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At least 1,063 records · Page 59Linked to original sources
PubMed1993

Poor plasma status of carotene and vitamin C is associated with higher mortality from ischemic heart disease and stroke: Basel Prospective Study.

Previous cross-cultural comparisons of the mortality from ischemic heart disease in European communities with associated plasma levels of essential antioxidants have revealed strong inverse correlations for vitamin E and relatively weak correlations for other antioxidants. Similarly, in a case-control study in Edinburgh low plasma levels of vitamin E were significantly associated with an increased risk of previously undiagnosed angina pectoris whereas low levels of other essential antioxidants lacked statistical significance. The current Basel Prospective Study is particularly well suited to elucidate the impact of antioxidants other than vitamin E. In this population (which was recently evaluated regarding cancer mortality) the plasma levels of vitamins E and A are exceptionally high and above the presumed threshold level of risk for ischemic heart disease. The present 12-year follow-up of cardiovascular mortality in this study reveals a significantly increased relative risk of ischemic heart disease and stroke at initially low plasma levels of carotene (< 0.23 mumol/l) and/or vitamin C (< 22.7 mumol/l), independently of vitamin E and of the classical cardiovascular risk factors. Low levels of both carotene and vitamin C increase the risk further, in the case of stroke even with significance for overmultiplicative interaction. In conclusion, in cardiovascular disease independent inverse correlations may exist for every major essential antioxidant although the latter can also interact synergistically. Therefore future intervention trials of antioxidants in the prevention of ischemic heart disease should primarily test the simultaneous optimization of the status of all principal essential antioxidants.

Adult↗
PubMed1994

Transport of vitamin C in animal and human cells.

The transport systems of animal and human tissues for vitamin C are reviewed with respect to their properties. It emerges that pure diffusion plays only a very minor role while a variety of more or less specific transporters is found on cellular membranes. Although most tissues prefer the reduced ascorbate over the oxidized dehydroascorbic acid and have high-affinity transporters for it, there are several examples for the reversed situation. Special attention is given to similarity or identity with glucose transporters, especially the GLUT-1 and the sodium-dependent intestinal and renal transporters, and to the very widespread dependence of ascorbate transport on sodium ions. The significance of ascorbate transport for vitamin C-requiring and nonrequiring species as well as alterations in states of disease can be seen from ample experimental evidence.

Animals↗
PubMed1989

The role of vitamins in the etiology of cervical neoplasia: an epidemiological review.

Diet may act as a cofactor in the development of cancer of the cervix. A consistent correlation exists between low tissue concentrations, low serum level, and low intake of vitamin A, beta-carotene, vitamin C, or folic acid and an increased prevalence of cervical neoplasia. A moderate effect is seen in clinical trials with vitamin treatment of cervical intraepithelial neoplasias. The studies reviewed here were not consistent especially in the choice of controls and methods for the assessment of dietary and confounding factors. Proper morphologic identification of cervical intraepithelial neoplasia was not always achieved. Longitudinal and prospective cohort studies using more reliable methods for diet monitoring may be valuable for future research in this field.

Ascorbic Acid Deficiency↗
PubMed1994

Administration of large doses of vitamin C does not decrease oxidant-induced lung lipid peroxidation caused by bacterial-independent acute peritonitis.

Acute zymosan-induced peritonitis in rats produces lung inflammation and lipid peroxidation. The effect of this process on plasma and lung tissue ascorbic acid was determined, as was the effect of infusing 150 mg/kg of ascorbic acid immediately after zymosan on the degree of lung insult. Ascorbic acid levels were significantly decreased in plasma and lung tissue at 24 h after zymosan, and lung tissue conjugated diene and neutrophil content was also significantly increased. Vitamin C infusion increased postzymosan plasma levels by 50% over normal control levels. However, lung tissue ascorbic acid was still decreased, and no decrease in the lung injury process was noted. Added ascorbic acid also did not prevent a decrease in plasma vitamin E with the peritonitis. We conclude that the amount of ascorbic acid given in this study did not diminish the lung oxidant inflammatory changes. An insufficient dose or inadequate time for plasma ascorbic acid to equilibrate with the lung cytosol are possible explanations for the lack of attenuation of lung oxidant stress.

