The human being is one of the few members of the animal kingdom that can not synthesize vitamin C.
In 1959 J.J. Burns showed that the few mammals susceptible to scurvy are unable to produce the active enzyme, L-gulonolactone oxidase, involved in the conversion of blood glucose to ascorbic acid, in their livers. The synthesis of vitamin C is involving four enzymes. Man has the first three enzymes. The missing fourth enzyme completely blocks the liver production of ascorbic acid.
Other animals, are not able to synthesize ascorbic acid, are primates, some birds, guinea pigs, and fruit bats.
Health benefits of vitamin C
Despite its simple structure, vitamin C functions as a primary coenzyme in numerous enzymatic reactions such as the synthesis of collagen, carnitine, and catecholamines.
Ascorbic acid also acts as a powerful antioxidant. Even small amounts of vitamin C can protect such vital molecules of the body as proteins, lipids (fats), carbohydrates and nucleic acids (DNA and RNA) from damage by free radicals and reactive oxygen species (ROS) what are produced during normal metabolism of active immune cells, and by exposure to toxins and contaminants (such as some chemotherapy drugs and cigarette smoke).
Vitamin C is also involved in redox transformations of other important antioxidants; for example, vitamin C is known to regenerate vitamin E from its oxidized form.
Vitamin C deficiency symptoms
Severe ascorbic acid deficiency has been known for centuries in the form of a potentially fatal disease such as scurvy.
The ascorbic acid name is a derivative of a- (meaning "no") and scorbutus (scurvy).
Symptoms of scurvy include subcutaneous bleeding, poor wound healing and easy bruising, loss of hair and teeth, as well as the pain and swelling in the joints.
These symptoms seem to be related to the weakening of blood vessels, connective tissue and bone, all of which contain collagen.
Scurvy early symptom, such as fatigue, may result from reduced levels of carnitine, which is required to obtain energy from fat, or due to decreased synthesis of catecholamines - norepinephrine.
The Recommended Dietary Allowance (RDA) of vitamin C
The RDA of ascorbic acid for adults is 90 mg / day for men and 75 mg / day for women.
The optimal daily dose - 250-1,000 mg.
Table of recommended daily allowance (RDA) of vitamin C intake in mg
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What foods contain vitamin C
The richest natural sources of vitamin C are fruits and vegetables. The best of them are asparagus, papaya, oranges and orange juice, cantaloupe, cauliflower, broccoli, Brussels sprouts, green peppers, grapefruit and grapefruit juice, kale, lemon, and strawberry.
Vitamin C value per 1 cup of a product
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Safety (Vitamin C overdose)
A tolerable upper intake level of ascorbic acid - 2 gram (2000 milligrams) per day is recommended for the prevention of diarrhea and other gastrointestinal disturbances.
Vitamin C for Heavy Metal Detox
“Vitamin C Basics” by Suzanne Humphries, MD
“Vitamin C - Antidote to all known toxins” by Thomas Levy, MD