An inadequate intake of vitamin C (ascorbic acid) can lead to symptoms of deficiency including scurvy, but too much vitamin C can also be harmful.
Ascorbic Acid Functions and Vitamin Recommendations
Vitamin C plays an important role in cell metabolism and acts as an antioxidant; that is, it removes free radicals (substances that can cause cell damage) from the body. The richest dietary sources of vitamin C are fruits and vegetables.
Recommendations for daily vitamin C intake differ between the various national and international authorities. The World Health Organization recommends 45 milligrams per day (mg/day) for adult men and women and the UK Food Standards Agency 40 mg/day, while the US guideline is 90 mg/day for men and 75 mg/day for women. These differences reflect an ongoing debate on how much vitamin C is needed for good health. The US Institute of Medicine has set an upper limit for safe vitamin C intake of 2,000 mg/day.
Signs of Overdose of Vitamin C
Although the accepted upper limit is 2,000 mg/day, adverse effects of vitamin C are most commonly reported after extremely large overdoses of more than 3,000 mg/day. Such cases are not uncommon, however, due to the popularity of taking high-dose vitamin C to prevent numerous illnesses including the common cold.
The main adverse effects of overdosing on vitamin C are gastrointestinal problems including flatulence (gas), nausea, abdominal pain and diarrhoea. There have been reports of an increased risk of kidney stones in people taking high-dose vitamin C, but there is as yet no conclusive evidence of any direct link.
Taking Vitamins Safely
The symptoms of overdose will usually disappear once vitamin C intake returns to a normal level. Although the precise recommendations vary, health professionals generally agree that the best way to obtain a healthy amount of vitamin C is to eat a balanced diet including plenty of fruit and vegetables. There is currently no scientific evidence that taking high-dose vitamin C supplements is beneficial to health. People who do choose to use a supplement should ensure they do not take too much, to avoid the potential harmful effects of vitamin C overdose.
References:
DRI Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Accessed 02-12-10
Vitamin C. Accessed 02-12-10
Vitamin C. Accessed 02-12-10
Disclaimer
The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.
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