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Topic Review
Vitamin D and Cancer
There is strong evidence from geographical ecological and observational studies that solar UVB exposure and serum 25-hydroxyvitamin D concentration are inversely correlated with risk of incidence and death from many types of cancer. Clinical trials have provided limited support for the UVB-vitamin D-cancer hypothesis due to poor design and execution. Many experimental studies in cultured cells and animal models have described a wide range of anticancer effects of vitamin D compounds.
  • 512
  • 27 Apr 2022
Topic Review
Vitamin D against COVID-19
Many studies suggest that vitamin D improves immune function, reducing susceptibility to infection. In contrast, an extensive number of scientific studies highlight its immunosuppressive effects. Thus, it seems that vitamin D supports immune response under physiological conditions, but it also has an active role in autoimmunity prevention. In short, its effects would depend on the immunological situation of the patient.
  • 472
  • 30 Dec 2021
Topic Review
Vitamin D
Vitamin D is a micronutrient with pleiotropic effects in humans. Due to sedentary lifestyles and increasing time spent indoors, a growing body of research is revealing that vitamin D deficiency is a global problem. Despite the routine measurement of vitamin D in clinical laboratories and many years of efforts, methods of vitamin D analysis have yet to be standardized and are burdened with significant difficulties. 
  • 1.0K
  • 07 Jun 2021
Topic Review
Vitamin C: AA vs. DHA
The reduced form of vitamin C (ascorbic acid, AA) is an essential micronutrient of small size; it is soluble in water and has two dissociable protons with pKa values of 4.2 and 11.8. At physiological pH, its reduced form predominates as the monovalent ascorbate anion (AA); when it loses the second proton, it is oxidized to dehydroascorbic acid (DHA). Most mammals can synthesize vitamin C from D-glucose in the liver, except guinea pigs, bats, and higher primates, including humans, due to the absence of the enzyme L-gulonolactone oxidase, which catalyzes the last step of the bio-synthesis of vitamin C . Therefore, to meet the body’s requirements, vitamin C must be incorporated into the diet. The best-known function of vitamin C is as an anti-oxidant agent that can act as a cofactor of enzymatic reactions involved in the synthe sis of catecholamines, carnitine, cholesterol, amino acids, and some hormonal peptides, as well as in the maintenance of brain function and the protection of central nervous system (CNS) structures . AA uptake in different cells is performed by the sodium-ascorbate cotransporters SVCT1 and SVCT2, which stereospecifically transport the reduced form of vitamin C, L-ascorbate . Vitamin C can also be transported in its oxidized form, DHA, through the facilitative glucose transporters GLUT1, GLUT2, GLUT3, GLUT4, and GLUT8. However, for a long time, it has been postulated that the contribution of DHA to the accumulation of vitamin C in tissues is relatively low. 
  • 899
  • 20 Feb 2021
Topic Review
Vitamin C Intervention for Critical COVID-19
Coronaviruses are single-stranded ribonucleic acid viruses comprising a lipid bilayer containing crown-like spikes (Latin, Corona = Crown) on their outer surface.
  • 499
  • 18 Nov 2021
Topic Review
Vitamin C in Various Diets
Recent research studies have shown that vitamin C (ascorbic acid) may affect bone mineral density and that a deficiency of ascorbic acid leads to the development of osteoporosis. Patients suffering from an inflammatory bowel disease are at a risk of low bone mineral density. It is vital to notice that patients with Crohn’s disease and ulcerative colitis also are at risk of vitamin C deficiency which is due to factors such as reduced consumption of fresh vegetables and fruits, i.e., the main sources of ascorbic acid. Additionally, some patients follow diets which may provide an insufficient amount of vitamin C. The entry contains information about vitamin C content and impact of various diets- Mediterranean diet, vegetarian diets, low-carbohydrates diets and low-FODMAP diet- on bone mineral density and inflammatory bowel disease course. 
  • 798
  • 08 Sep 2020
Topic Review
Vitamin C in Treatment of Patients with Cancer
Vitamin C is an essential micronutrient, that plays an important role in numerous physiological processes in the human body. Vitamin C stimulates the production and activation of immune cells, so perhaps supplementation could be used to improve the immunity in cancer patients .
  • 426
  • 04 Aug 2022
Topic Review
Vitamin C in COVID-19
There are limited proven therapies for COVID-19. Vitamin C’s antioxidant, anti-inflammatory and immunomodulating effects make it a potential therapeutic candidate, both for the prevention and amelioration of COVID-19 infection, and as an adjunctive therapy in the critical care of COVID-19. This literature review focuses on vitamin C deficiency in respiratory infections, including COVID-19, and the mechanisms of action in infectious disease, including support of the stress response, its role in preventing and treating colds and pneumonia, and its role in treating sepsis and COVID-19. The evidence to date indicates that oral vitamin C (2–8 g/day) may reduce the incidence and duration of respiratory infections and intravenous vitamin C (6–24 g/day) has been shown to reduce mortality, intensive care unit (ICU) and hospital stays, and time on mechanical ventilation for severe respiratory infections. Further trials are urgently warranted. Given the favourable safety profile and low cost of vitamin C, and the frequency of vitamin C deficiency in respiratory infections, it may be worthwhile testing patients’ vitamin C status and treating them accordingly with intravenous administration within ICUs and oral administration in hospitalised persons with COVID-19.
  • 715
  • 17 Dec 2020
Topic Review
Vitamin C Deficiency
Vitamin C is an essential nutrient that must be obtained through the diet in adequate amounts to prevent hypovitaminosis C, deficiency and its consequences—including the potentially fatal deficiency disease scurvy. Global vitamin C status and prevalence of deficiency has not previously been reported, despite vitamin C’s pleiotropic roles in both non-communicable and communicable disease. This entry highlights the global literature on vitamin C status and the prevalence of hypovitaminosis C and deficiency. Related dietary intake is reported if assessed in the studies. Overall, the entry illustrates the shortage of high quality epidemiological studies of vitamin C status in many countries, particularly low- and middle-income countries. The available evidence indicates that vitamin C hypovitaminosis and deficiency is common in low- and middle-income countries and not uncommon in high income settings. 
  • 1.5K
  • 27 Jul 2020
Topic Review
Vitamin C Anticancer Action
Vitamin C is an indispensable micronutrient in the human diet due to the multiple functions it carries out in the body. Reports of clinical studies have indicated that, when administered at high dosage by the intravenous route, vitamin C may exert beneficial antitumor effects in patients with advanced stage cancers, including those refractory to previous treatment with chemotherapy. 
  • 780
  • 19 May 2021
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