Updated: Sep 13
Vitamin C, also known as ascorbic acid, is needed for the growth and repair of tissues in every part of your body. Its importance was discovered during the 16th to 19th century when around fifty percent of sailors died on their journeys due to a vitamin C deficiency!
It is used to:
● Form an important protein used to make skin, tendons, ligaments, and blood vessels
● Heal wounds and form scar tissue
● Repair and maintain cartilage, bones, and teeth (1)
Vitamin C is one of many antioxidants, or nutrients that block some of the damage caused by free radicals. Free radicals are made when your body breaks down food or when you are exposed to tobacco smoke or radiation.The buildup of free radicals over time is thought to be largely responsible for the aging process, and may play a role in cancer, heart disease, and conditions like arthritis. (1)
Many components of the immune system are affected by vitamin C. For example, white blood cells that battle viruses, bacteria, and other foreign invaders need vitamin C to function, to stimulate production and protect them from oxidative damage.
In vitro studies have shown that vitamin C increases another type of immune cell, called interleukins. (2, 3, 4, 5)
Despite the clear benefits of vitamin C, humans are one of very few animals that are not able to synthesize their own vitamin C. We can't even store it.
For some unknown reason humans, primates, fruit bats and guinea pigs lost the ability to make vitamin C somewhere along the evolutionary road. However, some studies suggest we have a way to compensate for this "in built error"by sucking up DHA (the oxidised form) into red blood cells and transforming it to the reduced, antioxidant form of vitamin C.
Including plenty of vitamin C-containing foods in your daily diet is still vital to good health. (1)
The best food sources of vitamin C include: Capsicums, broccoli, citrus fruits, kiwifruit, pineapple, watermelon, leafy greens, tomatoes and even potatoes. (1, 2)
What are some signs you might be Vitamin C deficient?
Bleeding gums & gingivitis
Decreased ability to fight infection
Decreased wound-healing rate
Swollen and painful joints
Weakened tooth enamel
Dry and splitting hair
Rough, dry, scaly skin
Possible weight gain because of slowed metabolism
Let's also take a look at some other impressive benefits of vitamin C...
Cardiovascular Disease and Stroke
Studies indicate that higher intakes of vitamin C can reduce your risk of cardiovascular disease (CVDs) including coronary heart disease and stroke. (2, 6, 7)
Vitamin C supplementation (greater than 500mg/d) improved endothelial function (EF). (2,7) The endothelium is the inner lining of blood vessels and its function impacts blood pressure, blood clotting & ultimately cardiovascular diseases. The effect of vitamin C appears to be dependent on health status, with stronger effects in those with cardio-metabolic disorders. (7)
Vitamin C was shown to decrease serum cholesterol levels in those with high cholesterol levels and low vitamin C levels. Large doses as food supplements may even lower blood pressure. (2, 8)
The Immune System & The Common Cold
In 2005 a review was conducted on all placebo controlled trials between 1940 & 2004 that looked at vitamin C supplementation and its effect on the duration, severity and incidence of the common cold. (9,10)
It was found that, when taken as a continuous daily supplement of 200 mg to 2 g (43 trials), there was a reduction in the duration & severity of the common cold (when considering absence from school & work, & reduction in incidence of pneumonia). The effects were even more noticeable in children.
No reduction in the incidence of the common cold was seen in the general population, but the incidence was almost halved in those undergoing heavy physical stress (e.g marathon runners, skiers or soldiers in subarctic conditions). (9, 10)
When supplementation was taken at the onset of symptoms (only 7 trials, all in adults), benefits were not observed regarding the duration of episodes. However one large trial found a significant reduction when administered a single dose of 8 g on the day of symptom onset. (9, 10)
Also of note are the benefits of bioflavanoids found in vitamin C rich foods. Various viral infections do not produce symptoms until a protein coating surrounding the virus is broken down by enzymes. Two enzymes believed to be involved in this process are both blocked by these powerful plant derived anti-oxidants. (11)
Allergies & Inflammation
Bioflavanoids found in vitamin c rich foods may be helpful with allergies by reducing the symptom producing effects of histamine and inhibiting inflammatory substances into tissues. (12, 13, 14)
Haemorrhoids, Varicose Veins & Easy Bruising
This is thought to be through the beneficial effect of Vitamin C and bioflavanoids on blood vessel integrity, collagen synthesis and endothelial function. (15, 16)
More benefits may be found in conditions such as arthritis and gout (2), exercise induced asthma (2,17) and possible cancer (2).
