What does it do? Vitamin C is a water-soluble vitamin that has a number of biological functions. Acting as an antioxidant, one of vitamin C's important functions is to protect LDL cholesterol from oxidative damage. (Only when LDL is damaged does cholesterol appear to lead to heart disease, and vitamin C may be one of the most important antioxidant protectors of LDL.) Vitamin C may also protect against heart disease by reducing the stiffness of arteries and the tendency of platelets to clump together.
The antioxidant properties of vitamin C are thought to protect smokers, as well as people exposed to secondhand smoke, from the harmful effects of free radicals. A controlled trial demonstrated the ability of 3 grams of vitamin C, taken by non-smokers two hours prior to being exposed to cigarette smoke, to reduce the free radical damage and LDL cholesterol oxidation associated with exposure to cigarette smoke. The smoke-induced decline in total antioxidant defense was also diminished. These beneficial effects were not observed in non-smokers under normal conditions (no free radical exposure).
Vitamin C is needed to make collagen, the "glue" that strengthens many parts of the body, such as muscles and blood vessels. Vitamin C also plays important roles in wound healing and as a natural antihistamine. This vitamin also aids in the formation of liver bile and helps to fight viruses and to detoxify alcohol and other substances.
Recently, researchers have shown that vitamin C improves nitric oxide activity. Nitric oxide is needed for the dilation of blood vessels, potentially important in lowering blood pressure and preventing spasms of arteries in the heart that might otherwise lead to heart attacks. Vitamin C has reversed dysfunction of cells lining blood vessels. The normalization of the functioning of these cells may be linked to prevention of heart disease.
Evidence indicates that vitamin C levels in the eye decrease with age and that supplementing with vitamin C prevents this decrease, possibly leading to a lower risk of developing cataracts.
People with recurrent boils (furunculosis) may have defects in white blood cell function that are correctable with vitamin C supplementation. A preliminary study of people with recurrent boils and defective white blood cell function, found that 1 gram of vitamin C
taken daily for four to six weeks, resulted in normalization of white blood cell function.
Where is it found? Broccoli, red peppers, currants, Brussels sprouts, parsley, potatoes, citrus fruit, and strawberries are good sources of vitamin C.
Vitamin C has been used in connection with the following conditions:
- Anemia (if deficient)
- Athletic performance (if deficient, or to reduce pain and speed up muscle strength
- recovery after intense exercise)
- Bronchitis
- Bruising (for deficiency)
- Burns (sunburn only)
- Capillary fragility
- Common cold/sore throat
- Gingivitis (periodontal disease) (for deficiency only)
- Glaucoma
- Heart attack (for deficiency)
- High cholesterol
- Infection
- Infertility (male) (for sperm agglutination)
- Reflex sympathetic dystrophy (prevention)
- Scurvy
- Wound healing
- Asthma
- Atherosclerosis
- Athletic performance
- Autism
- Cataracts
- Childhood intelligence (for deficiency)
- Cold sores
- Diabetes
- Dysmenorrhea (plus vitamin B3 [niacin] and rutin)
- Gastritis
- Gingivitis
- Immune function
- Influenza
- Iron-deficiency anemia
- Pancreatic insufficiency
- Pre- and post-surgery health (if deficient)
- Preeclampsia (in combination with vitamin E; for high risk only)
- Schizophrenia
- Skin ulcers
- Sprains and strains
- Age-related cognitive decline
- Amenorrhea
- Bipolar disorder/manic depression
- Boils (recurrent furunculosis)
- Childhood diseases
- Chronic obstructive pulmonary disease (COPD)
- Colon cancer (reduces risk)
- Diabetic retinopathy (in combination with selenium, vitamin A, and vitamin E)
- Ear infections (recurrent)
- Eczema
- Gallstones
- Gout
- Halitosis (if gum disease and deficient)
- Hay fever
- Heart attack (for those not deficient)
- Hepatitis
- High blood pressure
- Hives
- Hypoglycemia
- Leukoplakia
- Low back pain
- Macular degeneration
- Menopause
- Menorrhagia (heavy menstruation)
- Morning sickness
- Parkinson's disease (in combination with Vitamin E)
Who is likely to be deficient? Although scurvy (severe vitamin C deficiency) is uncommon in Western societies, many doctors believe that most people consume less than optimal amounts. Fatigue, easy bruising, and bleeding gums are early signs of vitamin C deficiency that occur long before frank scurvy develops. Smokers have low levels of vitamin C and require a higher daily intake to maintain normal vitamin C levels. Women with preeclampsia have been found to have lower blood levels of vitamin C than women without the condition. Women who have lower blood levels of vitamin C have an increased risk of gallstones.
Are there any side effects or interactions? Some people develop diarrhea after as little as a few grams of vitamin C per day, while others are not bothered by ten times this amount. Strong scientific evidence to define and defend an upper tolerable limit for vitamin C is not available. A review of the available research concluded that high intakes (2-4 grams per day) are well-tolerated by healthy people. However, intake of large amounts of vitamin C can deplete the body of copper - an essential nutrient. People should be sure to maintain adequate copper intake at higher intakes of vitamin C.
