How Much Do You Really Know about Vitamin C?

Perhaps the most well-known vitamin, and one that is frequently cited as vital to good health, but what is Vitamin C exactly? Vitamin C or L-ascorbic acid is a key nutrient and antioxidant essential to our diet. When our bodies contain more free radicals than antioxidants, our bodies are said to be under oxidative stress [1]. Health issues that can arise from oxidative stress include hypertension, cardiovascular disease, chronic inflammatory disease and diabetes [2,3,4]. Vitamin C can help to protect the body against oxidative stress, by raising the levels of antioxidants in the body.

Many animals can synthesize Vitamin C in their bodies; however, humans have lost the ability to do so. One possible reason is that rapid evolutionary changes in humans caused us to lose the capability to produce our own Vitamin C supply [5,6,7], so we must stock up on the Vitamin through the consumption of fruits, vegetables and meats. Because our bodies can only store certain quantities of Vitamin C, it needs to be consumed on a regular basis, or diseases associated with Vitamin C deficiency such as scurvy may develop. However, scurvy is no longer a health issue associated with modern day Western society, since sufficient quantities of Vitamin C are consumed in a diet rich with vegetables and fruits.

If this is the case, then why is Vitamin C still so important? There are other chronic diseases associated with low consumption of Vitamin C such as cancer, heart disease and cataracts. One study found that in order to protect the body against these diseases, a daily intake of 90-100mg is required, higher than the 45mg prescribed against scurvy [8]. 

In addition to its antioxidant properties, Vitamin C has been found in high concentration in immune cells and it is consumed quickly during infections. It is also a natural antihistamine, preventing histamine release in the body and also detoxifying histamines already present in the body. This process can be helpful to people who suffer allergies or asthma. One study found that 2g of Vitamin C per day reduced levels of histamine in the blood [9].

The National American Dietary Reference Intake recommends a daily consumption of 90mg-1g per day [10]. The most effective method of keeping our Vitamin C levels high is through a healthy diet. Most fruits and vegetables, such as citrus fruits and rose hips, are very high in Vitamin C, and some meats, such as liver, also contain a good quantity. The extra intake of Vitamin C through supplements is not necessary for healthy adults who eat a balanced diet; however it is recommended for pregnant women, smokers and those under stress.

References Used:

[1] McGregor, GP; Biesalski, HK (2006). "Rationale and impact of vitamin C in clinical nutrition". Current opinion in clinical nutrition and metabolic care 9 (6): 697–703.

[2] Kelly, FJ (1998). "Use of antioxidants in the prevention and treatment of disease". Journal of the International Federation of Clinical Chemistry / IFCC 10 (1): 21–3.

[3] Mayne, ST (2003). "Antioxidant nutrients and chronic disease: use of biomarkers of exposure and oxidative stress status in epidemiologic research". The Journal of nutrition 133 Suppl 3: 933S–940S.

[4] Tak, PP; Zvaifler, NJ; Green, DR; Firestein, GS (2000). "Rheumatoid arthritis and p53: how oxidative stress might alter the course of inflammatory diseases". Immunology today 21 (2): 78–82.

[5] Challem, J; Taylor, EW (1998). "Retroviruses, Ascorbate, and Mutations, in the Evolution of Homo sapiens". Free Radical Biology and Medicine 25 (1): 130–2.

[6] Bánhegyi, G; Braun, L; Csala, M; Puskás, F; Mandl, J (1997). "Ascorbate Metabolism and Its Regulation in Animals". Free Radical Biology and Medicine 23 (5): 793–803.

[7] Stone, I (1979). "Homo sapiens ascorbicus, a biochemically corrected robust human mutant". Medical Hypotheses 5 (6): 711–21.

[8] A.C. Carr, B. Frei, "Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans", American Journal of Clinical Nutrition, Vol. 69, No. 6, 1086-1107, June 1999.

[9] Johnston, Carol S.; Martin, L. J.; Cai, X. (1992). "Antihistamine effect of supplemental ascorbic acid and neutrophil chemotaxis". Am Coll Nutr11 (2): 172–176.

[10] Accessed October 2011