 2 times a day for 6 weeks. We measured plasma vitamin C, $\alpha$-tocopherol, $\gamma$-tocopherol, $\alpha$-carotenoid, $\beta$-carotenoid, lycopene concentration and tail length, %DNA in tail, tail moment in lymphocyte DNA damage index. Vitamin E supplementation group had significantly increased plasma vitamin C(p<0.05), $\alpha$-tocopherol(p<0.000), whereas $\gamma$-tocopherol(p<0.000) and tail length(p<0.05) were significantly decreased. However, placebo supplementation group also had significantly increased plasma vitamin C(p<0.05). In conclusion, our study shows that vitamin E supplementation to Korean postmenopausal women may partially improve antioxidant status and lymphocyte DNA damage.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.8
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• pp.1088-1092
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• 2004

The present investigation was undertaken to study the status of plasma antioxidant vitamins in normal cycling and $\alpha$-tocopherol supplemented anestrus buffalo heifers. The pre-supplementation plasma levels ($\mu$mol/L) of vitamin E and $\beta$-carotene were significantly (p<0.05) lower and of vitamin C was significantly (p<0.05) higher in anestrus heifers (4.06$\pm$0.07; 4.56$\pm$0.17; 21.04$\pm$0.21) when compared to normal cycling ones (4.92$\pm$0.05; 6.76$\pm$0.12; 14.24$\pm$0.16). The oral supplementation of$\alpha$-tocopherol at 3,000 mg per week per animal in anestrus heifers resulted in a significant (p<0.01) increase in vitamin E and $\beta$-carotene levels and a significant (p<0.01) decrease in vitamin C concentration. Results indicated that supplementation of $\alpha$-tocopherol to anestrus buffalo heifers improved the antioxidant status by mitigating the harmful effects of free radical induced oxidative stress.

• The Korean Journal of Food And Nutrition
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• v.24 no.2
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• pp.226-232
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• 2011

In this study, for development of functional sprouts, we have investigated the change of antioxidant activity and quantity of vitamin C, germanium and selenium according to the addition of vitamin C, germanium oxide and selenium oxide on the during cultivation of various sprouts. We were cultivated the sprouts using water solution added vitamin C, germanium oxide and selenium oxide on the system of cultivation instrument. Analysis of quantity of vitamin C on control group and treatment group were conducted by HPLC. Quantity of germanium and selenium were analyzed by ICP-MS(Inductively Coupled Plasma-Mass Spectrometer), and antioxidant activities were checked by DPPH method. As a result, quantity of vitamin C, germanium and selenium on the treatment groups have increased tendency compared to the control group. And antioxidant activity of treatment groups showed increasing tendency compared to the control group.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.10
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• pp.4383-4386
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• 2015

Background: The C1561T variant of the glutamate carboxypeptidase II (GCPII) gene is critical for natural methylfolylpolyglutamte (methylfolate) absorption, and has been associated with perturbations in folate metabolism and disease susceptibility. However, little is known on C1561T-GCPII as a risk factor for colorectal cancer. Therefore, this study examined whether C1561T-GCPII influences folate metabolism and adenomatous polyp occurrence. Materials and Methods: 164 controls and 38 adenomatous polyp cases were analysed to determine blood folate and plasma homocysteine (Hcy) level, dietary intake of natural methylfolate, synthetic pteroylglutamic acid (PteGlu), vitamin C and C1561T-GCPII genotype. Results: In controls and cases, 7.3 and 18.4 percent of subjects respectively, were found to have the CT genotype, increasing the risk for adenomatous polyp occurrence 2.86 times (95% CI:1.37-8.0, p=0.035). Total dietary folate, methylfolate and PteGlu intake and the level of erythrocyte folate and plasma Hcy did not predict the occurrence of an adenomatous polyp. However, dietary natural vitamin C intake was associated with adenomatous polyp risk within C1561T-GCPII CT genotype subjects (p=0.037). Conclusions: The findings suggest that C1561T-GCPII variation may be associated with risk for adenomatous polyp, and vitamin C may modify risk by interacting with the variant gene, its expression product and/or folate substrates.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.1
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• pp.5-17
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• 2000

