Youn-Ok Cho

Effect of vitamin B6 deficiency on antioxidative status in rats with exercise-induced oxidative stress*

This study investigated the effect of vitamin B6 deficiency on antioxidant enzyme activities and lipid profile in rats with exercise-induced oxidative stress. Forty eight rats were fed either a vitamin B6 deficient diet (B6-) or a control diet (control) for 4 weeks and then subdivided into 3 groups: pre-exercise (PreE); post-exercise (PostE); recess after exercise (recessE). Compared to those of control group, plasma catalase and hepatic cytosol superoxide dismutase (SOD, EC 1.15.1.1) activities of B6- group were lower regardless of exercise. The ratio of reduced glutathione/oxidized glutathione (GSH/GSSG) of B6- group was lower in PreE and there was no difference between PostE and recessE. The level of malondialdehyde (MDA) of B6- was significantly higher in PreE and PostE. High-density lipoprotein-cholesterol (HDL-C) level of B6- group was lower regardless of exercise. Atherosclerotic index of B6- group was higher in PreE and there was no difference between PostE and recessE. It is suggested that a reduction in antioxidative status caused by vitamin B6 deficiency may be aggravated under exercise-induced oxidative stress.

The effects of physical training on antioxidative status under exercise-induced oxidative stress

This study investigated the effect of physical training and oxidative stress on the antioxidative activity and on plasma lipid profile. Forty eight rats were given either a physical training or no training for 4 weeks and were then subdivided into 3 groups: before-exercise (BE); during-exercise (DE); after-exercise (AE). The antioxidative activity was evaluated with the activities of catalase in plasma and superoxide dismutase (SOD), the ratio of reduced glutathione/oxidized glutathione (GSH/GSSG) and the level of malondialdehyde (MDA) in liver. The plasma concentrations of triglyceride (TG), total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C)) were also compared. Compared to those of non-training group, catalase activities of training group were lower before exercise but higher during and after exercise. SOD activities were higher regardless of exercise. GSH/GSSG ratio was higher before exercise but was not significantly different during exercise and even lower after exercise. There were no differences between non-training group and training group in MDA levels regardless of exercise. Compared to those of non-training group, atherosclerotic index of training group was lower after exercise and there were no significant differences before and during exercise. There were no differences between non-training group and training group in HDL-C regardless of exercise. These results suggest that moderate physical training can activate antioxidant defenses and decrease the atherosclerotic index and this beneficial effect is evident under exercise-induced oxidative stress.

Vitamin E status of 20- to 59-year-old adults living in the Seoul metropolitan area of South Korea

BACKGROUND/OBJECTIVES Vitamin E is a fat-soluble vitamin and functions primarily as a lipid antioxidant. Inadequate vitamin E status may increase risk of several chronic diseases. Thus, the objectives of this study were to estimate intake and plasma concentration of each tocopherol and to evaluate vitamin E status of Korean adults. SUBJECTS/METHODS Three consecutive 24-h food recalls and fasting blood samples were collected from healthy 20- to 59-y-old adults (33 males and 73 females) living in the Seoul metropolitan area, South Korea. α-, β-, δ-, and γ-tocopherol intakes and plasma concentrations of tocopherols (α-, δ-, and γ-tocopherol) were analyzed by gender. RESULTS Dietary vitamin E and total vitamin E intake (dietary plus supplemental vitamin E) was 17.68 ± 14.34 and 19.55 ± 15.78 mg α-tocopherol equivalents, respectively. The mean daily α-tocopherol, and γ-tocopherol intakes were 3.07 ± 2.27 mg and 5.98 ± 3.74 mg, respectively. Intakes of total vitamin E and each tocopherol of males were significantly higher than those of females (P < 0.05). Plasma α-tocopherol concentration was 15.45 ± 10.16 of males and 15.00 ± 4.54 µmol/L of females, respectively. There were no significant differences in plasma tocopherol concentrations by gender (P ≥ 0.05). Plasma α-tocopherol was negatively correlated with γ-tocopherol intake (P < 0.05). Twenty-three percent of the subjects had plasma α-tocopherol concentrations < 12 µmol/L indicating a biochemical deficiency of vitamin E. Approximately 8% and 9% of these participants had plasma α-tocopherol:total lipid ratio less than 1.59 µmol/mmol and plasma α-tocopherol:total cholesterol ratio less than 2.22 µmol/mmol, respectively, which are also indicative of vitamin E deficiency. CONCLUSIONS Vitamin E intakes of Korean adults were generally adequate with the Korean Dietary Reference Intakes for vitamin E. However, α-tocopherol intake was lower than that reported in other countries, and 23% of the subjects in the current study were vitamin E deficient based on plasma α-tocopherol concentrations.

