| May 9, 2000 |
National Academy of Sciences References
121. Angiologia 1991 Mar-Apr;43(2):77-81[The effect of VITAMIN C on the lipolytic activity in type-II diabetics with angiopathy].[Article in Spanish]Triana Mantilla ME, Simon Carballo R, Fernandez Montequin JI, Lima Santana B, Cardona Alvarez ME, Morejon Reinoso O Instituto de Angiologia y cirugia vascular, Ciudad de la Habana, Cuba.
Effects produced by different doses of Vit C (2, 3 and 4 gr/day) on lipoprotein and hepatic lipase activities were studied between a group of 35 ambulatory patients, men and women, affected by diabetes mellitus type II with macroangiopathy at lower limbs and/or food. The medium age of patients was 62 years, ranging from 44 to 82 years. Patients were aleatory divided into four groups. One from those four groups was treated with placebo, the other three received Vit C. In the group treated with 3 gr./day of Vit C we found a significant reduction and increase (p less than 0.05) of lipoprotein and hepatic lipase activities, respectively, when we compared outcomes before and after eight weeks of treatment with Vit C. By other hand, when we compared the different groups, we found a significant increase in the hepatic lipase activity in the same group, particularly between the patients whose plasmatic Vit C levels before treatment were reduced. We didn't found any significant change in the rest of parameters.122. IARC Sci Publ 1991;(105):139-42Effect of Ascorbic acid on the intragastric environment in patients at increased risk of developing gastric cancer.Reed PI, Johnston BJ, Walters CL, Hill MJ Lady Sobell Gastrointestinal Unit, Wexham Park Hospital, Slough, Berks, UK.
Ascorbic acid has been shown to decrease nitrosation in vivo, and epidemiological data suggest that the consumption of foods rich in this vitamin is associated with a reduced risk for gastric cancer. In order to study this suggestion further, fasting gastric juice samples were obtained from 62 high-risk patients (seven with atrophic gastritis, ten with pernicious anaemia, ten with partial gastrectomy, 21 with vagotomy and drainage and 14 with highly selective vagotomy), before, during four weeks' treatment with 1 g Ascorbic acid four times daily, and four weeks after treatment. Samples were analysed for pH, total and nitrate-reducing bacterial counts, nitrite and N-nitroso compounds. Treatment with Ascorbic acid lowered the median pH only in the vagotomized patients (p less than 0.001) but resulted in a reduction in median nitrate-reducing bacterial counts and in nitrite and N-nitroso compound concentrations in all groups, except for an increase in the nitrate-reducing bacterial count in atrophic gastritis patients and in nitrite in those with pernicious anaemia. These data suggest that treatment with a high dose of Ascorbic acid reduces the intragastric formation of nitrite and N-nitroso compounds.
123. Acta Med Hung 1991;48(1-2):73-8The effects of short-term VITAMIN C on plasma bun, uric acid, cholesterol and triglyceride levels.Beser E Department of Public Health, School of Medicine, Karadeniz Technical University, Trabzon, Turkey.
The effects of daily 0.5 g VITAMIN C on plasma urea nitrogen, uric acid, cholesterol and triglyceride levels were recorded over a period of one month. There was a significant reduction in plasma cholesterol level (P less than 0.05). There was no significant effect of VITAMIN C on plasma urea nitrogen, uric acid and triglyceride levels (P greater than 0.05). It was a placebo-controlled trial. The research and control groups were formed of 105 and 47 volunteer university students, respectively. In these groups the mean ages were 20 +/- 0.33 (mean +/- S.E.M.) and 20 +/- 0.49 years, respectively. Mean body mass indices were 22.2 +/- 0.13 and 22.3 +/- 0.19 kg/m2, respectively.
124. Ann Allergy 1990 Oct;65(4):311-4Effect of VITAMIN C on histamine bronchial responsiveness of patients with allergic rhinitis.Bucca C, Rolla G, Oliva A, Farina JC Dpt. di Scienze Biomediche e Oncologia Umana, Universita di Torino, Italy.
The effect of acute oral administration of 2 g VITAMIN C on bronchial responsiveness to inhaled histamine in 16 patients with allergic rhinitis was compared with placebo on two consecutive days in a double-blind, crossover design. The PC15FEV1 was significantly increased one hour after treatment with VITAMIN C but not after placebo.
125. Am J Clin Nutr 1990 Apr;51(4):649-55Ascorbic acid: effect on ongoing iron absorption and status in iron-depleted young women.Hunt JR, Mullen LM, Lykken GI, Gallagher SK, Nielsen FH US Department of Agriculture, ARS, Grand Forks Human Nutrition Research Center, ND.