To evaluate the possible therapeutic effects of growth hormone and vitamin C on multiorgan failure, a rat model was developed for LPS-induced sepsis. Using this model, the effects of growth hormone and vitamin C on tissue damages, catalase and i-NOS activities, and MDA levels were examined in the lung and liver. The level of TNF- in plasm was also examined. Male, Sprague-Dawley rats were injected with LPS intraperitoneally then divided into 3 groups : positive controls injected with LPS only, the ones injected with growth hormone or vitamin C immediately after the LPS injections. The lung and the liver were then isolated, blood samples were collected at 24 or 48 hours after the LPS injection, then examined for histopathological and biochemical changes. The results obtained were as follows. 1. LPS induced sinusoid vasodilation and mild destruction of lobular structure in the liver. In the lung, alveolar structure appeared to be thickened and interstitial edema was observed. The levels of MDA in the liver and the lung was increased by LPS, while the activity of catalase was decreased. The activity of i-NOS of those tissues was also increased, which was more pronounced at 24 hr. The level of TNF- in plasm was increased by LPS 2. In the lung, vitamin C suppressed lymphocyte and neutrophil infiltration, alveolar wall thickening and interstitial edema. In the liver, vitamin C protected against the destruction of the lobular structure. The activity of catalase reduced by LPS was reversed partly by vitamin C. The activity of i-NOS enhanced by LPS was also reversed by vitamin C. The level of TNF- in plasm reduced in some animals by vitamin C, which however was not significant statistically(p<0.05). 3. Growth hormone showed similar protective effects against inflammation and damages in the liver and lung tissues. Growth hormone reversed partly the LPS effects on the level of MDA, the activity of catalase and i-NOS induction in the liver and the lung. Growth hormone reduced plasma level of TNF-${\alpha}$ substantially, which contrasted from vitamin C. Besides this, overall protective effects of growth hormone against LPS-induced experimental sepsis were similar to those of vitamin C. From this results, the mechanism of growth hormone on suppression of LPS-induced tissue damage might be associated with production of antioxidative enzyme and suppression of plasma TNF- level.

• Journal of Nutrition and Health
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• v.42 no.2
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• pp.107-118
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• 2009

In patients with type 2 diabetes, oxidative stress could be increased by their metabolic changes. Elevated plasma homocysteine is considered as one of markers of enhanced oxidative stress. Due to oxidative stress, some complications like cardiovascular or renal diseases may develop in type 2 diabetes patients. Plasma homocysteine concentration may be increased if folate status were inadequate. Protective effects against oxidative stress may be diminished if the status of anti-oxidative nutrient as vitamin C was poor. It is, therefore, important to maintain adequate status of folate and vitamin C in type 2 diabetes patients. Thus, this study was performed to determine the effects of supplementation of folate and/or ascorbate on blood glycated hemoglobin ($HbA_{1c}$) level, serum concentrations of homocysteine and cholesterol, plasma oxidized low density-lipoprotein (LDL), concentration and plasma glutathione peroxidase (GSH-Px) activity in the patients with type 2 diabetes. A total of 92 type 2 diabetes patients participated voluntarily with written consents. They were divided into one of the four experimental groups; Control (C), Folate-supplemented (F), Ascorbate-supplemented (A), and Folate plus ascorbate-supplemented (FA). The subjects in C were taken placebo, those in F were supplemented 1 mg of folate, those in A received 1,000 mg of ascorbate, and those in FA were given 1 mg of folate plus 1,000 mg of ascorbate daily for 4 weeks. Supplementation of folate or ascorbate resulted to increase serum folate level or plasma ascorbate concentration apparently, respectively. Folate supplementation not ascorbate seemed to decrease plasma concentrations of homocysteine and oxidized LDL and reduce plasma GSH-Px activity. There might not be synergic effect of the supplementation of folate plus ascorbate. The results indicate that oxidative stress in the patients with type 2 diabetes may lower mainly by folate supplementation.