Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0018799 (heart disease)
 34,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A better understanding of the functions of ascorbic acid would help clarify the magnitude of the influence of this vitamin on health-related conditions. Many of the purported benefits require confirmation as well as a knowledge of the mechanism of action. The majority of investigations of the association of vitamin C with various types of cancer, with cardiovascular risk, and with cataract formation were epidemiologic studies. Often it was not possible to discern whether the apparent protective effect was due to vitamin C, vitamin E, or carotene, or to a combined effect of these nutrients or of additional factors. Human intervention trials may provide definitive and quantitative assessments of the role of vitamin C in health maintenance. We need to gain a more thorough understanding of the interactions of vitamin C with other nutrients, such as vitamin E and carotenoids, in order to appreciate the role of vitamin C in disease prevention. Investigators are increasingly recognizing the diverse functions of vitamin C in the body in addition to its role in collagen synthesis. However, the functional consequences of these many important roles of vitamin C remain essentially unknown. Excluding scurvy, the health consequences of inadequate vitamin C status are not well characterized. Nonetheless, epidemiologic evidence suggests a role for vitamin C in cancer and heart disease as well as in a number of other diseases.
 ...
PMID:Pharmacology of vitamin C. 794 25

Vitamin C is an essential dietary nutrient required as a co-factor for many enzymes, and humans are among the few animals that lack the ability to synthesize the compound from glucose. The reduced form of the vitamin, ascorbic acid, is an especially effective antioxidant owing to its high electron-donating power and ready conversion back to the active reduced form. Concentrations of the vitamin in body tissues and fluids are regulated through interactions of intestinal absorption, cellular transport, and excretion. The amount of vitamin C needed to prevent scurvy is very small and easily obtained in nearly all Western diets. There is great interest in the clinical roles of vitamin C because of evidence that oxidative damage is a root cause of, or at least associated with, many diseases. Population studies show that individuals with high intakes of vitamin C have lower risk of a number of chronic diseases, including heart disease, cancer, eye diseases, and neurodegenerative conditions. However, these results may simply reflect a more healthful diet or lifestyle for individuals with a high vitamin C intake. At present, data from controlled clinical trials have not established that higher intakes of vitamin C alone will help prevent chronic degenerative diseases. However, the evidence that ascorbic acid acts as an important antioxidant in many body tissues is convincing. The new higher Recommended Dietary Allowance (RDA) for vitamin C of 75 mg for women and 90 mg for men is, for the first time, based on the vitamin's role as an antioxidant as well as protection from deficiency. In healthy people, amounts greater than the RDA do not appear to be helpful. Vitamin C nutriture may be more important for people with certain diseases or conditions. High intakes of the vitamin are generally well tolerated; a Tolerable Upper Level was recently set at 2 g based on gastrointestinal upset that sometimes accompanies excessive intakes.
 ...
PMID:Vitamin C function and status in chronic disease. 1213 9

L-Ascorbic acid (AsA, vitamin C) is an essential human nutrient that must be obtained in the diet, with the vast majority being obtained from plant foods. A vitamin C-deficient diet results in the onset of scurvy, which can have lethal consequences. However, vitamin C has also been implicated in the prevention of chronic diseases such as heart disease, stroke, cancer, and several neurodegenerative diseases. Although the supporting evidence for these claims is disputed, the dietary allowances for vitamin C have been recently increased in several countries, including the United States. This scenario, together with the general perception by consumers of vitamin C as being of benefit in the prevention of several lifestyle diseases and associated with general "well-being", contributes to a market rationale for enhancing the vitamin C content of crops. In recent years, there has been substantial progress in the understanding of vitamin C biochemistry in plants with a number of structural genes cloned. Here these findings are reviewed, and a description of how such knowledge could be applied to the nutritional enhancement of crops is given.
 ...
PMID:Improving the nutritional value of crops through enhancement of L-ascorbic acid (vitamin C) content: rationale and biotechnological opportunities. 1596 4

Vitamin C is an essential component of the diet for humans, and an adequate intake is important not only for the prevention of scurvy but also to limit the risk of developing chronic diseases such as heart disease and cancer. To achieve a regular and adequate intake, daily consumption of fresh fruit and vegetables is recommended. The vitamin C content of food varies widely, however, and plasma levels generally reflect the amount consumed, regardless of its origin. Kiwifruit are one of the premier dietary sources of vitamin C, with all commercially important varieties having high content, and with one serving delivering the bulk of the recommended dietary intake. Recent studies have shown that the addition of kiwifruit to a marginal vitamin C diet markedly improves plasma vitamin C levels and can increase them to both healthy and optimal levels.
 ...
PMID:The bioavailability of vitamin C from kiwifruit. 2339 85

Vitamin C is a powerful dietary antioxidant that has received considerable attention in the literature related to its possible role in heart health. Although classical vitamin C deficiency, marked by scurvy, is rare in most parts of the world, some research has shown variable heart disease risks depending on plasma vitamin C concentration, even within the normal range. Furthermore, other studies have suggested possible heart-related benefits to vitamin C taken in doses beyond the minimal amounts required to prevent classically defined deficiency. The objective of this review is to systematically review the findings of existing epidemiologic research on vitamin C and its potential role in cardiovascular disease (CVD). It is well established that vitamin C inhibits oxidation of LDL-protein, thereby reducing atherosclerosis, but the cardiovascular outcomes related to this action and other actions of vitamin C are not fully understood. Randomized controlled trials as well as observational cohort studies have investigated this topic with varying results. Vitamin C has been linked in some work to improvements in lipid profiles, arterial stiffness, and endothelial function. However, other studies have failed to confirm these results, and observational cohort studies are varied in their findings on the vitamin's effect on CVD risk and mortality. Overall, current research suggests that vitamin C deficiency is associated with a higher risk of mortality from CVD and that vitamin C may slightly improve endothelial function and lipid profiles in some groups, especially those with low plasma vitamin C levels. However, the current literature provides little support for the widespread use of vitamin C supplementation to reduce CVD risk or mortality.
...
PMID:Vitamin C and Heart Health: A Review Based on Findings from Epidemiologic Studies. 2752 39