The effect of Ascorbic acid on iron retention from a diet with predicted low iron bioavailability (containing minimal meat and Ascorbic acid) was investigated in iron-depleted premenopausal women. Eleven women were depleted of storage iron (indicated by serum ferritin) through a combination of diet (5.0 mg Fe/2000 kcal for 67-88 d) and phlebotomy. They then consumed a diet containing 13.7 mg Fe/2000 kcal, supplemented with placebo or Ascorbic acid three times daily (1500 mg total) with meals for 5.5 wk. Ascorbic acid improved apparent iron absorption (balance method) [38 +/- 2% (means +/- SEM) vs 27 +/- 2%]. Ascorbic acid also improved hemoglobin, erythrocyte protoporphyrins, and serum iron but not hematocrit, serum ferritin, iron-binding capacity, or transferrin saturation. In iron-depleted women consuming a diet with predicted poor iron availability, Ascorbic acid supplementation enhanced body iron retention for 5.5 wk.
126. Biol Trace Elem Res 1990 Feb;24(2):109-17High dose antioxidant supplementation to MS patients. Effects on glutathione peroxidase, clinical safety, and absorption of selenium.Mai J, Sorensen PS, Hansen JC Department of Neurology, Arhus Kommunehospital, Denmark.
High-dose antioxidant supplementation has recently been recommended for multiple sclerosis (MS) patients. This study tests the clinical safety, the glutathione peroxidase (GSH-px) activity, and the absorption of selenium during such supplementation. Eighteen MS patients were given 6 tablets especially made for this study, equivalent to 6 mg sodium selenite, 2 g VITAMIN C, and 480 mg vitamin E a day for five wk. GSH-px, which was lower than in non-MS controls before the start of treatment, increased fivefold during 5 wk of treatment. Side effects were scarce. Ten MS patients were subjected to a 24-h selenium absorption study after ingestion of 2 active tablets, equivalent to 2 mg sodium selenite. Selenium, which was low initially, increased 24% during the first 3 h and then stabilized. It is concluded that the tested antioxidant treatment seems to be safe and that MS patients have low GSH-px, which may be increased by the tested antioxidant treatment.
127. Nutr Cancer 1998;31(2):106-10Effect of ascorbic acid dose taken with a meal on nitrosoproline excretion in subjects ingesting nitrate and proline.Mirvish SS, Grandjean AC, Reimers KJ, Connelly BJ, Chen SC, Morris CR, Wang X, Haorah J, Lyden EREppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha 68198, USA.
We determined the dose of ascorbic acid (ASC) given to subjects with a standard 400-calorie meal that inhibited N-nitrosoproline (NPRO) formation when we gave 400 mg of nitrate one hour before and 500 mg of L-proline with the standard meal. Volunteers consumed their normal US diets but restricted their intakes of nitrate, proline, NPRO, and ASC. NPRO and N-nitrososarcosine (NSAR) were determined in the 18-hour urines by methylation followed by gas chromatography-thermal energy analysis. Mean NPRO yields were 10.7, 41.9, 33.2, 22.3, and 23.1 nmol for groups of 9-25 subjects taking proline alone, proline + nitrate, and proline + nitrate + 120, 240, and 480 mg of ASC, respectively. There was a significant trend to lower NPRO yields as the ASC dose was raised. These results correspond to inhibitions by ASC of 28%, 62%, and 60%, respectively. Pairwise comparison showed that each group taking ASC formed significantly less NPRO than the group given only proline + nitrate. Mean NSAR yields were 9.0 nmol when proline alone was taken and 16.9-24.0 nmol when proline + nitrate + ASC was taken, with no trend to increase as the ASC dose was raised. However, NPRO and NSAR yields in individual urines were correlated with each other. We concluded that 120 mg of ASC taken with each meal (360 mg/day) would significantly reduce in vivo nitrosamine formation, similar to tests by Leaf and co-workers (Carcinogenesis 8, 791-795, 1987) in which the reactants were taken between meals. The inhibitory dose of ASC may be < 120 mg/meal when doses of nitrate and proline are not taken.
128. Clin Chem Lab Med 1998 Oct;36(10):767-70Biochemical evaluation of oxidative stress in propylthiouracil treated hyperthyroid patients. Effects of vitamin C supplementation.Seven A, Tasan E, Inci F, Hatemi H, Burcak GDepartment of Biochemistry, Cerrahpasa Medical Faculty, Istanbul University, Turkey.