Coffee intake can promote activity of antioxidant enzymes with increasing MDA level and decreasing HDL-cholesterol in physically trained rats

This study investigated the effect of coffee intake and exercise on the antioxidative activity and plasma cholesterol profile of physically trained rats while they were exercising. Forty eight rats were under either the control diet with water (C) or control diet with coffee (CF) and at the same time they were given physical training for 4 weeks. In terms of physical training, the rats were exercised on a treadmill for 30 minutes everyday. At the end of 4 weeks, animals in each dietary group were subdivided into 3 groups: before-exercise (BE); during-exercise (DE); after-exercise (AE). Animals in the DE group were exercised on a treadmill for one hour, immediately before being sacrificed. Animals in the AE group were allowed to take a rest for one hour after exercise. TG levels were significantly high in coffee intake group than in control group. Also TG level of AE group was significantly higher than that of BE group. Exercise and coffee-exercise interaction effects were significant in total cholesterol (P = 0.0004, 0.0170). The AE of coffee intake group showed highest total cholesterol levels. HDL-cholesterol was significantly lower in coffee intake group than in control group. Coffee, exercise, and coffee-exercise interaction effects were significant in SOD (P = 0.0001, 0.0001, and 0.0001). The AE and BE of coffee intake group showed higher SOD levels than the other four groups. Catalase activities were significantly higher in coffee intake group than control group. No significant main effect was found in GSH/GSSG. Coffee, exercise, and coffee-exercise interaction effects were significant in MDA levels (P = 0.0464, 0.0016, and 0.0353). The DE and AE of coffee intake group and the DE of control group showed higher MDA levels than the BE of control group. Therefore, coffee intake can promote activities of antioxidant enzyme but it also increases MDA and decreases HDL-cholesterol in physically trained rats.

Vitamin A Inadequacy Observed in a Group of 2- to 6-Year-Old Children Living in Kwangju, Republic of Korea

Dietary intakes and plasma concentrations of retinol and carotenoids were estimated in assessing the vitamin A status of young children in Kwangju, Republic of Korea. Three consecutive 24-hour food recalls and fasting blood samples were obtained from 123 healthy children (58 boys, 65 girls), aged 2-6 years. The daily vitamin A intake (mean +/- SD) was 355.9 +/- 178.1 microg retinol equivalents or 239.0 +/- 111.2 microg retinol activity equivalents. Provitamin A carotenoid intakes were 1211.2 +/- 840.0 microg/day beta-carotene, 234.6 +/- 231.7 microg/day alpha-carotene, and 149.1 +/- 160.7 microg/day beta-cryptoxanthin. Approximately 15-26% of subjects consumed < Korean Estimated Average Requirements (EAR) for vitamin A; whereas, 57-64% consumed < EAR for vitamin A for USA/Canadians. The mean plasma retinol concentration was 1.108 +/- 0.244 micromol/L. There were no significant correlations between intakes and plasma concentrations of retinol and carotenoids. Only 2.4% of children were vitamin A-deficient based on having plasma retinol concentrations <0.70 micromol/L. Plasma retinol concentrations of 42.3% of subjects were 0.70 - <1.05 micromol/L, which is considered indicative of potentially suboptimal vitamin A status. Therefore, some children may be at risk of inadequate vitamin A status in Kwangju, Republic of Korea.