Acute Disease↗
PubMed1993

The influence of ascorbic acid on selected parameters of cell immunity in guinea pigs exposed to cadmium.

The study investigated the possibility of influencing immunotoxic effects of Cd through ascorbic acid. Guinea pigs with high and low intake of ascorbic acid were perorally exposed to cadmium chloride (1 mg Cd/animal/day). The daily vitamin C intake was 2 and 100 mg per animal, respectively. Phagocytic activity of polymorphonuclear leucocytes and monocytes as well as the percentage of active and total T lymphocytes in peripheral blood of animals were evaluated. Five- and 12-week experiments showed a mutual potentiation of negative effects of Cd on the immune system by suboptimal intake of ascorbic acid. Toxic effects of Cd on the immune system can be reduced by a sufficient intake of vitamin C.

Animals↗
PubMed1995

[Antioxidative vitamins and cataracts in the elderly].

Senile cataract indicates the opacity of ocular lenses occurring in old and especially in very old people. Lens proteins are extremely long-living and often show oxidative damages. Aging and smoking appear to be the greatest risk factors for the development of lens opacities. The sufficient antioxidant protection of young lenses decreases with the aging process. Consequently, the importance of other protective factors increases. Nutritional factors, particularly vitamins with antioxidant properties, may influence the development of senile cataracts in the ocular lens. Meanwhile an association between the supply with vitamin C, E and beta-carotene and the risk of cataract development was demonstrated in animal studies and also in an increasing number of epidemiological studies. These epidemiological studies mainly support the hypothesis that higher vitamin intakes reduce the risk of developing cataracts in old age. The antioxidant properties of the named nutrients give a plausible explanation for the mechanism of cataractogenesis. On the basis of the present data definitive recommendation, necessary for cataract prevention can not yet be established. Some results seem to support higher recommendations. At the moment several large human intervention trials are carried out. Form these studies a further confirmation of the antioxidant hypothesis and of a dose-response-relationship are expected.

Adult↗
PubMed1976

Ascorbic acid and cholesterol: effect of graded oral intakes on cholesterol conversion to bile acids in guinea-pigs.

A significant correlation between liver ascorbic acid (AA) and total bile acids or liver bile acids has been established in guinea-pigs by direct determination of the bile acids, confirming an earlier hypothesis. The oxidation of cholesterol to bile acids is dependent on the AA status, but it cannot be further stimulated by AA when the animals are already on an adequate intake of the vitamin. This suggests that AA has a hypocholesterolaemic effect over a limited range of AA status.

Animals↗
PubMed1977

Vitamin C and gallstone formation: a preliminary report.

Gallstone formation in hypovitaminotic C guinea-pig fed a high cholesterol diet was associated with qualitative changes in the gallbladder bile, namely, a high cholesterol concentration, a lowered bile acid content and diminished phospholipid-to-cholesterol and bile acid-to-cholesterol ratio.

Animals↗
PubMed1977

Reduction of gallstone formation by ascorbic acid in hamsters.

The addition of 0.5% of ascorbic acid to the lithogenic diet of golden hamsters whose body pool was labelled with 26-14C-cholesterol, lowered the formation of gallstones, the cholesterol concentration and half-life in blood plasma and in the liver, and accelerated cholesterol transformation to bile acids.

Animals↗
PubMed1996

Effect of dietary paraquat on a rat mutant unable to synthesize ascorbic acid.

