 | Importance of Vitamin C Vitamin C (also known as ascorbic acid) is a nutrient that acts as a strong antioxidant in the body. As an antioxidant, Vitamin C is used to protect cells from free radicals by inhibiting oxidation and thereby preventing damage to proteins, DNA, and the lining of blood vessels. This nutrient is also important in the composition of connective tissue which is essential in the process of healing wounds. In general, this vitamin has been used to boost the immune system by facilitating the production of lymphocytes and phagocytes to fight infections. Research continues to progress to determine the benefits of Vitamin C in delaying or halting the progression of cardiovascular disease, certain cancers, and/or other diseases that can be attributed to the consequences of oxidative stress. Humans cannot synthesize Vitamin C endogenously; this means we have to obtain this nutrient via our diets. Although Vitamin C is present in many foods, it is also often taken as a dietary supplement to ensure that sufficient amounts of this nutrient are being absorbed. A deficiency of Vitamin C can lead to the onset of scurvy, weakening of connective tissue, joint pain, iron deficiency anemia, and if left untreated, potentially death. Vitamin C inadequacy is more common among certain groups including the following: smokers, elderly, those with limited food variety, and/or those with intestinal malabsorption. |
Absorption pathway of vitamin C
When taken orally Vitamin C must follow a specific path to be absorbed into the bloodstream. First it must be digested in the stomach, then it will travel to the small intestine where it is digested further and it will be absorbed in the large intestine. From here the vitamin will be transported to the lover and be processed and detoxified to be delivered into the blood vessels. From this point the vitamin can be absorbed into tissues and cells. This process shows that there are many steps in the final absorption of Vitamin C causing approximately 18% of the vitamin C consumed to actually be absorbed. This can be even more tricky for those with gastrointestinal issues or a leaky gut. At high doses, oral vitamin C can cause intestinal issues, abdominal cramps, and/or diarrhea.
Intravenous Vitamin C is able to avoid this absorption process as it is delivered directly to the bloodstream. This allows for 100% of the vitamin C to be absorbed and used in the body.
Intravenous (IV) Vitamin C vs Oral Vitamin C
According to a study conducted in 2004 regarding the comparison of oral and intravenous use of Vitamin C, it was found that at low doses both oral and IV administration showed similar levels of plasma vitamin C concentrations. At doses of approximately 1 gram, oral administration
indicated a vitamin C concentration of 100-200 μmol/L in plasma, while IV administration had a concentration of approximately 300-400 μmol/L. These results suggest that vitamin C IV’s are not necessary when administered at low dosages as they produce the similar blood levels of vitamin C as oral intake. It is also less expensive to use oral vitamin C when in need of low doses rather than an IV supplement.
However, there is a large distinction when dosage is increased as oral administration does not exceed vitamin C levels of approximately 220 μmol per liter of blood (even when administered at 3 gram doses 6 times each day). Vitamin C, on the other hand, exceeds this level of plasma concentration (by 1500 μmol/L) when administered at a dose of 3 grams. Furthermore, IV vitamin C has shown that it can reach maximum plasma concentration levels of 15000 μmol/L which is up to 50 times greater than oral intake can reach.
These high levels of vitamin C are not possible to achieve orally as only the IV can bypass specific transport mechanisms and intestinal absorption mentioned above that is involved in the intake of nutrients. High doses of intravenous vitamin C have most often been used in combination with chemotherapy for cancer patients. Studies have indicated that the use of high dose IV vitamin C can extend the median survival of cancer patients that are simultaneously being treated via radiation and chemotherapy when compared to patients that do not intake high doses of IV vitamin C. It is important to note that the same results were not reflected in a study that provided high oral doses of vitamin C (instead of the IV administration).
Dosages
The recommended daily allowance of vitamin C for adult males is 90 mg with a tolerable upper intake level of 2000 mg. The recommended daily allowance for adult females is 75 mg with a tolerable upper intake level of 2000 mg. A meta analysis of 29 trials studied the impact of doses from 200 mg to 2 g per day for a range of 2 weeks to 6 months. This study determined that those taking Vitamin C supplements at this low dose were 4% less likely to get a cold than those who weren’t. As these doses were fairly low and taken orally, it is possible that higher doses would have prevented colds more effectively. High doses of IV Vitamin C, used in conjunction with cancer treatments, combat scurvy, or for an immune boost, typically ranges from 35 to 100 grams depending on the severity and necessity for a supplement. At this high dosage the peak plasma level can reach up to 15 mmol/L, which allows the Vitamin C to be toxic to cancer cells.
Further Benefits of IV VItamin C
Studies using animal models have determined that IV Vitamin C (when taken with other chemotherapeutic agents) showed a decrease in xenograft tumor growth, specifically showing that this occurred in a chemotherapy-resistant pancreatic tumor model. Furthermore, studies have determined that IV Vitamin C lowered the toxic side effects of certain chemotherapy drugs, such as paclitaxel and doxorubicin, while allowing these drugs to continue their function. As an
antioxidant, Vitamin C has also been found to be beneficial in the treatment of Rheumatoid arthritis, an inflammatory joint disease with patients that typically present high oxidative stress. A study conducted on rheumatoid arthritis patients concluded that the administration of IV vitamin C resulted in lowered pain levels and inflammation as measured by C-reactive protein levels (which showed a 44% reduction). On a similar note, IV vitamin C has been acknowledged to aid in the treatment of chronic pain. As mentioned earlier, vitamin C is very important in joint, tissue, and bone health, which is why a Vitamin C deficiency can cause significant musculoskeletal pain. This, and the anti-inflammatory effects of vitamin C, are likely the reason that studies, such as one conducted on patients with nerve tissue damage due to herpes zoster, found that IV vitamin C significantly lowered pain levels. While much research still needs to be conducted regarding the direct roles of vitamin C in pain relief, these studies indicate that this nutrient is very important and essential in the treatment of many conditions.
Overall it is important to understand the distinction between oral and IV supplements. Oral supplements are useful adjunct treatments when in need of a low dose of Vitamin C, while IV administration is best for high dosages.
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