What is Vitamin C
Vitamin C is a water soluble vitamin which is essential to the human body and also known as Ascorbic acid. This vitamin is present in various fresh fruits and vegetables like citrus fruits (oranges, tangerines, etc) and some other foods (potatoes, tomatoes) as well.
Other dietary source of vitamin C include:
The body does not produce its own vitamin C and hence the daily requirements of vitamin C has to be met from external sources (either food or supplements).
Also, the body is not able to store vitamin C and therefore constant supply of it in the right concentration is essential for the body’s use.
What are the uses of Vitamin C
Everybody talks about the fact that you need to take more vitamin C but do you actually know what vitamin C is meant to be used for?
Here are some of the uses of Vitamin C that you need to know about:
- To prevent and treat scurvy:
Scurvy is a disease condition that occurs as a result of severe deficiency of vitamin C. It presents with symptoms like gum disease, loss of teeth, anaemia, corkscrew hairs and poor wound healing. Scurvy may be prevented with the normal dietary vitamin C. Infants and the elderly are more prone to having scurvy if the right amount of vitamin C is not obtained from their diets.
If you develop scurvy, you can still treat it with the dietary vitamin C but the use of therapeutic doses of vitamin C (as a doctor or pharmacist may prescribe) will provide a faster relief of the condition. This is so because the amount given therapeutically results in prompt saturation of tissue stores. As such, the body gets enough vitamin C for all the processes that require its use.
- Daily dietary requirement:
For every food nutrient, there is a Recommended Dietary Allowance (RDA) and you have to make sure to achieve them in order to ensure good health for yourself.
This recommended allowance is to help prevent scurvy and also to provide the body with enough antioxidant protection.
A deficiency in vitamin C is usually associated with the taking in of few fruits and vegetables, or high level of alcohol consumption or intake of certain drugs that may deplete vitamin C.
- Eye Disorders (Macular Degeneration):
Vitamin C is one of the vitamins that have been recommended for people with high risk of macular degeneration especially those that are age related. This is so because of the antioxidant effects of vitamin C.
The use of high dose vitamin C with other antioxidant vitamin supplements and zinc has been found to be effective in reducing the risk of visual acuity loss caused by old age-related macular degeneration.
- Other uses of vitamin C:
- Has been used as a urine acidifier (although efficacy has been questioned) in certain cases
- Has been used to correct tyrosinemia in premature infants on high protein diets.
- Used to facilitate absorption of certain medications like Iron supplements.
- Large doses have also been recommended for decreasing the severity of and for preventing the common cold.
- Used in collagen disorders
- Used to promote wound healing
How is Vitamin C taken
As a drug or a food supplement, ascorbic acid is administered or given by mouth (orally). However, other routes of administration can be adopted when the oral administration is not prefered (Eg. In patients who cannot swallow).
Also, for people who have a suspected malabsorption disorder, using an alternative route is recommended.
Some of the alternative routes include:
- Intramuscular (IM)
- Intravenous (IV)
- Subcutaneous (Sc)
For managing scurvy:
A dose of 100mg to 250mg of vitamin C to be taken 1-2 times in a day is recommended for adults. Taking this regimen of ascorbic acid for about 2days to 3 weeks will reverse the skeletal changes and hemorrhagic disorders associated with scurvy.
In children, a dose of about 100mg – 300mg of vitamin c given either orally or parenterally multiple times within a day for several days may result in rapid recovery.
Dietary and Replacement Requirements
The table below gives the reference values for the daily dietary required amount of vitamin C
|0 – 6 months
|7 – 12 months
|1 – 3 years
|4 – 8 years
|9 – 13 years
|14 – 18 years
|75mg daily (males)65mg daily (females)
|19 years and above
|90mg (for males)75mg (for females)
Note: These values will not be enough for people who smoke. This is because smoking is known to increase the oxidative stress of the body and hence metabolic usage of vitamin C goes up. About 35mg is added to the requirements of smokers.
Also, people under physical or emotional stress may require higher amounts of vitamin C because of the excess oxidative stress generated in the body.
Also in pregnancy, the hemodilution that occurs and demand by the fetus results in a higher than normal requirement.
Are there any Cautions when taking Vitamin C?
The use of vitamin C is non-toxic to the body but just like any drug, some side effects have been reported. Some of these include:
- Abdominal cramps
GI disturbances are the most prominent side effects observed with the use of vitamin C. This is usually the case when very high doses like 3g or more are taken daily.
However, after administration of 1g or greater, diarrhoea may occur. Flatulence too may be observed with high doses of ascorbic acid usage.
The intestinal absorption of vitamin C is tightly regulated and will cease at a certain concentration of vitamin C. As such, with higher doses of vitamin C, a lot of the vitamin C will pass into the intestine without being absorbed into the blood. This unabsorbed form of the vitamin C is commonly the cause of the GI disturbances observed.
Since ascorbic acid can cause acidification of urine, it can precipitate urate, cystine or oxalate stones or crystallization of drugs in the urinary tract.
Ingestion of high doses of vitamin C in pregnancy has resulted in rebound scurvy in the neonates.
Storage and Stability issues
Ascorbic acid darkens gradually on exposure to light, however, a slight discoloration does not impair its activity. The drug should however be protected from light and air.
What are the interactions that Vitamin C have
- Aspirin excretion may be impaired when high doses of ascorbic acid is administered concurrently with it
- Also, acidification of the urine from the administration of vitamin C may impair excretion of other medications.
How does vitamin C work (Pharmacology or Mechanism of Action of Vitamin C)
Vitamin C or ascorbic acid is able to act as an antioxidant because of its ability to donate electrons. It is able to scavenge reactive oxygen and nitrogen species.
These reactive species are responsible for causing diseases associated with oxidative stress. Examples of such diseases are the almighty cancer, cardiovascular diseases (eg. coronary atherosclerosis).
Ascorbic acid may also act as antioxidant by indirectly regenerating other biologic antioxidants such as glutathione and alpha-tocopherol back to their active state.
Effects on leukocytes and Inflammation:
Leukocytes are responsible for phagocytosis of foreign organisms in the body. In order to kill these microorganisms, they generate reactive oxygen or nitrogen species. A similar thing is known to happen during neutrophil activation in inflammation.
Thus vitamin C is needed to prevent or protect the cells from oxidative damage.
What happens to vitamin C in the body (Pharmacokinetics of ascorbic acid)
Absorption: Vitamin C absorption is prominent when given orally. However, it is through an active process and as such absorption may be impaired when high doses are given.
About 70 – 90% of vitamin C is absorbed with consumption of the dietary requirements (between 30 to 180 mg). At high doses exceeding 1g, the absorption goes down to about 50%.