Vitamin C is an essential nutrient for humans. It is a cofactor in at least eight enzymatic reactions, including several collagen synthesis reactions that are important in wound-healing and in preventing bleeding from capillaries. Vitamin C also acts as an antioxidant against oxidative stress.
Unlike many other animals, humans are unable to make Vitamin C from glucose because of their lack of one vital enzyme. Thus, humans must ingest Vitamin C – this is why it is called essential.
Vitamin C is an important antioxidant, and of particular importance is its antioxidant function with lipids (fats). The LDL (or “bad”) cholesterol is protected from free radical damage by Vitamin C. It helps to form strong connective tissue, repair wounds, improve gum health, and reduce bruising.
Vitamin C is able to regenerate Vitamin E.
Good food sources for Vitamin C include Acerola cherries, Seabuckthorn, Rose hip, red chili peppers, green peppers, guavas, papaya, oranges, cantaloupe, kiwi fruit, broccoli, cauliflower, Brussels sprouts, grapefruit, and strawberries. Fresh foods eaten immediately after harvest are the richest sources as the content declines rapidcly in foods once they have been picked or sliced.
Scruvy is a deficiency disease associated with lack of Vitamin C. Fatigue is one of the first deficiency signs of Vitamin C. Other signs include bleeding gums, haemorrhages under the tongue, impaired wound healing, joint pains, loose teeth, easy bruising, frequent infections, and cardiovascular disease.
Vitamin C can support the immune system by enhancing the activity of the white blood cells and production of immune-mediating chemicals. When the body is under a lot of stress, both emotional and physical, vitamin C may be excessively excreted (and found in urine samples) and greater intake may be necessary.
Because vitamin C can regenerate vitamin E, it is important to include it in any therapeutic antioxidant combination.
Many clinicians have seen benefits using doses from 1000 to 20,000 mg daily.
Safety and toxicity
Vitamin C is considered extremely safe. However individuals with glucose-6-phosphate dehydrogenase deficiency have been shown red blood cell destruction when large doses of Vitamin C were given intravenously.
Patients who are homozygous for haemochromatosis may experience increased iron uptake with vitamin C ingestion.
Several reviews raised no concerns that Vitamin C can cause kidney stones.
All excess vitamin C is disposed of through the urinary system.
Functional medicine considerations
Vitamin C insufficiency should be suspected when a patient is fatigued, especially if they show echymosis (bruises) or petechiae (caused by a minor bleed).