In this study the impact of vitamin C supplementation on oxidative damage as assessed by thiobarbituric acid reactive substances and markers of antioxidant status: namely Cu/Zn superoxide dismutase, glutathione peroxidase, glutathione reductase and glutathione were investigated in 24 hyperthyroid patients under propylthiouracil therapy (3x100 mg/day) for five days and in 15 healthy controls. Ascorbic acid (1000 mg/day) was given as a supplement for 1 month to both the patients and controls during the study period. Heparinised blood samples were taken at the beginning and the end of one month ascorbic acid supplementation. Comparison of the hyperthyroid patients with the controls revealed higher lipid peroxidation (p<0.001), higher Cu/Zn superoxide dismutase activity (p<0.001), higher glutathione level (p<0.001) and lower glutathione reductase activity (p<0.001). Vitamin C supplementation to hyperthyroid patients caused significant increases in glutathione concentration (p<0.001) and glutathione peroxidase activity (p<0.001), whereas there were significant decreases in glutathione reductase (p<0.001) and Cu/Zn superoxide dismutase activities (p<0.01). Thiobarbituric acid reactive substances and thiobarbituric acid reactive substances/glutathione ratio were significantly decreased (p<0.01). Vitamin C supplementation to euthyroid controls caused significant increases in glutathione concentration (p<0.001) and glutathione peroxidase and Cu/Zn superoxide dismutase activities (p<0.001), whereas there was a significant decrease in glutathione reductase (p<0.001). The thiobarbituric acid reactive substances/glutathione ratio was significantly decreased (p<0.05). Our findings reveal the potentiation of antioxidant status and a relief in oxidative stress in both propylthiouracil treated hyperthyroid patients and controls in response to vitamin C supplementation.
129. Immunopharmacol Immunotoxicol 1997 Aug;19(3):291-312Enhancement of natural killer cell activity and T and B cell function by buffered VITAMIN C in patients exposed to toxic chemicals: the role of protein kinase-C.Heuser G, Vojdani A Neuromed & Neurotox Associates, Thousand Oaks, CA 91361, USA.
After exposure to many toxic chemicals, NK function can be decreased significantly. Weeks or months later, natural killer (NK) function can rebound to normal levels in some and can be suppressed for prolonged periods of time in other patients. In view of this, we decided to study the effect of buffered VITAMIN C on NK, T and B cell function in patients who had been exposed to toxic chemicals. After the first blood draw, 55 patients immediately ingested granulated buffered VITAMIN C in water at a dosage of 60 mg/Kg body weight. Exactly 24 hours later, blood was again drawn for a follow-up study of NK, T and B cell function. VITAMIN C in high oral dose was capable of enhancing NK activity up to ten-fold in 78% of patients. Lymphocyte blastogenic responses to T and B cell mitogens were restored to the normal level after VITAMIN C usage. Signal transduction enzyme protein kinase C (PKC) appeared to be involved in the mechanism of induction of NK activity by VITAMIN C. We conclude that immune functional abnormalities can be restored after toxic chemical exposure by oral usage of VITAMIN C.
130. Ceylon Med J 1996 Dec;41(4):135-40Iron absorption from a traditional Sri Lankan weaning food and the enhancing effect of Ascorbic acid in adult male volunteers.Liyanage C, Goonaratna C, Thabrew I Department of Community Medicine, Faculty of Medicine, University of Ruhuna, Galle, Sri Lanka.
OBJECTIVE: To study absorption of iron from Centella gruel and the enhancing effect of Ascorbic acid in young adult males. DESIGN: An in vivo absorption study. SETTING: Faculty of Medicine, Galle. METHODS: The percentage of iron absorbed from the Centella gruel was measured using a double isotope technique with 55Fe and 59Fe on 10 healthy male volunteers. OUTCOME MEASURE: Percentage of iron absorption from the gruel with and without Ascorbic acid. RESULTS: The mean iron absorption from each meal of Centella gruel was 2.2% (SEM 0.8). This increased to 5% (SEM 1.6) by addition of 50 mg Ascorbic acid. When ingested with Ascorbic acid, the bioavailable nutrient density (BND) of the weaning food was increased from 0.23 to 0.53 mg iron/1,000 kcal. To satisfy the daily physiological requirements of iron in infants and toddlers, it was calculated that apart from Ascorbic acid supplementation, the total iron content also needs to be increased from 2.05 mg to 4.0 mg/meal. CONCLUSION: Centella gruel cannot provide the amount of iron to meet the BND for iron required by infants and toddlers, unless supplemented with an enhancer of iron absorption such as Ascorbic acid and its total iron content is increased.