How much vitamin C?
● The Micronutrient Information Centre at the Linus Pauling institute at Oregon State University recommends a daily vitamin C intake of at least 400 mg/day for adults. This is substantially higher than the current RDA but is based on all the studies and randomized controlled trials, and also the fact that large amounts of vitamin c (up to 10g /day) have not been found to be toxic or detrimental to health. (2)
● However a tolerable upper intake level (UL) of 2 grams (2000 mg) daily is recommended to prevent diarrhea and gastrointestinal disturbances. For 1-3 yrs old the UL is 400mg, 4-8yrs old 650mg, 9-13 yrs 1200mg, & 14-18yrs 1800mg. (2)
● Over 60s, those that smoke, are pregnant, under high levels of physical or mental stress, use aspirin or oral contraceptives may need even higher levels. (2)
● Consuming at least 5 servings (2 ½ cups) of fruit and vegetables per day provides about 200 mg of vitamin c. (2)
So, are you getting enough vitamin C daily?
(1) Vitamin c. U.S. National Library of Medicine - The World's Largest Medical Library. Review Date: 2/18/2013. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0003056/
(2) Oregan State University : Linus Pauling Institute: Micronutrient Information Center: Written in January 2006 by Jane Higdon, Ph.D.Updated in November 2013 by:
Giana Angelo, Ph.D. Reviewed in November 2013 by Balz Frei, Ph.D, Joan H. Facey, Alexander J. Michels, Ph.D. http://lpi.oregonstate.edu/infocenter/vitamins/vitaminC/
(3) Dahl H, Degre M. The effect of ascorbic acid on production of human interferon and the antiviral activity in vitro. Acta Pathol Microbiol Scand B. 1976;84B(5):280-284. (PubMed)
(4) Jariwalla RJ, Harakeh S. Mechanisms underlying the action of vitamin C in viral and immunodeficiency disease. In: Packer L, Fuchs J, eds. Vitamin C in Health and Disease. New York: Marcel Dekker, Inc.; 1997:309-322.
(5) Pauling L. The immune system. How to Live Longer and Feel Better. 20th Anniversary ed. Corvallis: Oregon State University Press; 2006:105-111.
(6) Ness AR1, Powles JW, Khaw KT.; Vitamin C and cardiovascular disease: a systematic review. J Cardiovasc Risk. 1996 Dec;3(6):513-21. www.ncbi.nlm.nih.gov/pubmed/9100087
(7) Ammar W. Ashoremailemail, Jose Lara, John C. Mathers, Mario Siervo. (2014). Effect of vitamin C on endothelial function in health and disease: A systematic review and meta-analysis of randomised controlled trials. Atherosclerosis. Volume 235, Issue 1, Pages 9–20. www.sciencedirect.com/science/article/pii/S0021915014002032
(8) Asplund, K. (2002). Antioxidant vitamins in the prevention of cardiovascular disease: a systematic review. Journal of Internal Medicine, Volume 251, Issue 5, pages 372–392, May 2002. http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2796.2002.00973.x/full
(9) Douglas RM, Hemila H, Chalker E, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev; 2007(3):CD000980.
(10) Hemila H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane database of systematic reviews. 2013;1:CD000980. (PubMed)
(11) Basu TK , Schorah CJ. Vitamin C in health and disease. AVI publishing Co, Inc Westport Conn 1982
(12) GaborM. Pharmacologic effect of flavonoids on blood vessels. Angiologica 1972;9:223-242, 355-374.
(13) Phister JR, et al. Inhibition of histamine-induced gastric secretion by flavone-6-carboxylic acids. J Med Chem 1980;23:335.
(14) Nandi BK, et al. Effect of ascorbic acid on detoxification of histamine unders stress conditions. Biochem Pharmacology. Pergamon Press 1974;23:643-647
(15) Drubaix I, Viljanen-Tarifa E, Robert AM, Robert L. [Role of glycosoaminoglycans in venous disease.
Mode of action of some flavonoid drugs] Pathol Biol (Paris). 1995 May;43(5):461-70.
(16) MacKay D. Hemorrhoids and varicose veins: a review of treatment options. Altern Med Rev. 2001 Apr;6(2):126-40
(17) Hemila H. Vitamin C may alleviate exercise-induced bronchoconstriction: a meta-analysis. BMJ Open. 2013;3(6). (PubMed)