Allium Vegetable Diet Can Reduce the Exercise-Induced Oxidative Stress but Does Not Alter Plasma Cholesterol Profile in Rats

Aims and Methods: This study investigated the effect of Allium vegetable intake on the antioxidative activity and on the plasma cholesterol profile during exercise in rats. Ninety rats were fed either a control diet or a diet with added Allium sativum (AS), Allium cepa (AC), Allium fistulosum (AF), or Allium tuberosum (AT) for 4 weeks and were then subdivided into three groups: before exercise (BE), during exercise (DE), and after exercise (AE). The DE group was exercised on a treadmill for 1 h immediately before being sacrificed. Animals in the AE group were allowed to take a rest for 2 h after having been exercised like the DE group. The antioxidative activity of the Allium vegetables was evaluated with the activities of catalase in plasma and superoxide dismutase (SOD), the ratio of reduced glutathione/oxidized glutathione (GSH/GSSG) and the level of malondialdehyde (MDA) in liver. The plasma concentrations of triglyceride, total cholesterol, and high-density lipoprotein cholesterol were also compared. Results: In AS, AC, AF and AT animals, the ratios of GSH/GSSG were significantly higher than those of the control animals in BE and AE. The level of liver MDA was lower than that of control animals in AE. Compared to control animals, catalase activity of AS animals was higher in BE but was lower in AE while SOD activity of AS animals was lower in both BE and AE. Catalase activity of AC animals was higher in BE and DE while SOD activity of AC animals was higher in DE. There were no differences between AF and control in catalase activities regardless of exercise. There were no differences between control animals and AT animals in SOD activities regardless of exercise. Plasma cholesterol profiles were not significantly different in rats fed different Allium vegetable diets. Conclusion: It is suggested that Allium vegetable diets have antioxidative activities and can reduce the oxidative stress that results from exercise in rats but do not alter the plasma cholesterol profile.

Evaluation of Riboflavin Intakes and Status of 20–64-Year-Old Adults in South Korea

A recent Korea National Health and Nutrition Survey indicated inadequate riboflavin intake in Koreans, but there is limited research regarding riboflavin status in South Korea. The purpose of this study was to determine riboflavin intake and status of Korean adults. Three consecutive 24-h food recalls were collected from 412 (145 men and 267 women) healthy adults, aged 20–64 years, living in South Korea and urine samples were collected from 149 subjects of all subjects. The dietary and total (dietary plus supplemental) riboflavin intake was 1.33 ± 0.34 and 2.87 ± 6.29 mg/day, respectively. Approximately 28% of the subjects consumed total riboflavin less than the Estimated Average Requirement. Urinary riboflavin excretion was 205.1 ± 190.1 μg/g creatinine. Total riboflavin intake was significantly positively correlated to the urinary riboflavin excretion. (r = 0.17171, p = 0.0363). About 11% of the Korean adults had urinary riboflavin <27 μg/g creatinine indicating a riboflavin deficiency and 21% had low status of riboflavin (27 μg/g creatinine ≤ urinary riboflavin < 80 μg/g creatinine). Thus, one-third of Korean adults in this study had inadequate riboflavin status. In some adults in Korea, consumption of riboflavin-rich food sources should be encouraged.

