Vitamin c and it’s defficiency
Vitamin C is an essential nutrient for certain animals including humans. The term vitamin C encompasses several vitamers that have vitamin C activity in animals. Ascorbate salts such as sodium ascorbate and calcium ascorbate are used in some dietary supplements. These release ascorbate upon digestion. Ascorbate and ascorbic acid are both naturally present in the body, since the forms interconvert according to pH . Oxidized forms of the molecule such as dehydroascorbic acid are converted back to ascorbic acid by reducing agents.
Vitamin C functions as a cofactor in many
enzymatic reactions in animals (and humans) that mediate a variety of essential biological functions, including wound healing and collagen synthesis. In humans, vitamin C deficiency leads to impaired
collagen synthesis, contributing to the more severe symptoms of scurvy . Another biochemical role of vitamin C is to act as an antioxidant (a
reducing agent ) by donating electrons to various enzymatic and non-enzymatic reactions. Doing so converts vitamin C to an oxidized state – either as semidehydroascorbic acid or dehydroascorbic acid . These compounds can be restored to a reduced state by glutathione and NADPH -dependent enzymatic mechanisms.
In plants, vitamin C is a substrate for ascorbate peroxidase . This enzyme utilizes ascorbate to neutralize excess hydrogen peroxide (H 2 O 2 ) by converting it to water (H 2 O) and oxygen
Serum levels are considered saturated, achieved by consuming supplement amounts above the Recommended Dietary Allowance, at >65 μmol/L (1.1 mg/dL). Adequate defined as ≥50 μmol/L, hypovitaminosis at ≤23 μmol/L and deficient at ≤11.4 μmol/L.  For people ≥20 years old, data from the U.S. 2003-04 NHANES survey showed mean and median serum concentrations of 49.0 and 54.4 μmol/L, respectively. The percent of people reported as deficient was 7.1%.
Scurvy is a disease resulting from a deficiency of vitamin C. Without this vitamin, collagen made by the body is too unstable to perform its function and several other enzymes in the body do not operate correctly. Scurvy is characterized by
spots on and bleeding under the skin, spongy gums, ‘corkscrew’ hair growth, and poor wound healing. The skin lesions are most abundant on the thighs and legs, and a person with the ailment looks pale, feels depressed, and is partially immobilized. In advanced scurvy there are open, suppurating wounds , loss of teeth, bone abnormalities and, eventually, death. The human body can store only a certain amount of vitamin C, and so the body stores are depleted if fresh supplies are not consumed.
Notable human dietary studies of experimentally induced scurvy were conducted on conscientious objectors during World War II in Britain and on Iowa state prisoners in the late 1960s to the 1980s. Men in the prison study developed the first signs of scurvy about four weeks after starting the vitamin C-free diet, whereas in the earlier British study, six to eight months were required, possibly due to the pre-loading of this group with a 70 mg/day supplement for six weeks before the scorbutic diet was fed. Men in both studies had blood levels of ascorbic acid too low to be accurately measured by the time they developed signs of scurvy. These studies both reported that all obvious symptoms of scurvy could be completely reversed by supplementation of only 10 mg
Vitamin C has a definitive role in treating scurvy, which is a disease caused by vitamin C deficiency. Beyond that, a role for vitamin C as prevention or treatment for various diseases is disputed, with reviews reporting conflicting results. A 2012
Cochrane review reported no effect of vitamin C supplementation on overall mortality.It is on the World Health Organization’s List of Essential Medicines , the safest and most effective medicines needed in a health system .
The disease scurvy is caused by vitamin C deficiency and can be prevented and treated with vitamin C-containing foods or dietary supplements. It takes at least a month of little to no vitamin C before symptoms occur.Early symptoms are malaise and lethargy, progressing to shortness of breath, bone pain, bleeding gums, susceptibility to bruising, poor wound healing, and finally fever, convulsions and eventual death. Until quite late in the disease the damage is reversible, as healthy collagen replaces the defective collagen with vitamin C repletion. Treatment can be orally or by intramuscular or intravenous injection. Scurvy was known to Hippocrates in the classical era. The disease was shown to be prevented by citrus fruit in an early controlled trial by a Royal Navy surgeon, James Lind, in 1747, and from 1796 lemon juice was issued to all Royal Navy crewmen.