To obtain some insight into the toxicity of paraquat (PQ) in humans, PQ dichloride at 250 ppm in the diet was administered to both normal (NO) rats and ODS-od/od (OD) rats which are unable to synthesize ascorbic acid (AsA). Firstly, OD rats and NO rats treated with PQ were compared with untreated NO rats (CO). Only OD rats displayed several symptoms of PQ poisoning such as anorexia, hypokinesia, diarrhea, epistaxis, tremor and their pili became rough about 9 days after. Their cysteine proteinase inhibitor level in plasma and lung increased to 2- and 6-fold, respectively, of CO. In contrast, NO rats treated with PQ resembled CO rats, and their cysteine proteinase inhibitor levels were unchanged until 11 days. After this period they began to display symptoms. Secondly, OD rats fed with different amounts of AsA were compared. Excess AsA delayed the onset of symptoms by only 1 day. Thirdly, the day of onset of symptoms was found to be influenced with the weight of rats.

Animals↗
PubMed2001

Role of biological antioxidants in benzanthrone toxicity.

Previous studies indicate that benzanthrone, an anthraquinone dye intermediate, caused significant depletion of ascorbic acid (AsA). In this investigation the effect of benzanthrone on the status of different forms of AsA and other bio-antioxidants such as glutathione (GSH) was studied. Oral administration of benzanthrone (50, 125 or 250 mg/kg body weight) resulted in a significant increase of urinary AsA levels with a concomitant decrease in the urinary dehydroascorbic acid (DHA) content in both rats and guinea-pigs. Benzanthrone caused a dose-dependent decrease in hepatic, adrenal and serum AsA levels with a subsequent increase in DHA and diketogulonic acid (DKA) levels in both rats and guinea-pigs. Following benzanthrone treatment, rats showed an increase in the scorbutic index (to 1.01-1.21) of the liver, adrenal glands and serum compared to controls (0.12-0.24). The scorbutic indices of liver, adrenal glands and serum were also substantially increased (to 3.61-11.20) in benzanthrone-treated guinea-pigs compared to controls (0.16-0.38). Single oral administration of benzanthrone to guinea-pigs caused a dose-dependent depletion of GSH in liver (15-51%), adrenal glands (27-64%) and serum (32-86%). Furthermore, the depletion of GSH by benzanthrone in rats was of a lesser degree. This suggests that continued exposure of guinea-pigs to benzanthrone may lead to scurvy-type changes in this animal species but not to the same extent in rats, since the latter has the enzymatic capacity to synthesise AsA. Therefore, it can be hypothesised that benzanthrone per se, or its metabolites, interact with reduced GSH thereby causing its depletion. Furthermore, in order to replenish the depleted GSH levels, AsA might be oxidized to DHA and hence the decrease in AsA with the simultaneous increase in DHA was observed.

2,3-Diketogulonic Acid↗
PubMed2004

Vitamin C enrichment of fruit juice based ready-to-serve beverages through blending of Indian gooseberry (Emblica officinalis Gaertn.) juice.

Physiconutritional qualities of fruits viz. apple, lime, pomegranate, Perlette grape, and Pusa Navrang grape were analyzed and compared with those of Indian gooseberry (Emblica officinalis Gaertn.). Indian gooseberry juice contained the highest vitamin C (478.56 mg/100 ml). Hence, when gooseberry juice was blended with other fruits' juice for the preparation of ready-to-serve (RTS) beverages, it boosted their nutritional quality in terms of vitamin C content. On the basis of overall sensory quality and vitamin C content, RTS beverage prepared by blending gooseberry and Pusa Navrang grape juice in 20:80 ratio was found to be the best.

Ascorbic Acid↗
PubMed2006

Vitamin C: research update.

For more than 50 years, the Food and Nutrition Board of the National Academy of Sciences has been reviewing nutrition research and defining nutrient requirements for healthy people, referred to as the Recommended Dietary Allowances (RDA). As new nutrition research is published, the importance of vitamins as vital nutrients is underscored, and new physiologic roles and applications to human health are examined and considered with regard to updating the RDA. Each year a substantial amount of new research is published on vitamins. This review examines recent research published on the importance of vitamin C with regard to general health.

Antioxidants↗