Evaluation of Vitamin B6 Status and RDA in Young Koreans

Aims and Methods: The vitamin B6 status of 294 healthy young Koreans (149 men, 145 women), aged 17–25 years, was estimated to establish the Korean Recommended Dietary Allowance (RDA) for vitamin B6. The dietary vitamin B6 intake was estimated based on a three-day recall method. Results: The average daily vitamin B6 intake of the subjects was 1.504 ± 0.825 mg/day (1.567 ± 0.968 mg/day for men and 1.439 ± 0.644 mg/day for women). The average ratio of vitamin B6 intake to daily protein intake was 0.019 ± 0.001 mg/g (0.015 ± 0.001 mg/g for men and 0.023 ± 0.001 mg/g for women). Foods from animal and plant sources provided 35.68 ± 16.16 and 64.18 ± 16.29% of total vitamin B6. Plasma pyridoxal 5′-phosphate (PLP) concentration of the subjects was 29.26 ± 16.84 nmol/l (30.52 ± 20.18 nmol/l for men and 28.21 ± 13.28 nmol/l for women). The vitamin B6 intake of the subjects whose PLP concentration was >30 nmol/l was 0.019 ± 0.001 mg vitamin B6/g protein intake (0.017 ± 0.001 and 0.023 ± 0.001 mg vitamin B6/g protein intake for men and women, respectively). The intake of vitamin B6 was significantly (p < 0.01–p < 0.001) positively correlated with the intake of all other nutrients. However, no significant correlation was found between PLP concentration and all nutrients examined. Conclusion: Our suggested adequate Korean RDA for vitamin B6 in young Koreans is 1.6 mg/day or 0.02 mg/g of protein intake in men and 1.5 mg/day or 0.02 mg/g of protein intake in women.

Tissue iron content in riboflavin and pyridoxine deficient rats.

The effect of riboflavin and (or) pyridoxine deficiency and repletion on tissue iron content was studied in rats. The iron content in liver, spleen, and kidney and plasma iron concentration of riboflavin deficient (RD) rats was lower, but hematocrit was not. In pyridoxine deficient (PD) rats versus control rats, the iron content in liver was significantly higher but not in spleen and kidney. In PD rats hematocrit was lower but plasma iron concentration was not. Although combined riboflavin and pyridoxine deficient (CD) rats had lower iron content in liver and spleen compared with control rats, these values were intermediate between those of RD rats and PD rats. After RD and PD rats were repleted, the iron content in liver, spleen, and kidney returned to that of control rats, and the hematological indices were improved significantly. These results suggest that riboflavin and pyridoxine deficiency may impair the absorption and utilization of iron and may result in altered tissue iron content.

Vitamin A status of 20- to 59-year-old adults living in Seoul and the metropolitan area, Korea

Dietary intakes and plasma concentrations of retinol and carotenoids were estimated in assessing the vitamin A status of Korean adults living in Seoul and the metropolitan area. Three consecutive 24-h food recalls were collected from 106 healthy subjects (33 males and 73 females) aged 20-59 years. Fasting blood samples of the subjects were obtained and plasma retinol and carotenoids were analyzed. The daily vitamin A intakes (mean ± SD) were 887.77 ± 401.35 µg retinol equivalents or 531.84 ± 226.42 µg retinol activity equivalents. There were no significant differences in vitamin A intakes among age groups. The retinol intake of subjects was 175.92 ± 129.87 µg/day. The retinol intake of the subjects in their 50s was significantly lower than those in their 20s and 30s (P < 0.05). Provitamin A carotenoid intakes were 3,828.37 ± 2,196.29 µg/day β-carotene, 472.57 ± 316.68 µg/day α-carotene, and 412.83 ± 306.46 µg/day β-cryptoxanthin. Approximately 17% of the subjects consumed vitamin A less than the Korean Estimated Average Requirements for vitamin A. The plasma retinol concentration was 1.22 ± 0.34 µmol/L. There was no significant difference in plasma retinol concentrations among age groups. However, the concentrations of β-carotene, lycopene, and lutein of subjects in their 50s were significantly higher than those of in their 20s. Only one subject had a plasma retinol concentration < 0.70 µmol/L indicating marginal vitamin A status. Plasma retinol concentration in 30% of the subjects was 0.70- < 1.05 µmol/L, which is interpreted as the concentration possibly responsive to greater intake of vitamin A. In conclusion, dietary intakes and status of vitamin A were generally adequate in Korean adults examined in this study.